UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

OFFICE OF

PREVENTION, PESTICIDES, AND

TOXIC SUBSTANCES

Memorandum 

DATE: 	October 23, 2008

SUBJECT: 	Corrections for the White Paper for the October 28 – 31,
2008 Session of the FIFRA Scientific Advisory Panel (SAP) Entitled
“Assessing Ecological Risks of Pesticides with Persistent,
Bioaccumulative and Toxic Characteristics”

FROM: 	Donald Brady, Director

Environmental Fate and Effects Division 

Office of Pesticide Programs (7507P)

TO: 		Myrta Christian, Designated Federal Official 

FIFRA Scientific Advisory Panel 

Office of Science Coordination and Policy (7201M) 

	Appendix 1 provides error corrections to the White Paper developed for
the October 28 - 31, 2008 FIFRA SAP session: “Assessing Ecological
Risks of Pesticides with Persistent, Bioaccumulative and Toxic
Characteristics”.   

Please feel free to call upon us if you have any questions.

Appendix 1.  Error Corrections

1.   The original text for charge question 10, under “Future
PBT-Related Refinements”

10.	The Agency is considering refinements to its problem formulation
process to improve the ecological risk assessment of pesticides with PBT
characteristics, as outlined in Chapter 8 of the White Paper.   In
particular, please comment on: 

The Agency’s proposed process for identifying (screening) pesticides
for potential PBT risk assessment issues need to be addressed  

On the priority for developing new models, methods, and information for
addressing PBT issues. 

Should be changed to

10. The Agency is considering refinements to its problem formulation
process to improve the ecological risk assessment of pesticides with PBT
characteristics, as outlined in Chapter 8 of the White Paper.   In
particular, please comment on: 

The Agency’s proposed process for identifying (screening) pesticides
with potential PBT risk assessment issues, and  

On the priority for developing new models, methods, and information for
addressing PBT issues

  

2. (p 53) The following tables were corrected.. 

Comparison of Total Residue Modeling Methods for Pesticide 1

	The 1-in-10 year EECs for the three TROC modeling approaches are shown
in   REF _Ref208794743 \h  \* MERGEFORMAT  Table 3.1 .  Although the
modeling strategies produce comparable EECs, the TR Method produced the
most conservative EECs for pesticide 1 among the various modeling
strategies.   

Table 3.  SEQ Table_3. \* ARABIC  1 . Comparison of 1 in 10 year EECs
for Pesticide 1 using Various TROC Modeling Strategies

Modeling Approach	Concentration (μg/L)

	Peak	21-Day

Average	60-Day

Average	90-Day

Average	Annual

Average

Residue Summation (RS Method	32.63	13.03	9.17	8.21	5.54

Simultaneous Formation/ 

Degradation Kinetics 

(FD method)	38.10	15.17	10.67	9.52	6.44

Total Residue (TR Method)	48.02	20.22	14.5	13.41	9.46



Because the simultaneous formation/decline kinetic approach(FD method)
is the preferred TROC modeling approach, time series of daily water
concentrations for the various TROC methods were compared to the time
series of daily water concentrations for the TROC using the FD method
(Table 3.2). These data indicate the residue summation method (RS)
accounts for 82% of concentration predicted using the FD method.  In
contrast, the total residue method accounts for only 144% of the FD
method.   

Table 3.  SEQ Table_3. \* ARABIC  2 . Mean Percentage of Total Residues
of Concern (TROC) estimated using the FD Method Represented by RS and TR
Methods for Pesticide 1 Over a 30-year Simulation with the FL Tomato
Scenario

Compared Modeling Approach	Mean % of  Method 

Residue Summation (RS Method)1	82% 

Total Residue (TR Method)2	144 % 

	1 (/RS method/ FD method)*100

	2 (TR method/FD method)*100

3. (p 160) The sentence “ Because of the volatility of Pesticide 1 and
its propensity to partition into air (high KOA) and its resistance to
degradation in the atmosphere, coupled with the persistence of degradate
1 (D1), total residues of this compound (P1, P2 isomers plus degradate
D1) have been documented to travel considerable distances from known use
sites” 

should be changed to 

“ Because of the volatility of Pesticide 1 and its propensity to
partition into air (low KOA) and its resistance to degradation in the
atmosphere, coupled with the persistence of degradate 1 (D1), total
residues of this compound (P1, P2 isomers plus degradate D1) have been
documented to travel considerable distances from known use sites”.

4. (p.161) The sentence “The CTD represents the potential of a
chemical to be transported over long distances in air or water. In the
OECD Tool,

the CTD is the distance at which the concentration of chemical decrease
to 37% due to transport of chemical by a constant flow of air (wind
speed of 0.02 m/s) or water (ocean water circulation speed of 0.02m/s)
(Scheringer et al., 2006)” 

should be changed to 

“The CTD represents the potential of a chemical to be transported over
long distances in air or water. In the OECD Tool, the CTD is the
distance at which the concentration of chemical decrease to 37% due to
transport of chemical by a constant flow of air (wind speed of 4 m/s) or
water (ocean water circulation speed of 0.02m/s) (Scheringer et al.,
2006)”.

5. (p.169) The EECs in Table 7.2 have been corrected.  

Table 7.2.  Summary of Aquatic Organism RQs for Pesticide 2

EEC Derivation Method

Peak EEC

LC50, Fish

RQ, Fish

	Parent Only

18 ug/L

100 ug/L

0.18

	Total Residues of Concern

19 ug/L

56 ug/L

140 ug/L

0.34

0.14

	6. (p 141) Original text:

(1) Laboratory Accumulation Studies in Fish 

	In fish, laboratory studies were used to evaluate bioaccumulation
potential from both dietary and water column exposures.  The
contribution of body burden in fish from exposure to contaminated water
was estimated using a 49-day spiked water bioconcentration study in
bluegill using the following equation (Newman, 1995).  

 	Ct = ku x C1 (1 – e-ke x t)

		  ke

Ct 	= concentration in the fish at time t 

C1 	= concentration in water associated with the LC50

ku 	= uptake rate constant 

ke 	= depuration rate constant 

t   	= time (days)

The equation should be changed to: 

 	Ct = ku x C1 (1 – e-ke x t)

		  ke

Ct 	= concentration in the fish at time t (60 days)

C1 	= concentration in water associated with the EEC

ku 	= uptake rate constant 

ke 	= depuration rate constant 

t   	= time (days)

7. The original Table 6.1: 

Table 6.1.  Physicochemical and environmental fate properties used as
input for estimating overall persistence and long-range transport
potential using the OECD Tool

Name of Chemical	Molecular Weight

g/mole	Log Kow a	Log KAw a	Half life in Air (hrs)	Half life in Water

(hrs)	Half life in Soil

(hrs)

p.p’ DDT b	345.5	6.39	-3.34	170	5500	17000

Aldrinb	364.9	4.94	-3.38	2.86	2670	3830

Endrinb	380.9	5.44	-3.11	12.72	78840	29070

Pesticide 1 (isomer P1)	406.9	4 .74	-2.58	48c	2736d	1368e

Pesticide 1 (isomer P2)	406.9	4.78	-3.45	48c	9072d	4992e

Pesticide 2	295.3	4.64	-2.75	22560f	4320d	4536e

Pesticide 3	506.4	5.10	-5.87	6.5g	2400d	3216e

Pesticide 4	491.1	8.10	-5.09	7.2g	4464e	5472e

a  Maximum reported value

b Input parameters for these chemical are based on the Reference
chemicals data in the OECD Tool.  

c  Reported half-life in air for pesticide 1 (TOXNET,   HYPERLINK
"http://www.toxnet.nlm.nih.gov/"  http://www.toxnet.nlm.nih.gov/  )

d The half-life in water based on PRZM/EXAM inputs

e Half-life in air based on measured value of similar structure of
pesticide 2. Determined half-life is based on 2nd order degradation
half-life (Brubaker and Hites, 1998)

f Represents the 90th %-ile confidence bound on the mean half-life

g  Half-life in air based on EPISUITE estimate



Should be replaced with 

Table 6.1.  Physicochemical and environmental fate properties used as
input for estimating overall persistence and long-range transport
potential using the OECD Tool

Name of Chemical	Molecular Weight

g/mole	Log Kow a	Log KAw a	Half life in Air (hrs)	Half life in Water

(hrs)	Half life in Soil

(hrs)

p.p’ DDT b	345.5	6.39	-3.34	170	5500	17000

Aldrinb	364.9	4.94	-3.38	2.86	2670	3830

Endrinb	380.9	5.44	-3.11	12.72	78840	29070

Pesticide 1 (isomer P1)	406.9	4 .74	-2.58	48c	2736d	1368e

Pesticide 1 (isomer P2)	406.9	4.78	-3.45	48c	9072d	4992e

Pesticide 2	295.3	4.64	-2.75	22560f	4320d	4536e

Pesticide 3	506.4	5.10	-5.87	6.5g	2400d	3216e

Pesticide 4	491.1	8.10	-5.09	7.2g	4464e	5472e

a  Maximum reported value

b Input parameters for these chemical are based on the Reference
chemicals data in the OECD Tool.  

c  Reported half-life in air for pesticide 1 (TOXNET,   HYPERLINK
"http://www.toxnet.nlm.nih.gov/"  http://www.toxnet.nlm.nih.gov/  )

d The half-life in water based on PRZM/EXAM inputs

e Represents the 90th %-ile confidence bound on the mean half-life

f Half-life in air based on measured value of similar structure of
pesticide 2. Determined half-life is based on 2nd order degradation
half-life (Brubaker and Hites, 1998)

g  Half-life in air based on EPISUITE estimate



8. The original Table:

Table 5.22 Estimated Concentrations of Pesticide 4 in Using Default
Parameterization of an Aquatic Food Web Model

Component	Estimated Residue Level

(μg/kg, whole organism)	Lipid or Organic Carbon Fraction 	Lipid
Normalized Estimated Residue Level

(μg/kg, lipid)

Sediment (in solid)	7,000	4%	175,000

Phytoplankton

 	200	0.5%	40,000

Zooplankton

 	1,000	2%	50,000

Benthic Invertebrates	100,000	2%	5,000,000

Filter Feeders

 	15,000	2%	750,000

Small Forage Fish	90,000	6%	1,500,000

Medium Forage Fish	100,000	6%	1,700,000

Piscivorous Fish

 	200,000	6%	3,300,000

Notes: Food web model based on Arnot and Gobas (2004).  Ecosystem
parameters defined in Appendix D.

Should be replaced with 

Table 5.22 Estimated Concentrations of Pesticide 4 in Using Default
Parameterization of an Aquatic Food Web Model

Component	Estimated Residue Level

(μg/kg, whole organism)	Lipid or Organic Carbon Fraction 	Lipid
Normalized Estimated Residue Level

(μg/kg, lipid)

Sediment (in solid)	7,200	4%	180,000

Phytoplankton

 	2,400	0.5%	4,800,000

Zooplankton

 	200,000	2%	10,000,000

Benthic Invertebrates	130,000	2%	6,300,000

Filter Feeders

 	390,000	2%	19,000,000

Small Forage Fish	530,000	6%	8,800,000

Medium Forage Fish	570,000	6%	9,500,000

Piscivorous Fish

 	1,300,000	6%	21,000,000

Notes: Food web model based on Arnot and Gobas (2004).  Ecosystem
parameter⁳敤楦敮⁤湩䄠灰湥楤⁸⹄഍⸹吠敨漠楲楧慮⁬
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敐瑳捩摩⁥‴湩䘠獩⁨獕湩⁧敍獡牵摥䬠‱湡⁤㉋爠瑡
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(μg/kg, whole fish)	Lipid Normalized Body Burden Based on 6% Lipid 

(μg/kg, lipid)

Small Forage Fish	2400	40,000

Medium Forage Fish	1700	28,333

Piscivorous Fish	170	2,833

Notes: Food web model based on Arnot and Gobas (2004).  Ecosystem
parameters defined in Appendix D.  A depuration rate constant value of
0.023 day-1 and an uptake rate constant of 600 day-1 were incorporated
into the body burden estimation.

Table 5.24. Estimated Concentrations of Pesticide 4 in Fish Using a
Measured Value for
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摲湥

(μg/kg, whole fish)	Lipid Normalized Body Burden Based on 6% Lipid 

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on as a k1 value, and the depuration rate constant of 0.067 was
incorporated as a ke based on the oral bioaccumulation study.  All other
elimination and growth constants were set to 0.



Should be replaced with 

Table 5.23. Estimated Concentrations of Pesticide 4 in Fish Using
Measured K1 and K2 rate Constants with an Aquatic Food Web Model

Taxonomic Group	Estimated Body Burden

(μg/kg, whole fish)	Lipid Normalized Body Burden Based on 6% Lipid 

(μg/kg, lipid)

Small Forage Fish	32,000	530,000

Medium Forage Fish	24,000	390,000

Piscivorous Fish	5,800	96,000

Notes: Food web model based on Arnot and Gobas (2004).  Ecosystem
parameters defined in Appendix D.  A depuration rate constant value of
0.023 day-1 and an uptake rate constant of 600 day-1 were incorporated
into the body burden estimation.

Table 5.24. Estimated Concentrations of Pesticide 4 in Fish Using a
Measured Value for Measured K1 and Ke Rate Constants with an Aquatic
Food Web Model

Taxonomic Group	Estimated Body Burden

@

(μg/kg, whole fish)	Lipid Normalized Body Burden Based on 6% Lipid 

(μg/kg, lipid)

Small Forage Fish	11,000	180,000

Medium Forage Fish	8,000	130,000

Piscivorous Fish	1,600	26,000

a  An uptake rate constant of 600 day-1 was incorporated into the body
burden estimation as a K1 value, and the depuration rate constant of
0.067 was incorporated as a Ke based on the oral bioaccumulation study. 
All other elimination and growth constants were set to 0.

 

