**UNITED STATES ENVIRONMENTAL PROTECTION AGENCY**

**WASHINGTON, DC 20460**

OFFICE OF PREVENTION, PESTICIDES, AND TOXIC SUBSTANCES

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  --------------------------- -------------------------------------------
  **DP Barcode:**             

  **Chemical:**               Creosote

  **PC Codes:**               022003, 025003, 25004

  **Case No.:**               0139
  --------------------------- -------------------------------------------

> March 7, 2008

**Memorandum:**

**Subject:** Updated Ecological Risk Assessment for Creosote

**To:** Tim McMahon, PhD., Senior Toxicologist and Risk Assessor

Jacqueline McFarlane, CRM

> Antimicrobial Division

**From:** William Erickson, Ph.D., Biologist

> RASSB/AD

**Thru:** Norm Cook, Branch Chief

Rick Petrie, Team Leader

> RASSB/AD

Attached is the updated ecological risk assessment for creosote. A
preliminary ecological risk assessment was issued in December, 2003.
That assessment addressed risks of whole creosote to aquatic and
terrestrial organisms. Based on stakeholder comments and additional
information now available, the aquatic assessment has been updated to
address the toxicity and exposure of the major component PAHs of
creosote expected in the aquatic environment. The aquatic exposure
modeling has been refined and additional data from field, microcosm,
mesocosm, and laboratory studies included to assess the potential for
acute and sublethal risks to fish and aquatic invertebrates exposed in
the water column or in aquatic sediment. Because guideline toxicity
studies are not available for these PAHs, AD is using the best available
information from the open literature and from existing evaluations.
However, data gaps are extensive, especially for the complexes of PAHs
likely to occur in the water column and in aquatic sediments. Therefore,
much of the risk presumptions are based on a qualitative assessment of
the available information.

Based on the existing laboratory and field data and modeling of PAH
aquatic concentrations from use of creosote-treated railroad ties and
aquatic structures, AD makes the following conclusions for risks to
freshwater and saltwater fish and invertebrates exposed in the water
column and/or in aquatic sediment:

**Aquatic structures:**

• the level of concern (LOC) is exceeded for acute risk to listed (i.e.,
endangered and threatened) freshwater and saltwater (estuarine/marine)
fish and aquatic invertebrates exposed to PAHs in the water column

• the LOC is exceeded for acute risk to non-listed saltwater
invertebrates exposed to PAHs in the water column

• chronic RQs can not be calculated due to lack of chronic toxicity
data, but available evidence indicates that chronic risk (survival,
growth, reproduction, immunotoxicity) is possible to aquatic organisms
inhabiting the water column

• based on findings from the Sooke Basin field study, PAH accumulation
in sediments is sufficiently high to pose a risk to benthic organisms in
the immediate vicinity of creosote-treated pilings for at least a year

• although survival and spawning were not affected, short-term adverse
affects on growth of mussels was reported immediately around pilings at
Sooke Basin

• one year after pilings were installed in Sooke Basin, an assemblage of
invertebrate organisms inhabited the creosote-treated pilings,
suggesting minimal long-term impacts to some non-listed species

• laboratory and field investigation found a major detrimental impact on
hatching and development of fish (herring) eggs attached to aquatic
pilings, even pilings that were 40 years old, suggesting that some
sensitive species may be adversely affected by creosote-treated pilings

• creosote had a significant and rapid adverse impact on total
abundance, number of taxa, and population dynamics of zooplankton in
microcosms

• impacts of creosote-treated aquatic pilings are likely to vary
locally, depending on abiotic and biotic factors such as current speed,
amount of structure per unit area, air and water temperature, salinity,
and the aquatic species occurring in the immediate area of the
structures; thus, a site evaluation is essential prior to installation
of new structures

• potential impacts to aquatic organisms, especially less mobile
species, may be exacerbated in the vicinity of treatment plants and
loading docks in aquatic areas

**Railroad structures:**

• the level of concern (LOC) is exceeded for acute risk to listed
freshwater and saltwater fish and aquatic invertebrates exposed to PAHs
expected to reaching the water column; in wetter areas, PAHs may
possibly remain at levels of concern to listed species for many weeks

• in wetter areas with more potential for movement of PAHs into the
aquatic environment, the LOC also is exceeded for acute risk to
non-listed fish (freshwater) and aquatic invertebrates exposed to PAHs
in the water column

• chronic RQs can not be calculated due to lack of chronic toxicity
data, but available evidence indicates that chronic risk is possible to
aquatic organisms inhabiting the water column

• based on a mesocosm study, sediment PAH levels around railroad ties
appear to be lower than those around aquatic pilings

**Listed Species Considerations**

The Endangered Species Act (ESA) requires that federal agencies consult
with the National Marine Fisheries Service and/or the United States Fish
and Wildlife Services (FWS) for listed organisms if a proposed
\"action\" may affect listed species or their designated habitat.
Because the ecological risk assessment for creosote indicates a
potential for exposure of listed fish and aquatic invertebrate species,
a refined assessment is needed that includes delineation of the action
area and species at risk and evaluation of direct, indirect, and habitat
effects. A refined listed-species assessment has not been conducted for
the current risk assessment but is deferred to Registration Review.

**Data gaps**

The following ecotoxicity guideline studies are outstanding:

**•** Freshwater fish acute toxicity (Guideline no. 850.1075)

**•** Freshwater invertebrate acute toxicity (850.1010)

**•** Estuarine/marine fish acute study (850.1075)

**•** Estuarine/marine shrimp acute study (850.1035)

**•** Estuarine/marine mollusk acute study (850.1025)

**•** Aquatic invertebrate (freshwater) life-cycle study (850.1300)

**•** Fish early life-stage (freshwater) study (850.1400)

**•** Aquatic invertebrate (estuarine/marine) life-cycle study
(850.1300)

**•** Fish early life-stage (estuarine/marine) study (850.1400)

**•** Whole sediment: acute freshwater invertebrates (850.1735)

**•** Whole sediment: acute marine invertebrates (850.1740)

**•** Whole sediment: chronic invertebrates (no guideline no.)

**•** Freshwater diatom (850.5400)

**•** Marine diatom (850.5400)

**•** Blue-green cyanobacteria (850.5400)

**•** Freshwater green alga (850.5400)

**•** Freshwater floating macrophyte duckweed (850.4400)

**•** Freshwater rooted macrophyte rice seedling emergence (850.4225)

**•** Freshwater rooted macrophyte rice vegetative vigor (850.4250)

Submission of the guideline studies would be valuable for refining acute
and chronic risks to aquatic organisms, especially for listed species.
Currently, insufficient toxicity data are available to calculate acute
and chronic risks to benthic organisms as well as chronic risk to
organisms (fish, invertebrates, plants) inhabiting the water column in
either the freshwater or saltwater environment. Acute toxicity data gaps
also exist for some PAHs, and the available data was not generated from
standardized protocols used for guideline studies (e. g., standard
period of exposure, no. concentrations tested, etc.). The ecotoxicity
data could be generated for each of the 8 PAHs addressed in this
assessment. Alternatively, the registrant may wish to conduct the
studies on a complex of the 8 PAHs according to the expected proportion
of each PAH in the water column or sediment. Before conducting any
testing on the complex, the registrant should consult with AD/RASSB to
ensure that any complex tested is deemed appropriate.

Additional data would be needed to further refine the risk
characterization for creosote leaching from either aquatic pilings or
railroad ties:

**•** Field study or simulated field study (850.1950): for aquatic
structures, sediment-concentration data are available for cool northern
conditions (Sooke Basin, Canada) and water-column concentrations have
been determined from microcosm studies; however, major uncertainties
exist for EECs in warmer areas such as the southern U. S. where
differences in environmental conditions will exist. The registrant
should consult RASSB about developing a suitable protocol if it is
decided that further characterization of exposure levels and effects is
warranted and can be addressed by a field study

**•** Leaching study for release of creosote components from
creosote-impregnated wood: an appropriate leaching study would help
refine EECs expected in water and sediments from aquatic structures and
railroad ties, which will be especially important for refining the
exposure assessment for listed species. The registrant should consult
RASSB about developing a suitable protocol

**Required Label Statements**

All creosote product labels must have the following **ENVIRONMENTAL
HAZARDS** statement:

\"This pesticide is highly toxic to aquatic organisms. Do not discharge
effluent containing this product into lakes, streams, ponds, estuaries,
oceans, or other waters unless in accordance with the requirements of a
National Pollutant Discharge Elimination System (NPDES) permit and the
permitting authorities are notified in writing prior to discharge. Do
not discharge effluent containing this product to sewer systems without
previously notifying the local sewage treatment plant authority. For
guidance contact your State Water Board or Regional Office of the EPA.\"

**Table of Contents**

+--------------------------------------------------------------------+---+
| Current Approach to Assessing Risks . . . . . . . . . . . . . . .  | 7 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .      |   |
+--------------------------------------------------------------------+---+
| Assessment Methods . . . . . . . . . . . . . . . . . . . . . . . . | 1 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 0 |
| . .                                                                |   |
+--------------------------------------------------------------------+---+
| > Aquatic Structures . . . . . . . . . . . . . . . . . . . . . . . | 1 |
| > . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 0 |
| > . . .                                                            |   |
+--------------------------------------------------------------------+---+
| Sooke Basin . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 1 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 0 |
+--------------------------------------------------------------------+---+
| Other sources . . . . . . . . . . . . . . . . . . . . . . . . . .  | 1 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    | 1 |
+--------------------------------------------------------------------+---+
| Railroad Ties . . . . . . . . . . . . . . . . . . . . . . . . . .  | 1 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 2 |
| . . .                                                              |   |
+--------------------------------------------------------------------+---+
| Modeling water-column EECs. . . . . . . . . . . . . . . . . . . .  | 1 |
| . . . . . . . . . . . . . . . . . . . . . . . . . .                | 2 |
+--------------------------------------------------------------------+---+
| Sediment concentrations . . . . . . . . . . . . . . . . . . . . .  | 1 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . .          | 3 |
+--------------------------------------------------------------------+---+
| Environmental Fate Summary. . . . . . . . . . . . . . . . . . . .  | 1 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    | 3 |
+--------------------------------------------------------------------+---+
| Aquatic EECs . . . . . . . . . . . . . . . . . . . . . . . . . . . | 1 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 5 |
| . . . .                                                            |   |
+--------------------------------------------------------------------+---+
| Aquatic Structures . . . . . . . . . . . . . . . . . . . . . . . . | 1 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 5 |
| .                                                                  |   |
+--------------------------------------------------------------------+---+
| Water-column concentrations . . . . . . . . . . . . . . . . . . .  | 1 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . .              | 5 |
+--------------------------------------------------------------------+---+
| Sediment concentrations . . . . . . . . . . . . . . . . . . . . .  | 1 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . .          | 7 |
+--------------------------------------------------------------------+---+
| Railroad Ties . . . . . . . . . . . . . . . . . . . . . . . . . .  | 1 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 8 |
| . . .                                                              |   |
+--------------------------------------------------------------------+---+
| Water-column EECs. . . . . . . . . . . . . . . . . . . . . . . . . | 1 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . .          | 8 |
+--------------------------------------------------------------------+---+
| Sediment concentrations . . . . . . . . . . . . . . . . . . . . .  | 1 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . .          | 9 |
+--------------------------------------------------------------------+---+
| Toxicity Data. . . . . . . . . . . . . . . . . . . . . . . . . . . | 2 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 0 |
| . . . . .                                                          |   |
+--------------------------------------------------------------------+---+
| Water Column. . . . . . . . . . . . . . . . . . . . . . . . . . .  | 2 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 1 |
| .                                                                  |   |
+--------------------------------------------------------------------+---+
| Acute toxicity. . . . . . . . . . . . . . . . . . . . . . . . . .  | 2 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 1 |
+--------------------------------------------------------------------+---+
| Chronic toxicity. . . . . . . . . . . . . . . . . . . . . . . . .  | 2 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    | 2 |
+--------------------------------------------------------------------+---+
| Sediments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . | 2 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 3 |
| . . .                                                              |   |
+--------------------------------------------------------------------+---+
| > Other Effects Information . . . . . . . . . . . . . . . . . . .  | 2 |
| > . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 5 |
| > .                                                                |   |
+--------------------------------------------------------------------+---+
| Zooplankton and phytoplankton communities . . . . . . . . . . . .  | 2 |
| . . . . . . . . . . . . . . . . . . . . .                          | 5 |
+--------------------------------------------------------------------+---+
| Herring. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . | 2 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 5 |
| .                                                                  |   |
+--------------------------------------------------------------------+---+
| Mussels . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 2 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 6 |
| .                                                                  |   |
+--------------------------------------------------------------------+---+
| Aquatic Risk Assessment . . . . . . . . . . . . . . . . . . . . .  | 2 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 7 |
| .                                                                  |   |
+--------------------------------------------------------------------+---+
| Water Column. . . . . . . . . . . . . . . . . . . . . . . . . . .  | 2 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 7 |
| .                                                                  |   |
+--------------------------------------------------------------------+---+
| Acute risks. . . . . . . . . . . . . . . . . . . . . . . . . . . . | 2 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 7 |
+--------------------------------------------------------------------+---+
| Chronic risks . . . . . . . . . . . . . . . . . . . . . . . . . .  | 2 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 9 |
+--------------------------------------------------------------------+---+
| Sediments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . | 2 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 9 |
| . . .                                                              |   |
+--------------------------------------------------------------------+---+
| Risk Characterization . . . . . . . . . . . . . . . . . . . . . .  | 3 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 1 |
| . . . .                                                            |   |
+--------------------------------------------------------------------+---+
| Aquatic Structures. . . . . . . . . . . . . . . . . . . . . . . .  | 3 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 1 |
| . .                                                                |   |
+--------------------------------------------------------------------+---+
| Railroad Ties. . . . . . . . . . . . . . . . . . . . . . . . . . . | 3 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 2 |
| . . .                                                              |   |
+--------------------------------------------------------------------+---+
| Listed Species Considerations . . . . . . . . . . . . . . . . . .  | 3 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 3 |
| .                                                                  |   |
+--------------------------------------------------------------------+---+
| Data Gaps . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 3 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 4 |
| . . . . . . .                                                      |   |
+--------------------------------------------------------------------+---+
| Required Label Statements. . . . . . . . . . . . . . . . . . . . . | 3 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 5 |
| .                                                                  |   |
+--------------------------------------------------------------------+---+
| References . . . . . . . . . . . . . . . . . . . . . . . . . . . . | 3 |
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  | 6 |
| . . . . . .                                                        |   |
+--------------------------------------------------------------------+---+
| Appendix A: EECs for Creosote PAHs Leached from Railroad Ties . .  | 4 |
| . . . . . . . . . . . . . . . . . . .                              | 2 |
+--------------------------------------------------------------------+---+
| Appendix B: Ecological Risk Assessment and Characterization. . . . | 5 |
| . . . . . . . . . . . . . . . . . . . . .                          | 5 |
+--------------------------------------------------------------------+---+

**Ecological Hazard and Environment Risk Assessment**

**Creosote Compounds**

Creosote is registered as a preservative to protect wood from fungi,
insects, and marine-boring organisms. Product is applied commercially by
pressurized spray to dry wood intended for exterior/outdoor uses only.
Those uses include railroad cross ties and treated timbers used for
track and bridge construction; electric and telephone utility poles; and
pilings for freshwater and marine docking, seawall structures, and
subsurface foundation support for buildings. According to the American
Wood Preserver's Association, nearly all railroad crossties, switch ties
and bridge timbers, and about 15% of all utility poles, are
pressure-treated with creosote.

Because environmental exposure levels from wood preservative
applications may be of concern for aquatic and terrestrial nontarget
organisms exposed to leachate or runoff, the Agency conducted a
preliminary ecological risk assessment for creosote in December, 2003.
The assessment concluded the following:

> \"The Agency has concluded that risk to birds and terrestrial mammals
> is likely to be minimal, due to lack of exposure and the ability of
> these organisms to avoid creosote. Risk to terrestrial plants would
> also be considered minimal due to lack of exposure. However, risk to
> freshwater and marine/estuarine aquatic organisms is harder to
> quantitate using these data. Certainly there will be some exposure due
> to leaching from the treated wood into the aquatic environment;
> however, determining the amount of exposure and the amount of toxicity
> due to this exposure is difficult using the data at hand. The RQ
> values calculated with the available data do not demonstrate a concern
> for acute effects on aquatic organisms or chronic effects on
> freshwater fish. However, the EECs were calculated for the component
> PAHs, while the aquatic toxicity data were generated using whole
> creosote. The available data found in the open literature were not
> adequate to supply the information needed to assess chronic effects to
> freshwater invertebrates or to marine/estuarine aquatic organisms. It
> is not possible, therefore, to determine the chronic risk creosote may
> present to freshwater invertebrates and marine/estuarine aquatic
> organisms. However, the data indicate that creosote does not exceed
> the level of concern for acute toxicity to fish and aquatic
> invertebrates or for chronic toxicity to freshwater fish.\"

As part of the reregistration process, those findings were deemed to be
preliminary and subject to additional analysis after public review and
comment. Based on stakeholder comments and additional information now
available, the Agency has updated the ecological risk assessment for
aquatic organisms. The preliminary findings of minimal risks to
terrestrial organisms are not being updated due to lack of any
additional information indicating any significant exposure or risk from
currently registered uses of creosote.

**Current Approach to Assessing Risks**

Whereas the preliminary ecological risk assessment only considered the
toxicity of total creosote, the current approach evaluates the toxicity
and exposure of the principal polycyclic aromatic hydrocarbons (PAHs).
Coal-tar creosote is derived from high-temperature carbonization of
bituminous coal, and PAHs comprise up to 85% of the total components of
liquid creosote. Although there are many PAHs in creosote, many occur
only in minor amounts in creosote and in the environment. The following
criteria were used to identify the PAHs of potential concern in the
aquatic environment from leaching of creosote-treated wood used in
railroad ties and aquatic structures:

• individual PAH should comprise at least 2% of total PAHs in creosote

• be a principal PAH detected in the water column and/or sediments of
the

available field and laboratory studies

• be an EPA Priority Pollutant as identified under the Clean Water Act

• exhibit high toxicity to fish and/or aquatic invertebrates

Based on these criteria, the 8 PAHs listed below are the focus of the
updated risk assessment.

+------------------------------------+---------------------------------+
| [PAH]{.underline}                  | \% of liquid                    |
|                                    |                                 |
|                                    | [creosote]{.underline}          |
+------------------------------------+---------------------------------+
| • naphthalene                      | 13                              |
+------------------------------------+---------------------------------+
| • phenanthrene                     | 13                              |
+------------------------------------+---------------------------------+
| • anthracene                       | 13                              |
+------------------------------------+---------------------------------+
| • fluorene                         | 8                               |
+------------------------------------+---------------------------------+
| • acenapthene                      | 4                               |
+------------------------------------+---------------------------------+
| • fluoranthene                     | 4                               |
+------------------------------------+---------------------------------+
| • chrysene                         | 2                               |
+------------------------------------+---------------------------------+
| • pyrene                           | 2                               |
+------------------------------------+---------------------------------+

Risk assessment and characterization integrates exposure and toxicity
information to evaluate the potential for adverse ecological effects. In
most OPP risk assessments for which data are available, acute and
chronic risk quotients (RQs) are determined for aquatic and terrestrial
taxa, where:

*RQ = Exposure estimate (EEC) / Toxicity value (e.g., LC50 or chronic
NOEC)*

Risk presumptions are then made by comparing the RQs to OPP\'s levels of
concern (LOCs) (see Appendix B for additional details). For creosote,
acute toxicity data for exposure in the water column (freshwater and
saltwater fish and invertebrates) are available for most of the 8 PAHs
that are the focus of this risk assessment. However, toxicity varies
among individual PAHs, and data for the individual constituents present
in creosote do not allow for assessing the combined toxicity of all PAHs
that may diffuse from treated wood (Poston 2001). Risk to aquatic
organisms from a PAH complex depends not only on the toxicity of the
individual PAHs in the complex but also on the relative proportions of
PAHs in the water column. Therefore, to calculate an acute toxicity
value for the complex of PAHs expected in the water column from
creosote-treated aquatic structures and railroad ties, individual PAH
toxicity values are weighted based on the relative proportion of each
PAH in liquid creosote. The sum of the toxicity value (LC50 or EC50)
times the percentage of each PAH is divided by the sum of each PAH in
creosote. A weighted acute toxicity value is calculated by taxa (fish,
aquatic invertebrate) and environmental media (freshwater, saltwater) as
follows:

*PAH Complex Toxicity = ∑ (LC50 or EC50 \* % of each PAH in creosote) /
∑ PAHs in creosote*

For most PAHs, little or no sediment-toxicity or chronic toxicity data
are available. Thus, by necessity, much of the assessment for chronic
exposure and exposure to PAHs in sediments relies mainly on a lines-of
evidence evaluation of the available field and laboratory data.

Many other uncertainties exist in assessing risks of creosote in the
aquatic environment. Local biotic and abiotic conditions will have a
considerable influence on the potential for adverse affects, and
site-specific assessments are needed to best evaluate those risks.
Hutton and Samis (2000 in SCI 2005) identified several key factors that
will impact exposure and toxicity on a site-specific basis:

• background water (and sediment) qualities

• velocity and direction of water currents

• proximity of structures to habitats of sensitive aquatic organisms

• the timing of construction of structures

• size of structure in relation to the receiving water body

• treatment methods

• cumulative effects from all sources of PAHs

Some of the factors mentioned above will be discussed in the assessment,
whereas little no information is available for others. Data exist
demonstrating that temperature and salinity impact creosote leaching
rates and possibly toxicity, and the amount of organic matter in
sediments will influence the amount of some PAHs in water and sediments.
The timing of construction of new aquatic structures may be important in
relation to exposure of sensitive life stages (e. g., embryo, juvenile)
of aquatic organisms present in the vicinity. Another confounding factor
in assessing risks of organisms from creosote is that PAHs reach the
aquatic environment from many other sources, including wood combustion,
coal-tar sealants, tire wear, vehicle exhaust, and numerous others
(Valle et al. 2007, Brooks 2004).

The current assessment for aquatic organisms exposed to creosote
components derived from aquatic structures is based in part on a field
study conducted in the Sooke Basin of Canada in the mid-1990s. The
purpose of the study was to evaluate the impact of creosote-treated wood
on the marine environment, especially from contaminated sediments. The
study focused on the chemical and biological effects from three newly
installed six-piling dolphins constructed of either freshly treated,
weathered (i. e., previously immersed for 8 years), or untreated
pilings. The following endpoints were evaluated:

• PAH concentrations in sediment as a function of time and distance from
dolphins

• infaunal response to treated pilings

• survival, growth, PAH accumulation, PAH partitioning in gonadal and
non-gonadal tissues and reproductive bioassays of mussels (*Mytilus
edulis edulis*)

• laboratory bioassays using pore water and solid phase Microtox™,
echinoid fertilization inhibition, and amphipod survival

• water-column PAH concentrations adjacent to pilings after 6 months

Because field data are not available for creosote use on railroad
structures, the major use of creosote, an updated modeling scenario is
used to estimate PAH exposure concentrations in the aquatic environment
resulting from environmental transport of PAHs from railroad beds. The
preliminary assessment relied on aquatic Estimated Environmental
Concentrations (EECs) derived from OPP\'s Generic Estimated Exposure
Concentrations (GENEEC) screening (first-tier) model. GENEEC uses
application information, soil/water partition data, and degradation
kinetics to estimate high-level exposure values for a farm-pond
scenario. Unlike higher-tier models, the program is generic in that it
is a single-event model and does not consider differences in climate,
soils, or topography in estimating potential pesticide exposure. The
updated risk assessment uses PRZM-EXAMS modeling to predict water column
concentrations resulting from creosote use on railroad ties. Some
information on PAH concentrations in sediments is available from a
mesocosm study conducted by Brooks (2004).

**Assessment Methods**

**Aquatic Structures**

[Sooke Basin]{.underline}

The Sooke Basin field study was initiated in 1995 to examine the
temporal and spatial effects of creosote-treated wood pilings placed in
the aquatic environment (Goyette and Brooks 1998, 2001). The site was
chosen due to low background PAH levels, minimal external sources of
contamination, and uniformity in sediment and oceanographic conditions
in the test area. Two treated and one untreated six-piling dolphins were
installed approximately 60 meters offshore in early October. Each
teepee-shaped dolphin was constructed of 30-cm diameter Douglas fir
pilings, arranged with a single center piling and a base diameter of at
least 2.5 to 3.0 m. This arrangement allowed sufficient area for
downstream sampling transects and gave the structure enough mass to
ensure chemical contamination of bottom sediments. One dolphin was
constructed with freshly treated pilings treated in accordance with the
wood-preservative industry's Best Management Practices (BMP)[^1]. Target
retention was 17 pounds of creosote per cubic foot of wood (pcf) in the
treated zone (the outer 6 cm shell of the piling); actual retention was
27 pcf. A second dolphin was constructed of 8-year-old weathered pilings
(WP) that had been previously treated by conventional methods. A third
untreated dolphin comprised a mechanical control (MC), and an open area
without any dolphin present was included as an unstructured open control
(OC).

Water column PAH concentrations were measured approximately 6 months
(April 1996) and 8 months (June 1996) after the dolphins were installed.
Semi-permeable membranes (30 x 60 cm polyethylene sheets) were used to
estimate concentrations of PAHs in the water column. The sheets
(prepared and analyzed by the Battelle Marine Sciences Laboratory,
Sequim, Washington) were deployed on metal hangars installed on the
piling by divers. Three membrane devices were suspended 15 cm from the
face of the BMP piling at a depth of 4 m; one upstream, one downstream,
and a third on the offshore side of the dolphin. The first set of sheets
was installed on April 1 (PAHs detected on all membranes) and a second
set was installed in early June (no PAH detections). Following exposure
for approximately two weeks for each set, the sheets were returned to
their polyethylene bags, brought to the surface, and shipped to the
Battelle Laboratory for analysis.

Sooke Basin sediment PAH concentrations were measured on upstream and
downstream transects as a function of time and distance from the various
dolphin treatments. Physical and chemical baseline sampling was
completed on September 14-15, 1995, and the baseline infaunal inventory
was accomplished just prior to piling installation on October 3. Post
installation sampling was conducted on Day 14 to assess the immediate
effects following construction; on Day 185 as a mid-point; and on Day
384. Some limited additional sampling was accomplished on Day 270 and
Day 535. Follow-up surveys were conducted 1360 and 1540 days after
construction to evaluate longer-term responses.

Sediment sampling transects consisted of four parallel lines, spaced
approximately 0.67 meters apart. Additional sampling transects were laid
out on the upstream side of each dolphin and along the centerline
between treatments. Upstream samples were collected to verify that
higher PAH accumulation occurred in sediments on the downstream
transect. The midpoint between treatment sites was also sampled to
provide chemistry data in case the influence from one treatment site
overlapped the adjacent treatment. Downstream sediment samples were
collected at 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 5.0, 7.5, 10.0, 20.0,
30.0, and 50.0 meters. Upstream samples from the BMP dolphin were
collected at 2.0, 5.0, and 10.0 meters and 2.0 and 28 meters from the
weathered pilings. At each sampling site, samples were collected from
the least contaminated sediments (most distant from the dolphin) to the
most contaminated sediments (adjacent to the dolphin) using a single
sampling fixture and utensils for each treatment site. Sediment samples
were collected by SCUBA divers using a 0.032 m^2^ hand-held sampler.

[Other sources]{.underline}

Sooke Basin PAH concentrations measured only after 6 months will not be
used to predict PAH concentrations expected within a few days or weeks
of installation of an aquatic structure. Because estimated half-lives of
PAHs in water are estimated to be in the range of 1 to a few weeks, PAH
concentrations are likely to be much higher in the first few days and
weeks after creosote reaches the water column. Field data are lacking,
but some information is available on measured PAH concentrations within
the first days and weeks after creosote-treated pilings were placed in
tanks of water. Ingram et al. (1982) immersed creosote-treated southern
pine pilings in 300-gal tanks of seawater at 18 to 21^0^C. The pilings
had been treated with 354-378 kg/m^3^ (22--23.5 lb/ft^3^) creosote and
aged for 6 months in open air before being immersed in the tanks**.**
PAH concentrations in the water were measured after 72 and 288 hours.
Bestari et al. (1998) measured PAH concentrations for 12 weeks in
12,000-L outdoor, freshwater microscosms designed to mimic
field-leaching from creosote-impregnated Douglas fir pilings (15- to
20-cm diameter, 1.2-m long pilings). A total of 6 treated and untreated
pilings were situated in each microcosm (0, 0.5, 1, 2, 3, 4, or 6
treated pilings per microcosm). The microscosms also contained sediment
and an array of aquatic organisms. The sediment was natural riverine
sediment consisting of 53% sand/gravel, 25% silt, 22% clay, with 5.1%
organic matter. Water and sediment samples were analyzed for PAH
concentrations the day before pilings were immersed in the microcosms, 2
and 5 days after immersion, weekly for 4 weeks, and biweekly thereafter.

> **Railroad Ties**

[Modeling water-column EECs]{.underline}

EPA's PE5 PRZM-EXAMS Model Shell is used to estimate PAH concentrations
in surface water and sediment pore water due to creosote leaching from
railroad ties (Appendix A). This model simulates the transport of
chemicals from agricultural settings to adjacent surface water bodies.
Inputs to the model include initial application rates of PAH compounds
to the agricultural soil compartment, physical-chemical properties of
the compounds, and assumptions regarding agricultural scenarios. Outputs
include instantaneous, 96-h, 21-, 60-, 90-day-avergage and
annual-average concentrations of selected PAHs in the water column,
sediment pore water, and soil.

PE5 was developed to evaluate surface water contamination resulting from
the application of chemicals (e.g., pesticides) to agricultural crops
and soil. Therefore, the model uses as an input a chemical application
rate in kilograms chemical applied per hectare of crop area. Because
this analysis uses PE5 to evaluate a wood preservative rather than an
agricultural pesticide, releases of the wood preservative chemicals from
treated wood surfaces must be expressed as a soil compartment loading
rate in kilograms per hectare. Chemical-specific properties required as
inputs to PE5 include molecular weights, Henry's Law Constants, vapor
pressures, solubility, soil partition coefficients (Koc), and half-lives
of each compound in water, soil, and sediment. Values for these inputs
were obtained from previously compiled chemical-specific data (Versar
2006).

PE5 was run for each of nine PAH compounds[^2] for two agricultural
scenarios: a California fruit orchard scenario and a Mississippi cotton
scenario. The scenarios differ in that they are characterized by
different local meteorological conditions and soil properties. The
scenarios also include assumptions about agricultural processes that
affect the fate and transport of chemicals in the farm environment.
Examples of these assumptions include the chemical application method,
incorporation depth, application efficiency, spray drift (if
applicable), and number of applications of the compound. Values for the
agricultural assumptions were made according to the guidance of R.
Parker (EPA Office of Pesticide Programs).

PE5 calculates multiple-year chemical concentrations in the water and
sediments (pore water), which are then reported as the single-day peak
concentration, the maximum 24-h, 96-h, 21-day, 60-day, and 90-day mean
concentrations, and the mean annual concentration (EPA 2006). Model
outputs display 3^rd^ through 96^th^ percentile concentrations of the
single-year results (e.g., the upper tenth percentile of the mean annual
concentrations).

The following assumptions are used to calculate the amount of individual
PAHs leached from the rail road ties into soil:

• a railroad crosses a 10-ha field that is 1000 m long

> • two sets of rails cross the field

• all crossties are treated with creosote

• crosstie specifications:

Width = 9 in (0.229 m)

Height = 7 in (0.178 m)

Length = 8.5 ft (2.590 m)

Spacing between the crossties on the rail = 0.495 m

[Sediment concentrations]{.underline}

Brooks (2004) used mesocosms to evaluate movement of PAHs from railroad
ties into ballast and adjacent wetland sediments in Illinois in 1998.
The study was conducted to determine potential risk of creosote to the
endangered Hines emerald dragonfly (*Somatochlora hineana*) that
inhabits wetland areas crossed by a rail line. Each mesocosm contained
freshwater, native wetland soil (60 cm deep), broken limestone ballast
(19-38 mm), and 3 standard-size railroad crossties placed in a manner
identical to the railroad right-of-way. One mesocosm contained newly
treated ties, a second contained weathered ties, and a third contained
untreated (red oak) ties. PAH levels were determined in ballast and
sediments in each mesocosm after 10 days and at 3, 6, 9, 12, 15, and 18
months. Ballast samples for PAH analysis were collected 5 to 30 cm from
the ties. Sediment samples were collected along transects from 0 to 75
cm away from the edge of the ballast. Some additional core samples also
were collected at the end of the study.

**Environmental Fate Summary**

Fate properties and expected pathways of the PAHs leached from
creosote-treated structures are presented in detail in the Updated
Creosote Environmental Fate Chapter. Only a brief mention of the data
relevant to the ecological risk assessment is presented here, including
half-lives of individual PAHs in various environmental compartments and
their potential for bioaccumulation in aquatic organisms. Those
properties relevant to the modeling of PAH leaching and environmental
transport from creosote-treated railroad structures are presented in
Appendix A.

Estimated half-lives of PAHs in water, soil and sediments are presented
in Table 1. The half-lives of the PAHs in these environmental
compartments tends to increase with increasing complexity of the
molecules (Howard et al. 1991). K~ow~ values also increase with the
complexity of the PAH. Half-lives in water (and air) are much lower than
in soils and sediments.

**Table 1. Estimated Half-lives of PAHs in Various Environmental Media**

+-------------+---------+---------+--------+--------+--------+-------+
| **PAH**     | **No.   | **Mol   | **Est. |        |        | **K~  |
|             | aro     | ecular\ | hal    |        |        | ow~** |
|             | matic** | wt**    | f-life |        |        |       |
|             |         |         | (we    |        |        |       |
|             | **      |         | eks)** |        |        |       |
|             | rings** |         |        |        |        |       |
+-------------+---------+---------+--------+--------+--------+-------+
|             |         |         | **w    | **     | **sedi |       |
|             |         |         | ater** | soil** | ment** |       |
+-------------+---------+---------+--------+--------+--------+-------+
| Naphthalene | 2       | 128     | 1      | 8      | 32     | 3.37  |
+-------------+---------+---------+--------+--------+--------+-------+
| Acenapthene | 3       | 152     | 3      | 32     | 104    | 4.03  |
+-------------+---------+---------+--------+--------+--------+-------+
| Fluorene    | 3       | 166     | 3      | 32     | 104    | 4.12  |
+-------------+---------+---------+--------+--------+--------+-------+
| P           | 3       | 178     | 3      | 32     | 104    | 4.57  |
| henanthrene |         |         |        |        |        |       |
+-------------+---------+---------+--------+--------+--------+-------+
| Anthracene  | 3       | 178     | 3      | 32     | 104    | 4.54  |
+-------------+---------+---------+--------+--------+--------+-------+
| F           | 4       | 202     | 8      | 104    | 312    | 5.22  |
| luoranthene |         |         |        |        |        |       |
+-------------+---------+---------+--------+--------+--------+-------+
| Pyrene      | 4       | 202     | 8      | 104    | 312    | 5.18  |
+-------------+---------+---------+--------+--------+--------+-------+
| Chrysene    | 4       | 228     | 8      | 104    | 312    | 5.91  |
+-------------+---------+---------+--------+--------+--------+-------+

Half-lives in tissues of aquatic organisms are discussed in the Updated
Creosote Environmental Fate Chapter. Aquatic organisms remove residues
with half-lives of only a few days for the PAHs addressed in this
assessment (Table 2). Biomagnification apparently is not a concern,
because vertebrates metabolically transform PAHs and excrete them before
they accumulate to higher levels (Brummelen et al. 1998 in Poston 2001).

**Table 2. Half-lives of PAHs in Aquatic Organisms**

  --------------------------------------------------------------------------
  **Species**            **PAH**                        **Half-life (days)**
  ---------------------- ------------------------------ --------------------
  ***Vertebrates:***                                    

  Rainbow trout          fluoranthene                   6

                         fluorene                       7

                         anthracene                     7

                         phenanthrene                   9

  ***Invertebrates:***                                  

  Mussel                 anthracene                     1.9

                         naphthalene                    2

                         phenanthrene                   1.9-2.2

                         fluoranthene                   2.0-11.1

                         pyrene                         4.1-5.5

                         chrysene                       5.0-14.2

                         fluoranthene                   29.8

  Clam                   napthalene                     2.0

                         chrysene                       3.3

                         fluoranthene                   3.3

                         pyrene                         3.6-10.3

                         phenanthrene                   4.5-6.1

                         fluoranthene                   8.4

  Oyster                 phenanthrene                   3.4

                         pyrene                         6.7

                         fluoranthene                   5.9

                         chrysene                       15.1

  Shrimp                 fluoranthene                   0.8

                         pyrene                         0.8

                         phenanthrene                   0.9

  Polychaete             chrysene                       4.3

                         phenanthrene                   4.8

                         pyrene                         4.8

                         fluoranthene                   5.8
  --------------------------------------------------------------------------

As discussed in the Updated Creosote Environmental Fate Chapter, the
rate at which PAHs leach from treated wood is a function of many factors
including the nature of the wood, the treatment solution and method, and
various environmental variables. Compounds with lower boiling points,
low molecular weight (\<200 atomic mass units) with 1 to 3 rings
dissolve more readily in the water column than heavier PAHs. The higher
molecular weight PAHs (\>200 atomic mass units) with more than 3 benzene
rings, are lost from the wood more slowly. These heavier PAHs are more
likely to accumulate in sediments than remain dissolved in the water
column (SCI 2005). The factors that affect leaching rates most
significantly are temperature, water chemistry, water flow, and
disturbance or abrasion (e.g., Ingram et al. 1982, Xiao et al. 2002).
Leaching rates are higher in freshwater than saltwater. The combined
effects of temperature and flow are greater than the effects of either
alone.

**Aquatic EECs**

**Aquatic Structures**

[Water-column concentrations]{.underline}

PAH concentrations in the water column adjacent to treated BMP pilings
in Sooke Basin are presented in Table 3. Concentrations were not
measured until early April, 1996, approximately 6 months after the
dolphins were installed. The total of all 16 PAHs after 6 months was
0.031 µg/L, with 5 of the 16 PAHs accounting for more than 91% of the
total amount detected in the water column at that time. PAHs were not
detected in the water column 2 months later (i. e., 8 months after
installation).

**Table 3. PAH Concentration in the Water Column within 25 cm of the
Creosote-treated Pilings at the BMP Dolphin in the Sooke Basin Creosote
Evaluation Study (from Goyette and Brooks 1998)**

  -----------------------------------------------------------------------
  **PAH**                           **Concentration (µg/L)**
  --------------------------------- -------------------------------------
  Acenaphthene                      0.007

  Naphthalene                       0.007

  Phenanthrene                      0.006

  Fluorene                          0.005

  Fluoranthene                      0.004

  Chrysene                          \<0.001

  Pyrene                            \<0.001

  Anthracene                        \<0.001

  Others^a^                         \<0.001

  Total PAH                         0.031
  -----------------------------------------------------------------------

^a^ acenaphthylene, benzo\[a\]anthracene, benzo\[a\]pyrene,
benzo\[ghi\]pereylene, benzofluoranthenes, ideno\[1,2,2-cd\]pyrene,
dibenzo\[a,h\]anthracene

The Sooke Basin water-column concentrations after 6 months may be
indicative of PAH concentrations due to long-term leaching out of
existing structures or might only be background levels. Because PAHs
degrade with estimated half-lives of one to several weeks in water,
concentrations likely were much higher in the first few days and weeks
after the dolphins were installed.

Although field data are not available, studies conducted in large tanks
provide evidence that initial PAH concentrations could be much higher
than the Sooke Basin values were after 6 months. Ingram et al. (1982)
reported a total PAH concentration of 432 ppb at 72 hours after
immersion of creosote-treated pilings in 300-gal tanks of saltwater
(Table 4). Total PAH concentration declined to 156 ppb after 288 hours
(12 days). In 12,000-L microscosms containing creosote-impregnated
pilings, Bestari et al. (1998) found that total PAH water-column
concentrations increased rapidly up to 7 days and were dose-dependant,
ranging from 7.3 µg/L (0.5-piling microcosm) to 97.2 µg/L (6-piling
microcosm). Total PAH concentration declined exponentially after 7 days
to 0.8 to 6.7µg/L (background concentrations) after 12 weeks.
Naphthalene, acenapthene, fluorine, phenanthrene, fluoranthene, and
pyrene were the most prevalent PAHs detected in the water column.

**Table 4. Total PAH Concentrations in Tanks and Outdoor Microcosms**

+------------------+---------------+--------------------+-------------+
| **Site**         | **Time after  | **Total PAH        | **Source**  |
|                  | initial       | concentration**    |             |
|                  | exposure**    |                    |             |
|                  |               | **(µg/L)**         |             |
+------------------+---------------+--------------------+-------------+
| 300-gal tanks of | 72 hr         | 432                | Ingram et   |
| seawater         |               |                    | al. 1982    |
+------------------+---------------+--------------------+-------------+
|                  | 12 days       | 156                |             |
+------------------+---------------+--------------------+-------------+
| 1200-L outdoor,  | 7 days        | 7.3-97.2           | Bestari et  |
| freshwater       |               |                    | al. 1998    |
| microcosms       |               |                    |             |
+------------------+---------------+--------------------+-------------+
|                  | 84 days       | 0.8-6.7            |             |
+------------------+---------------+--------------------+-------------+

Ingram et al. (1982) also evaluated leaching from samples of newly
treated and aged (12-year-immersed) pilings in freshwater and in
saltwater in 4-L glass beakers for 30 days. Final concentrations in were
\~750 µg/L for aged (12 year) wood in saltwater and \~1000 µg/L for
recently treated wood in freshwater, indicating considerable leaching
even from aged creosote-treated wood. The authors also reported that
leaching was higher in freshwater than in saltwater and increased with
increasing water temperature (20^0^ to 40^0^C).

[Sediment concentrations]{.underline}

Sooke Basin PAH sediment concentrations at various distances from
creosote-treated pilings after 384 days are presented in Table 5. The
maximum sediment concentration was observed 0.5 m down-gradient after 14
days (105 mg/kg TPAH). The higher molecular-weight PAHs (HPAH),
particularly fluoranthene and chrysene, were most prevalent in the
sediment. There was a general trend toward decreasing levels of low
molecular weight compounds (naphthalene, acenaphthylene, acenaphthene
and fluorene) over time, whereas the proportion of fluoranthene and
heavier compounds increased with time in the sediments. Differences in
the proportions of low and high molecular weight compounds were observed
between BMP and WP piling. Sediments adjacent to the BMP piling
contained a higher proportion of the more easily degraded low molecular
weight compounds and sediments associated with the WP piling contained a
higher proportion of the high molecular weight compounds. At 384 days,
the proportion of high molecular weight compounds associated with the
BMP piling was rapidly approaching that of the WP piling. These data
suggest that during the BMP treatment process, losses of low molecular
weight compounds, particularly naphthalene, acenaphthylene and
acenaphthene, do occur. The intermediate weight compounds, phenanthrene
and anthracene are enhanced, and those compounds heavier than anthracene
remained in a relatively constant proportion.

Maximum predicted and observed total PAH concentrations after 384 days
exposure were significantly elevated to a distance of 7.5 m downstream
from the BMP dolphin but not beyond. At 384 days, observed PAH
concentrations declined sharply between 7.5 and 10 meters. Small
increases of 0.2 to 0.3 µg/g TPAH (dry wt) sediment were observed
downstream to a distance of 50 m. Sediment concentrations were similar
at both the BMP and WP piling treatment sites. Due to the uneven nature
of the creosote contamination, a high degree of variability in PAH
concentrations was observed in replicate samples from the BMP and WP
piling sites, particularly near the dolphin structure.

**Table 5. PAH Sediment Concentration at Increasing Distances from
Creosote-treated Pilings at the BMP Dolphin in the Sooke Basin Creosote
Evaluation Study (from Goyette and Brooks 1998)**

  -------------------------------------------------------------------------------
  **PAH**                **Concentration                             
                         (µg/g dry                                   
                         wt)^a^**                                    
  ---------------------- ----------------- ------------ ------------ ------------
                         **0.5 m**         **1 m**      **5 m**      **10 m**

  Fluoranthene           3.480             1.514        0.689        0.212

  Chrysene               2.407             1.022        0.249        0.102

  Pyrene                 1.670             0.685        0.418        0.111

  Phenanthrene           1.564             0.603        0.405        0.094

  Anthracene             1.260             0.258        0.101        0.030

  Fluorene               0.425             0.156        0.107        0.035

  Acenaphthene           0.372             0.117        0.112        0.036

  Naphthalene            0.052             0.017        0.017        0.013

  Others^b^              4.894             2.122        0.611        0.265

  Total HPAH             12.420            5.327        1.962        0.294

  Total LPAH             3.705             1.166        0.747        0.210

  Total PAH              16.125            6.493        2.709        0.504
  -------------------------------------------------------------------------------

^a^ Goyette and Brooks (1998) also provide sediment concentrations at
1.5, 2.0, 2.5, 3.5, and 7.5 m from BMP pilings

^b^ benzofluoranthenes, benzo\[a\]anthracene, benzo\[a\]pyrene,
benzo\[e\]pyrene, ideno\[1,2,2-cd\]pyrene, benzo\[ghi\]pereylene,
dibenzo\[a,h\]anthracene, acenaphthylene

> **Railroad Ties**

[Water-column EECs]{.underline}

Modeled time-averaged EECs for creosote-treated railroad structures are
presented in Table 6. EECs are higher for the wet (MS) scenario than for
the dry (CA) scenario. See Appendix A for more information on these
scenarios and model assumptions.

**Table 6. Estimated PAH Concentrations (10^th^ percentile) in Surface
Water Due to Leaching from Creosote-treated Railroad Ties in Mississippi
and California Scenarios.**

  -------------------------------------------------------------------------------------------
  **PAH**          **avg. EEC                                                    
                   (µg/L)**                                                      
  ---------------- ---------- ----------- ------------ ------------ ------------ ------------
                   **0-hr**   **96-hr**   **21-day**   **60-day**   **90-day**   **annual**

  ***Mississippi                                                                 
  Cotton                                                                         
  Scenario:***                                                                   

  Naphthalene      90.5       56.6        29.2         14.9         11.4         3.3

  Anthracene       59         33.9        16.0         11.5         10.3         6.0

  Phenanthrene     57.1       31.4        14.1         9.4          8.6          4.6

  Fluorene         45.5       29.8        16.4         9.8          8.9          3.7

  Acenaphthene     22.8       14.9        8.2          5.0          4.5          1.9

  Fluoranthene     20.9       12.2        8.0          7.1          6.9          6.1

  Chrysene         7.4        3.1         1.4          0.9          0.9          0.6

  Pyrene           7.2        2.6         1.1          0.7          0.7          0.4

  subtotal         310.4      184.5       94.4         59.3         52.2         26.6

  ***California                                                                  
  Fruit Orchard                                                                  
  Scenario:***                                                                   

  Naphthalene      24.6       15.6        6.2          2.5          1.7          0.4

  Fluorene         8.1        5.5         2.1          0.8          0.6          0.2

  Anthracene       4.9        2.3         0.9          0.5          0.5          0.2

  Phenanthrene     4.8        2.1         0.7          0.4          0.4          0.2

  Acenaphthene     4.2        2.7         1.1          0.5          0.4          0.1

  Fluoranthene     1.4        0.6         0.3          0.2          0.2          0.2

  Chrysene         0.5        0.2         0.05         0.04         0.03         0.02

  Pyrene           0.5        0.15        0.04         0.03         0.02         0.01

  subtotal         49.0       29.1        11.4         5.0          3.8          1.3
  -------------------------------------------------------------------------------------------

[Sediment concentrations]{.underline}

Mean total PAH concentrations in mesocosm sediments after 10 days and
after 3, 12, and 18 months (Brooks 2004) are presented in Table 7. PAHs
also were detected in ballast at each of these times, but concentrations
were considerably lower and are not presented here (see Brooks 2004).
Sediment concentrations varied with time and distance in all treatments.

**Table 7. PAH Sediment Concentration at Selected Times and Distances
from Railroad Ties in Mesocosms (from Brooks 2004)**

+-----------+-----------+-----------+-----------+-----------+-----------+
| **M       | **D       | **Mean    |           |           |           |
| esocosm** | istance** | TPAH      |           |           |           |
|           |           | (µ        |           |           |           |
|           | **(cm)**  | g/g)^a^** |           |           |           |
+===========+===========+===========+===========+===========+===========+
|           |           | **10      | **3 mo.** | **12      | **18      |
|           |           | days**    |           | mo.**     | mo.**     |
+-----------+-----------+-----------+-----------+-----------+-----------+
| Untreated | 0         | 0.292     | 0.356     | 4.160     | 1.060     |
|           |           |           |           |           |           |
| ties      |           |           |           |           |           |
+-----------+-----------+-----------+-----------+-----------+-----------+
|           | 25        | 0.325     | nr^b^     | 4.213     | nr        |
+-----------+-----------+-----------+-----------+-----------+-----------+
|           | 50        | 0.425     | 0.744     | 1.520     | 1.589     |
+-----------+-----------+-----------+-----------+-----------+-----------+
|           | 75        | 0.314     | 0.366     | 1.347     | 1.191     |
+-----------+-----------+-----------+-----------+-----------+-----------+
| Newl      | 0         | 0.727     | 0.444     | 1.136     | 1.357     |
| y-treated |           |           |           |           |           |
|           |           |           |           |           |           |
| ties      |           |           |           |           |           |
+-----------+-----------+-----------+-----------+-----------+-----------+
|           | 25        | 0.456     | nr        | 1.439     | nr        |
+-----------+-----------+-----------+-----------+-----------+-----------+
|           | 50        | 0.376     | 0.743     | 1.610     | 1.306     |
+-----------+-----------+-----------+-----------+-----------+-----------+
|           | 75        | 0.319     | 0.407     | 1.319     | 0.747     |
+-----------+-----------+-----------+-----------+-----------+-----------+
| Weathered | 0         | 3.964     | 0.712     | 1.503     | 3.437     |
|           |           |           |           |           |           |
| ties      |           |           |           |           |           |
+-----------+-----------+-----------+-----------+-----------+-----------+
|           | 25        | 1.108     | nr        | 1.187     | nr        |
+-----------+-----------+-----------+-----------+-----------+-----------+
|           | 50        | 0.378     | 6.743     | 1.313     | 1.959     |
|           |           |           |           |           |           |
|           |           |           | (0.320)   |           |           |
+-----------+-----------+-----------+-----------+-----------+-----------+
|           | 75        | 0.274     | 0.534     | 1.232     | 1.708     |
+-----------+-----------+-----------+-----------+-----------+-----------+

^a^ Brooks (2004) also reported mean TPAH sediment concentrations after
6, 9, and 15 months

^b^ nr = not reported

**Toxicity data**

The toxicity endpoints typically used in OPP\'s assessments are obtained
from guideline toxicity studies conducted for wildlife, aquatic
organisms, and plants (40 CFR §158.2060). Guideline studies are required
for all pesticides to provide acute and chronic measures of effect for
one or more test species in several taxonomic groups. As noted in the
2003 preliminary ecological risk assessment, guideline toxicity studies
are not available for creosote. The preliminary assessment relied on the
whole creosote data available in the open literature, but insufficient
data were obtained to assess chronic effects to freshwater invertebrates
or to marine/estuarine aquatic organisms. For the updated assessment,
available acute and chronic toxicity information for the PAHs has been
obtained from the open literature, including relevant laboratory,
microcosm, and field studies obtained through ECOTOX searches and other
sources, including EPA Sediment Quality Criteria documents for
fluoranthene (EPA 1993a), phenanthrene (EPA 1993b), and acenaphthene
(EPA 1993c).

**Water Column**

[Acute toxicity]{.underline}

Most PAHs for which data are available are highly to very highly toxic
to freshwater and saltwater fish and invertebrates (Table 8), with
anthracene and fluoranthene being the most toxic PAHs in the water
column.

**Table 8. Acute Toxicity of Creosote PAHs to Fish and Invertebrates
Exposed in the Water Column**

+-------+--------------------------+---------+---------+-------------+
| **P   | **Species**              | **Exp   | **LC    | **Source**  |
| AH/** |                          | osure** | 50/EC50 |             |
|       |                          |         | (       |             |
| **    |                          | **d     | µg/L)** |             |
| media |                          | uration |         |             |
| ^a^** |                          | (h)**   |         |             |
+=======+==========================+=========+=========+=============+
| **An  |                          |         |         |             |
| thrac |                          |         |         |             |
| ene** |                          |         |         |             |
+-------+--------------------------+---------+---------+-------------+
| SW    | Fish - no data           |         |         |             |
+-------+--------------------------+---------+---------+-------------+
|       | Mysid shrimp             | 48      | 3.6     | Pelletier   |
|       |                          |         |         | 1997        |
+-------+--------------------------+---------+---------+-------------+
| FW    | Bluegill (*Lepomis       | 96      | 1.27    | McCloskey   |
|       | macrochirus*)            |         |         | 1991        |
+-------+--------------------------+---------+---------+-------------+
|       | Scud (*Hyalella azteca*) | 240     | 5.6     | Hatch 1999  |
+-------+--------------------------+---------+---------+-------------+
| *     |                          |         |         |             |
| *Fluo |                          |         |         |             |
| ranth |                          |         |         |             |
| ene** |                          |         |         |             |
+-------+--------------------------+---------+---------+-------------+
| SW    | Sheepshead minnow        | 96      | 0.8     | EPA 1993b   |
+-------+--------------------------+---------+---------+-------------+
|       | Mysid shrimp             | 96      | 0.58    | Spehar 1999 |
+-------+--------------------------+---------+---------+-------------+
| FW    | Fathead minnow           | 96      | 6.8     | Diamond     |
|       |                          |         |         | 1995        |
+-------+--------------------------+---------+---------+-------------+
|       | Water flea               | 48      | 0.97    | Spehar 1999 |
+-------+--------------------------+---------+---------+-------------+
| *     |                          |         |         |             |
| *Acen |                          |         |         |             |
| aphth |                          |         |         |             |
| ene** |                          |         |         |             |
+-------+--------------------------+---------+---------+-------------+
| SW    | Sheepshead minnow        | 96      | 2200    | Heitmuller  |
|       |                          |         |         | 1981        |
+-------+--------------------------+---------+---------+-------------+
|       | Mysid shrimp             | 96      | 160     | EPA 1993c   |
+-------+--------------------------+---------+---------+-------------+
| FW    | Brown trout (*Salmo      | 96      | 580     | Holcombe    |
|       | trutta*)                 |         |         | 1983        |
+-------+--------------------------+---------+---------+-------------+
|       | Stone fly (*Tallaperla   | 96      | 240     | Horn 1983   |
|       | maria*)                  |         |         |             |
+-------+--------------------------+---------+---------+-------------+
| **    |                          |         |         |             |
| Fluor |                          |         |         |             |
| ene** |                          |         |         |             |
+-------+--------------------------+---------+---------+-------------+
| SW    | Fish - no data           |         |         |             |
+-------+--------------------------+---------+---------+-------------+
|       | Polychaete worm          | 96      | 1000    | Rossi 1978  |
+-------+--------------------------+---------+---------+-------------+
| FW    | Bluegill                 | 96      | 760     | Mayer 1986  |
+-------+--------------------------+---------+---------+-------------+
|       | Water flea               | 48      | 420     |             |
+-------+--------------------------+---------+---------+-------------+
| **Nap |                          |         |         |             |
| hthel |                          |         |         |             |
| ene** |                          |         |         |             |
+-------+--------------------------+---------+---------+-------------+
| SW    | Sheepshead minnow        | 24      | 2400    | Anderson    |
|       |                          |         |         | 1974        |
+-------+--------------------------+---------+---------+-------------+
|       | Humpy shrimp (*Pandalus  | 96      | 971     | Korn 1979   |
|       | goniurus*)               |         |         |             |
+-------+--------------------------+---------+---------+-------------+
| FW    | Pink salmon              | 96      | 890     | Rice 1989   |
|       | (*Oncorhyncus            |         |         |             |
|       | gorbuscha*)              |         |         |             |
+-------+--------------------------+---------+---------+-------------+
|       | Water flea (*Daphnia     | 96      | 1000    | Trucco 1983 |
|       | pulex*)                  |         |         |             |
+-------+--------------------------+---------+---------+-------------+

  ------------------ -------------------------- ---------- ---------- --------------
  **Chrysene**                                                        

  SW                 Fish - no data                                   

                     Polychaete worm (*Neanthes 96         \<1000     Rossi 1978
                     arenaceodentata*)                                

  FW                 Fish - no data                                   

                     Water flea                 20         1900       Kagan et
                                                                      al.1987

  **Pyrene**                                                          

  SW                 Fish - no data                                   

                     Opossum shrimp             48         0.89       Pelletier et
                     (*Americamysis bahia*)                           al. 1997

  FW                 Fathead minnow             3.2        25.6       Oris 1987

                     Water flea                 2          4          Kagan et al.
                                                                      1987

  **Phenanthrene**                                                    

  SW                 Atlantic silverside        96         108        EPA 1993a
                     (*Menidia menidia*)                              

                     Mysid shrimp               96         17.7       

  FW                 Bluegill                   96         234        EPA 1993a

                     Hydra (*Hydra* sp.)        96         96         
  ------------------ -------------------------- ---------- ---------- --------------

^a^ SW = saltwater; FW = freshwater

[Chronic toxicity]{.underline}

No guideline chronic-toxicity studies are available to assess chronic
risks of the PAHs addressed in this assessment. Some data are available
in the EPA Sediment Quality Criteria documents for fluoranthene,
acenaphthene, and phenanthrene (Table 9). Adverse affects on survival,
growth, and reproduction have been reported at concentrations as low as
8 µg/L for phenanthrene and 18.8 µg/L for fluoranthene.

**Table 9. Chronic Toxicity of Creosote PAHs to Fish and Invertebrates
Exposed in the Water Column**

+-----+---------------------+----------+------------+----------------+
| **  | **Species**         | **N      | **Effect** | **Source**     |
| PAH |                     | OEC/LOEC |            |                |
| /** |                     | (µg/L)** |            |                |
|     |                     |          |            |                |
| **m |                     |          |            |                |
| edi |                     |          |            |                |
| a^a |                     |          |            |                |
| ^** |                     |          |            |                |
+=====+=====================+==========+============+================+
| *   |                     |          |            |                |
| *Fl |                     |          |            |                |
| uor |                     |          |            |                |
| ant |                     |          |            |                |
| hen |                     |          |            |                |
| e** |                     |          |            |                |
+-----+---------------------+----------+------------+----------------+
| SW  | Fish - no data      |          |            |                |
+-----+---------------------+----------+------------+----------------+
|     | Mysid               | 11.1 /   | survival,  | Champlin and   |
|     |                     | 18.8     | re         | Poucher 1991   |
|     |                     |          | production |                |
+-----+---------------------+----------+------------+----------------+
| FW  | Fathead minnow      | 10.4 /   | survival,  | Brooke 1991    |
|     |                     | 21.7     | growth     |                |
+-----+---------------------+----------+------------+----------------+
|     | *Daphnia magna*     | 10.6 /   | growth     | Brooke 1992    |
|     |                     | 21.2     |            |                |
+-----+---------------------+----------+------------+----------------+
| *   |                     |          |            |                |
| *Ac |                     |          |            |                |
| ena |                     |          |            |                |
| pht |                     |          |            |                |
| hen |                     |          |            |                |
| e** |                     |          |            |                |
+-----+---------------------+----------+------------+----------------+
| SW  | Fathead minnow      | 332 /    | growth     | Cairns and     |
|     |                     | 495      |            | Nebeker 1982   |
+-----+---------------------+----------+------------+----------------+
|     | Mysid (*M. bahia*)  | 44.6 /   | re         | Thursby et al. |
|     |                     | 91.8     | production | 1989           |
+-----+---------------------+----------+------------+----------------+
| FW  | Sheepshead minnow   | 520 /    | survival   | Ward et al.    |
|     |                     | 970      |            | 1981           |
+-----+---------------------+----------+------------+----------------+
|     | Midge               | 295 /    | egg        | NAS 1982       |
|     | (*Paratanytarsus*   | 575      | hatching   |                |
|     | sp.)                |          |            |                |
+-----+---------------------+----------+------------+----------------+
| *   |                     |          |            |                |
| *Ph |                     |          |            |                |
| ena |                     |          |            |                |
| nth |                     |          |            |                |
| ren |                     |          |            |                |
| e** |                     |          |            |                |
+-----+---------------------+----------+------------+----------------+
| SW  | Fish - no data      |          |            |                |
+-----+---------------------+----------+------------+----------------+
|     | Mysid               | 5.5 /    | survival   | Kuhn and       |
|     |                     | 11.9     |            | Lussier 1987   |
+-----+---------------------+----------+------------+----------------+
| FW  | Rainbow trout       | 5 / 8    | survival   | Call et al.    |
|     |                     |          |            | 1986           |
+-----+---------------------+----------+------------+----------------+
|     | *Daphnia magna*     | 57 / 163 | rep        |                |
|     |                     |          | roduction, |                |
|     |                     |          | survival   |                |
+-----+---------------------+----------+------------+----------------+

^a^ SW = saltwater; FW = freshwater

Some additional but scanty information is available for some PAHs.
Brooks (2000) reviewed the available data and concluded that \"it
appears that sustained water column concentrations of 30 to 50 ppb PAH
can have subtle, but important, chronic impacts on populations of marine
organisms.\" He cites Neff (1979) in reporting that copepod (*Eurytemora
affinis*) exposed to 10 ppb of naphthalene, 2-methylnaphthalene,
2,6-dimethylnaphthalene, or 2,3,5-trimethylnaphthalene displayed
significantly reduced lifespan and brood size. Moore et al. (1989 in
Brooks 2000) reported reduced feeding rates of mollusks at PAH levels of
30 to 40 ppb in seawater.

Poston (2001) cites two developmental studies with salmon and herring
exposed to PAHs from weathered crude oil (Heintz et al. 1999, Carls et
al. 1999). He concluded that developmental affects might occur at about
0.4 to 1.0 µg/L total dissolved PAH in the water column, and that
similar concentrations of PAHs leached from creosote-treated wood could
be expected to exert the same impact on aquatic organisms.

Karrow et al. (1999) evaluated the effects of creosote on immunotoxicity
to female rainbow trout in 12,000-L outdoor microcosms dosed with liquid
creosote. The fish were exposed for 28 days to creosote concentrations
ranging from 0 to 100 µl/L. Stimulatory and suppressive effects were
observed; a concentration-response relationship was evident. The LOEC
was 17 µl/L nominal creosote concentration, which represents 0.61 µg/L
total PAHs in the water. The researchers concluded \". . . that
environmental concentrations of PAHs can impair fish immune parameters,
possibly to a degree where resistance to disease is compromised.\"

**Sediments**

Sediment toxicity studies are not available for most of the PAHs.
However, the EPA Sediment Quality Criteria documents provide some
sediment and pore water LC50s for several species of saltwater and
freshwater organisms, mostly invertebrates, exposed to sediments spiked
with fluoranthene, acenaphthene, or phenanthrene (Table 10).

**Table 10. Toxicity of PAHs to Aquatic Organisms Exposed to Spiked
Sediments (from EPA 1993a,b,c)**

+-----+-----------------+-------+------+-------+-------+---+-----------+
| **  | **Species**     | **Exp | **   | **Sed | **    |   | *         |
| PAH |                 | osure | TOC^ | iment | Pore- |   | *Source** |
| /** |                 | durat | b^** | L     | water |   |           |
|     |                 | ion** |      | C50** | L     |   |           |
| **m |                 |       | **(  |       | C50** |   |           |
| edi |                 |       | %)** | **(µ  |       |   |           |
| a^a |                 |       |      | g/g** | **(µg |   |           |
| ^** |                 |       |      |       | /L)** |   |           |
|     |                 |       |      | **dry |       |   |           |
|     |                 |       |      | wt)** |       |   |           |
+=====+=================+=======+======+=======+=======+===+===========+
| *   |                 |       |      |       |       |   |           |
| *Fl |                 |       |      |       |       |   |           |
| uor |                 |       |      |       |       |   |           |
| ant |                 |       |      |       |       |   |           |
| hen |                 |       |      |       |       |   |           |
| e** |                 |       |      |       |       |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
| SW  | Amphipod        | 10 d  | 0.18 | 3.4   | 22.7  |   | Swartz et |
|     |                 |       |      |       |       |   | al. 1990  |
|     | (*Rhepoxynius   |       |      |       |       |   |           |
|     | abronius*)      |       |      |       |       |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     |                 |       | 0.31 | 6.5   | 29.4  |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     |                 |       | 0.48 | 10.7  | 24.2  |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     | Amphipod        | 10 d  | 0.34 | 15.0  | 14.1  |   | De Witt   |
|     |                 |       |      |       |       |   | et al.    |
|     | (*R. abronius*) |       |      |       |       |   | 1992      |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     |                 |       | 0.40 | 12.6  | 19.2  |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     |                 |       | 0.31 | 8.65  | 9.38  |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     | Amphipod        | 10 d  | nm   | 5.1   | nd    |   | De Witt   |
|     |                 |       |      |       |       |   | et al.    |
|     | (*Eohaustorius  |       |      |       |       |   | 1989      |
|     | estuaries*)     |       |      |       |       |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
| FW  | Fathead minnow  | 30 d  | nm   | 0.43  | nd    |   | Gendusa   |
|     |                 |       |      |       |       |   | 1990      |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     |                 | 96 h  |      | 0.97  |       |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     | Channel catfish | 96 h  | 0.70 | 3.68  | nd    |   |           |
|     |                 |       |      |       |       |   |           |
|     | (*Ictalurus     |       |      |       |       |   |           |
|     | punctatus*)     |       |      |       |       |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     | Amphipod        | 10 d  | 0.46 | 2.3   | 45.9  |   | Suedel et |
|     |                 |       |      |       |       |   | al. 1993  |
|     | (*Hyallela      |       |      |       |       |   |           |
|     | azteca*)        |       |      |       |       |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     |                 |       | 0.50 | 7.4   | 236.5 |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     |                 |       | 0.44 | 5.5   | 97.6  |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     | Midge           | 10 d  | 0.46 | 7.3   | 91.2  |   |           |
|     |                 |       |      |       |       |   |           |
|     | (Chir*onomus    |       |      |       |       |   |           |
|     | tentans*)       |       |      |       |       |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     |                 |       | 0.50 | 8.7   | 251.0 |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     |                 |       | 0.44 | 3.0   | 75.7  |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     | *Daphnia magna* | nr    | nm   | 4.2   | nd    |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
| *   |                 |       |      |       |       |   |           |
| *Ac |                 |       |      |       |       |   |           |
| ena |                 |       |      |       |       |   |           |
| pht |                 |       |      |       |       |   |           |
| hen |                 |       |      |       |       |   |           |
| e** |                 |       |      |       |       |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
| SW  | Amphipod        | 10 d  | 1.23 | 44.4  | 800   | S |           |
|     |                 |       |      |       |       | w |           |
|     | (*E.            |       |      |       |       | a |           |
|     | estuaries*)     |       |      |       |       | r |           |
|     |                 |       |      |       |       | t |           |
|     |                 |       |      |       |       | r |           |
|     |                 |       |      |       |       | z |           |
|     |                 |       |      |       |       | 1 |           |
|     |                 |       |      |       |       | 9 |           |
|     |                 |       |      |       |       | 9 |           |
|     |                 |       |      |       |       | 1 |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     |                 |       | 2.49 | 47.8  | 609   |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     |                 |       | 4.21 | 68.4  | 542   |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     | Amphipod        |       | 1.62 | \>193 | \     |   |           |
|     |                 |       |      |       | >1720 |   |           |
|     | (*Leptocheirus  |       |      |       |       |   |           |
|     | lumulosus*)     |       |      |       |       |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     |                 |       | 2.52 | 193   | 1410  |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     |                 |       | 3.66 | 382   | 1490  |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
| *   |                 |       |      |       |       |   |           |
| *Ph |                 |       |      |       |       |   |           |
| ena |                 |       |      |       |       |   |           |
| nth |                 |       |      |       |       |   |           |
| ren |                 |       |      |       |       |   |           |
| e** |                 |       |      |       |       |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
| SW  | Amphipod        | 10 d  | 1.02 | 39.2  | 138   | S |           |
|     |                 |       |      |       |       | w |           |
|     | (*E.            |       |      |       |       | a |           |
|     | estuaries*)     |       |      |       |       | r |           |
|     |                 |       |      |       |       | t |           |
|     |                 |       |      |       |       | r |           |
|     |                 |       |      |       |       | z |           |
|     |                 |       |      |       |       | 1 |           |
|     |                 |       |      |       |       | 9 |           |
|     |                 |       |      |       |       | 9 |           |
|     |                 |       |      |       |       | 1 |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     |                 |       | 2.47 | 97.2  | 139   |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     |                 |       | 3.33 | 122   | 146   |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     | Amphipod        |       | 1.96 | 92.4  | 387   |   |           |
|     |                 |       |      |       |       |   |           |
|     | (*L.            |       |      |       |       |   |           |
|     | plumulosus*)    |       |      |       |       |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     |                 |       | 2.50 | 162   | 306   |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+
|     |                 |       | 3.60 | 255   | 360   |   |           |
+-----+-----------------+-------+------+-------+-------+---+-----------+

^a^ SW = saltwater; FW = freshwater

^b^ OC = organic carbon; nm = not measured; nd = not determined

Some additional information is available for creosote or creosote
components. Tagatz et al. (1983) evaluated the toxicity of
creosote-contaminated sediment (sand) to field- and laboratory-colonized
estuarine benthic communities exposed for 8 weeks to concentrations of
177, 844, or 4420 µg/g. At the two highest concentrations, the number of
individuals and species were significantly reduced from the control
numbers. Animal abundance also was reduced at 177 µg/g in the field.
Echinoderm, annelid, and arthropod numbers were adversely affected at
the lowest concentration. Mollusks numbers were significantly reduced at
844 µg/g. Changes in indices of species diversity and dominance occurred
at the middle and high concentrations. Creosote sediment concentrations
decreased by 30% in the laboratory and 42% in the field during the 8
weeks of exposure.

Padma et al. (1998) exposed mysid shrimp to creosote-contaminated
sediment and to the water-soluble portion of the sediment. The 24-h LC50
was 700 µg/L for mysid exposed to the whole sediment. The 24-h LC50 was
180 µg/L for mysid exposed to the water-soluble fraction of the
sediment, which contained higher concentrations of the low-molecular
PAHs than did the whole sediment.

**Other Effects Information**

[Zooplankton and phytoplankton communities]{.underline}

Sibley et al. (2001a,b) examined the structure and dynamics of
zooplankton communities (86 spp.) and phytoplankton (200 spp.) for up to
83 days following single applications of liquid creosote directly to
water in 12,000-L outdoor microcosms. Concentrations ranged from 0.06 to
109 mg/L. Results indicate that zooplankton communities may be highly
sensitive to creosote exposure. Creosote had a significant and rapid
adverse impact on total abundance, number of taxa, and population
dynamics of individual taxa at all concentrations. Community-level EC50s
were 44.6 µg/L (NOEC = 13.9 µg/L) at 5 days and 46.6 µg/L (NOEC = 5.6
µg/L) at days. Creosote had no direct adverse affect on the
phytoplankton community based on total abundance and number of taxa.

[Herring]{.underline}

Vines et al. (2000) investigated the effects of creosote-treated wood on
embryonic development in Pacific herring (*Clupea pallasi*) in the
laboratory and in the field. Herring spawn their eggs onto various
substrates, including aquatic pilings, and creosote diffused from
pilings had a detrimental affects on hatching rate and survival of
embryos. In the laboratory, embryos were incubated in glass bowls of
seawater containing either creosote-treated wood (from pilings at least
40 years old), untreated wood (Douglas fir), or only seawater. The LC50
for hatching success was 50 µg/L, with statistically significant
reductions in hatching success at \~9 µg/L. None of the eggs adhering to
treated wood hatched, and only 9% of free-floating eggs hatched in bowls
containing treated wood. Hatching success was 89% for the control and
73% for untreated wood. The effects observed in the laboratory also were
observed in the field, where herring eggs deposited onto aged
creosote-treated pilings (Fort Baker, CA) did not hatch.

Other effects were observed in the laboratory study. For embryos not
attached to wood but exposed to creosote in the water, 40-50 % exhibited
delayed development. All creosote-exposed embryos that survived to hatch
were abnormal as compared to 20% in the wood-only treatment and 8% in
the control. Abnormalities included fluid retention in the visceral
cavity (ascites), fluid accumulation around the heart (pericardial
edema), and spinal curvature (scoliosis). Embryonic heart rates measured
post-fertilization increased from 92 and 97 beats/min on Day 5 to 127
and 130 beats/min at Day 9 in the control and wood-only treatments,
respectively, but decreased from about 50 beats/min to \<10 beats/min in
the creosote-exposed treatment. Other effects recorded only in the
exposed treatment included severe arrhythmic heart contraction patterns,
erratic and increased body movements within the chorion (egg wall), and
embryo tremors and twitches.

[Mussels]{.underline}

No adverse effects on the survival of mussels (*Mytilus edulis edulis*)
suspended in cages from the Sooke Basin pilings were observed in a two
year *in-situ* bioassay. However, mussels grown in close proximity (15
to 30 cm) to either the WP piling or BMP piling grew more slowly than
did mussels grown farther away (Table 11).

**Table 11. Survival and Growth of Mussels after Dolphin Installation in
the Sooke Basin Field Study**

  ------------------------------------- ---------- -------- --------- ---------
  **Station (distance from pilings)**   **%                           
                                        survival                      
                                        over                          
                                        time**                        

                                        **0 d**    **14 d** **185 d** **384 d**

  BMP treated dolphin (0.5 m)           100        100      97        79

  BMP treated dolphin (2.0 m)           100        100      100       88

  BMP treated dolphin (10.0 m)          100        99       98        81

  WP piling (0.5 m)                     100        100      99        88

  Open control                          100        100      99        80

                                                                      

  **Station and distance from pilings** **Growth                      
                                        (valve                        
                                        length,                       
                                        mm) over                      
                                        time**                        

                                        **0**      **14**   **185**   **384**

  BMP treated dolphin (0.5 m)           29         32.5     46.7      59.3

  BMP treated dolphin (2.0 m)           29.5       32.7     51.6      67.2

  BMP treated dolphin (10.0 m)          31.2       33.3     56.6      68.7

  WP Piling (0.5 m)                     29.1       31.4     49.1      64.2

  Open Control                          30.2       32.4     55.6      69.5
  ------------------------------------- ---------- -------- --------- ---------

Prior to being placed in the water at Sooke Basin, mussel-tissue PAH
concentrations were relatively low (16.15[+]{.underline} 2.19 ng/g).
These levels increased an average of 328% on Day 14 of the study. The
most significant increases were observed in close proximity (within 0.5
m) of either the BMP or WP dolphins. Following that initial increase,
levels returned to normal by Day 185 and were slightly lower than the
baseline levels by Day 384. Higher levels of PAHs were observed in
gonadal tissue than were observed in whole body tissues as shown below
(Table 12). Overall, tissue concentrations were low.

**Table 12. Low and High Molecular Weight PAHs in Gonad and Whole-body
Tissue of Mussels (*Mytilus edulis edulis*) Grown at Varying Distances
from Creosote-treated Dolphins**

  --------------------------------------------------------------------------------------------
  **PAH component**    **concentration                                              
                       (ng/g wet tissue)                                            
                       at each site^1^**                                            
  -------------------- ----------------- ---------- ---------- --------- ---------- ----------
                       **OC^2^**         **BMP      **BMP      **BMP     **WP       **Avg.**
                                         0.5^3^**   2.0^3^**   10^3^**   0.5^4^**   

  LPAH in Gonad        14.8              15.1       18.2       10.0      16.4       15.0

  HPAH in Gonad        22.0              29.2       32.4       15.6      32.4       26.3

  LPAH in Whole Tissue 6.7               6.4        9.8        5.6       6.1        6.9

  HPAH in Whole Tissue 15.0              15.4       26.0       11.5      16.7       16.9

  Total PAH in Gonad   36.7              44.3       50.6       25.5      48.8       41.2

  Total PAH in Whole   21.7              21.9       35.8       17.0      25.5       24.4
  Tissue                                                                            
  --------------------------------------------------------------------------------------------

^1^ tissues were analyzed at Day 185 when the mussels were ripe and
ready to spawn

^2^ OC = open control site located upstream of all structures

^3^ BMP = creosote-treated piling produced using Best Management
Practices at specifed distance (m)

^4^ WP = 8-year-old weathered creosote treated piling

**Aquatic Risk Assessment**

**Water column**

[Acute risks]{.underline}

When a new creosote-treated wood structure is installed in an aquatic
environment, there is an immediate release of creosote components into
the water column. During their study in the Sooke Basin, Goyette and
Brooks (1998) report that creosote leaching from the portions of aquatic
pilings above the water line initially forms a sheen on the water
surface. They speculated that microdoplets from the surface sheen
subsequently move down through the water column and into the sediment,
with little of that creosote dissolving in the water column. However,
they did not measure water-column concentrations until 6 months after
pilings (dolphins) were installed in Sooke Basin. Ingram et al. (1982)
and Bestari et al. (1998) measured PAH concentrations in the water
column in the initial days and weeks and found levels that might be of
concern for exposure of aquatic organisms.

Acute RQs for aquatic organisms exposed to the PAH component expected in
the water column are presented in Table 13. The weighted acute toxicity
values used to calculate RQs for the total PAH component are as follows:

Freshwater fish weighted LC50 = 405 µg/L

Freshwater invertebrate weighted EC50 = 267 µg/L

Saltwater fish weighted LC50 = 1150 µg/L

Saltwater invertebrate weighted EC50 or LC50 = 399 µg/L

**Table 13. Acute RQs for Exposure of Aquatic Organisms to PAHs in the
Water Column**

+-----------------+-----------+---------+---------+---------+--------+
| **Site**        | **Time    | **F     |         | **      |        |
|                 | after     | reshwat |         | Estuari |        |
|                 | initial   | er^a^** |         | ne/Mari |        |
|                 | e         |         |         | ne^a^** |        |
|                 | xposure** |         |         |         |        |
+=================+===========+=========+=========+=========+========+
|                 |           | *       | **In    | *       | **Inv  |
|                 |           | *Fish** | vert.** | *Fish** | ert.** |
+-----------------+-----------+---------+---------+---------+--------+
| 300-gal tanks;  | 72 hr     | n/a     | n/a     | **0     | **1.08 |
| seawater        |           |         |         | .37\*** | \*\*** |
|                 |           |         |         |         |        |
| (Ingram et      |           |         |         |         |        |
| al.1982)        |           |         |         |         |        |
+-----------------+-----------+---------+---------+---------+--------+
|                 | 12 day    | n/a     | n/a     | **0     | **0.   |
|                 |           |         |         | .13\*** | 39\*** |
+-----------------+-----------+---------+---------+---------+--------+
| 1200-L outdoor  | 7 day     | **0     | **0     | n/a     | n/a    |
| microcosms;     |           | .24\*** | .36\*** |         |        |
| freshwater      |           |         |         |         |        |
|                 |           |         |         |         |        |
| (Bestari et     |           |         |         |         |        |
| al.1998)        |           |         |         |         |        |
+-----------------+-----------+---------+---------+---------+--------+
|                 | 3 mo.     | 0.02    | 0.02    | \<0.01  | 0.02   |
+-----------------+-----------+---------+---------+---------+--------+
| Sooke Basin;    | 6 mo.     | n/a     | n/a     | \<0.01  | \<0.01 |
| marine          |           |         |         |         |        |
|                 |           |         |         |         |        |
| (Goyette and    |           |         |         |         |        |
| Brooks 1998)    |           |         |         |         |        |
+-----------------+-----------+---------+---------+---------+--------+
| Railroad        | 0 hr      | **0.7   | **1.1   | **0     | **0.78 |
|                 |           | 7\*\*** | 6\*\*** | .27\*** | \*\*** |
| (wet scenario)  |           |         |         |         |        |
+-----------------+-----------+---------+---------+---------+--------+
|                 | 96 hr     | **0     | **0.6   | **0     | **0.   |
|                 |           | .45\*** | 9\*\*** | .16\*** | 46\*** |
+-----------------+-----------+---------+---------+---------+--------+
|                 | 21-day    | **0     | **0     | **0     | **0.   |
|                 | avg.      | .23\*** | .35\*** | .08\*** | 24\*** |
+-----------------+-----------+---------+---------+---------+--------+
|                 | 60-day    | **0     | **0     | **0     | **0.   |
|                 | avg.      | .15\*** | .22\*** | .05\*** | 15\*** |
+-----------------+-----------+---------+---------+---------+--------+
|                 | 90-day    | **0     | **0     | 0.04    | **0.   |
|                 | avg.      | .13\*** | .20\*** |         | 13\*** |
+-----------------+-----------+---------+---------+---------+--------+
| Railroad        | 0 hr      | **0     | **0     | 0.04    | **0.   |
|                 |           | .12\*** | .18\*** |         | 12\*** |
| (dry scenario)  |           |         |         |         |        |
+-----------------+-----------+---------+---------+---------+--------+
|                 | 96 hr     | **0     | **0     | 0.02    | **0.   |
|                 |           | .07\*** | .11\*** |         | 07\*** |
+-----------------+-----------+---------+---------+---------+--------+
|                 | 21-day    | 0.03    | 0.04    | \<0.01  | 0.03   |
|                 | avg.      |         |         |         |        |
+-----------------+-----------+---------+---------+---------+--------+
|                 | 60-day    | 0.01    | 0.02    | \<0.01  | 0.01   |
|                 | avg.      |         |         |         |        |
+-----------------+-----------+---------+---------+---------+--------+
|                 | 90-day    | \<0.01  | 0.01    | \<0.01  | \<0.01 |
|                 | avg.      |         |         |         |        |
+-----------------+-----------+---------+---------+---------+--------+

**^a^** based on weighted toxicity values: FW fish = 405 ppb; FW
invertebrate = 267 ppb;

SW fish = 1150 ppb; SW invertebrate = 399 ppb

***\*\**** exceeds the acute LOC for non-listed spp. (RQ
[\>]{.underline}0.5) and listed spp. (RQ [\>]{.underline}0.05)

***\**** exceeds the acute LOC for listed spp.

The RQs determined for Sooke Basin do not exceed the Agency\'s acute
LOC; however, those concentrations were measured 6 months after pilings
were installed and may simply represent background PAH concentrations.
Based on the total PAH concentrations reported in seawater by Ingram et
al. (1982) and in freshwater by Bestari et al. (1998) and the weighted
toxicity values, the acute LOC is exceeded for listed fish and aquatic
invertebrates. The acute LOC also is exceeded for non-listed
estuarine/marine invertebrates. Exceedance of an LOC indicates a
potential for adverse effects on nontarget organisms and identifies a
need for regulatory action to mitigate risk (Appendix B).

Based on the EECs modeled for railroad structures, the acute LOC for
listed freshwater and saltwater species is exceeded in wet areas (MS
scenario). Exposure levels of concern potentially exist for several
months. Non-listed species also are at acute, short-term risk. In drier
areas (CA scenario), the acute LOC is only exceeded for listed species
and only in the short-term.

Zooplankton communities also may be at acute risk. Comparing the 5-day
EC50 of 44.6 µg/L for community-level effects to the aquatic EECs
(Tables 3 and 5) indicates that the LOC would be exceeded 1- to 10-fold
for acute risks due to creosote leaching from aquatic structures and
railroad structures.

[Chronic risks]{.underline}

Insufficient data exist to calculate weighted toxicity values for the
PAH component; therefore, chronic RQs are not calculated. However,
comparing EECs to the available data (previously presented in the
Toxicity Data section) indicate that adverse affects on survival,
growth, and/or reproduction could be expected in some situations (Table
14). Chronic risk is presumed in OPP risk assessments when the chronic
EEC (21-day-avg. for invertebrates and 60-day-avg. for fish) exceeds the
NOEC. Chronic exposure in the water column potentially poses risks to
fish and/or aquatic invertebrates around aquatic structures and,
especially in wetter areas, where leachate from railroad structures may
move into the aquatic environment.

**Table 14. EECs and Adverse Effects from Chronic Exposure in the Water
Column**

+-----------------+------------------+---------------------------------+
| **Site**        | **EEC (µg/L)**   | **Reported effect**             |
|                 |                  |                                 |
|                 |                  | **concentrations (µg/L)**       |
+=================+==================+=================================+
| 300-g SW tanks  | 156 (12 d)       | 0.4-1.0 (salmon, herring;       |
|                 |                  | development)                    |
|                 |                  |                                 |
|                 |                  | 0.61 (rainbow trout;            |
|                 |                  | immunotoxicty)                  |
|                 |                  |                                 |
|                 |                  | 9 (herring; hatching sig.       |
|                 |                  | reduced)                        |
|                 |                  |                                 |
|                 |                  | 44.6 (zooplankton; community    |
|                 |                  | EC50)                           |
|                 |                  |                                 |
|                 |                  | 30-50 (invertebrates; survival, |
|                 |                  | brood size)                     |
|                 |                  |                                 |
|                 |                  | 5-57 (phenanthrene NOECs^a^)    |
|                 |                  |                                 |
|                 |                  | 10-11 (fluoranthene NOECs^a^)   |
|                 |                  |                                 |
|                 |                  | 44-520 (acenapthene NOECs^a^)   |
+-----------------+------------------+---------------------------------+
| 12,000-L FW     | 0.8-6.7 (84 d)   |                                 |
| microcosms      |                  |                                 |
+-----------------+------------------+---------------------------------+
| Railroad        | 94.4 (21-d-avg.) |                                 |
|                 |                  |                                 |
| (wet scenario)  | 59.3 (60-d-avg.) |                                 |
+-----------------+------------------+---------------------------------+
| Railroad        | 11.4 (21-d-avg.) |                                 |
|                 |                  |                                 |
| (dry scenario)  | 5.0 (60-d-avg.)  |                                 |
+-----------------+------------------+---------------------------------+

^a^ NOECs based on survival, growth, and reproduction

**Sediments**

Due to lack of sediment-toxicity data for most PAHs and the total PAH
component, RQs cannot be calculated for acute and chronic risks to
benthic organisms potentially exposed to the PAH matrix in sediments.
However, the Sooke Basin study provides information on the potential
adverse affects of creosote-contaminated sediments. Goyette and Brooks
(1998) compared sediment loads (see Table 4) to proposed or interim
sediment quality criteria for Canada and Washington State. Based on
those criteria, several PAHs pose potential risks to benthic organisms
in sediments immediately around aquatic pilings (Table 15).

**Table 15. PAHs Exceeding Canadian and/or Washington State Sediment
Quality Criteria at Various Distanced from the BMP Dolphin in Sooke
Basin After 384 Days (from Goyette and Brooks 1998)**

  ----------------------------------------------------------------------------
  **PAH**            **Distance                                     
                     (m) from                                       
                     pilings**                                      
  ------------------ ------------ ----------- ---------- ---------- ----------
                     **0.5 m**    **1 m**     **1.5 m**  **7.5 M**  **10 m**

  Fluoranthene       ●            ●                                 

  Acenaphthene       ●            ●                                 

  Phenanthrene       ●            \*          \*         \*         

  Chrysene           ●            \*                                

  Fluorene           ●                                              

  Pyrene                                                            

  Anthracene                                                        

  Naphthalene                                                       
  ----------------------------------------------------------------------------

● exceeds Canadian and WA State Sediment Quality Criteria

\* exceeds Canadian Sediment Quality Criteria

Goyette and Brooks (2001**)** also conducted various tests to evaluate
sediment toxicity in proximity to the creosote-treated pilings in Sooke
Basin. Marine amphipods (*Rhepoxynius abronius* and *Eohaustorius
washingtonianus*) were exposed to sediments from the BMP and control
sites. Because these amphipods are not supported in the Sooke Basin,
control reference sediments also were collected from elsewhere for
comparison to the toxicity from exposure to BMP sediments. Sediments
collected within 0.5 m of the BMP dolphin at Days 14 and 185 were toxic
in comparison to the reference sediments. Fluoranthene and phenanthrene
appeared to be the major contributors to this toxicity. At Days 1360 and
1540, toxicity was found in some, but not all, samples within 2 m of the
BMP dolphin. However, by this time elevated hydrogen sulfide levels were
elevated in the sediments (from buildup and decomposition of fouling
organisms and their waste falling from the pilings) and were thought to
have contributed to the observed toxicity. Pore-water toxicity testing
with Microtox™ assays and a marine bioluminescent bacterium demonstrated
toxic conditions in sediments within 2 m of the BMP dolphin and beneath
the WP dolphin, but not at the open control site. Fertilization tests
with sea urchins at Day 535 also indicated toxicity within 0.5 m and
below the BMP, WP, and untreated dolphins.

Regarding the PAH sediment concentrations detected in mesocosm
sediments, Brooks (2004) concluded that newly treated railway ties pose
minimal environmental risk to the endangered dragonfly inhabiting
wetland areas crossed by a rail line. Using benchmark methodology
proposed by Swartz (1999), Brooks (2004) also concludes that no adverse
biological effects can be expected at the observed PAH levels. However,
due to the lack of sediment-toxicity tests and actual field monitoring,
the potential for adverse affects to aquatic organisms exposed to PAH in
sediments from leaching from railroad structures remains uncertain.

One other study deserves mention regarding contaminated river sediments.
Pastorok et al. (1994) investigated the effect of creosote-contaminated
sediments on aquatic organisms nearby a creosote-treatment plant in the
lower Willamette River in Oregon. Endpoints evaluated included amphipod
(*Hyalella azteca*) mortality and Microtox (*Photobacterium
phosphoreum*) bioluminescence. Toxicity occurred within approximately
300 feet of the shoreline, with a highly toxic area near a dock used for
creosote off-loading. A low level of contamination of crayfish and lack
of serious liver lesions in suckers collected near the site suggest that
risk to mobile species from chronic contamination is low. There was no
evidence of adverse effects throughout the rest of the main channel of
the river.

**Risk Characterization**

**Aquatic structures**

Based on the available toxicity and exposure data, acute risk is
presumed for listed freshwater and saltwater fish and aquatic
invertebrates exposed to PAHs in the water column. Acute risk also is
presumed for non-listed saltwater invertebrates. These risk presumptions
are made from LOC exceedances determined from RQs calculated from
water-column EECs generated in outdoor microcosms and large tanks and
from weighted toxicity values for the PAH complex expected in the water
column. Insufficient data are available to determine chronic toxicity of
the PAH complex or even the toxicity of the individual PAHs addressed in
this assessment. Therefore, chronic RQs cannot be determined. Limited
data from the literature indicate that adverse chronic effects
(survival, growth, reproduction, immunotoxicity) are possible from some
PAHs or mixtures of PAHs at exposure levels expected in the water
column. Guideline studies for acute and chronic toxicity testing with
freshwater and saltwater fish and invertebrates exposed to the PAH
complex would be needed to further characterize acute and chronic risks
to aquatic animals inhabiting the water column. Guideline data also are
not available to assess risks to aquatic plants. Uncertainties exist
with the available data on creosote leaching from treated wood into the
environment. Additional data would help to refine acute and chronic
EECs. Field monitoring of aquatic concentrations also could be
undertaken in areas of newly installed structures to further refine PAH
concentrations over time.

Based on findings from the Sooke Basin field study in Canada, PAH
accumulation in sediments is believed to be sufficiently high to pose a
risk to benthic organisms in the immediate vicinity of creosote-treated
pilings for at least a year. Risk could be better characterized if acute
and chronic sediment-toxicity guideline studies were available. These
guideline studies are outstanding for creosote. Moreover, movement into
and retention of PAHs in sediments around creosote-treated aquatic
pilings are likely to vary locally, depending on abiotic and biotic
factors such as current speed, amount of treated structure per unit
area, air and water temperature, salinity, and the infaunal species
occurring in the immediate area of the structures. Therefore, many
uncertainties exist in extrapolating findings from the Sooke Basin to
warmer locales in the southern U. S. Because of those uncertainties,
prior to installation of any new aquatic structures, a site evaluation
is essential to evaluate potential risks, particularly to listed (i. e.,
endangered or threatened) or other sensitive species or sensitive life
stages. Risk could be further characterized with additional field or
simulated field studies representing the environmental conditions and
species assemblages occurring in the southern U. S.

Existing aquatic structures are likely to continue leaching creosote to
the aquatic environment, but at lower rates than newly installed
structures. In some situations, such as noted at Sooke Basin after about
a year, leaching from submerged pilings might possibly be limited due to
the mass of organisms attached to the pilings. Even in those situations,
leaching may still occur in the pilings above the waterline, especially
in hot weather. In other areas, such as where herring or other organisms
attach their eggs directly to creosote-treated pilings, even pilings
that have been submerged for many years, eggs may not hatch or surviving
embryos may not develop normally. Developmental or other sublethal
impacts also might occur where aquatic organisms are exposed to low PAH
concentrations but for prolonged periods. Chronic guideline studies with
freshwater and saltwater fish and invertebrates would provide additional
information for assessing such risks.

Long-term findings from the Sooke Basin field study deserve mention. The
researchers reported that a substantial community of mussels, anemones,
and other invertebrates inhabited the creosote-treated pilings after the
first year. Sediment concentrations also decreased at that time, which
they speculate may have been due to the physical barrier of organisms
precluding additional movement of creosote into the water column and
sediments. However, despite the apparent lack of long-term adverse
affects on some organisms, sensitive species might be adversely affected
by short-term exposure. Additional acute-toxicity data generated in
guideline studies and refinement of initial EECs in the water column
would help address that risk, especially for listed species.

**Railroad ties**

Based on modeled EECs using PRZM/EXAMS scenarios, and the weighted
toxicity values for the PAH complex, acute risk is presumed for listed
freshwater and saltwater fish. Based on the scenario for wetter areas,
acute risk also is presumed for non-listed freshwater fish and aquatic
invertebrates exposed to PAHs in the water column. Chronic risk can not
be assessed due to the lack of chronic toxicity data, but some available
evidence indicates that chronic risk is possible to aquatic organisms
inhabiting the water column. As noted for aquatic structures, further
characterization of acute and chronic risks would require acute and
chronic toxicity testing with fish and aquatic invertebrates exposed to
the PAH complex in the water column. Acute and chronic EECs could be
refined from creosote leaching studies in the water column over time, or
from field monitoring in areas where railroad ties are in proximity to
surface waters. Data obtained from a mesocosm study indicate that
sediment PAH levels leached from railroad ties appear to be lower than
those around aquatic pilings, and the PAHs do not move any substantial
distance from the railway ballast.

**Listed Species Considerations**

Section 7 of the Endangered Species Act (ESA), 16 U.S.C. Section
1536(a)(2), requires that federal agencies consult with the National
Marine Fisheries Service (NMFS) for marine and andronomus listed
species, or with the United States Fish and Wildlife Services (FWS) for
listed wildlife and freshwater organisms, if proposing an \"action\"
that may affect listed species or their designated habitat. Each federal
agency is required under the Act to insure that any action they
authorize, fund, or carry out is not likely to jeopardize the continued
existence of a listed species or result in the destruction or adverse
modification of designated critical habitat. To jeopardize the continued
existence of a listed species is to \"to engage in an action that
reasonably would be expected, directly or indirectly, to reduce
appreciably the likelihood of both the survival and recovery of a listed
species in the wild by reducing the reproduction, numbers, or
distribution of the species.\" 50 C.F.R. §402.02.

To comply with subsection (a)(2) of the ESA, EPA's Office of Pesticide
Programs has established procedures to evaluate whether a proposed
registration action may directly or indirectly appreciably reduce the
likelihood of both the survival and recovery of a listed species in the
wild by reducing the reproduction, numbers, or distribution of any
listed species (U.S. EPA 2004). If any of the Listed Species LOC
Criteria are exceeded for either direct or indirect effects in the
Agency's screening-level risk assessment, the Agency identifies any
listed or candidate species that may occur spatially and temporally in
the footprint of the proposed use. Further biological assessment is
undertaken to refine the risk. The extent to which any species may be at
risk determines the need to develop a more comprehensive consultation
package as required by the ESA.

The ecological risk assessment for creosote indicates a potential for
exposure of listed fish and aquatic invertebrate species that warrants a
more refined assessment to include direct, indirect, and habitat
effects. The refined assessment should involve clear delineation of the
action area associated with proposed use of creoste and best available
information on the temporal and spatial co-location of listed species
with respect to the action area. This analysis has not been conducted
for this assessment. An endangered species effect determination will not
be made at this time.

**Data Gaps**

The following ecotoxicity guideline studies are outstanding:

**•** Freshwater fish acute toxicity (Guideline no. 850.1075)

**•** Freshwater invertebrate acute toxicity (850.1010)

**•** Estuarine/marine fish acute study (850.1075)

**•** Estuarine/marine shrimp acute study (850.1035)

**•** Estuarine/marine mollusk acute study (850.1025)

**•** Aquatic invertebrate (freshwater) life-cycle study (850.1300)

**•** Fish early life-stage (freshwater) study (850.1400)

**•** Aquatic invertebrate (estuarine/marine) life-cycle study
(850.1300)

**•** Fish early life-stage (estuarine/marine) study (850.1400)

**•** Whole sediment: acute freshwater invertebrates (850.1735)

**•** Whole sediment: acute marine invertebrates (850.1740)

**•** Whole sediment: chronic invertebrates (no guideline no.)

**•** Freshwater diatom (850.5400)

**•** Marine diatom (850.5400)

**•** Blue-green cyanobacteria (850.5400)

**•** Freshwater green alga (850.5400)

**•** Freshwater floating macrophyte duckweed (850.4400)

**•** Freshwater rooted macrophyte rice seedling emergence (850.4225)

**•** Freshwater rooted macrophyte rice vegetative vigor (850.4250)

Submission of the guideline studies would be valuable for refining acute
and chronic risks to aquatic organisms, especially for listed species.
Currently, insufficient toxicity data are available to calculate acute
and chronic risks to benthic organisms as well as chronic risk to
organisms (fish, invertebrates, plants) inhabiting the water column in
either the freshwater or saltwater environment. Acute toxicity data gaps
also exist for some PAHs, and the available data was not generated from
standardized protocols used for guideline studies (e. g., standard
period of exposure, no. concentrations tested, etc.). The ecotoxicity
data could be generated for each of the 8 PAHs addressed in this
assessment. Alternatively, the registrant may wish to conduct the
studies on a complex of the 8 PAHs according to the expected proportion
of each PAH in the water column or sediment. Before conducting any
testing on the complex, the registrant should consult with AD/RASSB to
ensure that any complex tested is deemed appropriate.

Additional data would be needed to further refine the risk
characterization for creosote leaching from either aquatic pilings or
railroad ties:

**•** Field study or simulated field study (850.1950): for aquatic
structures, sediment-concentration data are available for cool northern
conditions (Sooke Basin, Canada) and water-column concentrations have
been determined from microcosm studies; however, major uncertainties
exist for EECs in warmer areas such as the southern U. S. where
differences in environmental conditions will exist. The registrant
should consult RASSB about developing a suitable protocol if it is
decided that further characterization of exposure levels and effects is
warranted and can be addressed by a field study

**•** Leaching study for release of creosote components from
creosote-impregnated wood: an appropriate leaching study would help
refine EECs expected in water and sediments from aquatic structures and
railroad ties, which will be especially important for refining the
exposure assessment for listed species. The registrant should consult
RASSB about developing a suitable protocol

**Label Statements**

All product labels must have the following **ENVIRONMENTAL HAZARDS**
statement:

\"This pesticide is highly toxic to aquatic organisms. Do not discharge
effluent containing this product into lakes, streams, ponds, estuaries,
oceans, or other waters unless in accordance with the requirements of a
National Pollutant Discharge Elimination System (NPDES) permit and the
permitting authorities are notified in writing prior to discharge. Do
not discharge effluent containing this product to sewer systems without
previously notifying the local sewage treatment plant authority. For
guidance contact your State Water Board or Regional Office of the EPA.\"

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**Appendix A: EECs for Creosote Leached from Railroad Ties**

**UNITED STATES ENVIRONMENTAL PROTECTION AGENCY**

**WASHINGTON, D.C. 20460**

**February 5, 2008**

![](media/image2.png){width="5.330555555555556in"
height="0.4777777777777778in"}

**[MEMORANDUM]{.underline}**

**SUBJECT: Estimated Environmental Concentrations for Creosote Leached
from Rail Road Ties into Soil and Water using PE5 PRZM-EXAMS Model
Shell**

**From: Siroos Mostaghimi, Ph.D., Senior Scientist**

**Risk Assessment and Science Support Branch (RASSB)**

**Antimicrobials Division (7510P)**

**To: Norm Cook, Chief**

**Risk Assessment and Science Support Branch (RASSB)**

**Antimicrobials Division (7510P)**

**Compound: Creosote**

**Chemical No**. : N/A

**Barcode:** N/A

Number range CHAPTERAttached please find estimated environmental
concentrations (EECs) for creosote leached from treated rail road ties
into soil and water. The PE5 PRZM-EXAMS Model Shell was used for this
assessment.

> **Introduction**

This report presents estimated environmental concentrations of
components of coal tar creosote in surface water and sediment pore
water. Coal tar creosote is used most widely in the United States as a
wood preservative to treat railroad ties and telephone poles. Coal tar
creosote is a mixture of multiple chemicals including polyaromatic
hydrocarbons (PAHs). Based on the availability of the ecological data,
nine PAHs were chosen by the RASSB scientists as a representative of the
PAHs in creosote for environmental modeling. There are eco data from
several sources on all 9 of these compounds. These data may not all be
useful for risk assessment endpoints, and may not be comparable in
species representation or endpoint type across the various PAHs, but
there appears to be enough to have at least a qualitative idea of the
toxicity of each PAH to aquatic organisms (including algae and plants),
as well as terrestrial invertebrates (mostly earthworms). The selected
PAHs were:

Acenaphthene

Anthracene

Biphenyl

Chrysene

Fluoranthene

Fluorene

Naphthalene

Phenanthrene

Pyrene

Environmental concentrations were estimated for the above nine PAHs .
Table 1 shows the nine selected PAHs for modeling and their physical
/chemical characteristics as reported in the creosote RED fate chapter.

<table>
<colgroup>
<col style="width: 12%" />
<col style="width: 12%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 8%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 6%" />
<col style="width: 7%" />
<col style="width: 8%" />
</colgroup>
<thead>
<tr class="header">
<th colspan="12"><strong>Table 1. Physical and chemical characteristics
of Polyaromatic Hydrocarbones (PAHs).</strong></th>
</tr>
<tr class="odd">
<th>PAH</th>
<th>Chemical Structure<sup>a</sup></th>
<th>Molecular Formula<sup>a</sup></th>
<th>Molecular Weight<sup>b</sup></th>
<th>Percent Found in Creosote<sup>c</sup></th>
<th>Amount in soil (lbs/ac) <sup>d</sup></th>
<th>Water Solubility at 25°C (mg/L)<sup>b</sup></th>
<th>Vapor Pressure at 25°C (mm Hg)<sup>b</sup></th>
<th><p>Log K<sub>ow</sub> at 25°C<sup>b</sup></p>
<p>(K<sub>ow</sub>)</p></th>
<th><p>Log K<sub>oc</sub> at 25°C<sup>b</sup></p>
<p>(K<sub>oc</sub>)</p></th>
<th><p>Photolysis half-life</p>
<p>(days)</p></th>
<th>Henry’s Law Constant at 25°C (Pa m<sup>3</sup>/mol)<sup>b</sup></th>
</tr>
</thead>
<tbody>
<tr class="odd">
<td>Naphthalene</td>
<td><img src="media/image3.png"
style="width:1.13403in;height:1.01458in" /></td>
<td>C<sub>10</sub>H<sub>8</sub></td>
<td>128.2</td>
<td>9.1/13</td>
<td>752.7</td>
<td>3.1 x 10<sup>-2</sup></td>
<td>7.8 x 10<sup>-2</sup></td>
<td><p>3.37</p>
<p>(2344)</p></td>
<td><p>3.29</p>
<p>(1950)</p></td>
<td>2.96</td>
<td>43.01</td>
</tr>
<tr class="even">
<td>Acenaphthene</td>
<td><img src="media/image4.png"
style="width:1.16042in;height:1.03194in" /></td>
<td>C<sub>12</sub>H<sub>10</sub></td>
<td>154.2</td>
<td>8.4/4</td>
<td>231.6</td>
<td>3.8 x 10<sup>-3</sup></td>
<td>2.2 x 10<sup>-3</sup></td>
<td><p>3.92</p>
<p>(8318)</p></td>
<td><p>3.79</p>
<p>(6166)</p></td>
<td>1</td>
<td>12.17</td>
</tr>
<tr class="odd">
<td>Biphenyl</td>
<td><img src="media/image5.png"
style="width:1.15278in;height:1.03125in" /></td>
<td>C<sub>12</sub>H<sub>12</sub></td>
<td>154.2</td>
<td>8</td>
<td>463.2</td>
<td>7.0 x 10<sup>-3</sup></td>
<td>9.97 x 10<sup>-3</sup></td>
<td><p>3.90</p>
<p>(7943)</p></td>
<td><p>3.57-3.77</p>
<p>(3715-5888)</p></td>
<td></td>
<td>28.64</td>
</tr>
<tr class="even">
<td>Fluorene</td>
<td><img src="media/image6.png"
style="width:1.14583in;height:1.00833in" /></td>
<td>C<sub>13</sub>H<sub>10</sub></td>
<td>166.2</td>
<td>6.3/8</td>
<td>463.2</td>
<td>1.9 x 10<sup>-3</sup></td>
<td>6.7 x 10<sup>-4</sup></td>
<td><p>4.18</p>
<p>(15136)</p></td>
<td><p>3.76</p>
<p>(5754)</p></td>
<td>4.6</td>
<td>7.87</td>
</tr>
<tr class="odd">
<td>Anthracene</td>
<td><img src="media/image7.png"
style="width:1.11042in;height:0.98958in" /></td>
<td>C<sub>14</sub>H<sub>10</sub></td>
<td>178.2</td>
<td>3.3/13</td>
<td>752.7</td>
<td>4.5 x 10<sup>-5</sup></td>
<td>7.5 x 10<sup>-6</sup></td>
<td><p>4.54</p>
<p>(34673)</p></td>
<td><p>4.42</p>
<p>(26302)</p></td>
<td>0.34</td>
<td>3.96</td>
</tr>
<tr class="even">
<td>Phenanthrene</td>
<td><img src="media/image8.png"
style="width:0.89514in;height:0.80417in" /></td>
<td>C<sub>14</sub>H<sub>10</sub></td>
<td>178.2</td>
<td>13.3/13</td>
<td>752.7</td>
<td>1.1 x 10<sup>-3</sup></td>
<td>1.5 x 10<sup>-4</sup></td>
<td><p>4.57</p>
<p>(37153)</p></td>
<td><p>4.42</p>
<p>(1738)</p></td>
<td></td>
<td>3.24</td>
</tr>
<tr class="odd">
<td>Pyrene</td>
<td><img src="media/image9.png"
style="width:1.19653in;height:1.07361in" /></td>
<td>C<sub>16</sub>H<sub>10</sub></td>
<td>202.3</td>
<td>4.3/2</td>
<td>115.8</td>
<td>1.3 x 10<sup>-4</sup></td>
<td>4.5 x 10<sup>-6</sup></td>
<td><p>5.18</p>
<p>(151356)</p></td>
<td><p>4.92</p>
<p>(83176)</p></td>
<td></td>
<td>0.92</td>
</tr>
<tr class="even">
<td>Fluoranthene</td>
<td><img src="media/image10.png"
style="width:1.20833in;height:1.07361in" /></td>
<td>C<sub>16</sub>H<sub>10</sub></td>
<td>202.3</td>
<td>5.3/4</td>
<td>231.6</td>
<td>2.6 x 10<sup>-4</sup></td>
<td>9.0 x 10<sup>-6</sup></td>
<td><p>5.22</p>
<p>(165958)</p></td>
<td><p>4.74</p>
<p>(54954)</p></td>
<td>0.88</td>
<td>1.037</td>
</tr>
<tr class="odd">
<td>Chrysene</td>
<td><img src="media/image11.png"
style="width:1.08472in;height:0.96875in" /></td>
<td>C<sub>18</sub>H<sub>12</sub></td>
<td>228.3</td>
<td>1.9/2</td>
<td>115.8</td>
<td>--</td>
<td>4.2 x 10<sup>-9</sup></td>
<td><p>1.65</p>
<p>(44.7)</p></td>
<td><p>4.89</p>
<p>(77624)</p></td>
<td>4.2</td>
<td>5.86</td>
</tr>
</tbody>
</table>

**Assumptions for Estimating the Concentrations of PAHs in Soil:**

The following assumptions are used to calculate the amount of different
PAHs leached from the rail road ties into soil:

**Crossties Specifications:**

Width= 9 in = 0.229 m

Height= 7 in = 0.178 m

Length = 8.5 ft = 2.590 m

Spacing between the crossties on the rail = 19 in = 0.495 m

**Other Assumptions:**

1.  A rail road crosses a 10 ha filed. There are two sets of rails in
    the same field. The crossties are treated with creosote.

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```
1.  The length of the 10 ha field is 1000 m.

**Calculations:**

**Wood:**

Total surface area of each cross tie (m^2^) = width (0.229) x length
(2.590) = 0.593 m^2^

Total length covered by each crosstie and spacing between cross tie (m)
= Width of crosstie

(0.229 m) + Spacing (0.495 m) = 0.724 m

Number of crossties for one rail cross the filed = (Length of the filed,
1000 m) /0.724 m = 1381

Total Number of crossties in the fields = 1381 X 2 = 2762

Wood area above the soil = 2762 X 0.593 m^2^ = 1638.43 m^2^

**Soil:**

These assumptions were used for soil calculations:

Assume a rectangle underneath of each cross tie

Width = 0.229 m

Length = 2.59 m

Depth of soil = 0.1 m

Soil volume underneath of each crosstie m^3^ = 0.229 x 2.590 x 0.1 =
0.0593 m^3^

Total soil volume under crossties in a 10 ha filed = 0.0593 m^3^ x 2762
= 163.79 m^3^

According to Brooks (2004) the target retention specified by AWPA
standard C6 (AWPA 1996) for oak crossties is 112 kg/m3.

Therefore,

Volume of Treated wood= 1638.4 m^2^ of wood with 0.178 m width = 291.64
m^3^ of treated wood

291.64 m3 x 112 kg/m3 = 32663.66 kg Creosote applied to crossties.

Therefore:

If we assume that 4% of the total creosote applied to the cross ties is
leached out into the soil:

332663.66 kg of Creosote x 0.04 = 1306.54 Kg Creosote which has leached
to the soil under the crossties.

The nine PAHs which were chosen for modeling constitute 67 percent of
the creosote mixture, therefore,

Total amount of PAHs leached to the soil = 1306.54 kg x 0.67 = 875.39 kg
/ 10 ha = 87.5 kg/ha. This value will be used to calculate amount of
each PAH in soil.

The percentage of the PAHs in the creosote composition will be used to
calculate the amount of each PAH leached into soil are shown in Table 2:

+------------------------+----------------------+----------------------+
| Table 2. Percent of    |                      |                      |
| the PAHs found in      |                      |                      |
| creosote and the       |                      |                      |
| amount (Kg/Ha) applied |                      |                      |
| to the soil.           |                      |                      |
+========================+======================+======================+
| PAH                    | PAH Percentage in    | Soil Loading Rate    |
|                        |                      |                      |
|                        | Creosote             | (Kg/Ha)              |
+------------------------+----------------------+----------------------+
| Naphthalene            | 13                   | 16.92                |
+------------------------+----------------------+----------------------+
| Acenaphthene           | 4                    | 5.27                 |
+------------------------+----------------------+----------------------+
| Biphenyl               | 8                    | 10.42                |
+------------------------+----------------------+----------------------+
| Fluorene               | 8                    | 10.42                |
+------------------------+----------------------+----------------------+
| Anthracene             | 13                   | 16.92                |
+------------------------+----------------------+----------------------+
| Phenanthrene           | 13                   | 16.92                |
+------------------------+----------------------+----------------------+
| Pyrene                 | 2                    | 2.58                 |
+------------------------+----------------------+----------------------+
| Fluoranthene           | 4                    | 5.27                 |
+------------------------+----------------------+----------------------+
| Chrysene               | 2                    | 2.58                 |
+------------------------+----------------------+----------------------+

**PE5 PRZM-EXAMS Modeling**

The methodology for this analysis used EPA's PE5 PRZM-EXAMS Model Shell
(version 5.0). This model simulates the transport of chemicals from
agricultural settings to adjacent surface water bodies. Inputs to the
model include initial application rates of PAH compounds to the
agricultural soil compartment, physical-chemical properties of the
compounds, and assumptions regarding agricultural scenarios. Soil
compartment loading rates are shown in Table 2.

**1. Methodology**

EPA's PE5 PRZM-EXAMS Model Shell (referred to hereafter as PE5) was used
to estimate concentrations of PAH compounds in dissolved surface water
and sediment pore water. This section describes the following components
of the modeling methodology: soil compartment loading rates,
chemical-specific input values, and agricultural scenarios and
assumptions.

PE5 was developed to evaluate surface water contamination resulting from
the application of chemicals (e.g., pesticides) to agricultural crops
and soil. Therefore, the model uses as an input a chemical application
rate in kilograms chemical applied per hectare of crop area. Because
this analysis uses PE5 to evaluate a wood preservative rather than an
agricultural pesticide, releases of the wood preservative chemicals from
treated wood surfaces must be expressed as a soil compartment loading
rate in kilograms per hectare. The soil compartment loading rates for
this analysis are shown in Table 2 and are associated with the treatment
of railroad ties.

Chemical-specific properties required as inputs to PE5 include molecular
weights, Henry's Law Constants, vapor pressures, solubilities, soil
partition coefficients (Koc), and half-lives of each compound in water,
soil, and sediment. Values for these inputs were obtained from
previously compiled chemical-specific data (**Versar, 2006).**

PE5 was run for each of the nine PAH compounds for two agricultural
scenarios: a California fruit orchard scenario and a Mississippi cotton
scenario. The scenarios differ in that they are characterized by
different local meteorological conditions and soil properties. The
scenarios also include assumptions about agricultural processes that
affect the fate and transport of chemicals in the farm environment.
Examples of these assumptions include the chemical application method
(CAM), incorporation depth, application efficiency, spray drift (if
applicable), and number of applications of the compound. Values for the
agricultural assumptions were made according to the guidance of Dr.
Ronald Parker at EPA's Office of Pesticide Programs (Parker, 2007).

PE5 calculates multiple-year chemical concentrations in the water and
benthic sediments, which are then reported, for each year, the
single-day peak concentration, the maximum 24-hour, 96-hour, 21-day,
60-day, and 90-day mean concentrations, and the mean annual
concentration (EPA, 2006). Model outputs display 3^rd^ through 96^th^
percentile concentrations of the single-year results (e.g., the upper
tenth percentile of the mean annual concentrations).

**2. Estimated PAH Concentrations in Dissolved Surface Water and
Sediment Pore Water**

1.  **Results**

The 10^th^ percentile concentrations of PAH compounds in dissolved
surface and sediment pore water in the California fruit orchard and
Mississippi cotton scenario are presented in Tables 3 through 6.

**2.2 Discussion**

The results of the analyses suggested some trends regarding
environmental concentrations of PAHs.  First, it appeared that higher
percentages of PAHs in creosote were associated with higher estimated
concentrations of PAHs in water and sediment pore water.  Of the PAHs
evaluated in this analysis, naphthalene, anthracene, and phenanthrene
were the most abundant PAH compounds in coal tar creosote (each
accounting for 13%, see Table 2).  Figures 1 and 2 compare the dissolved
surface water and sediment pore water 96-hour 10^th^ percentile
concentrations in the California fruit orchard and Mississippi cotton
scenarios. 

**Table 3. 10^th^ Percentile Estimated Environmental Concentrations of
PAH Compounds in Dissolved Surface Water (µg/L) in the California Fruit
Orchard Scenario**

+------------+-----------+---------+---------+-------+-------+-------+
| **PAH**    | **Instan  | **      | *       | **6   | **9   | **A   |
|            | taneous** | 96-Hour | *21-Day | 0-Day | 0-Day | nnual |
|            |           | (       | (       | (µg   | (µg   | (µg   |
|            | *         | µg/L)** | µg/L)** | /L)** | /L)** | /L)** |
|            | *(µg/L)** |         |         |       |       |       |
+------------+-----------+---------+---------+-------+-------+-------+
| N          | 2.46E+01  | 1       | 6       | 2.5   | 1.7   | 4.3   |
| aphthalene |           | .56E+01 | .25E+00 | 1E+00 | 2E+00 | 6E-01 |
+------------+-----------+---------+---------+-------+-------+-------+
| Ac         | 4.25E+00  | 2       | 1       | 5.2   | 3.8   | 1.1   |
| enaphthene |           | .72E+00 | .07E+00 | 2E-01 | 3E-01 | 7E-01 |
+------------+-----------+---------+---------+-------+-------+-------+
| Biphenyl   | 5.21E+00  | 3       | 1       | 6.3   | 4.2   | 1.0   |
|            |           | .51E+00 | .60E+00 | 3E-01 | 6E-01 | 5E-01 |
+------------+-----------+---------+---------+-------+-------+-------+
| Fluorene   | 8.12E+00  | 5       | 2       | 7.9   | 5.7   | 2.5   |
|            |           | .49E+00 | .12E+00 | 6E-01 | 9E-01 | 0E-01 |
+------------+-----------+---------+---------+-------+-------+-------+
| Anthracene | 4.89E+00  | 2       | 8       | 5.5   | 4.6   | 2.3   |
|            |           | .29E+00 | .71E-01 | 3E-01 | 6E-01 | 8E-01 |
+------------+-----------+---------+---------+-------+-------+-------+
| Ph         | 4.83E+00  | 2       | 7       | 4.4   | 3.6   | 1.6   |
| enanthrene |           | .15E+00 | .43E-01 | 5E-01 | 4E-01 | 5E-01 |
+------------+-----------+---------+---------+-------+-------+-------+
| Pyrene     | 5.22E-01  | 1       | 4       | 2.8   | 2.3   | 1.1   |
|            |           | .47E-01 | .45E-02 | 5E-02 | 6E-02 | 6E-02 |
+------------+-----------+---------+---------+-------+-------+-------+
| Fl         | 1.42E+00  | 6       | 3       | 2.4   | 2.2   | 1.7   |
| uoranthene |           | .25E-01 | .36E-01 | 5E-01 | 4E-01 | 5E-01 |
+------------+-----------+---------+---------+-------+-------+-------+
| Chrysene   | 5.43E-01  | 1       | 5       | 4.0   | 3.4   | 1.9   |
|            |           | .71E-01 | .84E-02 | 0E-02 | 3E-02 | 2E-02 |
+------------+-----------+---------+---------+-------+-------+-------+

**Table 4. 10^th^ Percentile Estimated Environmental Concentrations of
PAH Compounds in Dissolved Surface Water (µg/L) in the Mississippi
Cotton Scenario**

+---------------+-----------+---------+-------+-------+-------+-------+
| **PAH**       | **Instan  | **      | **2   | **6   | **9   | **A   |
|               | taneous** | 96-Hour | 1-Day | 0-Day | 0-Day | nnual |
|               |           | (       | (µg   | (µg   | (µg   | (µg   |
|               | *         | µg/L)** | /L)** | /L)** | /L)** | /L)** |
|               | *(µg/L)** |         |       |       |       |       |
+---------------+-----------+---------+-------+-------+-------+-------+
| Naphthalene   | 9.05E+01  | 5       | 2.9   | 1.4   | 1.1   | 3.3   |
|               |           | .66E+01 | 2E+01 | 9E+01 | 4E+01 | 0E+00 |
+---------------+-----------+---------+-------+-------+-------+-------+
| Acenaphthene  | 2.28E+01  | 1       | 8.2   | 4.9   | 4.5   | 1.9   |
|               |           | .49E+01 | 1E+00 | 8E+00 | 2E+00 | 2E+00 |
+---------------+-----------+---------+-------+-------+-------+-------+
| Biphenyl      | 3.67E+01  | 2       | 1.2   | 5.7   | 4.0   | 1.0   |
|               |           | .38E+01 | 3E+01 | 2E+00 | 4E+00 | 7E+00 |
+---------------+-----------+---------+-------+-------+-------+-------+
| Fluorene      | 4.55E+01  | 2       | 1.6   | 9.8   | 8.9   | 3.7   |
|               |           | .98E+01 | 4E+01 | 3E+00 | 3E+00 | 5E+00 |
+---------------+-----------+---------+-------+-------+-------+-------+
| Anthracene    | 5.91E+01  | 3       | 1.6   | 1.1   | 1.0   | 6.0   |
|               |           | .39E+01 | 0E+01 | 5E+01 | 3E+01 | 5E+00 |
+---------------+-----------+---------+-------+-------+-------+-------+
| Phenanthrene  | 5.71E+01  | 3       | 1.4   | 9.4   | 8.5   | 4.6   |
|               |           | .14E+01 | 1E+01 | 0E+00 | 8E+00 | 1E+00 |
+---------------+-----------+---------+-------+-------+-------+-------+
| Pyrene        | 7.22E+00  | 2       | 1.0   | 7.1   | 6.6   | 3.6   |
|               |           | .64E+00 | 9E+00 | 5E-01 | 9E-01 | 6E-01 |
+---------------+-----------+---------+-------+-------+-------+-------+
| Fluoranthene  | 2.09E+01  | 1       | 8.0   | 7.1   | 6.9   | 6.0   |
|               |           | .22E+01 | 4E+00 | 0E+00 | 5E+00 | 8E+00 |
+---------------+-----------+---------+-------+-------+-------+-------+
| Chrysene      | 7.45E+00  | 3       | 1.3   | 9.4   | 8.9   | 5.5   |
|               |           | .09E+00 | 7E+00 | 0E-01 | 6E-01 | 9E-01 |
+---------------+-----------+---------+-------+-------+-------+-------+

**Table 5. 10^th^ Percentile Estimated Environmental Concentrations of
PAH Compounds in Sediment Pore Water (µg/L) in the California Fruit
Orchard Scenario**

+---------------+-----------+---------+-------+-------+-------+-------+
| **PAH**       | **Instan  | **      | **2   | **6   | **9   | **A   |
|               | taneous** | 96-Hour | 1-Day | 0-Day | 0-Day | nnual |
|               |           | (       | (µg   | (µg   | (µg   | (µg   |
|               | *         | µg/L)** | /L)** | /L)** | /L)** | /L)** |
|               | *(µg/L)** |         |       |       |       |       |
+---------------+-----------+---------+-------+-------+-------+-------+
| Naphthalene   | 1.58E+00  | 1       | 1.4   | 1.2   | 1.1   | 3.8   |
|               |           | .57E+00 | 9E+00 | 5E+00 | 0E+00 | 7E-01 |
+---------------+-----------+---------+-------+-------+-------+-------+
| Acenaphthene  | 2.97E-01  | 2       | 2.8   | 2.6   | 2.5   | 1.1   |
|               |           | .96E-01 | 7E-01 | 6E-01 | 0E-01 | 4E-01 |
+---------------+-----------+---------+-------+-------+-------+-------+
| Biphenyl      | 2.53E-01  | 2       | 1.8   | 9.0   | 6.2   | 1.5   |
|               |           | .49E-01 | 9E-01 | 8E-02 | 6E-02 | 5E-02 |
+---------------+-----------+---------+-------+-------+-------+-------+
| Fluorene      | 6.40E-01  | 6       | 6.1   | 5.4   | 4.9   | 2.1   |
|               |           | .39E-01 | 2E-01 | 5E-01 | 3E-01 | 6E-01 |
+---------------+-----------+---------+-------+-------+-------+-------+
| Anthracene    | 3.24E-01  | 3       | 3.1   | 3.1   | 3.0   | 2.0   |
|               |           | .24E-01 | 7E-01 | 2E-01 | 3E-01 | 0E-01 |
+---------------+-----------+---------+-------+-------+-------+-------+
| Phenanthrene  | 2.60E-01  | 2       | 2.5   | 2.4   | 2.4   | 1.4   |
|               |           | .60E-01 | 4E-01 | 6E-01 | 0E-01 | 5E-01 |
+---------------+-----------+---------+-------+-------+-------+-------+
| Pyrene        | 1.36E-02  | 1       | 1.3   | 1.2   | 1.2   | 7.7   |
|               |           | .36E-02 | 2E-02 | 7E-02 | 4E-02 | 8E-03 |
+---------------+-----------+---------+-------+-------+-------+-------+
| Fluoranthene  | 1.34E-01  | 1       | 1.3   | 1.3   | 1.3   | 1.1   |
|               |           | .34E-01 | 3E-01 | 1E-01 | 0E-01 | 8E-01 |
+---------------+-----------+---------+-------+-------+-------+-------+
| Chrysene      | 2.00E-02  | 2       | 1.9   | 1.9   | 1.8   | 1.2   |
|               |           | .00E-02 | 6E-02 | 0E-02 | 7E-02 | 9E-02 |
+---------------+-----------+---------+-------+-------+-------+-------+

**Table 6. 10^th^ Percentile Estimated Environmental Concentrations of
PAH Compounds in Sediment Pore Water (µg/L) in the Mississippi Cotton
Scenario**

  --------------- ------------------- ----------- ---------- ---------- ---------- ----------
  **PAH**         **Instantaneous**   **96-Hour   **21-Day   **60-Day   **90-Day   **Annual
                                      (µg/L)**    (µg/L)**   (µg/L)**   (µg/L)**   (µg/L)**

  Naphthalene     1.74E+01            1.73E+01    1.68E+01   1.50E+01   1.35E+01   4.94E+00

  Acenaphthene    4.91E+00            4.90E+00    4.85E+00   4.50E+00   4.29E+00   2.36E+00

  Biphenyl        3.73E+00            3.64E+00    3.02E+00   1.82E+00   1.26E+00   3.13E-01

  Fluorene        9.89E+00            9.88E+00    9.75E+00   9.02E+00   8.56E+00   4.68E+00

  Anthracene      8.14E+00            8.13E+00    8.06E+00   7.80E+00   7.67E+00   5.35E+00

  Phenanthrene    7.03E+00            7.02E+00    6.85E+00   6.67E+00   6.51E+00   4.26E+00

  Pyrene          4.06E-01            4.05E-01    3.95E-01   3.83E-01   3.77E-01   2.54E-01

  Fluoranthene    4.47E+00            4.47E+00    4.46E+00   4.43E+00   4.42E+00   4.14E+00

  Chrysene        5.39E-01            5.38E-01    5.28E-01   5.21E-01   5.12E-01   3.77E-01
  --------------- ------------------- ----------- ---------- ---------- ---------- ----------

The graphs indicate that these three PAHs generally were among the most
abundant of the compounds in both dissolved surface water and sediment
pore water in both media, particularly with the Mississippi cotton
scenario.  Fluorene and biphenyl are also relatively abundant in
creosote (8%) and were also found in high concentrations relative to the
other PAH compounds.  Differences between the initial relative abundance
of the PAHs in coal tar creosote and their final relative abundances in
environmental media may be attributable to differences in
chemical-specific properties that affect mobility and persistence in the
environment.  Chrysene and pyrene contribute the least to coal tar
creosote of all of the PAH compounds (2%) and were estimated to have low
environmental concentrations in the California fruit orchard and the
Mississippi cotton scenarios.

Figures 1 and 2 also show that the environmental concentrations
estimated for the Mississippi cotton scenario were higher than the
estimated environmental concentrations for the California fruit orchard
scenario for every PAH in both dissolved surface water and sediment pore
water. As soil loading rates were constant for both scenarios, the
difference in concentrations could be attributable to meteorological
differences (e.g., precipitation, temperature), environmental
differences (e.g., soil type, water chemistry), and/or different
agricultural practices associated with fruits vs. cotton in the two
scenarios.

It was also observed that PAH concentrations were higher in dissolved
surface water than in sediment pore water. This trend suggests limited
mobility of the PAH compounds in the sediment pore water relative to the
water column. For example, the time required for exchange between the
water column and sediment pore to reach equilibrium may be greater than
the 96-hour time frame of the concentration estimates.

Figure 3 presents estimated concentrations of PAH compounds in dissolved
surface water over time for the California fruit orchard scenario. The
results depicted in this figure also are presented in Table 2. The first
water concentration estimates (i.e., at day zero) are the
"instantaneous" PE5 estimates and the last water concentrations are the
estimates at 90 days. The initial concentrations were the highest for
all PAH compounds, and concentrations declined steadily over time. The
declining trend in surface water concentrations suggests both a
decreasing soil compartment source and increasing chemical degradation
(e.g., photolysis).

**Figure 1. Estimated 96-Hour 10^th^ Percentile Concentrations of PAHs
in Dissolved Surface Water (in µg/L)**

![](media/image12.wmf){width="6.184027777777778in"
height="3.236111111111111in"}

**Figure 2. Estimated 96-Hour 10^th^ Percentile Concentrations of PAHs
in Sediment Pore Water (in µg/L)**

![](media/image13.wmf){width="6.21875in" height="3.53125in"}

**Figure 3. Estimated Dissolved Surface Water Concentrations of PAHs in
the California Fruit Orchard Scenario Over Time (in µg/L)**

![](media/image14.wmf){width="6.430555555555555in" height="2.89375in"}

**3. Uncertainties and Limitations**

-   PE5 estimates PAH concentrations in sediment pore water.
    Concentrations of PAH compounds adsorbed to sediment are not
    calculated.

-   Hydrolysis half-life values were unavailable for all PAH compounds.
    The aerobic aquatic metabolism half-life values (defined as the
    "water" half-life variable in PE5) was used as proxies for
    hydrolysis half-lives.

-   Hydrolysis and aerobic aquatic metabolism half-life values were
    unavailable for biphenyl. The hydrolysis and aerobic aquatic
    metabolism half-life values for fluorene were used as proxy inputs.
    Values for fluorene were selected because fluorene and biphenyl have
    comparable chemical structures.

**4. References**

Brooks, K.M. 2004. Polycyclic aromatic hydrocarbon migration from
creosote-treated railway ties into ballast and adjacent wetlands. USDA.
Forrest Service. Research paper FPL-RP-617

EPA, 2006. "PE5 User's Manual for PRZM EXAMS Modeling Shell, Version
5.0." Environmental Fate and Effects Division. Office of Pesticide
Programs, U.S. Environmental Protection Agency. November 15 2006.

Parker, Ronald. 2007. Office of Pesticide Programs. U.S. Environmental
Protection Agency. Personal communication with ICF. November.

EPA, 2006. "Updated Creosote Environmental Fate Chapter.

File: C:\\MYFiles\\ 2008 Reports\\Creosote\|\\Environmental Modeling\\
Estimated Environmental Concentrations for Creosote Leached from Rail
Road Ties into Soil and Water using PE5 PRZM-EXAMS Model Shell

CC: RASB Chemical Files

Siroos Mostaghimi, RASSB

**Appendix B: Ecological Risk Assessment and Characterization**

Risk assessment and characterization integrates exposure and toxicity
information to evaluate the potential for adverse ecological effects.
Risk quotients (RQs) are determined for each taxa or ecological group by
comparing exposure estimates (Estimated Environmental Concentrations,
EECs) to the available acute and chronic ecotoxicity values, where:

RQ = Exposure estimate (EEC) / Toxicity value

RQs are compared to OPP\'s levels of concern (LOCs). Exceedance of an
LOC indicates a potential for acute or chronic adverse effects on
nontarget organisms and identifies a need for regulatory action to
mitigate risk. LOCs currently address the following risk presumptions:

+----------------+-----------------------------------------------------+
| acute:         | regulatory action may be warranted to reduce or     |
|                | preclude                                            |
|                |                                                     |
|                | acute exposure                                      |
+----------------+-----------------------------------------------------+
| acute, listed  | additional regulatory action may be warranted to    |
| species:       | protect                                             |
|                |                                                     |
|                | listed (i.e., endangered or threatened) species     |
+----------------+-----------------------------------------------------+
| chronic:       | regulatory action may be needed to reduce or        |
|                | preclude                                            |
|                |                                                     |
|                | chronic exposure                                    |
+----------------+-----------------------------------------------------+

The LOCs for the various risk presumptions are listed below for
terrestrial and aquatic animals and plants:

+-----------------------+---+---------+---+---------+---+------------------+
|                       | A |         | T |         | [ |                  |
|                       | q |         | e |         | P |                  |
|                       | u |         | r |         | l |                  |
|                       | a |         | r |         | a |                  |
|                       | t |         | e |         | n |                  |
|                       | i |         | s |         | t |                  |
|                       | c |         | t |         | s |                  |
|                       |   |         | r |         | ] |                  |
|                       | [ |         | i |         | { |                  |
|                       | A |         | a |         | . |                  |
|                       | n |         | l |         | u |                  |
|                       | i |         | [ |         | n |                  |
|                       | m |         | A |         | d |                  |
|                       | a |         | n |         | e |                  |
|                       | l |         | i |         | r |                  |
|                       | s |         | m |         | l |                  |
|                       | ] |         | a |         | i |                  |
|                       | { |         | l |         | n |                  |
|                       | . |         | s |         | e |                  |
|                       | u |         | ] |         | } |                  |
|                       | n |         | { |         |   |                  |
|                       | d |         | . |         |   |                  |
|                       | e |         | u |         |   |                  |
|                       | r |         | n |         |   |                  |
|                       | l |         | d |         |   |                  |
|                       | i |         | e |         |   |                  |
|                       | n |         | r |         |   |                  |
|                       | e |         | l |         |   |                  |
|                       | } |         | i |         |   |                  |
|                       |   |         | n |         |   |                  |
|                       |   |         | e |         |   |                  |
|                       |   |         | } |         |   |                  |
+-----------------------+---+---------+---+---------+---+------------------+
| Acute:                |   | 0.5     |   | 0.5     |   | 1                |
+-----------------------+---+---------+---+---------+---+------------------+
| Acute, listed         |   | 0.05    |   | 0.1     |   | 1                |
| species:              |   |         |   |         |   |                  |
+-----------------------+---+---------+---+---------+---+------------------+
| Chronic:              |   | 1       |   | 1       |   | n/a              |
+-----------------------+---+---------+---+---------+---+------------------+

The following toxicity endpoints are used as inputs to the RQ method for
expressing risk:

  ---------------------- ------------------------------------------------
  [Aquatic               
  Animals]{.underline}   

  Acute:                 Lowest tested EC50 or LC50 for freshwater fish
                         and invertebrates and estuarine/marine fish and
                         invertebrates

  Chronic:               Lowest NOEC for freshwater fish and
                         invertebrates and estuarine/marine fish and
                         invertebrates (early life-stage or full
                         life-cycle tests)

  [Terrestrial           
  Animals]{.underline}   

  Avian acute:           Lowest LD50 (single oral dose) and LC50
                         (subacute dietary)

  Avian chronic:         Lowest NOEC (21-week avian reproduction test)

  Mammalian acute:       Lowest LD50 from single oral dose test.
  ---------------------- ------------------------------------------------

+------------------+---+------------------------------------------------+
| Mammalian        |   | Lowest NOEC for two-generation reproduction    |
|                  |   | test                                           |
| chronic:         |   |                                                |
+------------------+---+------------------------------------------------+
| [Pla             |   |                                                |
| nts]{.underline} |   |                                                |
+------------------+---+------------------------------------------------+
| Terrestrial:     | L |                                                |
|                  | o |                                                |
|                  | w |                                                |
|                  | e |                                                |
|                  | s |                                                |
|                  | t |                                                |
|                  | E |                                                |
|                  | C |                                                |
|                  | 2 |                                                |
|                  | 5 |                                                |
|                  | v |                                                |
|                  | a |                                                |
|                  | l |                                                |
|                  | u |                                                |
|                  | e |                                                |
|                  | s |                                                |
|                  | f |                                                |
|                  | r |                                                |
|                  | o |                                                |
|                  | m |                                                |
|                  | b |                                                |
|                  | o |                                                |
|                  | t |                                                |
|                  | h |                                                |
|                  | s |                                                |
|                  | e |                                                |
|                  | e |                                                |
|                  | d |                                                |
|                  | l |                                                |
|                  | i |                                                |
|                  | n |                                                |
|                  | g |                                                |
|                  | e |                                                |
|                  | m |                                                |
|                  | e |                                                |
|                  | r |                                                |
|                  | g |                                                |
|                  | e |                                                |
|                  | n |                                                |
|                  | c |                                                |
|                  | e |                                                |
|                  | a |                                                |
|                  | n |                                                |
|                  | d |                                                |
|                  | v |                                                |
|                  | e |                                                |
|                  | g |                                                |
|                  | e |                                                |
|                  | t |                                                |
|                  | a |                                                |
|                  | t |                                                |
|                  | i |                                                |
|                  | v |                                                |
|                  | e |                                                |
|                  | v |                                                |
|                  | i |                                                |
|                  | g |                                                |
|                  | o |                                                |
|                  | r |                                                |
|                  | f |                                                |
|                  | o |                                                |
|                  | r |                                                |
|                  | b |                                                |
|                  | o |                                                |
|                  | t |                                                |
|                  | h |                                                |
|                  | m |                                                |
|                  | o |                                                |
|                  | n |                                                |
|                  | o |                                                |
|                  | c |                                                |
|                  | o |                                                |
|                  | t |                                                |
|                  | s |                                                |
|                  | a |                                                |
|                  | n |                                                |
|                  | d |                                                |
|                  | d |                                                |
|                  | i |                                                |
|                  | c |                                                |
|                  | o |                                                |
|                  | t |                                                |
|                  | s |                                                |
+------------------+---+------------------------------------------------+
| Terrestrial      | L |                                                |
|                  | o |                                                |
| listed:          | w |                                                |
|                  | e |                                                |
|                  | s |                                                |
|                  | t |                                                |
|                  | E |                                                |
|                  | C |                                                |
|                  | 0 |                                                |
|                  | 5 |                                                |
|                  | o |                                                |
|                  | r |                                                |
|                  | N |                                                |
|                  | O |                                                |
|                  | E |                                                |
|                  | C |                                                |
|                  | f |                                                |
|                  | o |                                                |
|                  | r |                                                |
|                  | b |                                                |
|                  | o |                                                |
|                  | t |                                                |
|                  | h |                                                |
|                  | s |                                                |
|                  | e |                                                |
|                  | e |                                                |
|                  | d |                                                |
|                  | l |                                                |
|                  | i |                                                |
|                  | n |                                                |
|                  | g |                                                |
|                  | e |                                                |
|                  | m |                                                |
|                  | e |                                                |
|                  | r |                                                |
|                  | g |                                                |
|                  | e |                                                |
|                  | n |                                                |
|                  | c |                                                |
|                  | e |                                                |
|                  | a |                                                |
|                  | n |                                                |
|                  | d |                                                |
|                  | v |                                                |
|                  | e |                                                |
|                  | g |                                                |
|                  | e |                                                |
|                  | t |                                                |
|                  | a |                                                |
|                  | t |                                                |
|                  | i |                                                |
|                  | v |                                                |
|                  | e |                                                |
|                  | v |                                                |
|                  | i |                                                |
|                  | g |                                                |
|                  | o |                                                |
|                  | r |                                                |
|                  | f |                                                |
|                  | o |                                                |
|                  | r |                                                |
|                  | b |                                                |
|                  | o |                                                |
|                  | t |                                                |
|                  | h |                                                |
|                  | m |                                                |
|                  | o |                                                |
|                  | n |                                                |
|                  | o |                                                |
|                  | c |                                                |
|                  | o |                                                |
|                  | t |                                                |
|                  | s |                                                |
|                  | a |                                                |
|                  | n |                                                |
|                  | d |                                                |
|                  | d |                                                |
|                  | i |                                                |
|                  | c |                                                |
|                  | o |                                                |
|                  | t |                                                |
|                  | s |                                                |
+------------------+---+------------------------------------------------+
| Aquatic vascular | L |                                                |
|                  | o |                                                |
| and algae:       | w |                                                |
|                  | e |                                                |
|                  | s |                                                |
|                  | t |                                                |
|                  | E |                                                |
|                  | C |                                                |
|                  | 5 |                                                |
|                  | 0 |                                                |
+------------------+---+------------------------------------------------+
| Aquatic vascular | N |                                                |
|                  | O |                                                |
| listed:          | E |                                                |
|                  | C |                                                |
|                  | o |                                                |
|                  | r |                                                |
|                  | E |                                                |
|                  | C |                                                |
|                  | 0 |                                                |
|                  | 5 |                                                |
+------------------+---+------------------------------------------------+

Relevant toxicity measures or other appropriate information from
non-guideline studies or from the open literature also may be used to
assess and characterize risks.

When measured exposure values from relevant field or monitoring studies
are not available, OPP uses computer simulation models to estimate
exposure of aquatic organisms to an active ingredient. These models
estimate EECs in surface waters using product-label information (e.g.,
treatment site, application rate, application method) and available
environmental-fate data to determine how fast the pesticide breaks down
and its expected movement in the environment.

For aquatic organisms, the following EECs are used to calculate the RQ
for each taxa:

  ----------------------------- -----------------------------------------------
  [Fish]{.underline}            

  Acute:                        Instantaneous

  Chronic:                      60-day average

  [Invertebrates]{.underline}   

  Acute:                        Instantaneous

  Chronic:                      21-day average

  [Plants]{.underline}          

  Acute:                        Instantaneous

  Chronic:                      Not applicable
  ----------------------------- -----------------------------------------------

[^1]: the Canadian and U.S. wood-treating industry developed BMPs for
    creosote and other wood preservatives to reduce the amount of
    material lost to the aquatic environment (CITW/WWPI 1997). According
    to the study authors, BMP's require using "clean" creosote in a
    process designed to reduce surface residues of tar and creosote and
    the amount of creosote available to move from interior wood cells to
    the surface of the wood

[^2]: including biphenyl, which is not an EPA Priority Pollutant and is
    not included in the risk assessment