UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, DC 20460

			OFFICE OF  PREVENTION, PESTICIDES,  AND TOXIC SUBSTANCES

DP Barcode:

	Chemical:	Creosote

PC Codes:	022003, 025003, 25004

Case No.:	0139



August 26, 2008

Memorandum:

Subject:	Ecological Risk Assessment for Creosote:  Response to Public
Comments

To:	Jacqueline McFarlane, CRM

	Antimicrobial Division

From: 	William Erickson, Ph.D., Biologist

	RASSB/AD

Thru:	Norm Cook, Branch Chief

	RASSB/AD 

RASSB has reviewed the public comments on the Updated Ecological Risk
Assessment for Creosote.  Comments on the ecological risk assessment
were provided by The Creosote Council; Beyond Pesticides; and the
California Regional Water Quality Control Board, San Francisco Bay
Region.  The comments and RASSB's response to those comments are
provided below.

Comment (Creosote Council):  EPA needs to make better and more extensive
use of the creosote ecological studies conducted by Dr. Kenneth Brooks. 
The work of Dr. Kenneth Brooks established that use of creosote-treated
wood products (e.g., marine piling) in or near water does not pose an
environmental hazard.

RASSB Response:  The studies of Dr. Brooks are evaluated in the risk
assessment including their strengths and limitations.  RASSB disagrees
with the Creosote Council's conclusion that creosote-treated wood
products in or near water do not pose any environmental hazard.  Dr.
Brooks concluded that PAHs accumulating in sediments near aquatic
pilings can pose a risk to aquatic organisms.  He concluded that such
impacts might be limited to within a few meters of a six-piling dolphin
structure in the Sooke Basin of Canada.  However, the footprint of
potential impact could be much more extensive where a larger volume of
aquatic pilings was placed in an aquatic environment.  Elsewhere, Dr.
Brooks (1995) has advocated not installing creosote-treated aquatic
structures in areas where current speeds are less than or equal to 1.0
cm/sec without further assessment.  He stated that an individual project
risk assessment should be required under certain conditions, including
current speed, inter-piling distances, proximity to existing creosote
structures, and other factors.  Clearly, Dr. Brooks recognizes that
creosote leaching from treated aquatic structures poses risk to some
aquatic organisms.  Elsewhere, as discussed in the risk assessment,
creosote has been shown to have a significant and rapid impact on
zooplankton communities (NOEC = 13.9 ppb), and 40-year-old
creosote-treated pilings caused hatching failures and embryonic
abnormalities in Pacific herring.  Based on all available information,
it is misleading to claim that creosote-treated wood placed in the
aquatic environment poses no hazard to aquatic organisms.

Regarding risk to organisms in the water column of the Sooke Basin in
Canada, Dr. Brooks states that water-column concentrations of PAHs are
extremely low and not likely to be of concern for aquatic organisms. 
However, as discussed in the risk assessment, water-column
concentrations were not measured until six months after aquatic pilings
were installed.  Microcosm studies (discussed in the risk assessment)
demonstrate that water-column concentrations of PAHs may be sufficiently
high in the first few days or weeks to cause adverse affects (lethal and
sublethal) to aquatic organisms.  

RASSB also strongly believes that the uncertainties in extrapolating PAH
concentrations in pristine Canadian waters in winter may not adequately
reflect water-column and sediment concentrations that might occur in
coastal Florida, Mississippi, Texas or other southern U. S. areas with
different biotic and abiotic factors.  Data from these areas would
provide for a more refined risk assessment.  As discussed in the risk
assessment, environmental factors such as salinity, temperature, pH,
organic matter of sediments, water currents, tides, and others have been
shown to influence both leaching of PAHs from treated wood and toxicity
to aquatic organisms.

Comment (Creosote Council):  In 1995 EPA waived all data requirements in
favor of relying upon the public literature.

RASSB Response:  EPA did not waive the data but did state that the
registrant could use available published literature where appropriate. 
Although a field study from Canada (Sooke Basin) was subsequently
submitted, no literature or laboratory studies have been submitted to
satisfy the standard ecotoxicity tests required for all pesticides
registered and reregistered under FIFRA.  The data gaps are specified in
the ecological risk assessment.  However, RASSB realizes the difficulty
in conducting standard ecological toxicity tests for creosote, because
it is a mixture of a variety of PAHs with differing toxicities in
differing concentrations that change over time.  RASSB believes that in
lieu of standardized laboratory tests, a field or simulated study might
better address exposure and hazard concerns for aquatic organisms. 
RASSB will be working with the Creosote Council to determine appropriate
means of testing.

Comment (Beyond Pesticides):  Emphasize that an endangered species
determination is legally required.

RASSB Response:  The screening-level ecological risk assessment
identifies the taxa (e. g., saltwater invertebrates) at risk, based on
exceedances of the acute and/or chronic levels of concern.  As noted in
the screening assessment, a refined listed-species assessment will be
conducted under Registration Review to assess risk to individual species
in those taxa.  The listed-species assessment will be conducted in
accordance with the OPPTS' overview document.      HYPERLINK
"http://www.epa.gov/espp/"  http://www.epa.gov/espp/ 

Comment (California Regional Water Quality Control Board, SF Bay
Region):  Recent research provides additional information about the
hazards that PAHs in creosote pose to fish. We have enclosed recent
research papers on this topic.

RASSB Response:  The information in these articles may be useful for
further characterizing ecological risks of creosote, but there appears
to be no new information that would change RASSB's risk conclusions at
this time.  The information will be used, as deemed appropriate, when
RASSB conducts a refined listed-species assessment (including listed
salmonids) or conducts any additional ecological risk assessments for
creosote-treated structures.

Comment (California Regional Water Quality Control Board, SF Bay
Region):  Important data needs include sufficient aquatic toxicity data
to calculate acute and chronic risks to benthic organisms and sufficient
aquatic toxicity data to calculate chronic risk to organisms (fish,
invertebrates, plants) inhabiting the water column in both freshwater
and saltwater.

RASSB Response:  RASSB agrees that additional data are needed and
identifies these data gaps in the ecological assessment.  See also
RASSB's response to the Creosote Council regarding the data
requirements.

 

 USEPA.  2004.  Overview of the Ecological Risk Assessment Process in
the Office of Pesticide Programs, U.S. Environmental Protection Agency: 
Endangered and Threatened Species Effects Determinations.  Office of
Prevention, Pesticides and Toxic Substances, Office of Pesticide
Programs, Washington, D.C.  

 

