  SEQ CHAPTER \h \r 1 	UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

	WASHINGTON, D.C. 20460

OFFICE OF                  

PREVENTION, PESTICIDES AND 

    TOXIC SUBSTANCES        

May 30, 2006

Memorandum

SUBJECT: 	Review of the, “Assessment of Potential Inhalation Exposure
to Hexavalent Chromium at Wood Treatment Facilities using CCA”, MRID
No. 467208-01, submitted by FPRL to be used as a surrogate to assess
Acid Copper Chromate (ACC).  DP Barcode 329690.

FROM: 	Tim Leighton, Environmental Scientist 

		Antimicrobials Division 

							

TO:		Mark Hartman, Branch Chief, 

Antimicrobials Division 

	Attached is a review of the worker inhalation exposure study conducted
with CCA to be used as a surrogate in support of ACC-treated wood.  The
study was submitted by Forest Products Research Laboratory (FPRL) LLC. 

EXECUTIVE SUMMARY

	

	Acid Copper Chromate (ACC) is proposed as an alternative wood
preservative to Chromated Copper Arsenate (CCA) for pressure-treated
lumber. One of the pieces of data that EPA has cited as needed in order
to make the necessary finding to support the registration is a worker
inhalation study at pressure treatment facilities to determine
inhalation exposures of hexavalent chromium (Cr+6).  EPA provided FPRL
with two options in selecting the test substance:  (1) the study could
be conducted with CCA (applied at a similar Cr+6 concentration), or (2)
EPA could issue a non-destruct Experimental Use Permit (EUP) for ACC. 
FPRL selected the first option and submitted this study as a result. 

The study was conducted to estimate the potential worker inhalation
exposure to Cr+6 at three treatment facilities in the Unites States
treating dimensional lumber, plywood, and poles with CCA.  The
commercial facilities, which operated under normal circumstances, were
located in Rainier, OR; Savannah, GA; and Tampa, FL.  Each site had a
unique layout, but all sites used similar CCA pressure treatment
processes.  The wood at each facility was treated at nominal retention
rates of 0.25 to 2.5 pounds per cubic foot (pcf).  A variety of tasks
were monitored at each site.  Even though many of the tasks overlapped
job functions, the worker replicates were assigned to the following job
functions: treatment operator, treatment assistant, forklift operator,
packer, tagger, supervisor, and test borer.  The job functions monitored
at each site consisted of at least five replicates each. The duration of
inhalation monitoring was approximately 6 working hours per replicate. 

Inhalation exposure was monitored using two sampling train
configurations: (1) cassettes containing a PVC filter used to collect
inhalable particles (>10 μm diameter cut point) and (2) a personal
environmental monitor (PEM) containing a PTFE filter used to collect
thoracic-sized particles (10 (m diameter cut point).  Several method
validation experiments and storage stability experiments were conducted
prior to the initiation of the study to verify recovery efficiency and
storage stability under the conditions to be used in the study.  These
experiments validated the limit of quantitation (LOQ) at 100 ng/sample
at flow rates of both 7 and 10 liters per minute.   

	Pre-field recovery testing was performed using only PVC filters and
resulted in recoveries which ranged from 92-100%.  The average recovery
was reported to be 97.3 ± 3.1%.  Field fortification samples were also
taken during the study at each of the three test sites for both the PVC
filters and PTFE filters.  Spike levels ranged from 100 to 1000 ng at
the Rainier site and from 100 to 2000 ng at the Savannah and Tampa
sites.  For the Rainier site, the average recovery was 86.9 ± 14.4% for
the PVC filters and 90.0 ± 15% for the PTFE filters (Note:  one sample
from each set of field fortifications for each filter type was reported
to be an anomaly and was not included in the calculations of overall
recovery).  For the Savannah site, the average recovery was 97.6 ± 5.8%
for the PVC filters and 97.4 ± 9.5% for the PTFE filters.  For the
Tampa site, the average recovery was 102.0% ± 7.3% for the PVC filters
and 102.2 ± 3.6% for the PTFE filters.

μg/m3 (or the previously proposed OSHA PEL of 1 μg/m3).  

Between 71 and 1,189 pounds of chromic acid was absorbed by all charges
during each work shift. The average amount of chromic acid absorbed by
all charges during each work shift was 117 pounds at the Rainier site,
280 pounds at the Savannah site, and 877 pounds at the Tampa site.  When
normalized by the average amount of chromic acid absorbed by charges,
the inhalable and respirable air concentrations (ng Cr(VI)/m3/lb chromic
acid) for all job functions combined were highest at the Rainier
treatment facility.  Inhalable Cr(VI) air averaged 0.17, 0.21, and 0.42
ng/m3/lb chromic acid at the Tampa, Savannah, and Rainier sites,
respectively.  Respirable Cr(VI) particles averaged 0.068, 0.23, and
0.39 ng/m3/lb chromic acid at the Tampa, Savannah, and Rainier sites,
respectively.  A separate inhalation risk assessment will be developed
to assess this use.  As indicated in this review, these data can be used
as a surrogate to assess ACC treatment plant worker’s inhalation
exposure and risk.

1.0  INTRODUCTION

	Forest Products Research Laboratory (FPRL) has requested a “me-too”
registration for an Acid Copper Chromate (ACC) formulation consisting of
14.07% Cupric Oxide (CuO) and 35.46% Chromic Acid (CrO3) to be used as a
wood preservative alternative to CCA for pressure treatment.  ACC
treatment solution contains ~50 percent more hexavalent chromium (Cr+6)
than CCA.  At this time, inhalation exposure is EPA’s primary concern
for workers at ACC-treatment facilities.  Dermal contact issues for
dermal sensitization will be mitigated via personal protective equipment
(PPE) such as long pants, long sleeved shirts, and gloves.  

	The FPRL study entitled, “Assessment of Potential Inhalation Exposure
to Hexavalent Chromium at Wood Treatment Facilities using CCA” was
conducted to determine the inhalable and respirable air concentrations
of  Cr+6 in the breathing zone of workers working at pressure treatment
facilities.  

Citation 	

Study Director:		David Dodge

Title:               			“Assessment of Potential Inhalation Exposure
to Hexavalent

				Chromium at Wood Treatment Facilities using CCA”

Report Date:			December 20, 2005

Performing Laboratory:	Interlox, Inc

				2505 – 2nd Avenue, Suite 415

				Seattle, WA 98121-1492

Identifying Codes:		Study #FPRL123105

				MRID 467208-01

	

Sponsor:			Forest Products Research Laboratory, LLC

				4660 Main Street, Suite B320

				Springfield, OR 97478

COMPLIANCE

	Signed and dated GLP and Data Confidentiality statements were provided.
A Quality Assurance statement was not provided. The study sponsor waived
claims of confidentiality within the scope of FIFRA Section 10(d) (1)
(A), (B), or (C).  The study sponsor and author stated that the study
was conducted under EPA Good Laboratory Practice Standards (40 CFR part
160), with five exceptions.  These exceptions were noted in the study
report.  The exceptions noted appeared to be typical situations based on
the large volume of CCA at pressure treatment plants.  None of these GLP
deviations are believed to compromise the scientific integrity of the
study.

GUIDELINE OR PROTOCOL FOLLOWED	

	

	The study report stated that the study was conducted under OPPTS Test
Guidelines Series 875, Occupational and Residential Exposure Test
Guidelines, Group A: 875.1100 (dermal exposure), and 875.1300
(inhalation exposure).  However, since the study only examined
inhalation exposure, the review focused on guideline 875.1300.  A
compliance checklist is provided in Appendix B.

2.0  TEST MATERIALS

CCA was used as a surrogate for ACC at the pressure treatment plants. 
Specifically, the following formulations were used: Wolmanac®
Concentrate 50% (EPA Reg. No. 62190-2) or 60% Wood Preservative (EPA
Reg. No. 62190-14).  Since the test sites were commercial facilities
operated under normal circumstances, the test substances used consisted
of CCA lots already on site at the time the field study was being
conducted.

Table 1 presents information for the arsenic, copper, and chromium in
these CCA formulations, as well as that proposed for ACC.  

Table 1.  Information on Active Ingredients in CCA 

Used in Test Formulations and Proposed ACC

Parameter	Chromic Acid	Copper Oxide	Arsenic Acid	Arsenic Pentoxide

CAS Reg. No.	1333-82-0	1317-38-0	7778-39-4	1303-28-2

Formula	CrO3	CuO	H3ASO4	As2O5

Wolmanac Concentrate 50% (CCA)	23.75%a	9.0%a	17.4%a	N/Ab

60% Wood Preservative (CCA)	28.5%	11.1%	20.4%	N/Ab

Treaters Choice (ACC)c	35.46%	14.07%	N/Ab	N/Ab

According to the label (EPA Reg# 62190-2), the percent active
ingredients are as follows: chromic acid, 23.7%; cupric oxide, 9.3%;
arsenic acid, 21%.  The study report notes this discrepancy and states
that the manufacturer has been notified.

N/A = not applicable

c.	Proposed label (EPA Reg. No. 075832-x).

The following reference standard was used to fortify blank filters,
calibrate instruments and generate calibration curves:

Chemical name:	Potassium dichromate

Formula:		K2Cr2O7

Source:		Aldrich

Grade:			Certified ACS

Lot Number:		N13819CR

Purity:			>99%

3.0  STUDY DESIGN

	FPRL submitted a protocol to EPA in response to EPA’s request for a
worker inhalation exposure study (i.e., monitoring air concentrations of
Cr+6 at pressure treatment facilities (FPRL 2005)).  EPA provided
comments on the protocol (USEPA, 2004).  The reader is referred to the
protocol and EPA protocol review for specific details.  The design and
analytical methods are described below.  

3.1  Site Description

Three sites were included in the conduct of this study:  (1) Rainier,
OR; (2) Savannah, GA; and (3) Tampa, FL.  Specific information for each
site is provided in Table 2.

Table 2.  Study Site Parameters

Parameter	Rainier, OR	Savannah, GA	Tampa, FL

Treatment-related Parameters

Number and type of cylinders	3 cylinders:

1 @ 6½’ x 82’

1 @ 6’ x 80’

1 @ 6’ x 62’ 

(used exclusively for CCA)	3 cylinders:

1 out of service

2 @ 6’ x 60’

newer one used exclusively for borate

other one used exclusively for CCA	4 cylinders

1 @ 6’ x 86’ (utilize copper azole preservative)

2 @ 6’ x 82’ (one dedicated to CCA 

1 @ 6’ x 80’ (utilize copper azole preservative)

CCA articles treated during study	Plywood and 6 x 6 lumber	Mostly 0.25
pcf retention plywood

0.4 pcf cross arms (for utility poles)

10’ x 12’ beams	0.4 pcf retention fence posts

2.5 pcf poles for marine applications (primary articles treated)

0.6 pcf poles for near salt water application

0.25 pcf plywood

Type of plant (i.e. pressure treatment capacity)	Automateda	Manualb
Automatica

Rail bridge (connects track on pad with tracks into cylinder)	Pneumatic
rail bridge with expanded metal walking surface lowered in place	2
single rails put in place by worker; glove use inconsistent	2 single
rails put in place by worker; glove use inconsistent

Cylinder door	Closed/opened manually, sealed pneumatically	Left open
from last charge

Closed/opened/sealed  manually	Left open from last charge

Closed/opened manually, sealed pneumatically

Due to sump/door configuration, worker must open door in front of him
and cross through the mist escaping from cylinder

Ventilation system	Local exhaust canopy above all 3 cylinder doors	None
mentioned	None mentioned

Relative wind direction	Workers generally upwind of cylinders	Not
specified in relationship to workers	Workers generally upwind of
cylinders

Removal of debris from cylinder	After completion of cycle:  worker uses
hose to spray off excess solution and debris from bottom of cylinder
After completion of cycle:  worker uses hose to spray off excess
solution and debris from bottom of cylinder	Before cycle:  worker uses
piece of wood or metal to scrape out debris at bottom of cylinder and in
lower lip of door

Sampling/study-related Parameters

Sampling dates	September 12 - 16	October 10 - 14	November 7 - 11

Number of test days c	5c	5	5

No. of charges monitored	16	17	32

Total cubic feet of wood treated over study duration	5,414	6,870	18,790

Total pounds of Chromic acid absorbed over study durationd	1,339	1,455
8,065

Average lbs of   CrO3 absorbed during a monitoring period	117	280	877

Mean charge duration	3.7 hours	0.75 hourse	1 hour

Mean retention (pcf)	0.58	0.48	0.95

Automatic = duration of the treatment cycles and the concentration of
the preservative to be pumped into the cylinders are determined by
operations software from input parameters.  The treatment cycles advance
automatically and operations can be monitored from an enclosed
operations area above the cylinders.

Manual = Treatment operation valves are opened and closed by the
Treatment Operator

At the Rainier site, three shifts were monitored: day, swing, and
overnight.  The study team members left workers unattended from midnight
to 7:00 AM.

Report lists this as total pounds of chromic acid absorbed, but states
that the form of chromium in chromic acid is hexavalent.  Chromic acid
is 47.5% of CCA by weight.

Study report states that this value is estimated because not all charge
durations were reported.

3.2 Meteorological Conditions

	The following table (Table 3) provides a summary of the weather
conditions collected from the closest and best matched official National
Weather Service (NWS) reporting station. 

Table 3.  Summary of Weather Conditions at each Study Site

Site	NWS Location	Date	Temperature (oF)	Precipitation



	Min	Max

	Rainier, OR	Longview/Kelso	9/12/05	50	73	none



9/13/05	46	75



	9/14/05	48	75



	9/15/05	48	68



	9/16/05	52	64

	Savannah, GA	Hunter AAF	10/10/05	70	75



	10/11/05	70	79



	10/12/05	68	73



	10/13/05	63	73



	10/14/05	61	82

	Tampa, FL	Tampa Int’l Airport	11/7/05	64	84	none



11/8/05	69	85



	11/9/05	66	81



	11/10/05	61	81



	11/11/05	59	81

	

3.3  Job Functions and Test Subjects 

3.3.1  Job Functions

The tasks performed by workers at pressure treatment plants vary from
plant to plant and many tasks are shared by different job functions;
therefore, it is difficult to definitively assign each replicate
monitored to a specific job function.  However, the replicates in this
study were each assigned a job function based on general job functions
that were described in a previous CCA worker exposure study (MRID
45502101).  The responsibilities of the workers under each job function
category (or similar exposure group (SEG)) used in this study are
described for each site in Table 4.  

Table 4.  Job functions and responsibilities at each of the facilities

Job function	Responsibilities at each site

	Rainier	Savannah	Tampa

Treatment Operator	Responsible for monitoring treatment cycle of wood,
mixing treatment chemicals, and loading and unloading charges of work
from treatment cylinder

	Workers performed tasks largely on the drip pad, including chaining and
unchaining charges, opening and closing cylinder door, and moving wood
to and from the tracks with a forklift.

Workers also performed tasks of Test Borer, taking core samples from
treated wood	Worker remained within the enclosed treatment office
overlooking drip pad, with occasional visits to the drip pad to
communicate with workers and perform wood counts

Treatment Assistant	Workers performed tasks largely on the drip pad,
including chaining and unchaining charges, opening and closing cylinder
door, and moving wood to and from the tracks with a forklift.

	Workers were also observed performing post-treatment tasks such as
packaging, banding and tagging wood	No additional details provided

Forklift Operator	Workers in several job functions were observed
operating forklifts, however, at the Savannah and Tampa sites, some
individuals spent more time than others so that a separate job function
was created.  Workers loaded/unloaded trams before and after treatment,
stacked wood in storage, and loaded/unloaded wood on trucks for
shipping/receiving

	Forklifts capable of having an enclosed cab, but side doors were always
observed open	Open air cabs	Open air cabs

Packager	Workers observed performing post-treatment tasks, such as
tagging, banding, packaging treated wood, moving stacks of wood with a
forklift.  Activities took place on treatment floor, adjacent to
cylinder tracks.  Workers performed other tasks such as
sweeping/cleaning cylinder tracks.

	Had workers dedicated to packager job function	No additional details
provided	No additional details provided

Tagger	Workers applied plastic tags with manual or pneumatic staplers to
ends of treated wood

	No additional details provided	Temporary workers hired to fill 5
full-time shifts	One workers performed full-time for the monitoring week

Supervisor	Workers spent a portion of time on treatment floor
supervising workers.

	Supervisor also performed forklift duties all over the plant	Members of
study team acted as supervisor; spent time in main office and in
treatment area	Supervisor spent considerable amount of time away from
treatment area and when in area, was typically in treatment office
overlooking drip pad

Test Borer	Workers collected all test boring samples, performed analyses
and collected CCA work tank samples

	No additional details provided	No additional details provided	Has
workers dedicated to this job function



3.3.2  Test Subjects

Test subjects used in this study included regular workers at the
treatment facility, temporary workers hired specifically to monitor the
tagging operations, and study team members that served as proxy workers.
 The test subjects were reported to have signed worker consent forms;
however, only a blank copy of the worker consent form was included in
the study report.

Table 5 identifies the job functions monitored at each site, the number
of replicates monitored per job function, and the number of test
subjects per job function. Not all monitored replicates resulted in
reliable samples due to pump faults, tubing disconnect, or other
factors; however, at least five reliable replicates were collected for
each job function monitored.  Overall, the number of replicates
collected for each job function included 18 treatment operators (TO), 22
treatment assistants (TA), 8 packers (PK), 15 supervisors (SU), 12
forklift operators (FO), 10 taggers (TG), and 7 test borers (TB). 

Table 5. Replicates monitored and number of workers by site and job
function

Site	Job Function	Number of monitored replicates	Number of subjects

Ranier	TO	Treatment Operator	8	3

	TA	Treatment Assistant	8	3

	FO	Forklift Operator	No dedicated workers in this SEG at this site

	PK	Packager	10	4

	TG	Tagger	No dedicated workers in this SEG at this site

	SU	Supervisor	5	2

	TB	Test Borer	No dedicated workers in this SEG at this site

Total	31	12

Savannah	TO	Treatment Operator	5	1

	TA	Treatment Assistant	8	2

	FL	Forklift Operator	5	1

	PK	Packager	No dedicated workers in this SEG at this site

	TG	Tagger	5	3

	SU	Supervisor	5	2

	TB	Test Borer	No dedicated workers in this SEG at this site

Total	28	9

Tampa	TO	Treatment Operator	6	2

	TA	Treatment Assistant	7	2

	FL	Forklift Operator	7	2

	PK	Packager	No dedicated workers in this SEG at this site

	TG	Tagger	5	1

	SU	Supervisor	5	1

	TB	Test Borer	7	2

Total	37	10

Overall total	96	31



3.4  Treatment Processes

	The following summarizes the treatment processes performed at the test
sites:

Workers moved untreated poles or other wood products from holding areas
using a forklift and stacked them onto wheeled metal trams on railroad
tracks leading into a treatment cylinder.

The items on each tram were secured in place with chains once enough had
been loaded to fill a cylinder.

The filled trams (i.e., charge) was pushed into the cylinder by a
forklift (Rainier and Tampa sites) or pulled in by a cable loop and
winch system (Savannah site).

The cylinder door was closed by workers and the Treatment Operator
started the treatment process.

The treating solutions were pumped into the cylinder, after an initial
vacuum, and were pressurized to force the preservative to permeate the
wood.

To achieve different retentions, the concentration of the preservative
in the treating solution was changed versus changing the amount of
solution applied.

Excess treating solution was pumped out of the cylinder after treatment
and a finish vacuum and empty cycle was usually performed to remove
excess preservative.

The duration of a complete cycle ranged from 0.5 to 5.5 hours.

The cylinder door was manually opened at the end of treatment and the
workers removed the charge from the cylinder by pulling it out with a
forklift or cable loop and winch system.  

The charge was pulled onto a “drip pad” and workers removed the
chains.

After excess treatment solution dripped from the charge, the wood was
transferred by forklift to a storage area.

While on the trams or in the storage area, workers took narrow cores of
the wood with power drills to determine the depth of penetration of the
preservative and the amount of preservative that was absorbed by the
wood.

3.5  Retention

The wood articles were treated at a variety of retention rates in this
study. The nominal retention rate of CCA at the Rainier site for plywood
and 6 x 6 lumber was not reported.  The Savannah site treated utility
pole cross arms at a retention of 0.4 pcf and plywood/beams at 0.25 pcf.
 The Tampa site treated fence posts at a retention of 0.4 pcf.  Poles
for marine applications and for near salt water applications were
treated at a retention of 2.5 pcf and 0.6 pcf, respectively.  Plywood
was also treated at a retention of 0.25 pcf.  According to the study
report (Section 3.1), the mean retention rate during the study was 0.58
pcf at the Rainier site, 0.48 pcf at the Savannah site, and 0.95 pcf at
the Tampa site.

4.0  SAMPLING

4.1  Inhalation Exposure Monitoring

Air concentrations were monitored in the breathing zone of the workers. 
Each worker wore two sampling trains for the collection of inhalable and
respirable particles.  The air sampling pumps (Leland Legacy) were
calibrated pre- and post-sample collection.  In addition, these pumps
had a counter to record time and air volumes.  The two sets of monitors
were run concurrently for ~6 hours during the work day.  Workers wore
the pumps during work activities; some pumps were removed (and turned
off) at lunch time (such stoppages were recorded).

	Two sets of monitors were used to collect inhalable and respirable
particles.  The inhalable particles are those that enter the respiratory
tract (generally less than 100 microns) and the respirable particles are
those that do not get filtered out in the   SEQ CHAPTER \h \r 1 upper
respiratory tract and reach the lungs.  The respirable particles in this
study are defined as diameters less than 10 microns and are monitored
with a Personal Environmental Monitor (PEM).  A cassette (CAS) was used
to monitor the inhalable particles.  The description of the sampling
trains was presented in the study report as follows:

e (PVC) filter (5-μm pore size) contained in a polystyrene cassette. 
The polystyrene cassette allows for collection of inhalable particle
sizes (>10 μm diameter cut point) and smaller.  The target flow rate
ranged from 7.5 to 8.5 L/min.”

Respirable:  “… a Personal Environmental Monitor (PEM) (SKC
761-200B) with a 10 μm 50% cut-point and a flow rate of 10 L/min. 
Particles smaller than the 50% cut-point pass through the impactor and
were collected on a 37-mm diameter Teflon® [Polytetrafluoroethylene
(PTFE)] filter (2-μm pore size) with PMP (polymethylpentene) support
ring (SKC 225-1709).  The PEM was selected to capture thoracic-sized
particulates (10 μm diameter cut point).”

4.2  Sample Collection and Handling

Inhalation Monitoring:  At the end of the monitoring duration, PVC
samples in polystyrene cassette samples were capped.  The PTFE filters
in the PEM were extracted using disposable, single-use, forceps and
placed into Filter-Keepers.  All samples were labeled and bagged.  The
samples were coded for unique identification (see study report for
details).  Both the control and field samples were shipped on the same
day or next day, Federal Express, to Clayton Group Services, Novi,
Michigan, for extraction and analysis.  The samples were shipped without
refrigeration and included chain of custody forms.  Shipments included
trip blanks and field blanks.

Treatment Solution Monitoring:  Two samples per site of different
treatment solutions were collected by the Test Borer or Treatment
Operator during the monitoring periods. According to the study report,
individual cycle concentrations vary with target retention, and blowback
from every charge changes the concentration in the working tank. 
Therefore, samples were collected directly from concentrate and working
strength tanks at each facility.  Duplicate samples were collected in 30
mL glass containers, which were closed with a screw top, shrink sealed,
labeled and shipped via Federal Express to Clayton Group Services for
analysis.  These samples were shipped separately from the regular study
samples.

5.0  METHODS

5.1  Analytical Methods

	Samples were analyzed for hexavalent chromium using the OSHA Method
ID-215, which involves extraction of the hexavalent chromium from the
PVC or PTFE filter and analysis by ion chromatography using a
post-column derivatization with diphenyl carbazide and UV-visible
spectrophotometric detection.  A summary of the analytical laboratory
work is provided in Appendix E of the study report.

	Extraction Procedure:  An aqueous solution containing 10% sodium
carbonate/2% sodium bicarbonate and a mixture of phosphate
buffer/magnesium sulfate was used to extract hexavalent chromium from
the PVC and PTFE filters.  

	Analytical Procedure:  An aliquot of the diluted extraction solution
was analyzed by ion chromatography using a post-column derivatization
with 1, 5-diphenyl carbazide and UV-visible spectrophotometric detection
at a 540 nm wavelength.  According to the OSHA Method ID-215, the
quantitative detection limit is 3 ng/sample.  The recommended sampling
rate is 2 L/min, which results in a sample volume of 960 L for an 8-hour
sampling day.  

	Modified Analytical Procedure:  During sampling activities in 2004,
quality control spiked samples were run at the same flow rate and
duration as the actual field samples.  These samples were collected at
separate locations from the sampling locations.  The QC set was spiked
at 10 ng, 100 ng, and 200 ng (three replicates each).  These samples,
however, provided poor recovery.  The Clayton Group initiated a series
of laboratory studies to determine recovery efficiency of spiked samples
both with and without air flow through samples and with varying storage
times.  Several refinements to the method were developed and are
outlined in the study report (p. 22).  The authors state that these
refinements are considered acceptable in OSHA Method ID-215.  With the
refinements, the group was able to obtain reliable quantification (i.e.,
recoveries within 10% of fortification level) of fortification samples
at or above 100 ng/sample, but not below, for flow rates of 7 L/min and
10 L/min.  The method validation experiments are summarized in the next
section.

5.2  Quality Control Samples

As modifications to OSHA Method ID-215 were required to accommodate a
large sample volume (and hence, an increased flow rate) as well as new
equipment capable of capturing thoracic-sized particles, a variety of
quality control experimental trials were initiated.  The objective of
these trials was to define the statistical precision and accuracy of
spiked Cr(VI) recoveries after incorporating the modifications to OSHA
Method ID-215.

μm pore size) and 37-mm PTFE (Teflon®) filters (2 μm pore size).  A
hexavalent chromium solution prepared from potassium dichromate in water
was used to spike the filters.  The spiked samples were allowed to air
dry for 3 hours before sampling to prevent sample loss during shipment. 
After the filters were spiked, they were mounted in 37 mm polystyrene
cassettes or PEM with a 50% cut-point of 10 μm.  Filters and housing
were either assembled in the laboratory or in the field, and were
connected by Tygon® tubing.  The flow rates were calibrated at 7-10
L/min and ambient air was run through the filters for 6-8 hours.  The
samples were extracted and stored for various amounts of time before
analysis.  Details on these experiments are provided in Appendix F of
the study report.

5.2.1  Method Validation and Storage Stability

Method validation was performed for both the cassettes and the Personal
Environmental Monitors (PEM).   Storage stability studies were performed
for up to 6 and 10 days.  Actual study samples were generally extracted
and analyzed within 6 days of sampling/fortification.  In one instance,
however, the samples were analyzed after 7 days.  Additional storage
stability samples were, therefore, prepared to validate storage up to 10
days.  Storage of samples was under ambient conditions.

Below are summaries of the method validation and storage stability
studies performed prior to study initiation.  

(1) Method validation using PVC filters at flow rate of 7 L/min in
Cassette:  This experiment was run to determine if there were any
stability issues when using a higher sampling rate than that recommended
in the OSHA method.  Eight PVC filters were spiked with 100 ng
hexavalent chromium and mounted in 37-mm polystyrene cassettes.  Air was
drawn through five of the eight cassettes for 480 min at 7 L/min.  The
remaining three cassettes served as controls. The time from sampling to
extraction was 1 day.  The control recovery averaged 95.1% ± 1.2% and
the spike recovery averaged 97.6% ± 1.1%. See Table 6a for summary of
results.

Table 6a.  Method validation using PVC filters at flow rate of 7 L/min

Spike level (ng)	Range of recoveries (%)	Spike Recovery (%) 

100	Control: 94.2% – 96.5%	Control: 95.1% ± 1.2%

	Spike: 95.9% - 98.9%	Spike:  97.6%   1.1%



(2) Method validation and storage stability using PVC filters at 10
L/min in PEM:  This experiment was run to evaluate the use of PEM.  Four
PVC filters were spiked with hexavalent chromium at 100 ng.  One PVC
filter served as a blank.  The filters were mounted in PEM and air was
drawn through at 10 L/min for 8 hours.  The filters were transferred
from the PEM monitor to plastic Filter-Keepers.  Two
storage-to-extraction time periods were tested: 12 hours and 6 days. 
The average recovery for the samples stored for 12-hours was 91.7 ±
9.5%. The average recovery for the samples stored for 6 days was 103 ±
2.4%. See Table 6b for summary of results.

Table 6b. Method validation and storage stability using PVC filters at
10 L/min in PEM

Spike level (ng)	Range of recoveries (%)	Spike Recovery (%) 

12-hour Storage

100	 78.0% -  99.4%	 91.7% ± 9.5%

6-day Storage

100	100.3% -  106.2% 	103.0% ± 2.4%



(3) Method validation and storage stability using PTFE filters at 10
L/min in PEM:  This experiment was run to determine the stability of
hexavalent chromium on PEM/PFTE combinations.  Five PTFE filters were
spiked with 100 ng hexavalent chromium.  One filter was used as a
reference blank.  The filters were mounted in the PEM and air was drawn
through at 10 L/min for 8 hours.  The filters were transferred to
plastic Filter-Keepers.  Two storage-to-extraction time periods were
tested: 14 hours and 6 days.  The average recovery for the samples
stored for 14-hours was 106.8 ± 2.8 %.  The average recovery for the
samples stored for 6 days was 106.8 ± 7.5%. See Table 6c for summary of
results.

Table 6c.  Method validation and storage stability using PTFE filters at
10 L/min in PEM

Spike level (ng)	Range of recoveries (%)	Spike Recovery (%)

14-hour Storage

100	104.0% -  110.0% 	 106.8% ± 2.8%

6-day Storage

100	 98.1% - 113.0%	106.8% ± 7.5%



 (4) Storage stability using PVC filters at 7 L/min in Cassette:  This
experiment was run to further examine the effects of storage at ambient
temperatures.  For this experiment, 24 cassette filters were spiked with
100 ng hexavalent chromium.  Air was drawn through for 480 min at 7
L/min.  Six filters were extracted and analyzed on days 0, 2, 4, and 6. 
Another 24 filters were also spiked at 75 ng and run through the same
procedure.  For the 100 ng spike level, recoveries ranged from
90.3-137.1%.  For days 0, 2, 4 and 6, recoveries averaged 98.1 ± 1.6%,
94.0 ± 2.1%, 94.6 ± 2.9%, and 109.3 ± 14.7%, respectively.  For the
75 ng spike level, recoveries ranged from 52.5-134.3%.  For days 0, 2,
4, and 6, recoveries averaged 81.6 ± 4.2%, 70.8 ± 7.2%, and 96.2 ±
20.6%, respectively. See Table 6d for summary of results.

Table 6d.  Storage stability using PVC filters at 7 L/min

Sampling Day	Range of recoveries (%)	Spike Recovery (%) 

 Spike level (ng):	75 ng	100 ng	75 ng	100 ng

Day 0	 76.7% - 87.3%	95.9% -  100.6%	81.6% ± 4.2%	98.1% ±1.6%

Day 2	60.7% - 81.0% 	92.2% -  97.2%	70.8% ± 7.2%	94.0% ± 2.1%

Day 4	52.5% -73.3%  	90.3% -  98.9%	65.1% ± 8.6%	 94.6% ± 2.9%

Day 6	79.7% - 134.3%	96.4% - 137.1%	96.2 ± 20.6%	109.3 ± 14.7%



(5) Extended storage stability testing using PVC and PTFE filters:   For
this experiment, seven PTFE and seven PVC filters were spiked with 100
ng of hexavalent chromium.  The samples were stored for 10 days before
extraction.  One filter of each type served as a reference blank.  The
average recovery for the PTFE filters was 103.3 ± 2.9%.  The average
recovery for the PVC filters was 102.7 ± 9.4%.  According to the
results provided in the Appendix, there was one sample with poor
recovery (82%).  Excluding this value from the average calculation
results in an average recovery of 106 ± 2.6% (with 2.6% being the
relative standard deviation).  See table 6e for summary of results.

Table 6e.  Extended storage stability testing using PVC and PTFE filters

Spike level (ng)	Range of recoveries (%)	Spike Recovery (%) 

PVC filters

100	82.0% - 110.0%	With poor recovery data point (82%)	Without poor
recovery data point (82%)



102.7% ± 9.4%	Reported in Appendix:  106 ± 2.6% 

PTFE filters

100	99.0% - 106.0%	 103.3% ± 2.9%



(6) Breakthrough/retention testing of PVC air sampling filters:  For
this experiment, 18 cassette PVC filters were spiked with 1500 ng
hexavalent chromium.  Air was drawn through at 7 L/min for 480 min.  Six
filters were extracted and analyzed on day 0 and three filters were
extracted and analyzed on days 2, 4, and 6.  The overall average
recovery ranged from 89.8 to 108.4%.  The average recoveries for days 0,
2, 4, and 6 were 96.3 ± 3.5%, 107.0 ± 1.3%, 98.0 ± 6.7%, and 98.0 ±
1.7%, respectively. See Table 6f for summary of results.

Table 6f.  Breakthrough/retention testing of air sampling filters

Sampling day	Spike level (ng)	Range of recoveries (%)	Spike Recovery (%)


Day 0	1500	89.8% - 99.7%	96.3% ± 3.5%

Day 2	1500	106.0% - 108.4%	107.0% ± 1.3%

Day 4	1500	90.3% - 102.6% 	98.0% ± 6.7%

Day 6	1500	96.1% - 99.2%	98.0% ± 1.7%



(7) Pre-field recovery testing: This experiment was performed to ensure
that sampling under field conditions would produce similar results.  For
this experiment, eight PVC filters were mounted in polystyrene cassettes
fortified at 100 ng hexavalent chromium by Clayton Group Services.  They
were then shipped to Intertox in Seattle, WA.  Air was drawn through the
filters using Leland Legacy sampling pumps, connected to filter
cassettes with Tygon® tubing.  The pumps were run for 6 hours at 7
L/min to simulate field conditions.  Two blank filter cassettes were
also run.  The control samples had levels of hexavalent chromium below
the detection limit.  Recoveries for the spiked samples ranged from
92-100%.  The average recovery was 97.3 ± 3.1%. See Table 6g for
summary of results.

Table 6g.  Pre-field recovery testing

Spike level (ng)	Range of recoveries (%)	Spike Recovery (%)

100	92.0% - 100.0%	97.3% ± 3.1%



5.2.2  Concurrent Laboratory Recoveries

	The study report does not mention if separate concurrent laboratory
fortification samples were run with the actual study samples.  In
Appendix E (Clayton Group Services, Analytical Support Summary), there
is a list of standard quality assurance and quality control procedures
incorporated into each sample set.  Laboratory fortification samples
were not included in this list.  However, the field recoveries were
analyzed concurrently with the actual field samples, and therefore, are
considered to be representative of concurrent laboratory recoveries.

5.2.3  Field Recoveries

At each study site, triplicate samples were collected at 3 fortification
levels for both the cassette and PEM samples.  Samples were exposed to
the environmental conditions at each site, shipped, stored, and analyzed
with the actual field samples. The samples were exposed in a stationary
position away from the potential influence of treatment processes.
Samples were fortified at 100, 200, and 1000 ng at the Rainier site and
at 100, 1000, and 2000 ng at the Savannah and Tampa sites.  The duration
of the sample collection was similar to the actual field sampling. The
results of the field recovery samples are presented in Table 7.  

The individual field recoveries for all sites and all filter types
ranged from 11% to 120% with means ranging from 57% to 102.7%.  The
study indicates that the two low field recoveries (i.e., 11% for the PVC
filter and 59% for the PTFE filter at the Rainier site) appear to be
anomalies, but the exact cause is not known.  It was theorized that the
results may have resulted from errors in spiking or handling of the
spiked samples.  For the PFTE filters, the low recovery may have been
due to the liquid spike droplet rolling off to the side of the filter. 
Spiking of the PTFE filters was reported to have been difficult due to
the water repellency of the PFTE material.  The study authors recommend
that these data points be dropped from the data analysis based on the
statistical tests for outliers and their first-hand observations over
the course of the study.

Table 7.  Summary of Field Fortification Recoveries

Site	Filter Type	Fortification level (ng)	Recovery (ng)	% Recovery
Average % Recovery	SD	Overall Average % Recovery	Overall SD

Rainier	PVC (inhalable portion)	100	72	72%	75.0%	2.6%	78.4%

(86.9%) b	28.7%

(14.4%)b



	76	76%







	77	77%







200	22	11%a	57.0%

(80%) b	40.1%

(7.1%) b





	170	85%







	150	75%







1000	1000	100%	103.3%	5.8%





	1100	110%







	1000	100%





	PTFE (respirable portion)	100	72	72%	71.0%

(77%)c	11.5%

(7.1%)c	86.6%

(90%)c	17.4%

(15%)c



	82	82%







	59	59%a







200	190	95%	83.3%	10.4%





	160	80%







	150	75%







1000	960	96%	105.3%	8.1%





	1100	110%







	1100	110%





Savannah	PVC (inhalable portion)	100	92	92%	91.0%	1.0%	97.6%	5.8%



	91	91%







	90	90%







1000	1000	100%	100.0%	0.0%





	1000	100%







	1000	100%







2000	2100	105%	101.7%	5.8%





	1900	95%







	2100	105%





	PTFE (respirable portion)	100	95	95%	88.0%	10.4%	97.4%	9.5%



	76	76%







	93	93%







1000	1100	110%	102.7%	6.4%





	980	98%







	1000	100%







2000	2000	100%	101.7%	2.9%





	2000	100%







	2100	105%





Tampa	PVC (inhalable portion)	100	94	94%	104.7%	13.6%	102.0%	7.3%



	100	100%







	120	120%







1000	1000	100%	99.7%	0.6%





	990	99%







	1000	100%







2000	2000	100%	101.7%	2.9%





	2100	105%







	2000	100%





	PTFE (respirable portion)	100	110	110%	103.3%	5.8%	102.2%	3.6%



	100	100%







	100	100%







1000	1000	100%	100.0%	0.0%





	1000	100%







	1000	100%







2000	2100	105%	103.3%	2.9%





	2000	100%







	2100	105%





SD = standard deviation

a	The study indicated that the 11% and 59% were anomalies.

b	Average % Recovery without anomaly: 80 ± 7.1%.  Overall Average %
Recovery without anomaly: 86.9 ± 14.4%.

c	Average % Recovery without anomaly: 77 ± 7.1%.  Overall Average %
Recovery without anomaly: 90 ± 15%.

5.2.4  Blank Controls

	At each facility, one set of triplicate background samples (upwind) was
collected for both cassette and PEM sampling train configurations.  In
addition, each shipment of samples included a PVC cassette trip blank
along with the field blank.  For the PTFE blank, an unused PTFE filter
loaded into a Filter-Keeper was used.	

	According to the summary tables in the study report (Tables 8a-8c), all
field blank control samples were non-detect.  According to Appendix G
(Clayton Group Services, Analytical Reports), all trip blanks and field
blanks were less than the reporting limit (0.011 μg).

6.0  RESULTS

6.1 Results of the CCA Treatment Solution Analysis

Two samples per site of different treatment solutions were collected and
analyzed for chromic acid (all sites) and total chromium (Tampa site
only).  Results of this analysis are provided in Table 8.  

Table 8.  Summary of Results of the CCA Treatment Solution Monitoring

Site	Treatment formulation (pcf)	% chromic acid in the treatment
solution	Total chromium (μg/L)

Rainier, OR	0.25	0.51	N/A

	0.60	0.77

	Savannah, GA	0.25	0.39



0.60	1.0

	Tampa, FL	0.40	0.58	2,600,000

	2.5	4.4	19,000,000



  

6.2  Results of the Hexavalent Chromium Air Monitoring

The results of the air monitoring data at the three sites for the
cassette and PEM monitors are reported in Tables 9, 10, and 11.  The
average amount of chromic acid handled at each site per monitoring
period was 117 pounds at Rainier, 280 pounds at Savannah, and 877 pounds
at Tampa.  The actual pounds of chromic acid absorbed by charges for
each worker monitoring period is reported on pages 61 through 67 of the
study report.  The study report footnotes these amounts as follows: 
“includes the sum of chromic acid absorbed in all charges ending
between one hour before a worker’s monitoring period to the end of his
monitoring period.”  Tables 12 and 13 compare the arithmetic means of
Cr+6 air concentrations as monitored (ng/m3) and normalized to the
amount of chromic acid absorbed during the monitoring period (ng/m3/lb
CrO3) for the cassette monitors by job function.  The same summary is
presented in Tables 14 and 15 for the PEMs.  Individual air
concentrations along with summary statistics for each job function are
presented in Appendix A.  The data were not corrected for field
fortification recoveries.  It should be noted that the statistics for
all job functions combined for the Savannah site include two replicates
that were assigned a job function of “none”.  The study report did
not provide any description of the responsibilities performed by these
workers identified as “none”.  The air concentrations are 62 and 17
ng Cr(VI)/m3 for the cassette replicates and 12 and 13 ng Cr(VI)/m3 for
the PEM replicates for the job function identified as “none”.

Table 9.  Summary Statistics for Air Concentrations at the Rainier Site

(All Job Functions)

Summary Statistics	Air concentrations

(ng Cr(VI)/m3)	lbs Chromic Acid Absorbed by Charges During Shift	Air
concentrations

(ng/m3/lb CrO3)

	CAS	PEM

CAS	PEM

Average	43	39	117	0.42	0.39

Standard Deviation	34	33	45	0.37	0.41

Geometric Mean	32	29	110	0.29	0.26

Median	40	26	90	0.28	0.24

75th  Percentile	56	58	164	0.61	0.42

90th Percentile	93	77	186	0.88	0.93

Maximum	130	150	198	1.51	1.74

Count	27	26	27	27	26



Table 10.  Summary Statistics for Air Concentrations at the Savannah
Site

(All Job Functions)

Summary Statistics	Air concentrations

(ng Cr(VI)/m3)	lbs Chromic Acid Absorbed by Charges during Shift	Air
concentrations

(ng/m3/lb CrO3)

	CAS	PEM

CAS	PEM

Average	54	58	280	0.21	0.23

Standard Deviation	74	68	66	0.32	0.29

Geometric Mean	34	35	273	0.13	0.13

Median	19	34	274	0.11	0.11

75th Percentile	63	68	336	0.25	0.28

90th Percentile	100	135	394	0.40	0.45

Maximum	410	310	394	1.79	1.35

Count	30	30	30	30	30



Table 11.  Summary Statistics for Air Concentrations at the Tampa Site

(All Job Functions)

Summary Statistics	Air concentrations

(ng Cr(VI)/m3)	lbs Chromic Acid Absorbed by Charges during Shift	Air
concentrations

(ng/m3/lb CrO3)

	CAS	PEM

CAS	PEM

Average	140	55	877	0.17	0.068

Standard Deviation	117	58	182	0.15	0.075

Geometric Mean	105	38	858	0.12	0.044

Median	110	38	897	0.12	0.046

75th Percentile	150	59	990	0.19	0.071

90th Percentile	252	114	1110	0.35	0.14

Maximum	560	300	1189	0.62	0.40

Count	37	37	37	37	37



Table 12.  Arithmetic Mean Comparisons of Air Concentrations Measured
using

Cassettes for each Site and Job Function (ng/m3)

Site	Average CrO3 handled (lbs)	Overall	TO	TA	PK	SU	FL	TG	TB

Rainier	117	43	59	63	29	17	N/A	N/A	N/A

Savannah	280	54	148	64	N/A	18	22	16	N/A

Tampa	877	140	107	114	N/A	85	296	41	149



Table 13.  Arithmetic Mean Comparisons of Air Concentrations Measured
using

Cassettes for each Site and Job Function (ng/m3/lb CrO3)

Site	Average CrO3 handled (lbs)	Overall	TO	TA	PK	SU	FL	TG	TB

Rainier	117	0.42	0.62	0.54	0.29	0.19	N/A	N/A	N/A

Savannah	280	0.21	0.60	0.25	N/A	0.074	0.087	0.054	N/A

Tampa	877	0.17	0.12	0.13	N/A	0.12	0.36	0.047	0.17



Table 14.  Arithmetic Mean Comparisons of Air Concentrations Measured
using 

PEM for each Site and Job Function (ng/m3)

Site	Average CrO3 handled (lbs)	Overall	TO	TA	PK	SU	FL	TG	TB

Rainier	117	39	50	67	21	17	N/A	N/A	N/A

Savannah	280	58	150	78	N/A	37	18	12	N/A

Tampa	877	55	42	34	N/A	33	141	20	44



Table 15.  Arithmetic Mean Comparisons of Air Concentrations Measured
using 

PEM for each Site and Job Function (ng/m3/lb CrO3)

Site	Average CrO3 handled (lbs)	Overall	TO	TA	PK	SU	FL	TG	TB

Rainier	117	0.39	0.49	0.70	0.18	0.17	N/A	N/A	N/A

Savannah	280	0.23	0.58	0.31	N/A	0.176	0.063	0.040	N/A

Tampa	877	0.068	0.047	0.041	N/A	0.052	0.17	0.023	0.053



7.0  DISCUSSION

A comparison of air concentrations measured for various job functions at
wood treatment facilities using either cassettes or PEM did not reveal
large differences between the two methods, except at the Tampa site.  At
the Tampa site, the air concentrations were generally higher for the
cassettes than the PEM. At the Savannah and Rainier sites, the air
concentrations were fairly similar using both types of monitors.  The
highest levels of Cr(VI) found were associated with those workers whose
activities required them to be close to the treatment cylinders, such as
Treatment Operators, Treatment Assistants, Forklift Operators (at the
Tampa Site), and Test Borers.  The Forklift Operators had the biggest
difference in inhalation exposure levels between sites. At the Tampa
site, the Forklift Operators worked with freshly treated charges and at
the Savannah and Rainier sites, the Forklift Operators typically worked
with untreated or stored wood for shipping and receiving purposes.  The
air concentrations associated with the Treatment Operators were higher
at the Savannah and Tampa sites than at the Rainier site, which may be
due to the automatic versus manual treatment plant facilities.  It was
also noted that at the Savannah and Tampa sites, the cylinder door was
left open after each charge.  However, this same trend among sites for
the Treatment Operators was not observed with the air concentrations
measured using the PEM.  

Linear regressions of the overall average air concentrations measured
using cassettes at each site were plotted against the total pounds of
chromic acid absorbed by the wood, the average pounds of chromic acid
absorbed by the wood and the total number of charges monitored (Figures
1-3).  A positive correlation was observed for each comparison (r2
values of 0.9925, 0.9893, and 0.9979, respectively).  This same
correlation was not observed for the air concentrations measured using
PEM.

	This study met most of the 875.1300 (inhalation exposure) guidelines. 
Appendix B provides the Checklist for OPPTS Test Guidelines 875.1300. 
Some issues of note include:

The number of replicates monitored per job function (a minimum of 5 per
site) for some of the job functions was less than the guideline
recommended number of 15.

It is assumed that PVC filters were used exclusively in the cassette
monitors and PTFE filters were used exclusively in the PEM monitors. 
This is suggested in the study report on page 19 (and summarized in this
review on page 10).  A method validation experiment was performed using
PVC filters in PEM, but it is assumed that this was only done since the
OSHA method calls for the use of PVC filters.  Another method validation
experiment was performed to validate the use of PTFE filters in PEM.  If
each filter was used exclusively in either the cassettes or PEM, then
the recoveries from the field fortification samples can be used to
correct the actual field samples.  The study authors did not correct
samples for the field fortification recoveries.  Several of the
recoveries were less than 100% (and some less than 90%) at all of the
sites.  It is not clear why correction was not performed.

Extended storage stability testing was only performed on filters without
air sampling pumps.  The filters were spiked and then stored for 10
days.  

Storage stability tests performed on PVC filters using an airflow rate
of 7 lpm and storage durations of 0, 2 and 4 days showed average
recoveries of 81.6%, 70.8% of 65.1%, respectively.  The recovery on Day
4 is less than the generally acceptable range of 70 to 120%.  In the
extended storage stability study (10 day), the average recovery was
within the acceptable range (106.2% including one poor recovery data
point); however, the filters were not attached to air sampling pumps. 

Breakthrough/retention testing was only performed on PVC filters, not
PTFE filters.

Pre-field recovery testing was only performed on PVC filters, not PTFE
filters.

It is not clear if concurrent laboratory spiked samples were run with
the actual field samples.  This type of QA/QC sample is not listed in
the analytical report provided in the Appendix.

A discussion of the blank control samples was not included in the study
report; only raw data was provided.

Two replicates at the Savannah site were assigned a job function of
“none”.  The study report did not provide any description of the
responsibilities performed by these workers.  The air concentrations are
62 and 17 ng Cr(VI)/m3 for the cassette replicates and 12 and 13 ng
Cr(VI)/m3 for the PEM replicates.  These values were included in the
statistics that summarized the data for all job functions combined.

8.0  CONCLUSIONS

μg/m3.  A separate inhalation risk assessment will be developed.  As
indicated in this review, these data can be used as a surrogate to
assess ACC treatment plant worker’s inhalation exposure and risk.

9.0  REFERENCES

American Chemistry Council (ACC). 2002.  Assessment of Potential
Inhalation and Dermal Exposure Associated With Pressure Treatment of
Wood with Arsenical Wood Products.  MRID 455021-01.

FPRL.  2004.  CCA Pressure Treatment Worker Exposure Study Design. 
Prepared by Forest Products Research Laboratory (FPRL), LLC.  Dated June
4, 2004.

FPRL.  2005.  Assessment of Potential Inhalation Exposure To Hexavalent
Chromium At Wood Treatment Facilities Using CCA.  Final Report. 
Prepared by Intertox, Inc for Forest Products Research Laboratory
(FPRL), LLC.  FPRL Study Number 123105.  Dated December 20, 2005.

USEPA.  2004.  Review of the Acid Copper Chromate (ACC) Worker
Inhalation Study Protocol, “CCA Pressure Treatment Worker Exposure
Study Design.”  Memorandum from Tim Leighton, Doreen Aviado, Winston
Dang (USEPA/OPP/AD) to Jack Housenger (USEPA/OPP/AD).  Dated July 14,
2004.

Appendix A

Hexavalent Chromium Individual Air Concentration Measurements



Table A1.  Summary of Air Concentrations at the Rainier Site.

Job Function	ng Cr(VI)/sample	Sample Volume (L)	Air Concentrations

(ng Cr(VI)/m3)	lbs Chromic Acid absorbed 	Air Concentrations per lb
Chromic acid absorbed

(ng/m3/lb CrO3)

	CAS	PEM	CAS	PEM	CAS	PEM

CAS	PEM

TO	50a	100	3797	4498	13	23	186	0.070	0.12

	160	50a	3798	4449	41	b	90	0.46	b

	290	350	3283	4412	90	79	80	1.13	0.99

	220	210	4130	5469	53	38	83	0.64	0.46

	160	170	3588	4842	44	35	157	0.28	0.22

	130	210	3327	4418	40	47	164	0.24	0.29

	480	360	3694	4748	130	75	86	1.51	0.87

Summary statistics for TO	Average	213	207	3660	4691	59	50	121	0.62	0.49

	Std	139	116	294	383	39	23	46	0.52	0.36

	Geo Mean	175	173	3649	4678	48	45	114	0.42	0.38

	Median	160	210	3694	4498	44	43	90	0.46	0.37

	75%tile	255	280	3798	4795	72	68	161	0.88	0.77

	90%tile	366	354	3931	5093	106	77	173	1.28	0.93

	Maximum	480	360	4130	5469	130	79	186	1.51	0.99

	Count	7	7	7	7	7	6	7	7	6

TA	480	160	4173	4917	110	33	186	0.59	0.18

	470	320	5174	6109	92	52	198	0.46	0.26

	230	290	3725	4377	62	66	80	0.78	0.83

	210	270	3740	4425	55	62	83	0.66	0.75

	310	420	3337	4414	94	94	90	1.04	1.04

	50a	50a	3305	4399	15	11	164	0.091	0.067

	50a	580	3439	3775	15	150	86	0.17	1.74

Summary statistics for TA	Average	257	299	3842	4631	63	67	127	0.54	0.70

	Std	176	171	660	731	38	45	53	0.33	0.59

	Geo Mean	188	242	3798	4586	50	52	118	0.42	0.45

	Median	230	290	3725	4414	62	62	90	0.59	0.75

	75%tile	390	370	3957	4671	93	80	175	0.72	0.93

	90%tile	474	484	4573	5394	100	116	191	0.88	1.32

	Maximum	480	580	5174	6109	110	150	198	1.04	1.74

	Count	7	7	7	7	7	7	7	7	7

PK	210	280	4027	4651	52	60	186	0.28	0.32

	50a	100	3711	4398	13	23	186	0.07	0.12

	50a	50a	4236	4920	12	10	108	0.11	0.09

	50a	50a	4191	4853	12	10	108	0.11	0.09

	50a	50a	3869	4566	13	11	80	0.16	0.14

	240	120	4211	4981	56	23	80	0.70	0.29

	100	110	3569	4721	29	24	86	0.34	0.28

	150	50a	3567	4772	41	10	71	0.58	0.14

Summary statistics for PK	Average	113	101	3923	4733	29	21	113	0.29	0.18

	Std	78	78	284	192	19	17	47	0.23	0.10

	Geo Mean	91	83	3914	4729	23	17	106	0.22	0.16

	Median	75	75	3948	4747	21	17	97	0.22	0.14

	75%tile	165	113	4196	4870	44	23	128	0.40	0.28

	90%tile	219	168	4219	4938	53	35	186	0.61	0.30

	Maximum	240	280	4236	4981	56	60	186	0.70	0.32

	Count	8	8	8	8	8	8	8	8	8

SU	50a	50a	3728	4732	13	11	108	0.12	0.10

	50a	50a	3897	4598	13	11	93	0.14	0.12

	50a	110	3508	4489	14	24	164	0.095	0.15

	100	120	3349	4471	31	28	86	0.36	0.33

	50a	50a	3173	4275	16	12	71	0.23	0.17

Summary statistics for SU	Average	60	76	3531	4513	17	17	104	0.19	0.17

	Std	22	36	289	169	8	8	36	0.11	0.090

	Geo Mean	57	70	3522	4510	16	16	100	0.16	0.16

	Median	50	50	3508	4489	14	12	93	0.14	0.15

	75%tile	50	110	3728	4598	16	24	108	0.23	0.17

	90%tile	80	116	3829	4678	25	26	142	0.31	0.26

	Maximum	100	120	3897	4732	31	28	164	0.36	0.33

	Count	5	5	5	5	5	5	5	5	5

Overall Summary Statistics	Average	186	192	3435	4216	43	39	117	0.42	0.39

	Std	141	144	1255	1530	34	33	45	0.37	0.41

	Geo Mean	127	131	2321	2787	32	29	110	0.29	0.26

	Median	160	168	3740	4651	40	26	90	0.28	0.24

	75%tile	240	285	3992	4848	56	58	164	0.61	0.42

	90%tile	470	360	4219	5093	93	77	186	0.88	0.93

	Maximum	480	580	5174	6109	130	150	198	1.51	1.74

	Count	51	51	51	51	27	26	27	27	26

a	For concentrations reported as less than the LOQ (100 ng), ½ the LOQ
was used in calculations (50 ng).

b	According to study report, sample not used because of unreliability. 
Subject reportedly abandoned running pumps at ~04:00.



Table A2.  Summary of Air Concentrations at the Savannah Site.

Job Function	ng Cr(VI)/sample	Sample Volume (L)	Air concentrations

(ng Cr(VI)/m3)	lbs Chromic Acid absorbed	Air concentrations per lbs
chromic acid

(ng/m3/lb CrO3)

	CAS	PEM	CAS	PEM	CAS	PEM

CAS	PEM

TO	410	810	3532	4471	110	180	274	0.40	0.66

	170	290	3559	3907	49	74	284	0.17	0.26

	1100	1100	2686	3621	410	310	229	1.79	1.35

	260	350	2870	2765	92	130	336	0.27	0.39

	200	200	2541	3427	77	58	222	0.35	0.26

Summary statistics for TO	Average	428	550	3038	3638	148	150	269	0.60
0.58

	Std	387	387	478	627	148	101	46	0.67	0.46

	Geo Mean	331	448	3008	3594	109	126	266	0.41	0.47

	Median	260	350	2870	3621	92	130	274	0.35	0.39

	75%tile	410	810	3532	3907	110	180	284	0.40	0.66

	90%tile	824	984	3548	4245	290	258	315	1.23	1.08

	Maximum	1100	1100	3559	4471	410	310	336	1.79	1.35

	Count	5	5	5	5	5	5	5	5	5

TA	210	220	3336	4484	63	50	274	0.23	0.18

	50a	130	3124	4136	16	30	284	0.06	0.11

	140	200	3153	4193	45	47	284	0.16	0.17

	140	320	3223	4171	43	76	229	0.19	0.33

	280	700	2772	3727	100	190	229	0.44	0.83

	310	520	2989	3895	100	130	336	0.30	0.39

	160	140	2861	3801	57	37	222	0.26	0.17

	270	270	2902	4230	91	63	222	0.41	0.28

Summary statistics for TA	Average	195	313	3045	4080	64	78	260	0.25	0.31

	Std	88	200	195	253	30	55	41	0.13	0.23

	Geo Mean	172	266	3040	4073	56	65	257	0.22	0.25

	Median	185	245	3057	4154	60	57	252	0.24	0.23

	75%tile	273	370	3171	4202	93	90	284	0.33	0.35

	90%tile	289	574	3257	4306	100	148	300	0.42	0.52

	Maximum	310	700	3336	4484	100	190	336	0.44	0.83

	Count	8	8	8	8	8	8	8	8	8

FL	50a	50a	3462	4594	14	11	274	0.051	0.040

	50a	50a	3037	4169	16	12	284	0.056	0.042

	50a	50a	2956	4141	17	12	229	0.074	0.052

	50a	150	2885	3729	17	39	336	0.051	0.12

	120	50a	2641	3552	45	14	222	0.20	0.06

Summary statistics for FL	Average	64	70	2996	4037	22	18	269	0.087	0.063

	Std	31	45	299	409	13	12	46	0.065	0.031

	Geo Mean	60	62	2985	4020	20	15	266	0.074	0.058

	Median	50	50	2956	4141	17	12	274	0.056	0.052

	75%tile	50	50	3037	4169	17	14	284	0.074	0.063

	90%tile	92	110	3292	4424	34	29	315	0.15	0.09

	Maximum	120	150	3462	4594	45	39	336	0.20	0.12

	Count	5	5	5	5	5	5	5	5	5

TG	50a	50a	2701	3610	19	14	394	0.048	0.036

	50a	50a	2706	3477	18	14	394	0.046	0.036

	50a	50a	3438	4457	15	11	229	0.066	0.048

	50a	50a	3308	4396	15	11	229	0.066	0.048

	50a	50a	3248	4408	15	11	336	0.045	0.033

Summary statistics for TG	Average	50	50	3080	4070	16	12	316	0.054	0.040

	Std	0	0	351	483	2	2	83	0.011	0.007

	Geo Mean	50	50	3064	4046	16	12	307	0.053	0.039

	Median	50	50	3248	4396	15	11	336	0.048	0.036

	75%tile	50	50	3308	4408	18	14	394	0.066	0.048

	90%tile	50	50	3386	4437	19	14	394	0.066	0.048

	Maximum	50	50	3438	4457	19	14	394	0.066	0.048

	Count	5	5	5	5	5	5	5	5	5

SU	50a	140	2716	3587	18	38	394	0.046	0.10

	50a	120	2917	3874	17	30	394	0.043	0.076

	50a	250	2748	3626	18	70	163	0.11	0.43

	50a	110	2678	3641	19	30	163	0.12	0.18

	50a	110	2753	3679	18	31	336	0.054	0.092

Summary statistics for SU	Average	50	146	2762	3681	18	40	290	0.074	0.18

	Std	0	59	91	113	1	17	118	0.036	0.15

	Geo Mean	50	138	2761	3680	18	38	268	0.067	0.14

	Median	50	120	2748	3641	18	31	336	0.054	0.10

	75%tile	50	140	2753	3679	18	38	394	0.11	0.18

	90%tile	50	206	2851	3796	19	57	394	0.11	0.33

	Maximum	50	250	2917	3874	19	70	394	0.12	0.43

	Count	5	5	5	5	5	5	5	5	5

None b	200	50	3185	4079	62	12	274	0.23	0.04

	50a	50a	2925	3848	17	13	336	0.051	0.039

Overall Summary Statistics b	Average	159	223	2995	3923	54	58	280	0.21
0.23

	Std	204	253	290	406	74	68	66	0.32	0.29

	Geo Mean	103	138	2982	3902	34	35	273	0.13	0.13

	Median	50	135	2921	3885	19	34	274	0.11	0.11

	75%tile	200	265	3214	4188	63	68	336	0.25	0.28

	90%tile	283	538	3440	4458	100	135	394	0.40	0.45

	Maximum	1100	1100	3559	4594	410	310	394	1.79	1.35

	Count	30	30	30	30	30	30	30	30	30

a	For concentrations reported as less than the LOQ (100 ng), ½ the LOQ
was used in calculations (50 ng).

b	The overall statistics included two additional replicates that were
assigned a job function of “none”.  A description of the
responsibilities performed by these workers was not provided.

 



Table A3.  Summary of Air Concentrations at the Tampa Site.

Job Function	ng Cr(VI)/sample	Sample Volume (L)	Air concentration 

(ng Cr(VI)/m3)	lbs Chromic Acid absorbed	Air concentrations per lbs
chromic acid

(ng/m3/lb CrO3)

	CAS	PEM	CAS	PEM	CAS	PEM

CAS	PEM

TO	430	170	3446	4491	130	37	897	0.14	0.041

	410	110	3403	4540	120	24	1189	0.10	0.020

	290	140	3474	4715	82	30	725	0.11	0.041

	270	180	3441	4578	79	38	1057	0.075	0.036

	500	300	3471	4704	150	64	990	0.15	0.065

	290	270	3563	4776	82	56	709	0.12	0.079

Summary statistics for TO	Average	365	195	3466	4634	107	42	928	0.12
0.047

	Std	95	74	54	113	30	15	189	0.028	0.021

	Geo Mean	355	183	3466	4633	104	39	912	0.11	0.043

	Median	350	175	3459	4641	101	38	944	0.11	0.041

	75%tile	425	248	3473	4712	128	52	1040	0.14	0.059

	90%tile	465	285	3519	4746	140	60	1123	0.15	0.072

	Maximum	500	300	3563	4776	150	64	1189	0.15	0.079

	Count	6	6	6	6	6	6	6	6	6

TA	250	50a	3427	4753	74	11	897	0.082	0.012

	260	50a	3548	4713	74	11	1189	0.062	0.009

	330	120	3388	4561	97	27	725	0.13	0.037

	400	170	3630	4756	110	36	1057	0.10	0.034

	430	180	2944	3912	150	47	928	0.16	0.051

	510	290	3594	4802	140	59	709	0.20	0.083

	480	180	3118	3835	150	46	745	0.20	0.062

Summary statistics for TA	Average	380	149	3378	4476	114	34	893	0.13
0.041

	Std	103	84	257	419	34	18	182	0.055	0.026

	Geo Mean	367	125	3370	4458	109	28	878	0.12	0.032

	Median	400	170	3427	4713	110	36	897	0.13	0.037

	75%tile	455	180	3571	4755	145	47	993	0.18	0.056

	90%tile	492	224	3608	4774	150	52	1110	0.20	0.070

	Maximum	510	290	3630	4802	150	59	1189	0.20	0.083

	Count	7	7	7	7	7	7	7	7	7

FL	1800	470	3128	3864	560	120	897	0.62	0.13

	740	160	3311	4434	220	36	1189	0.19	0.03

	1400	610	3326	4396	420	140	725	0.58	0.19

	470	260	3544	3865	130	68	1057	0.12	0.06

	290	870	3109	4152	93	210	990	0.09	0.21

	740	480	3351	4420	220	110	709	0.31	0.16

	1400	1300	3178	4240	430	300	745	0.58	0.40

Summary statistics for FL	Average	977	593	3278	4196	296	141	902	0.36
0.17

	Std	559	388	153	248	175	89	186	0.23	0.12

	Geo Mean	826	487	3275	4189	249	116	886	0.28	0.13

	Median	740	480	3311	4240	220	120	897	0.31	0.16

	75%tile	1400	740	3339	4408	425	175	1024	0.58	0.20

	90%tile	1560	1042	3428	4426	482	246	1110	0.60	0.29

	Maximum	1800	1300	3544	4434	560	300	1189	0.62	0.40

	Count	7	7	7	7	7	7	7	7	7

TG	50a	130	3805	5031	13	25	897	0.014	0.028

	50a	50a	3687	4910	14	10	774	0.018	0.013

	120	50a	3607	4912	32	10	990	0.032	0.010

	270	230	2590	5393	110	43	894	0.12	0.048

	130	50a	3685	3795	36	13	742	0.049	0.018

Summary statistics for TG	Average	124	102	3475	4808	41	20	859	0.047
0.023

	Std	90	79	500	600	40	14	101	0.044	0.015

	Geo Mean	101	82	3442	4775	30	17	855	0.035	0.020

	Median	120	50	3685	4912	32	13	894	0.032	0.018

	75%tile	130	130	3687	5031	36	25	897	0.049	0.028

	90%tile	214	190	3758	5248	80	36	953	0.093	0.040

	Maximum	270	230	3805	5393	110	43	990	0.12	0.048

	Count	5	5	5	5	5	5	5	5	5

SU	230	50a	3444	4569	68	11	934	0.073	0.012

	260	110	3446	4590	75	23	748	0.10	0.031

	450	220	3449	4554	130	47	1031	0.13	0.046

	270	180	3646	4924	75	37	532	0.14	0.070

	270	230	3529	4610	78	49	474	0.16	0.10

Summary statistics for SU	Average	296	158	3503	4649	85	33	744	0.12	0.052

	Std	88	77	88	155	25	16	243	0.036	0.036

	Geo Mean	287	138	3502	4647	83	29	711	0.12	0.041

	Median	270	180	3449	4590	75	37	748	0.13	0.046

	75%tile	270	220	3529	4610	78	47	934	0.14	0.070

	90%tile	378	226	3599	4798	109	48	992	0.16	0.090

	Maximum	450	230	3646	4924	130	49	1031	0.16	0.10

	Count	5	5	5	5	5	5	5	5	5

TB	270	50	3401	4311	79	12	897	0.088	0.013

	580	120	3481	4547	170	27	1189	0.14	0.023

	540	210	3287	4415	160	49	725	0.22	0.068

	160	50a	3242	4377	50	11	1057	0.047	0.010

	630	290	3168	4128	200	70	990	0.20	0.071

	290	230	3587	4800	82	47	709	0.12	0.066

	890	350	2956	3994	300	89	745	0.40	0.12

Summary statistics for TB	Average	480	186	3303	4367	149	44	902	0.17
0.053

	Std	254	117	210	265	87	29	186	0.12	0.040

	Geo Mean	417	147	3297	4361	127	34	886	0.14	0.038

	Median	540	210	3287	4377	160	47	897	0.14	0.066

	75%tile	605	260	3441	4481	185	60	1024	0.21	0.069

	90%tile	734	314	3523	4648	240	78	1110	0.29	0.090

	Maximum	890	350	3587	4800	300	89	1189	0.40	0.12

	Count	7	7	7	7	7	7	7	7	7

Overall Summary Statistics	Average	464	242	3389	4496	140	55	877	0.17
0.068

	Std	377	247	243	369	117	58	182	0.15	0.075

	Geo Mean	354	170	3380	4481	105	38	858	0.12	0.044

	Median	330	180	3444	4554	110	38	897	0.12	0.046

	75%tile	510	270	3548	4753	150	59	990	0.19	0.071

	90%tile	800	474	3636	4911	252	114	1110	0.35	0.14

	Maximum	1800	1300	3805	5393	560	300	1189	0.62	0.40

	Count	37	37	37	37	37	37	37	37	37

a	For concentrations reported as less than the LOQ (100 ng), ½ the LOQ
was used in calculations (50 ng).



Appendix B

Checklist for OPPTS Test Guidelines 875.1300

DRAFT

COMPLIANCE CHECKLIST

GUIDELINE 875.1300

INHALATION EXPOSURE- OUTDOOR HANDLER

Investigators should submit protocols for review purposes prior to the
inception of the study. This criterion was met.

Expected deviations from GLPs should be presented concurrently with any
protocol deviations and their potential study impacts. This criterion
was met.

The test substance should be a typical end use product of the active
ingredient. This criterion was met.

The application rate used in the study should be provided and should be
the maximum rate specified on the label.  However, monitoring following
application at a typical application rate may be more appropriate in
certain cases. This criterion does not apply to this study.  Workers
were monitored in wood treatment facilities.  The pounds of chromic acid
absorbed by the wood were provided.

Selected sites and seasonal timing of monitoring should be appropriate
to the activity. This criterion was met.

A sufficient number of replicates should be generated to address the
exposure issues associated with the population of interest.  For outdoor
exposure monitoring, each study should include a minimum of 15
individuals (replicates) per activity. This criterion was partially met.
Overall, the number of replicates collected for each job function
included 18 treatment operators (TO), 22 treatment assistants (TA), 8
packers (PK), 15 supervisors (SU), 12 forklift operators (FO), 10
taggers (TG), and 7 test borers (TB). 

The quantity of active ingredient handled and the duration of the
monitoring period should be reported for each replicate.  This criterion
was met.  The pounds of chromic acid absorbed by charges during a
worker’s shift were provided as well as the sampling duration for each
replicate.

Test subjects should be regular workers, volunteers trained in the work
activities required, or typical homeowners.  This criterion was
partially met.  However, some of the test subjects were temporary
workers hired specifically to monitor the tagging operations and study
team members that served as proxy workers.

The monitored activity should be representative of a typical working day
for the specific task in order to capture all related exposure
activities. This criterion was apparently met.  However, no information
was provided to determine how much wood is typically handled at
treatment facilities.  It is unknown if records/surveys are available to
determine how much wood is treated at various types of facilities (e.g.,
range, typical/average).

When both dermal and inhalation monitoring are required, field studies
designed to measure exposure by both routes on the same subjects may be
used.  This criterion does not apply to this study.

The analytical procedure must be capable of measuring exposure to 1
ug/hr (or less, if the toxicity of the material under study warrants
greater sensitivity).  This criterion was met.  The LOQ reported in the
study report was 100 ng/sample.

A trapping efficiency test for the monitoring media chosen must be
documented.  This criterion was met.  

Air samples should also be tested for breakthrough to ensure that
collected material is not lost from the medium during sampling. It is
recommended that at least one test be carried out where the initial trap
contains 10X the highest amount of residue expected in the field.  This
criterion was partially met.  Breakthrough testing was performed on PVC
filters only; not PTFE filters.

The extraction efficiency of laboratory fortified controls is considered
acceptable if the lower limit of the 95% confidence interval is greater
than 75%, unless otherwise specified by the Agency.  At a minimum, seven
determinations should be made at each fortification level to calculate
the mean and standard deviation for recovery. Total recovery from
field-fortified samples must be greater than 50% for the study.  This
criterion was met.  

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Hm field samples are to be stored after exposure, a stability test of
the compound of interest must be documented.  Media must be stored under
the same conditions as field samples.  Storage stability samples should
be extracted and analyzed immediately before and at appropriate periods
during storage. The time periods for storage should be chosen so that
the longest corresponds to the longest projected storage period for
field samples.  This criterion was met.  Storage stability tests were
performed up to the maximum storage duration.  

A personal monitoring pump capable of producing an airflow of at least 2
L/min. should be used and its batteries should be capable of sustaining
maximum airflow for at least 4 hours without recharging. Airflow should
be measured at the beginning and end of the exposure period.  This
criterion was met.

Appropriate air sampling media should be selected. The medium should
entrap a high percentage of the chemical passing through it, and it
should allow the elution of a high percentage of the entrapped chemical
for analysis.  This criterion was met.

If exposed media are to be stored prior to extraction, storage envelopes
made from heavy filter paper may be used.  The envelope must be checked
for material that will interfere with analysis.  Unwaxed sandwich bags
should be used to contain the filter paper envelopes to help protect
against contamination.  This criterion was met. PVC filters in cassettes
were capped, labeled and bagged.  PTFE filters were placed in
Filter-Keepers, labeled and bagged.

Personal monitors should be arranged with the intake tube positioned
downward, as near as possible to the nose level of the subject.  This
criterion was met.

Field calibration of personal monitors should be performed at the
beginning and end of the exposure period.  This criterion was met.  

Field fortification samples and blanks should be analyzed for correction
of residue losses occurring during the exposure period.  Fortified
samples and blanks should be fortified at the expected residue level of
the actual field samples.  Fortified blanks should be exposed to the
same weather conditions.  This criterion was met.

Respirator pads should be removed using clean tweezers and placed in
protective white crepe filter paper envelopes inside sandwich bags.  The
pads should be stored in a chest containing ice until they are returned
to the laboratory, where they should be stored in a freezer prior to
extraction.  This criterion does not apply to this study.

Field data should be documented, including chemical information, area
description, weather conditions, application data, equipment
information, information on work activity monitored, sample numbers,
exposure time, and any other observations. This criterion was met. 

Analysis methods should be documented and appropriate. This criterion
was met.

A sample history sheet must be prepared by the laboratory upon receipt
of samples. This criterion was met.

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