+-----------------------------------------------------------------------+
| **ENVIRONMENTAL RISK RED CHAPTER**                                    |
|                                                                       |
| **Prepared for:**                                                     |
|                                                                       |
| **Regulatory Management Branch II**                                   |
|                                                                       |
| **Antimicrobial Division**                                            |
|                                                                       |
| **Office of Pesticide Programs**                                      |
|                                                                       |
| **U.S. Environmental Protection Agency**                              |
|                                                                       |
| **Arlington, VA 22202**                                               |
|                                                                       |
| **Prepared by:**                                                      |
|                                                                       |
| **Risk Assessment and Science Branch**                                |
|                                                                       |
| **Antimicrobial Division**                                            |
|                                                                       |
| **Office of Pesticide Programs**                                      |
|                                                                       |
| **U.S. Environmental Protection Agency**                              |
|                                                                       |
| **Arlington, VA 22202**                                               |
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**Executive Summary**

This environmental risk assessment addresses hazard to birds, mammals,
plants, insects, fish, and aquatic invertebrates from the components of
inorganic arsenical wood preservatives. The predicted exposure to these
compounds from the use of these wood preservatives is also estimated as
part of the risk assessment process. The hazard and exposure information
are then combined to estimate the risk inorganic arsenical wood
preservatives pose to plants and animals in terrestrial and aquatic
habitats.

Certain registered inorganic arsenical products are mixtures of several
active ingredients. Some active ingredients in these product mixtures
are not covered under this Inorganic Arsenicals RED but have been or
will be assessed for reregistration eligibility under separate RED
cases:

> Cupric Oxide, the form of copper used in CCA treatment solutions, is
> not included as an active ingredient covered under this RED.
> Reregistration requirements for Cupric Oxide will be addressed
> separately in a RED document for Copper, and oxides, Case Number 4025,
> to be issued at a future date.
>
> Zinc Oxide, the zinc component of ACZA, has already been assessed by
> the Agency for the wood preservative use patterns under the Zinc Salts
> RED, Case Number 4099, dated August, 1992.

Inorganic Arsenical wood preservatives are most commonly formulated as
Chromated Copper Arsenate (CCA). Ecological toxicity data are available
for the components of CCA in the form of studies that have been
submitted to the Agency and studies found in the open literature. In
some cases, the toxicity studies evaluated other forms of the metals
than the specific compounds found in CCA (e.g., arsenic acid and chromic
acid).

The results of the terrestrial risk assessment indicate that the
potential for adverse effects to birds and mammals from exposure to
***average*** concentrations of CCA components in soil is low. Average
soil concentrations are considered more likely to represent the exposure
level for mobile receptor species such as birds and mammals than maximum
soil concentrations. It should be noted, however, that the risk
assessment was only based on exposure to CCA components in soil. A
quantitative assessment of the risks to birds and mammals from direct
contact with CCA-treated lumber was not conducted due to the lack of
exposure and toxicity data available. As a result, the potential risks
from direct contact with CCA-treated wood were not evaluated. Additional
uncertainties associated with the assessment are discussed in the
Uncertainty section of this report.

A numerical risk assessment was not conducted for aquatic organisms.
There is a lack of validated models available to estimate the
water-column concentrations of arsenic and chromium as leached from
CCA-treated wood structures. The open literature provides
laboratory-derived leaching study values, but these data are highly
variable as leaching rates of the metals are highly dependent on the
test conditions as well as the age of the wood and CCA retention level.
Additionally, water-column concentrations of these metals in aquatic
habitats would likely be much lower than the values obtained in leaching
studies conducted in small vessels, due to dispersion in the water body
and partitioning into biota and sediment. Calculating risk quotients (RQ
) using the published values as "worst-case" EECs was considered, but
due to the variability of the published data, as well as the high degree
of uncertainty in extrapolating the results to "real-world" conditions,
it was determined that this approach would not provide meaningful
estimates of the risk to aquatic organisms from CCA-treated wood. There
are some published studies on the effects of CCA-treated wood on aquatic
organisms, which indicate that the metals released from the treated wood
are taken up by biota and cause adverse effects to aquatic organisms, at
both community and individual levels (Weis et al., 1991; Weis and Weis,
1995; Weis and Weis, 1996).

**I. Ecological Effects Hazard Assessment**

The toxicity endpoints (e.g., LC50, NOEC, etc.) used in the ecological
risk assessment were obtained from several sources. Primary sources
include the Pesticide Ecotoxicity Database maintained by the U.S. EPA,
Office of Prevention, Pesticides and Toxic Substances/Office of
Pesticide Programs (U.S. EPA, 2002a), and the Health Effects Division's
Hazard Identification Assessment Review Committee's (HIARC) report on
arsenic and chromium, which included several toxicity endpoints for
mammalian species.

A secondary source for toxicity information is the ECOTOX database
maintained by the U.S. EPA, Office of Research and Development (ORD),
and the National Health and Environmental Effects Research Laboratory's
(NHEERL's) Mid-Continent Ecology Division (U.S. EPA, 2002b). This
database includes both aquatic and terrestrial toxicity studies from
peer-reviewed literature. The information in this database is generally
limited to toxicity endpoints; it does not include sufficient detail
about study methodology to determine whether the studies would meet EPA
Guideline requirements. Since the data are obtained from peer-reviewed
literature, they are considered scientifically sound, and provide
supplemental data which can be used in a risk assessment.

If a toxicity endpoint was not available in the primary or secondary
sources, a review of the open literature was performed. The
ecotoxicological effects literature on arsenic and chromium is fairly
extensive. Toxicity data obtained from the open literature were included
in the risk assessment only in cases where similar data were not found
in either the primary or secondary sources. As with the data from the
databases discussed above, the information in articles from the open
literature is usually not detailed enough regarding study methodology to
determine whether the study would meet EPA Guideline requirements.
However, since they are published in peer-reviewed journals, the studies
are considered scientifically sound and provide supplemental data which
is appropriate for use in a risk assessment.

**A. Toxicity to Terrestrial Animals**

**1. Birds, Acute and Subacute**

**a. Arsenic acid**

An acute oral toxicity study using the technical grade of the active
ingredient (TGAI) is required to establish the toxicity of arsenic acid
to birds. The preferred test species is either mallard duck (a
waterfowl) or bobwhite quail (an upland game bird). The results of two
studies identified in the pesticide database are presented in the
following table.

# Table 1. Acute Oral Toxicity of Arsenic Acid to Birds

+------------+---------------+------------+-----------------+---------+
| Substance/ | Organism      | Endpoin    | Comments        | Re      |
| % Active   |               | ts/Results |                 | ference |
| Ingredient |               | (mg/kg)    |                 |         |
| (AI)       |               |            |                 |         |
+------------+---------------+------------+-----------------+---------+
| arsenic    | Northern      | LD50 =     | \- core study   | Fl      |
| acid/ 75%  | bobwhite      | 28.9       |                 | etcher, |
|            | (*Colinus     |            | \- organism     | 1987    |
|            | virginianus*) |            | age: 27 wks     | (40     |
|            |               |            |                 | 409013) |
|            |               |            | \- 21 day test  |         |
|            |               |            | duration        |         |
+------------+---------------+------------+-----------------+---------+
| arsenic    | Northern      | LD50 = 46  | \- core study   | C       |
| acid/      | bobwhite      |            |                 | ampbell |
| 76.1%      | (*Colinus     | NOEL =     | \- organism     | et al., |
|            | virginianus*) | 12.5       | age: 18 wks     | 1990    |
|            |               |            |                 |         |
|            |               |            | \- 14 day test  | \(417   |
|            |               |            | duration        | 19201\) |
|            |               |            |                 |         |
|            |               |            | \- NOEL effect: |         |
|            |               |            | weight loss     |         |
+------------+---------------+------------+-----------------+---------+
|            |               |            |                 |         |
+------------+---------------+------------+-----------------+---------+

These results indicate that arsenic acid is highly toxic to avian
species on an acute oral basis. The guideline requirement (71-1/OPPTS
850.2100) is fulfilled (MRID# 40409013, 41719201).

Two subacute dietary studies using the TGAI are required to establish
the toxicity of arsenic acid to birds. The preferred test species are
mallard duck (a waterfowl) and bobwhite quail (an upland gamebird). The
results of three avian subacute dietary tests that were included in the
pesticide database are tabulated below.

**Table 2. Subacute Dietary Toxicity of Arsenic Acid to Birds**

+------------+---------------+-----------+-----------------+---------+
| Substance/ | Organism      | Endpoint  | Comments        | Re      |
| % Active   |               | s/Results |                 | ference |
| Ingredient |               | (mg/kg)   |                 |         |
| (AI)       |               |           |                 |         |
+------------+---------------+-----------+-----------------+---------+
| arsenic    | Northern      | LC50 =    | \- core study   | EPA     |
| acid/ 75%  | bobwhite      | 168.5     |                 | 2002a   |
|            | (*Colinus     |           | \- 8 day test   |         |
|            | virginianus*) |           | duration        | \(001   |
|            |               |           |                 | 21618\) |
+------------+---------------+-----------+-----------------+---------+
| arsenic    | Northern      | LC50 =    | \- core study   | Long et |
| acid/ 76%  | bobwhite      | 432       |                 | al,     |
|            | (*Colinus     |           | \- organism     | 1990    |
|            | virginianus*) | NOEL =    | age: 10d        |         |
|            |               | 15.6      |                 | \(417   |
|            |               |           | \- 8 day test   | 19202\) |
|            |               |           | duration        |         |
|            |               |           |                 |         |
|            |               |           | \- NOEL effect: |         |
|            |               |           | pharmacotoxic   |         |
|            |               |           | signs           |         |
+------------+---------------+-----------+-----------------+---------+
| arsenic    | Fulvous       | LC50 =    | \- core study   | Fl      |
| acid/ 75%  | whistling     | 1145      |                 | etcher, |
|            | duck          |           | \- organism     | 1987    |
|            | (*Dendrocygna | NOEC \<   | age: 9 days     |         |
|            | bicolor*)     | 156       |                 | \(404   |
|            |               |           | \- 8 day test   | 09012\) |
|            |               |           | duration        |         |
|            |               |           |                 |         |
|            |               |           | \- NOEL effect: |         |
|            |               |           | reduced weight  |         |
|            |               |           | gain            |         |
+------------+---------------+-----------+-----------------+---------+

These results indicate that arsenic acid is slightly to highly toxic to
avian species on a subacute dietary basis. The guideline requirement
(71-2/OPPTS 850.2200) is fulfilled (MRID \# 00121618, 41719201,
40409012).

**b. Chromic acid**

An acute oral toxicity study using the TGAI is required to establish the
toxicity of a chromic acid to birds. The preferred test species is
either mallard duck (a waterfowl) or bobwhite quail (an upland
gamebird). The results of two studies are presented in the following
table.

**Table 3 . Acute Oral Toxicity** **of Chromic Acid** **to Birds**

+-----------+--------------+-----------+-----------------+-----------+
| S         | Organism     | Endpoint  | Comments        | Reference |
| ubstance/ |              | s/Results |                 |           |
| % Active  |              | (mg/kg)   |                 |           |
| I         |              |           |                 |           |
| ngredient |              |           |                 |           |
| (AI)      |              |           |                 |           |
+-----------+--------------+-----------+-----------------+-----------+
| chromic   | Northern     | LD50 =    | \- core study   | Hoxter.,  |
| acid/ 57% | bobwhite     | 93.5      |                 | 1990      |
|           | (*Colinus    |           |                 |           |
|           | v            |           |                 | \(4       |
|           | irginianus*) |           |                 | 1621104\) |
+-----------+--------------+-----------+-----------------+-----------+
| chromic   | Northern     | LC50 =    | \- core study   | #         |
| acid/ 57% | bobwhite     | 164       |                 | Hobden, 2 |
|           | (*Colinus    |           | \- organism     | 000 (T15) |
|           | v            | NOEL \>   | age: 38wks      |           |
|           | irginianus*) | 62        |                 |           |
|           |              |           | \- 14 day test  |           |
|           |              |           | duration        |           |
|           |              |           |                 |           |
|           |              |           | \- NOEL effect: |           |
|           |              |           | weight loss     |           |
+-----------+--------------+-----------+-----------------+-----------+

These results indicate that chromic acid is moderately toxic to avian
species on an acute oral basis. The guideline requirement (71-1/OPPTS
850.2100) is fulfilled (MRID# 41621104).

Two subacute dietary studies using the TGAI are required to establish
the toxicity of chromic acid to birds. The preferred test species are
mallard duck (a waterfowl) and bobwhite quail (an upland gamebird). The
results of avian subacute dietary tests are tabulated below.

**Table 4. Subacute Dietary Toxicity of Chromic Acid to Birds**

+-----------+--------------+-----------+-----------------+-----------+
| S         | Organism     | Endpoint  | Comments        | Reference |
| ubstance/ |              | s/Results |                 |           |
| % Active  |              | (mg/kg)   |                 |           |
| I         |              |           |                 |           |
| ngredient |              |           |                 |           |
| (AI)      |              |           |                 |           |
+-----------+--------------+-----------+-----------------+-----------+
| chromic   | Mallard duck | LC50 \>   | \- core study   | Hoxter,   |
| acid/ 57% |              | 5100      |                 | 1990      |
|           | *(Anas       |           | \- organism     |           |
|           | pla          |           | age: 10d        | \(4       |
|           | tyrhynchus)* |           |                 | 1621102\) |
|           |              |           | \- 8 day test   |           |
|           |              |           | duration        |           |
+-----------+--------------+-----------+-----------------+-----------+
| chromic   | Northern     | LC50 \>   | \- core study   | Ho        |
| acid/ 57% | bobwhite     | 5100      |                 | xter,1990 |
|           | (*Colinus    |           | \- organism     |           |
|           | v            |           | age: 10d        | \(4       |
|           | irginianus*) |           |                 | 1621101\) |
|           |              |           | \- 8 day test   |           |
|           |              |           | duration        |           |
+-----------+--------------+-----------+-----------------+-----------+

These results indicate that chromic acid is practically non-toxic to
avian species on a subacute dietary basis. The guideline requirement
(71-2/OPPTS 850.2200) is fulfilled (MRID \# 41621102, 41621101).

**2. Birds, Chronic**

Avian reproduction studies using the TGAI may be required for a
pesticide when any of the following conditions are met: (1) birds may be
subject to repeated or continuous exposure to the pesticide, especially
preceding or during the breeding season, (2) the pesticide is stable in
the environment to the extent that potentially toxic amounts may persist
in animal feed, (3) the pesticide is stored or accumulated in plant or
animal tissues, and/or, (4) information derived from mammalian
reproduction studies indicates reproduction in terrestrial vertebrates
may be adversely affected by the anticipated use of the product.

Avian chronic toxicity tests are required for the components of CCA
because birds may be exposed to the compound on treated outdoor
structures (e.g., docks, utility poles, etc.) or to residues from these
structures during daily activities such as feeding, nesting and
grooming. There were no avian chronic toxicity studies for arsenic acid
or chromic acid in the pesticide database; the data requirement
(850.2300/old 71-4) are required as confirmatory data.

A study found in the open literature (Sample et al.,1996) identified a
chronic avian NOAEL of 5.1 mg/kg-day for sodium arsenite (As 3+). This
value was based on the results of a chronic dietary study that evaluated
the effects of sodium arsenite (As 3+) to mallard ducks over a 128-day
study period. Sample et al. (1996) also identified a chromium avian
NOAEL of 1 mg/kg-day. This value was based on the results of a chronic
dietary study that evaluated the effects of chromium (as Cr III) to
black ducks during a ten month study duration.

**3. Mammals, Acute and Subacute**

Wild mammal testing is required on a case-by-case basis, depending on
the results of lower tier laboratory mammalian studies, intended use
pattern and pertinent environmental fate characteristics. In most cases,
toxicity values for laboratory animals (e.g., rat, mouse) obtained from
the Agency\'s Health Effects Division (HED) substitute for wild mammal
testing.

> **a. Arsenic acid**

No studies on the acute effects of arsenic acid to wild mammals were
found in the primary or secondary data sources considered for this
assessment; therefore, laboratory mammal acute toxicity endpoints are
used. Acute toxicity values identified for arsenic acid in Chen et al.
(2001) are summarized in the table below.

**Table 5. Mammalian Acute Toxicity of Arsenic Acid**

+-----------+--------------+-----------+-----------------+-----------+
| S         | Organism     | Endpoint  | Comments        | Reference |
| ubstance/ |              | s/Results |                 |           |
| % Active  |              | (mg/kg)   |                 |           |
| I         |              |           |                 |           |
| ngredient |              |           |                 |           |
| (AI)      |              |           |                 |           |
+-----------+--------------+-----------+-----------------+-----------+
| Arsenic   | Laboratory   | LD50 =    | LD50 is the     | #40409001 |
| acid/ 75% | mouse (*Mus  | 150       | mean value for  | as cited  |
|           | musculus*)   |           | male (141mg/kg) | in Chen   |
|           |              |           | and female mice | et al,.   |
|           |              |           | (160mg/kg)      | 2001      |
+-----------+--------------+-----------+-----------------+-----------+
| Arsenic   | Laboratory   | LD50 = 52 | LD50 is the     | \# 26356  |
| acid/ 75% | rat          |           | mean value for  | as cited  |
|           |              |           | male (76mg/kg)  | in Chen   |
|           | *(Rattus     |           | and female rats | et al,.   |
|           | norvegicus)* |           | (37mg/kg)       | 2001      |
+-----------+--------------+-----------+-----------------+-----------+

These results indicate that arsenic acid is moderately to highly toxic
to mammalian species on an acute oral basis. The guideline requirement
(81-1/OPPTS 870.1100) is fulfilled (MRID# 40409001, 26356).

> **b. Chromic acid**

No studies on the acute effects of chromic acid to wild mammals were
found in the primary or secondary data sources considered for this
assessment; therefore, laboratory mammal acute toxicity endpoints are
used. The results of one acute toxicity study identified in McMahon and
Chen (2001) for chromic acid are provided in the table below.

**Table 6. Mammalian Acute Toxicity of Chromic Acid**

  ------------ --------------- ------------------- ------------------ ------------
  Substance/ % Organism        Endpoints/Results   Comments           Reference
  Active                       (mg/kg)                                
  Ingredient                                                          
  (AI)                                                                

  Chromic      Laboratory rat  LD50 = 52           LD50 is the mean   MRID#
  acid/ 100%   *(Rattus                            value for male (56 434294-01 as
               norvegicus)*                        mg/kg) and female  cited in
                                                   mice (48mg/kg)     McMahon and
                                                                      Chen, 2001
  ------------ --------------- ------------------- ------------------ ------------

This study indicates that chromic acid is highly toxic to mammalian
species on an acute oral basis. The guideline requirement (81-1/OPPTS
870.1100) is fulfilled (MRID# 434294-01).

4\. Mammals, Chronic

Mammalian reproduction studies using the TGAI may be required for a
pesticide; this requirement is considered in the human toxicology
assessment portion of this RED document. Chronic hazard to wild mammals
from CCA is of concern due to the potential for repeated or continuous
mammalian exposure to CCA components from either direct contact with
treated structures or exposure to residues in soil and/or water from
treated structures.

**a. Arsenic acid**

The Health Effects Division's Hazard Identification Assessment Review
Committee's (HIARC) report on arsenic (McMahon and Chen, 2001) included
several toxicity endpoints for mammalian species. These endpoints have
been provided in the following table.

**Table 7 . Mammalian Chronic Toxicity of Arsenic Acid**

+-----------+------------+-----------+-------------------+-----------+
| S         | Organism   | Endpoint  | Comments          | Reference |
| ubstance/ |            | s/Results |                   |           |
| % Active  |            | (m        |                   |           |
| I         |            | g/kg/day) |                   |           |
| ngredient |            |           |                   |           |
| (AI)      |            |           |                   |           |
+-----------+------------+-----------+-------------------+-----------+
| arsenic   | Laboratory | LOAEL =   | \- gavage         | Nemac     |
| acid/ 75% | mouse      | 64        | administration to | 1968b,    |
|           |            |           | pregnant females  | cited in  |
|           | (*Mus      | NOAEL =   | during day 6-15   | McMahon   |
|           | musculus*) | 32        | of gestation      | and Chen, |
|           |            |           |                   | 2001      |
|           |            |           | \- effects were   |           |
|           |            |           | reduced body      |           |
|           |            |           | weight, increased |           |
|           |            |           | mortality and     |           |
|           |            |           | increased total   |           |
|           |            |           | litter resorption |           |
+-----------+------------+-----------+-------------------+-----------+
| arsenic   | New        | LOAEL = 4 | \- gavage         | Nemac     |
| acid/ 75% | Zealand    |           | administration to | 1988a,    |
|           | White      | NOAEL = 1 | pregnant females  | cited in  |
|           | Rabbit     |           | during day 6-18   | McMahon   |
|           |            |           | of gestation      | and Chen, |
|           |            |           |                   | 2001      |
|           |            |           | \- effects were   |           |
|           |            |           | reduced body      |           |
|           |            |           | weight, increased |           |
|           |            |           | mortality and     |           |
|           |            |           | histological      |           |
|           |            |           | effect to the     |           |
|           |            |           | liver/kidneys     |           |
+-----------+------------+-----------+-------------------+-----------+
| arsenic   | Dog --     | LOAEL =   | \- study duration | Byron et  |
| V/ AI not | Beagle     | 2.4       | -- 2 yrs          | al.,      |
| available |            |           |                   | 1967,     |
|           |            | NOAEL = 1 | \- endpoint was   | cited in  |
|           |            |           | histology effects | ATSDR,    |
|           |            |           | to the liver and  | 1997      |
|           |            |           | anemia            |           |
+-----------+------------+-----------+-------------------+-----------+

These studies indicate that arsenic acid is moderately toxic to
mammalian species on a chronic basis.

b\. Chromic acid

The Health Effects Division's Hazard Identification Assessment Review
Committee's (HIARC) review of chromium (McMahon and Chen, 2001) included
several toxicity endpoints for mammalian species. These endpoints have
been provided in the following table.

**Table 8. Mammalian Chronic Toxicity of Chromic Acid**

+------------+---------------+-----------+-----------------+---------+
| Substance/ | Organism      | Endpoint  | Comments        | Re      |
| % Active   |               | s/Results |                 | ference |
| Ingredient |               | (m        |                 |         |
| (AI)       |               | g/kg/day) |                 |         |
+------------+---------------+-----------+-----------------+---------+
| Chromic    | Laboratory    | LOAEL =   | \- effects      | Tyl,    |
| acid/ 55%  | rabbit        | 0.48      | included        | 1991,   |
|            |               |           | reduced body    | cited   |
|            |               | NOAEL =   | weight,         | in      |
|            |               | 0.12      | increased       | McMahon |
|            |               |           | mortality       | and     |
|            |               |           |                 | Chen,   |
|            |               |           |                 | 2001    |
+------------+---------------+-----------+-----------------+---------+
| Potassium  | Swiss albino  | LOAEL =   | \- administered | Junaid  |
| d          | mice          | 42.1      | through         | et al., |
| ichromate/ |               |           | drinking water  | 1996,   |
| AI not     |               | NOAEL =   | during days     | cited   |
| available  |               | 22.3      | 6-14 of         | in      |
|            |               |           | gestation       | McMahon |
|            |               |           |                 | and     |
|            |               |           | \- effects were | Chen,   |
|            |               |           | reduced         | 2001    |
|            |               |           | maternal body   |         |
|            |               |           | weight,         |         |
|            |               |           | retarded fetal  |         |
|            |               |           | development and |         |
|            |               |           | increased fetal |         |
|            |               |           | resorption      |         |
|            |               |           |                 |         |
|            |               |           | \- NOTE: The    |         |
|            |               |           | endpoints were  |         |
|            |               |           | based on        |         |
|            |               |           | maternal        |         |
|            |               |           | effects, the    |         |
|            |               |           | fetal effects   |         |
|            |               |           | were seen at    |         |
|            |               |           | every dose      |         |
|            |               |           | tested so a     |         |
|            |               |           | developmental   |         |
|            |               |           | NOAEL could not |         |
|            |               |           | be determined   |         |
+------------+---------------+-----------+-----------------+---------+

These studies indicate that chromic acid is moderately to highly toxic
to mammalian species on a chronic basis.

**5. Insects**

A honey bee acute contact study using the TGAI is required for the
active components of CCA because its use as a wood preservative may
result in honey bee exposure. Results of this test for arsenic acid are
tabulated below.

**Table 9. Nontarget Insect Acute Contact Toxicity of Arsenic Acid**

+------------+---------------+-----------+-----------------+---------+
| Substance/ | Organism      | Endpoint  | Comments        | Re      |
| % Active   |               | s/Results |                 | ference |
| Ingredient |               | (ug/bee)  |                 |         |
| (AI)       |               |           |                 |         |
+------------+---------------+-----------+-----------------+---------+
| arsenic    | Honey bee     | LD50 =    | \- core study   | Hoxter, |
| acid/      |               | 7.7       |                 | 1987    |
| 75.1%      | *(Apis        |           |                 |         |
|            | mellifera*)   |           |                 | \(403   |
|            |               |           |                 | 51301\) |
+------------+---------------+-----------+-----------------+---------+

The results indicate that arsenic acid is highly toxic to bees on an
acute contact basis. The guideline requirement (141-1/OPPTS 850.3020) is
fulfilled (MRID #40351301).

There were no honey bee studies identified for chromic acid in the
pesticide database; the guideline requirement (141-1/OPPTS 850.3020) is
not fulfilled for chromic acid, and is now required as confirmatory
data.

> **6. Terrestrial Field Testing**

Terrestrial field testing is not required for the wood preservative use
of CCA.

**B. Toxicity to Freshwater Aquatic Animals**

> **1. Freshwater Fish, Acute**
>
> **a. Arsenic acid**

Two freshwater fish toxicity studies using the TGAI are required to
establish the toxicity of arsenic acid to fish. The preferred test
species are rainbow trout (a coldwater fish) and bluegill sunfish (a
warmwater fish). Several acute toxicity studies were identified for each
compound of interest in the pesticide database. The results of these
tests are summarized below.

**Table 10. Freshwater Fish Acute Toxicity of Arsenic Acid**

+------------+--------------+------------+------------------+---------+
| Substance/ | Organism     | Endpoin    | Comments         | Re      |
| % Active   |              | ts/Results |                  | ference |
| Ingredient |              | (mg/L)     |                  |         |
| (AI)       |              |            |                  |         |
+------------+--------------+------------+------------------+---------+
| arsenic    | Rainbow      | LC50 = 72  | \- core study    | Le      |
| acid/      | trout        |            |                  | Lievre, |
| 76.1%      |              | NOEL = 3.4 | \- static system | 1990    |
|            | *(           |            |                  |         |
|            | Oncorhynchus |            | \- 96-hr test    | \(416   |
|            | mykiss)*     |            | duration         | 20003\) |
+------------+--------------+------------+------------------+---------+
| arsenic    | Rainbow      | LC50 = 53  | \- supplemental  | EPA     |
| acid/ 75%  | trout        |            | study            | 2002 a  |
|            |              |            |                  | (MRID   |
|            | *(           |            | \- static system | \# not  |
|            | Oncorhynchus |            |                  | re      |
|            | mykiss)*     |            | \- 96-hr test    | ported) |
|            |              |            | duration         |         |
|            |              |            |                  |         |
|            |              |            | \- test organism |         |
|            |              |            | weight 0.57g     |         |
+------------+--------------+------------+------------------+---------+
| arsenic    | Bluegill     | LC50 = 50  | \- core study    | M       |
| acid/      | sunfish      |            |                  | achado, |
| 75.8%      |              | NOEL = 10  | \- flow-through  | 1991    |
|            | *(Lepomis    |            | system           |         |
|            | m            |            |                  | \(419   |
|            | acrochirus)* |            | \- 96-hr test    | 50601\) |
|            |              |            | duration         |         |
|            |              |            |                  |         |
|            |              |            | \- test organism |         |
|            |              |            | weight 1.1g      |         |
+------------+--------------+------------+------------------+---------+
| arsenic    | Bluegill     | LC50 = 54  | \- supplemental  | Sup     |
| acid/ 75%  | sunfish      |            | study            | renant, |
|            |              | NOEL \< 12 |                  | 1987    |
|            | *(Lepomis    |            | \- static system |         |
|            | m            |            |                  | \(404   |
|            | acrochirus)* |            | \- 96-hr test    | 09014\) |
|            |              |            | duration         |         |
|            |              |            |                  |         |
|            |              |            | \- test organism |         |
|            |              |            | weight 1.8g      |         |
+------------+--------------+------------+------------------+---------+

These results indicate that arsenic acid is slightly toxic to freshwater
fish on an acute basis. The guideline requirement (72-/OPPTS 850.1075)
is fulfilled (MRID #41620003, 41950601).

**b. Chromic acid**

Two freshwater fish toxicity studies using the TGAI are required to
establish the toxicity of chromic acid to fish. The preferred test
species are rainbow trout (a coldwater fish) and bluegill sunfish (a
warmwater fish). Two acute toxicity studies were identified for this
compound in the pesticide database. The results of these tests are
summarized below.

**Table 11. Freshwater Fish Acute Toxicity of Chromic Acid**

+-----------+--------------+-----------+-----------------+-----------+
| S         | Organism     | Endpoint  | Comments        | Reference |
| ubstance/ |              | s/Results |                 |           |
| % Active  |              | (mg/L)    |                 |           |
| I         |              |           |                 |           |
| ngredient |              |           |                 |           |
| (AI)      |              |           |                 |           |
+-----------+--------------+-----------+-----------------+-----------+
| Chromic   | Rainbow      | LC50 = 28 | \- core study   | LeLievre, |
| acid/ 57% | trout        |           |                 | 1990      |
|           |              | NOEL =    | \- static       |           |
|           | *(           | 8.6       | system          | \(4       |
|           | Oncorhynchus |           |                 | 1621105\) |
|           | mykiss)*     |           | \- 96-hr test   |           |
|           |              |           | duration        |           |
|           |              |           |                 |           |
|           |              |           | \- test         |           |
|           |              |           | organism weight |           |
|           |              |           | -- 0.5g         |           |
+-----------+--------------+-----------+-----------------+-----------+
| Chromic   | Bluegill     | LC50 = 44 | \- core study   | LeLievre, |
| acid/ 57% | sunfish      |           |                 | 1990      |
|           |              | NOEL = 13 | \- static       |           |
|           | *(Lepomis    |           | system          | \(4       |
|           | m            |           |                 | 1658401\) |
|           | acrochirus)* |           | \- 96-hr test   |           |
|           |              |           | duration        |           |
|           |              |           |                 |           |
|           |              |           | \- test         |           |
|           |              |           | organism weight |           |
|           |              |           | -- 0.5g         |           |
+-----------+--------------+-----------+-----------------+-----------+

These results indicate that chromic acid is slightly to moderately toxic
to freshwater fish on an acute basis. The guideline requirement
(72-/OPPTS 850.1075) is fulfilled (MRID #41621105, 41658401).

> **2. Freshwater Fish, Chronic**

Fish early life stage tests are required if the product is applied
directly to water or expected to be transported to water from the
intended use site, and when any one or more of the following conditions
apply: (1) if the pesticide is intended for use such that its presence
in water is likely to be continuous or recurrent regardless of toxicity;
(2) if any LC~50~ or EC~50~ value determined in acute toxicity testing
is less than 1 mg/L; or (3) if the estimated concentration in water is
equal to or greater that 0.01 of any EC~50~ or LC~50~ determined in
acute toxicity testing; (4) if the actual or estimated environmental
concentration in water resulting from use is less than 0.01 of any
EC~50~ or LC~50~ determined in acute toxicity testing and any of the
following conditions exist: (a) studies of other organisms indicate the
reproductive physiology of fish and /or invertebrates may be affected;
(b) physicochemical properties indicate cumulative effects; (c) the
pesticide is persistent in water (e.g. half-life in water greater than 4
days). The preferred test species is fathead minnow (*Pimephales
promelas*), but other species may be used. Fish early life-stage testing
is required due to the likelihood of continuous exposure from
CCA-treated structures in aquatic habitats. Freshwater and
marine/estuarine fish are comparably sensitive to arsenic acid and
chromic acid on an acute basis, so early life-stage testing on either
type of fish is sufficient to satisfy guideline requirements. Early
life-stage testing was submitted to the agency for arsenic acid and
chromic acid using freshwater species; that data is summarized below.

**a. Arsenic acid**

**Table 12. Freshwater Fish Early Life Stage Toxicity of Arsenic Acid**

+-----------+--------------+-----------+-----------------+-----------+
| S         | Organism     | Endpoint  | Comments        | Reference |
| ubstance/ |              | s/Results |                 |           |
| % Active  |              | (mg/L)    |                 |           |
| I         |              |           |                 |           |
| ngredient |              |           |                 |           |
| (AI)      |              |           |                 |           |
+-----------+--------------+-----------+-----------------+-----------+
| Arsenic   | Fathead      | LOAEC =   | \- core study   | Machado,  |
| acid/     | minnow       | 1.9       |                 | 1991      |
| 76.1%     |              |           | \- flow-through |           |
|           | *(Pimphales  | NOAEC =   | system          | \(4       |
|           | promelas)*   | 0.97      |                 | 1802201\) |
|           |              |           | \- 35 day test  |           |
|           |              |           | duration        |           |
|           |              |           |                 |           |
|           |              |           | \- endpoint is  |           |
|           |              |           | larval survival |           |
+-----------+--------------+-----------+-----------------+-----------+

The results of this study indicate that arsenic acid affects fish larval
survival at levels greater than 0.97 ppm. The guideline requirement
(72-4/OPPTS 850.1400) is fulfilled (#41802201).

**b. Chromic acid**

**Table 13. Freshwater Fish Early Life Stage Toxicity of Chromic Acid**

+-----------+--------------+-----------+-----------------+-----------+
| S         | Organism     | Endpoint  | Comments        | Reference |
| ubstance/ |              | s/Results |                 |           |
| % Active  |              | (mg/L)    |                 |           |
| I         |              |           |                 |           |
| ngredient |              |           |                 |           |
| (AI)      |              |           |                 |           |
+-----------+--------------+-----------+-----------------+-----------+
| chromic   | Fathead      | LOAEC =   | \- core study   | Machado,  |
| acid/ 57% | minnow       | 8.2       |                 | 1991      |
|           |              |           | \- flow-through |           |
|           | *(Pimphales  | NOAEC =   | system          | \(4       |
|           | promelas)*   | 4.0       |                 | 1974901\) |
|           |              |           | \- 35 day test  |           |
|           |              |           | duration        |           |
|           |              |           |                 |           |
|           |              |           | \- endpoint is  |           |
|           |              |           | larval growth   |           |
+-----------+--------------+-----------+-----------------+-----------+

This result indicates that chromic acid causes larval growth effects at
levels above 4.0 ppm. The guideline requirement (72-4/OPPTS 850.1400)
is fulfilled (#41974901).

**3. Freshwater Invertebrates, Acute**

A freshwater aquatic invertebrate toxicity test using the TGAI is
required to establish the toxicity of the components of CCA to aquatic
invertebrates. The preferred test species is *Daphnia magna*. Results of
this test for arsenic acid and chromic acid are provided in the tables
below.

**Table 14. Acute Toxicity of Arsenic Acid to Freshwater Invertebrates**

+------------+---------------+-----------+-----------------+---------+
| Substance/ | Organism      | Endpoint  | Comments        | Re      |
| % Active   |               | s/Results |                 | ference |
| Ingredient |               |           |                 |         |
| (AI)       |               | (mg/L)    |                 |         |
+------------+---------------+-----------+-----------------+---------+
| arsenic    | Water flea    | EC50 = 15 | \- core study   | Le      |
| acid/      | *(Daphnia     |           |                 | Lievre, |
| 76.1%      | magna)*       | NOEL =    | \- static       | 1990    |
|            |               | 2.6       | system          |         |
|            |               |           |                 | \(416   |
|            |               |           | \- 48-hour test | 20001\) |
|            |               |           | duration        |         |
|            |               |           |                 |         |
|            |               |           | \- endpoint is  |         |
|            |               |           | immobilization  |         |
+------------+---------------+-----------+-----------------+---------+

This study indicates that arsenic acid is slightly toxic to aquatic
invertebrates on an acute basis. The guideline requirement (72-2) is
fulfilled (41620001).

**Table 15. Acute Toxicity of Chromic Acid to Freshwater Invertebrates**

+--------------+----------+------------+--------------------+---------+
| Substance/ % | Organism | Endpoin    | Comments           | Re      |
| Active       |          | ts/Results |                    | ference |
| Ingredient   |          |            |                    |         |
| (AI)         |          | (mg/L )    |                    |         |
+--------------+----------+------------+--------------------+---------+
| chromic      | Water    | EC50 =     | \- core study      | Le      |
| acid/ 57%    | flea     | 0.76       |                    | Lievre, |
|              |          |            | \- static system   | 1990    |
|              | *        | NOEL \<    |                    |         |
|              | (Daphnia | 0.35       | \- 48-hour test    | \(416   |
|              | magna)*  |            | duration           | 21103\) |
|              |          |            |                    |         |
|              |          |            | \- endpoint is     |         |
|              |          |            | immobilization     |         |
+--------------+----------+------------+--------------------+---------+

This study indicates that chromic acid is highly toxic to aquatic
invertebrates on an acute basis. The guideline requirement (72-2) is
fulfilled (MRID# 416211043).

**4. Whole Sediment Acute Invertebrate, Freshwater**

Whole sediment acute invertebrate, freshwater studies (1) may be
required when treated wood will be used in the aquatic environment or
use in aquatic sites is not prohibited: (2) may be required on a
case-by-case basis depending on the results of lower tier ecological
studies (e.g., active ingredient or end-use products are highly toxic to
aquatic organisms) and/or pertinent environmental characteristics (e.g.,
Kow is greater than or equal to ([\>]{.underline}) 1,000 or hydrolysis
half-life is greater than (\>) 5 days); and (3) required for
organic-based compounds with a Koc (organic carbon coefficient) greater
than (\>) 1,000 and solubility is less than, or equal to,
([\<]{.underline}) 0.1 mg/ml. The components of CCA meet the above
environmental fate criteria for whole sediment toxicity testing since
CCA-treated wood is used in aquatic environments and available data
regarding the acute toxicity of the components of CCA indicates high
toxicity to freshwater invertebrates from chromic acid. Whole sediment
acute testing is therefore required as confirmatory data. Because no
data on this topic could be located, the risk to invertebrates from
exposure to CCA- contaminated sediment cannot be addressed at this time.

**5. Freshwater Invertebrate, Chronic**

A freshwater invertebrate life-cycle test using the TGAI is required for
a pesticide when it is used in the aquatic environment or use in aquatic
sites is not prohibited and when any of the following conditions apply:
(1) if any LC~50~ or EC~50~ value determined in acute toxicity testing
is less than 1 mg/L; (2) if the estimated environmental concentration is
water is greater than or equal to ([\>]{.underline}) 0.01 of any EC~50~
or LC~50~ determined in acute toxicity testing; (3) if the actual or
estimated environmental concentration in water is less than 0.01 of any
EC~50~ or LC~50~ determined in acute toxicity testing and any of the
following conditions exist: (a) studies of other organisms indicate the
reproductive physiology of fish/invertebrates may be affected; (b)
physicochemical properties indicate cumulative effects may occur and/or;
(c) the pesticide is persistent in water. The preferred test species is
*Daphnia magna*.

Aquatic invertebrate life-cycle testing is required for the components
of CCA since CCA-treated lumber will be used to construct structures in
aquatic environments (e.g., pier, piling, or dock uses). The results of
these tests for arsenic acid and chromic acid are provided below.

**Table 16. Freshwater Aquatic Invertebrate Life-Cycle Toxicity of**
**Arsenic Acid**

+------------+---------------+-----------+-----------------+---------+
| Substance/ | Organism      | Endpoint  | Comments        | Re      |
| % Active   |               | s/Results |                 | ference |
| Ingredient |               |           |                 |         |
| (AI)       |               | (ug/L )   |                 |         |
+------------+---------------+-----------+-----------------+---------+
| arsenic    | Water flea    | LOEC = 38 | \- supplemental | Mc      |
| acid/      | *(Daphnia     |           | study           | Namara, |
| 76.1%      | magna)*       | NOAEC =   |                 | 1991    |
|            |               | 20        | \- flow-through |         |
|            |               |           | system          | \(420   |
|            |               |           |                 | 01601\) |
|            |               |           | \- 21day test   |         |
|            |               |           | duration        |         |
|            |               |           |                 |         |
|            |               |           | \- NOAEC        |         |
|            |               |           | effect - growth |         |
+------------+---------------+-----------+-----------------+---------+

These results indicate that arsenic acid impacts the growth of aquatic
invertebrates at levels greater than 20 ppb. The guideline requirement
(72-4b) is fulfilled (MRID #42001601).

**Table 17. Freshwater Aquatic Invertebrate Life-Cycle Toxicity of**
**Chromic Acid**

+------------+---------------+-----------+-----------------+---------+
| Substance/ | Organism      | Endpoint  | Comments        | Re      |
| % Active   |               | s/Results |                 | ference |
| Ingredient |               |           |                 |         |
| (AI)       |               | (ug/L )   |                 |         |
+------------+---------------+-----------+-----------------+---------+
| Chromic    | Water flea    | LOEC \<   | \- core study   | Mc      |
| acid/ 57%  | *(Daphnia     | 8.6       |                 | Namara, |
|            | magna)*       |           | \- flow-through | 1991    |
|            |               | NOAEC \<  | system          |         |
|            |               | 2.6       |                 | \(418   |
|            |               |           | \- 21day test   | 81501\) |
|            |               |           | duration        |         |
|            |               |           |                 |         |
|            |               |           | \- NOAEC effect |         |
|            |               |           | -reproduction   |         |
+------------+---------------+-----------+-----------------+---------+

These results indicate that chromic acid impacts the reproduction of
aquatic invertebrates at levels greater than 2.6 ppb. The guideline
requirement (72-4b) is fulfilled (MRID#41881501).

**6. Acute Pore Water, Fish and Invertebrates**

An acute pore water, fish and invertebrates study may be required when
(1) treated wood will be used in the aquatic environment or use in
aquatic sites is not prohibited; (2) on a case-by -case basis, depending
on the results of lower tier ecological studies (e.g., active ingredient
or end-use products are highly toxic to aquatic organisms) and /or
pertinent environmental characteristics (e.g., Kow is greater than or
equal to ([\>]{.underline}) 1,000 or hydrolysis half-life is greater
than (\>) 5 days); and (3) required for organic-based compounds with a
Koc (organic carbon coefficient) greater than (\>) 1,000 and solubility
is less than, or equal to, ([\<]{.underline}) 0.1 mg/l. The components
of CCA meet the above environmental fate criteria for acute pore water
toxicity testing since CCA-treated wood is used in aquatic environments
and available data indicate a high level of toxicity to invertebrates
from chromic acid. Acute pore water testing is therefore required as
confirmatory data. Because this data was not readily available in the
primary sources, the risk to fish and invertebrates from exposure to
CCA-contaminated pore water cannot be addressed at this time.

**7. Freshwater Field Studies**

Simulated or actual field testing may be required on a case-by-case
basis depending on the results of lower tier ecological studies (e.g.,
active ingredient or end-use products are highly toxic to aquatic
organisms) and/or pertinent environmental characteristics (e.g., Kow is
greater than or equal to ([\>]{.underline}) 1,000 or hydrolysis
half-life is greater than (\>) 5 days). Certain components of CCA meet
these environmental fate criteria, therefore, confirmatory aquatic field
data are needed to fully characterize the risk CCA poses to aquatic
organisms. This data was unavailable at the time of this risk
assessment, so the potential impact of CCA-treated wood to organisms in
aquatic habitats cannot be fully assessed at this time.

> **8. Freshwater Organism Toxicity Data from Published Scientific
> Literature**

Several studies in the open literature have evaluated the effects of CCA
components to aquatic organisms. Scientific literature indicates that
aquatic organisms may be adversely affected by the components of CCA if
they are exposed to very high concentrations of the metals. For example,
benthic organisms that occur near CCA-treated structures such as docks
and bulkheads are likely to be exposed to very high metal concentrations
(Weis et al., 1991). Actual concentrations of arsenic and chromium in
surface water and sediment as the result of leaching from CCA-structures
are dependent on many factors such as size of the waterbody, flow
patterns (e.g., current, tides), physiochemical properties of the
surface water and sediment, and characteristics of the treated structure
(e.g., size, wood type, structural age).

**C. Toxicity to Estuarine and Marine Animals**

**1. Estuarine and Marine Fish, Acute**

Acute toxicity testing with estuarine/marine fish using the TGAI is
required for a pesticide when the end-use product is intended for direct
application to the marine/estuarine environment or the active ingredient
is expected to reach this environment because of its use in coastal
counties. The preferred test species is sheepshead minnow.
Marine/estuarine acute testing was required for the components of CCA
due to its use as a wood preservative for lumber used to construct
docks, piers and pilings. Results of these tests are tabulated below for
arsenic acid and chromic acid.

**Table 18. Acute Toxicity of Arsenic Acid to Estuarine/Marine Fish**

+------------+---------------+------------+-----------------+---------+
| Substance/ | Organism      | Endpoin    | Comments        | Re      |
| % Active   |               | ts/Results |                 | ference |
| Ingredient |               |            |                 |         |
| (AI)       |               | (mg/L )    |                 |         |
+------------+---------------+------------+-----------------+---------+
| arsenic    | Sheepshead    | LC50 = 28  | \- core study   | 4       |
| acid/      | minnow        |            |                 | 1620004 |
| 76.1%      |               | NOEL = 13  | \- static       |         |
|            | *(Cyprinodon  |            | system          | Le      |
|            | variegatus)*  |            |                 | Lievre, |
|            |               |            | \- 96 hour test | 1990    |
|            |               |            | duration        |         |
+------------+---------------+------------+-----------------+---------+

This study indicates that arsenic acid is moderately toxic to
estuarine/marine fish on an acute basis. The guideline requirement
(72-3a) is fulfilled (MRID #41620004).

**Table 19. Acute Toxicity of Chromic Acid to Estuarine/Marine Fish**

+------------+---------------+------------+----------------+----------+
| Substance/ | Organism      | Endpoin    | Comments       | R        |
| % Active   |               | ts/Results |                | eference |
| Ingredient |               |            |                |          |
| (AI)       |               | (mg/L)     |                |          |
+------------+---------------+------------+----------------+----------+
| chromic    | Sheepshead    | LC50 = 39  | \- core study  | 41703601 |
| acid/ 57%  | minnow        |            |                |          |
|            |               | NOEL = 20  | \- static      | LeLie    |
|            | *(Cyprinodon  |            | system         | vre/1990 |
|            | variegatus)*  |            |                |          |
|            |               |            | \- 96 hour     |          |
|            |               |            | test duration  |          |
+------------+---------------+------------+----------------+----------+

The results indicate that chromic acid is moderately toxic to
estuarine/marine fish on an acute basis. The guideline requirement
(72-3a) is fulfilled (MRID #41703601).

**2. Estuarine and Marine Fish, Chronic**

Fish early life-stage testing using the TGAI is required for wood
preservatives if the product will be used to treat wood used in an
aquatic habitat, such as piers, pilings, and docks. Early life-stage
toxicity data are required on the more sensitive type of fish,
freshwater or estuarine/marine. Based on review of the acute toxicity
data, freshwater and marine/estuarine fish appear to be comparably
sensitive to arsenic acid and chromic acid. Since acceptable fish early
life-stage data were available for the freshwater species fathead
minnow, fish early life-stage testing with a marine/estuarine fish is
not required for either arsenic acid or chromic acid.

**3. Estuarine and Marine Invertebrates, Acute**

Acute toxicity testing with estuarine/marine invertebrates using the
TGAI is required for a pesticide when the end-use product is intended
for direct application to the marine/estuarine environment or the active
ingredient is expected to reach this environment because of its use in
coastal counties. The preferred test species are mysid shrimp and
eastern oyster. Estuarine/marine invertebrate testing was required for
the components of CCA due to its use as a wood preservative for lumber
used to construct docks, piers and pilings in coastal waters. Results of
these tests are tabulated below.

**Table 20. Acute Toxicity of Arsenic Acid to Estuarine/Marine
Invertebrates\***

+------------+---------------+------------+---------------+-----------+
| Substance/ | Organism      | Endpoin    | Comments      | Reference |
| % Active   |               | ts/Results |               |           |
| Ingredient |               |            |               |           |
| (AI)       |               | (mg/L )    |               |           |
+------------+---------------+------------+---------------+-----------+
| arsenic    | Mysid         | LC50 = 2   | \- core study | 41620002  |
| acid/      |               |            |               |           |
| 76.1%      | (*Mysidopsis  | NOEL \<    | \- static     | LeLi      |
|            | bahia*)       | 0.32       | system        | evre/1990 |
|            |               |            |               |           |
|            |               |            | \- 96 hour    |           |
|            |               |            | test duration |           |
+------------+---------------+------------+---------------+-----------+

> \* Note: Oyster testing was waived for arsenic acid

The results indicate that arsenic acid is moderately to highly toxic to
estuarine/marine invertebrates on an acute basis. The guideline
requirement 72-3b is waived, and the guideline requirement 72-3c is
fulfilled (MRID #4160002).

**Table 21. Acute Toxicity of Chromic Acid to Estuarine/Marine
Invertebrates\***

+------------+------------+--------------+-----------------+---------+
| Substance/ | Organism   | Endpo        | Comments        | Re      |
| % Active   |            | ints/Results |                 | ference |
| Ingredient |            |              |                 |         |
| (AI)       |            | (mg/L )      |                 |         |
+------------+------------+--------------+-----------------+---------+
| chromic    | Mysid      | LC50 = 5.9   | \- core study   | 4       |
| acid/ 57%  |            |              |                 | 1703602 |
|            | (*         | NOEL = 2.3   | \- static       |         |
|            | Mysidopsis |              | system          | Le      |
|            | bahia*)    |              |                 | Lievre, |
|            |            |              | \- 96 hour test | 1990    |
|            |            |              | duration        |         |
+------------+------------+--------------+-----------------+---------+

> \* Note: Oyster testing was waived for chromic acid

The results indicate that chromic acid is moderately to highly toxic to
estuarine/marine invertebrates on an acute basis. The guideline
requirement 72-3b is waived, and the guideline requirement 72-3c is
fulfilled (MRID #41703602).

**4. Whole Sediment Acute Invertebrate, Marine**

Whole sediment acute invertebrate, marine studies are required for uses
in estuarine/marine environments and may be required when (1) treated
wood will be used in the aquatic environment or use in aquatic sites is
not prohibited; (2) may be required on a case-by-case basis depending on
the results of lower tier ecological studies (e.g., active ingredient or
end-use products are highly toxic to aquatic organisms) and/or pertinent
environmental characteristics (e.g., Kow is greater than or equal to
([\>]{.underline}) 1,000 or hydrolysis half-life is greater than (\>) 5
days); and (3) required for organic-based compounds with a Koc (organic
carbon coefficient) greater that (\>) 1,000 and solubility is less than
or equal to ([\<]{.underline}) 0.1 mg/l.

Several published studies have evaluated the effects of CCA to marine
and estuarine sediment-dwelling organisms. Weis et al. (1998) studied
five CCA-treated wood bulkheads of different ages in estuaries from New
York to South Carolina. These authors concluded that metals leached from
the treated wood and accumulated in the fine-grain fractions of nearby
sediments. Benthic community species richness, diversity and biomass
were reduced at sample stations one meter from the bulkheads, generally
returning to background characteristics at a distance of 10 meters from
the bulkheads.

**5. Estuarine and Marine Invertebrate, Chronic**

Aquatic invertebrate life-cycle testing using the TGAI is required for
wood preservatives if the product will be used to treat wood used in an
aquatic habitat, such as piers, pilings, and docks. Data are required on
the more sensitive type of invertebrate, freshwater or estuarine/marine.
Acute data show that freshwater and marine/estuarine invertebrates are
comparably sensitive to arsenic acid, and that freshwater invertebrates
are more sensitive than marine/estuarine invertebrates to chromic acid.
Since acceptable aquatic invertebrate life-cycle data was submitted for
the freshwater species *Daphnia magna*, testing with a marine/estuarine
invertebrate is not required for arsenic acid or chromic acid.

**6. Estuarine and Marine Field Studies**

Simulated or actual field testing may be required on a case-by-case
basis depending on the results of lower tier ecological studies (e.g.,
active ingredient or end-use products are highly toxic to aquatic
organisms) and/or pertinent environmental characteristics (e.g., Kow is
greater than or equal to ([\>]{.underline}) 1,000 or hydrolysis
half-life is greater than (\>) 5 days). Certain components of CCA meet
these environmental fate criteria, therefore, confirmatory aquatic field
data are needed to fully characterize the risk CCA poses to aquatic
organisms. This data was unavailable at the time of this risk
assessment, so the potential impact of CCA-treated wood to organisms in
aquatic habitats cannot be fully assessed at this time.

**D. Toxicity to Plants**

**1. Terrestrial / Semi-aquatic**

Terrestrial plant testing, including seedling emergence (123-1/OPPTS
850.4100) and vegetative vigor testing (123-1/OPPTS 850.4150), is
required for wood preservatives in cases where the treated wood will be
used in the aquatic environment (e.g., pier, piling or dock uses). Only
one plant species, rice (*Oryza sativa*), must be tested. CCA meets the
criteria for testing, since CCA-treated wood can be used in the aquatic
environment. These tests (123-1a/850.4100 and 123-1b/850.4150) are now
required as confirmatory data. Several studies in the open literature
have evaluated the effects of CCA components to various terrestrial
plant species. The results of these studies are summarized below.

**a. Arsenic**

Arsenic is taken up actively by plant roots, with arsenate being more
easily absorbed than arsenite. Because arsenic is chemically similar to
phosphorus, it is translocated in the plant in a similar manner and is
able to replace phosphorus in many cell reactions. Mechanisms of arsenic
(V) toxicity to terrestrial plants include interrupted phosphorylation
and adverse effects to enzyme systems (Efroymson et al. 1997).

In review of the literature, one study evaluated the toxicity of arsenic
(V) to corn grown from seed for 4 weeks in a loamy sand with a pH of
7.1. Results of the study indicated that corn fresh weight reductions
rose from less than 10% with the addition of 10 ppm arsenic to more than
65% with the addition of 100 ppm arsenic (Efroymson et al. 1997).
Another study assessed the toxicity of arsenic (III) and arsenic (V)
added to soil on the yield of ryegrass and barley grown from seed for 1
year in a greenhouse. According to the study, there was a significant
reduction in the yield of ryegrass (63%) following the addition of 250
ppm arsenic (V) to the soil (Efroymson et al., 1997). It should be noted
that rice and legumes appear to be more sensitive to arsenic than other
plants. Symptoms include wilting of new-cycle leaves, followed by
retardation of root and top growth, and leaf necrosis.

**b. Chromium**

Chromium VI is more soluble and available to plants than chromium III
and is therefore considered to be the more toxic form. Chromium that is
taken up by plants generally remains in the roots because of the many
binding sites in the cell wall capable of binding chromium ions.
Symptoms of chromium toxicity in plants include stunted growth, poorly
developed roots and leaf curling. Chromium may interfere with carbon
(C), nitrogen (N), phosphorus (P) and iron (Fe) metabolism and enzyme
reactions (Efroymson et al., 1997).

One study investigated the effect of chromium (VI) on soybean seedlings
grown three days in a loam soil. The study found that fresh shoot weight
was reduced 30% following the addition of 30ppm chromium, while 10 ppm
chromium had no observed effect. Another study calculated EC50
concentrations for effects of chromium (VI) on lettuce, tomato and oats
grown in a growth chamber from seed for 14 days. Test plants grown in a
loam soil had EC50 values ranging from 1.8 ppm (in lettuce) to 7.4 ppm
(in oats). Test plants grown in a humic sand soil appeared to be
relatively less sensitive to chromium (VI) exposure with EC50 values
ranging from \> 11 ppm (in lettuce) to 31 ppm (in oats), respectively
(Efroymson et al.,1997).

**2. Aquatic Plants**

Aquatic plant testing is required for wood preservatives if they are
used to treat wood intended for use in aquatic environments (e.g., pier,
piling, or dock uses). Testing is conducted with one species of aquatic
vascular plant (usually *Lemna gibba*) and four species of algae
(*Skeletonema costatum*, *Anabaena flos-aquae*, *Selenastrum
capricornutum* and a freshwater diatom). CCA meets the criteria for
testing, since CCA-treated wood can be used in the aquatic environment.
The results of the submitted data for this requirement are listed below.

**Table 22. Acute Toxicity of Arsenic Acid to Aquatic Plants**

+--------------+--------------+--------------+--------------+---------+
| Substance/ % | Organism     | Endpo        | Comments     | Re      |
| Active       |              | ints/Results |              | ference |
| Ingredient   |              |              |              |         |
| (AI)         |              | (mg/L )      |              |         |
+--------------+--------------+--------------+--------------+---------+
| arsenic acid | Duckweed     | EC50 \> 9.8  | \- core      | EPA     |
| / 75.8%      | (Lemna       | ppm          | study        | 2002a   |
|              | gibba)       |              |              | (42     |
|              |              | NOEL \< 9.8  | \- static    | 290901) |
|              |              | ppm          | system       |         |
|              |              |              |              |         |
|              |              |              | \- 14 day    |         |
|              |              |              | test         |         |
|              |              |              | duration     |         |
+--------------+--------------+--------------+--------------+---------+
| arsenic acid | Green alga   | EC50 = 0.038 | \- core      | E       |
| / 75.8%      | (Selenastrum | ppm          | study        | PA2002a |
|              | ca           |              |              |         |
|              | pricornutum) | NOEL =0.005  | \- static    | \(422   |
|              |              | ppm          | system       | 90902\) |
|              |              |              |              |         |
|              |              |              | \- 5 day     |         |
|              |              |              | test         |         |
|              |              |              | duration     |         |
+--------------+--------------+--------------+--------------+---------+
| arsenic acid | Freshwater   | EC50 = 1.4   | \-           | E       |
| / 75.8%      | diatom       | ppm          | supplemental | PA2002a |
|              | (*Navicula   |              | study        |         |
|              | p            | NOEL \< 0.66 |              | \(422   |
|              | elliculosa*) | ppm          | \- static    | 90903\) |
|              |              |              | system       |         |
|              |              |              |              |         |
|              |              |              | \- 5 day     |         |
|              |              |              | test         |         |
|              |              |              | duration     |         |
+--------------+--------------+--------------+--------------+---------+
| arsenic acid | Marine       | EC50 =       | \-           | EPA     |
| / 75.8%      | diatom       | 0.0092 ppm   | supplemental | 2002a   |
|              | (            |              | study        | (42     |
|              | *Skeletonema | NOEL \<      |              | 278801) |
|              | costatum*)   | 0.007 ppm    | \- static    |         |
|              |              |              | system       |         |
|              |              |              |              |         |
|              |              |              | \- 5 day     |         |
|              |              |              | test         |         |
|              |              |              | duration     |         |
+--------------+--------------+--------------+--------------+---------+
| arsenic acid | Bluegreen    | EC50 \> 2.4  | \-           | E       |
| / 75.8%      | alga         | ppm          | supplemental | PA2002a |
|              | (*Anabaena   |              | study        |         |
|              | flos-aquae*) | NOEL = 0.28  |              | \(422   |
|              |              | ppm          | \- static    | 78802\) |
|              |              |              | system       |         |
|              |              |              |              |         |
|              |              |              | \- 5 day     |         |
|              |              |              | test         |         |
|              |              |              | duration     |         |
+--------------+--------------+--------------+--------------+---------+

The results indicate that arsenic acid is moderately toxic to very
highly toxic to aquatic plants. The guideline (123-2) is partially
fulfilled. Studies which were classified as supplemental should be
repeated as confirmatory data, particularly with the marine diatom,
*Skeletonema costatum*, since it appears to be substantially more
sensitive to arsenic acid than the other species tested.

Aquatic plant toxicity data have not been submitted for chromic acid.
Two studies were identified in the ECOTOX database that evaluated the
effects of chromic acid to aquatic plants. Results of these studies are
summarized in the following table:

**Table 23. Acute Toxicity of Chromic Acid to Aquatic Plants**

+--------------+--------------+---------------+-------------+---------+
| Substance/ % | Organism     | Endp          | Comments    | Re      |
| Active       |              | oints/Results |             | ference |
| Ingredient   |              |               |             |         |
| (AI)         |              | (mg/L )       |             |         |
+--------------+--------------+---------------+-------------+---------+
| chromic acid | Green alga   | EC50 = 0.2    | \- static   | EPA,    |
| / AI not     | (Selenastrum | ppm           | system      | 2002b,  |
| available    | ca           |               |             | (ref    |
|              | pricornutum) |               | \- 120 hour | #3690)  |
|              |              |               | test        |         |
|              |              |               | duration    |         |
|              |              |               |             |         |
|              |              |               | \- endpoint |         |
|              |              |               | is          |         |
|              |              |               | population  |         |
|              |              |               | growth      |         |
+--------------+--------------+---------------+-------------+---------+
| chromic      | Marine       | EC50 = 14.7   | \- static   | EPA,    |
| acid,        | diatom       | ppm           | system      | 2002b   |
| dipotassium  | (            |               |             | (ref    |
| salt / AI    | *Skeletonema |               | \- 5 day    | #2233)  |
| not          | costatum*)   |               | test        |         |
| available    |              |               | duration    |         |
|              |              |               |             |         |
|              |              |               | \- endpoint |         |
|              |              |               | is          |         |
|              |              |               | population  |         |
|              |              |               | growth      |         |
+--------------+--------------+---------------+-------------+---------+

The results indicate that chromic acid is moderately to highly toxic to
aquatic plants. The guideline (123-2) is not fulfilled since the studies
were not submitted to the Agency and only two species of aquatic plants
were evaluated. The full set of aquatic plant toxicity studies for
chromic acid are now required as confirmatory data.

**V. Ecological Risk Assessment**

Risk assessment integrates the results of the exposure and ecotoxicity
data to evaluate the likelihood of adverse ecological effects. One
method of integrating the results of exposure and ecotoxicity data is
called the quotient method. For this method, risk quotients (RQs) are
calculated by dividing exposure estimates by ecotoxicity values, both
acute and chronic:

RQ = EXPOSURE/TOXICITY

RQs are then compared to AD\'s levels of concern (LOCs). These LOCs are
criteria used by OPP to indicate potential risk to nontarget organisms
and the need to consider regulatory action. The criteria indicate that a
pesticide used as directed has the potential to cause adverse effects on
nontarget organisms. LOCs currently address the following risk
presumption categories: (1) **acute high** - potential for acute risk is
high regulatory action may be warranted in addition to restricted use
classification; (2) **acute restricted use** - the potential for acute
risk is high, but this may be mitigated through restricted use
classification; (3) **acute endangered species** - the potential for
acute risk to endangered species is high, and regulatory action may be
warranted, and (4) **chronic risk** - the potential for chronic risk is
high, and regulatory action may be warranted. Currently, AD does not
perform assessments for chronic risk to plants, acute or chronic risks
to nontarget insects, or chronic risk from granular/bait formulations to
mammalian or avian species.

The ecotoxicity test values (i.e., measurement endpoints) used in the
acute and chronic risk quotients are derived from the results of
required studies. Examples of ecotoxicity values derived from the
results of short-term laboratory studies that assess acute effects are:
(1) LC50 (fish and birds) (2) LD50 (birds and mammals (3) EC50 (aquatic
plants and aquatic invertebrates) and (4) EC25 (terrestrial plants).
Examples of toxicity test effect levels derived from the results of
long-term laboratory studies that assess chronic effects are: (1) LOEC
(birds, fish, and aquatic invertebrates) (2) NOEC (birds, fish and
aquatic invertebrates) and (3) MATC (fish and aquatic invertebrates).
For birds and mammals, the NOEC value is used as the ecotoxicity test
value in assessing chronic effects. Other values may be used when
justified. Generally, the MATC (defined as the geometric mean of the
NOEC and LOEC) is used as the ecotoxicity test value in assessing
chronic effects to fish and aquatic invertebrates. However, the NOEC is
used if the measurement endpoint is production of offspring or survival.

Risk presumptions, along with the corresponding RQs and LOCs are
tabulated below.

  -----------------------------------------------------------------------
  **Risk Presumptions for Terrestrial Animals**
  -----------------------------------------------------------------------

  -----------------------------------------------------------------------

  ------------------------------------------------------------------------
  Risk Presumption         RQ                                    LOC
  ------------------------ ------------------------------------- ---------

  ------------------------------------------------------------------------

  -----------------------------------------------------------------------
  **Birds and Wild Mammals**

  -----------------------------------------------------------------------

  ------------------------ ------------------------------------- ---------
  Acute High Risk          EEC^1^/LC50 or LD50/sqft^2^ or        0.5
                           LD50/day^3^                           

  Acute Restricted Use     EEC/LC50 or LD50/sqft or LD50/day (or 0.2
                           LD50 \< 50 mg/kg)                     

  Acute Endangered Species EEC/LC50 or LD50/sqft or LD50/day     0.1

  Chronic Risk             EEC/NOEC                              1
  ------------------------ ------------------------------------- ---------

^1^ abbreviation for Estimated Environmental Concentration (ppm) on
avian/mammalian food items

^2^ [mg/ft^2^]{.underline} ^3^ [mg of toxicant consumed/day]{.underline}

LD50 \* wt. of bird LD50 \* wt. of bird

  -----------------------------------------------------------------------
  **Risk Presumptions for Aquatic Animals**

  -----------------------------------------------------------------------

  ------------------------------- ------------------------------ --------
  Risk Presumption                RQ                             LOC

  Acute High Risk                 EEC^1^/LC50 or EC50            0.5

  Acute Restricted Use            EEC/LC50 or EC50               0.1

  Acute Endangered Species        EEC/LC50 or EC50               0.05

  Chronic Risk                    EEC/MATC or NOEC               1
  ------------------------------- ------------------------------ --------

^1^ EEC = (ppm or ppb) in water

  ------------------------------- ------------------------------ --------
  **Risk Presumptions for                                        
  Plants**                                                       

  Risk Presumption                RQ                             LOC
  ------------------------------- ------------------------------ --------

+-----------------------------------------------------------------------+
| ## Terrestrial and Semi-Aquatic Plants                                |
+-----------------------------------------------------------------------+

  ------------------------------- ------------------------------ --------
  Acute High Risk                 EEC^1^/EC25                    1

  Acute Endangered Species        EEC/EC05 or NOEC               1
  ------------------------------- ------------------------------ --------

+-----------------------------------------------------------------------+
| ## Aquatic Plants                                                     |
+-----------------------------------------------------------------------+

  ------------------------------- ------------------------------ --------
  Acute High Risk                 EEC^2^/EC50                    1

  Acute Endangered Species        EEC/EC05 or NOEC               1
  ------------------------------- ------------------------------ --------

^1^ EEC = lbs ai/A

^2^ EEC = (ppb/ppm) in water

> **A. Exposure and Risk to Nontarget Terrestrial Animals**

Exposure to avian and mammalian species from the application of
pesticides is usually estimated using the ELL-Fate Model (version 1.2)
(EPA, 1999) or other similar terrestrial model. The ELL-Fate model was
developed for agricultural pesticide uses, and calculates the decay of a
chemical applied to foliar surfaces for single and multiple
applications. The model takes into account the weight (lbs.) of active
ingredient applied per acre, the number of applications per year and the
half-life of the chemical in soil in order to estimate the chemical
concentration in the treated foliage.

Based on review of the model parameters, the ELL-Fate model was
determined to be inappropriate for the evaluation of risks to
terrestrial species from exposure to CCA, since this compound is applied
to processed lumber rather than agricultural crops. Birds, insects,
mammals, and plants may be exposed to CCA through direct contact with
treated lumber and contact with metals that have leached from treated
lumber into the surrounding soil. Uptake of these metals into plants and
insects, which are subsequently consumed by birds or mammals, can also
result in exposure. Exposure and toxicity data for direct contact with
treated lumber were not readily available; therefore, the terrestrial
assessment was based on exposure of ecological receptors to CCA
components in soil.

Risks to birds and mammals were evaluated using a simple terrestrial
food web model. To estimate exposure for receptor species, it was
assumed that metal leaching occurs from in-service CCA-treated wood into
the surrounding soil. The leached metals in soil were then assumed to be
taken up by terrestrial vegetation. Based on these conditions, the model
assumed that avian and mammalian receptor species would be exposed to
components of CCA through ingestion of vegetation and incidental
ingestion of soil.

The EECs used in this model were based on metal concentrations observed
in soils below seven CCA-treated decks ranging in age from 4 months to
15 years (Stilwell and Gorney, 1997). These data, summarized in the
table below, are assumed to be representative of metal concentrations in
soil that ecological receptors may be exposed to as the result of metal
leaching from CCA-treated structures.

**Table 24. Summary of Metal Concentrations (mg/kg) in Soil Under
CCA-Treated Decks\***

  -------------------------- --------------------- ----------------------
                             Maximum Concentration Mean Concentration

  Arsenic                    350                   76

  Chromium                   154                   43
  -------------------------- --------------------- ----------------------

> \*data from Stilwell and Gorny (1997).

The methods used to estimate the potential dose of CCA components to
avian and mammalian species through the ingestion of vegetation and soil
are provided in Appendix A. The results of the exposure assessment for
avian and mammalian species have been provided in Tables A1 through A40.
These tables also contain the estimated risk quotients (RQs) for avian
and mammalian species.

When more than one toxicity reference value was available for a
compound, toxicity data were selected for the risk assessment using the
following hierarchy of sources: 1) core studies from the pesticide
database, 2) supplemental studies from the pesticide database, 3) Health
Effects Division's Hazard Identification Assessment Review Committee
(HIRAC) reviews, 4) ECOTOX studies, and 5) studies from the open
literature. In cases where there was more than one toxicity value for
the same source, the lowest toxicity value was selected in order to be
conservative.

> **1. Birds**

As shown in Table A1, the risks to avian species from exposure to
arsenic and chromium in soil as a result of leaching from CCA-treated
structures do not appear to be significant. The acute RQs based on
*maximum* soil concentrations were all less than the acute high risk
level of concern of 0.5. The only exceedence for acute exposure was the
**RQ for arsenic of 0.16 which was greater than the acute endangered
species level of concern of 0.1**. The chronic RQs based on maximum soil
concentrations only **exceeded the chronic risk level of concern for
chromium VI with an RQ of 1.5**. Notably, the acute and chronic RQs that
were based on *mean* soil concentrations did not exceed any of the
respective levels of concern.

**2. Mammals**

The risk to mammalian species exposed to leached metals in soil from
CCA-treated structures is low. The acute RQs based on *maximum* soil
concentrations (Table A2) did not exceed the acute high risk level of
concern of 0.5. However, **the RQ for arsenic exceeded the acute
restricted use levels of concern**. The chronic RQs based on maximum
soil concentrations **exceeded the chronic risk level of concern for
both arsenic and chromium**, although only chromium had a significantly
elevated RQ of 15.7. As shown in Table A2, the RQs based on *mean* soil
concentrations did not exceed any of the acute levels of concern.
**Chronic RQs based on mean soil concentrations exceeded the chronic
risk level of concern for arsenic with an RQ of 1.2 and chromium VI with
an RQ of 4.4**. The actual risk levels for mammalian species may be
lower than the estimated RQs due to the conservative assumptions used in
the model.

> **Conclusions of the Risk Assessment for Birds and Mammals:**

The results indicate that the potential for adverse effects to birds and
mammals from exposure to ***average*** concentrations of CCA components
in soil is low. Average soil concentrations are considered more likely
to represent the exposure level for mobile receptor species such as
birds and mammals than maximum soil concentrations. It should be noted,
however, that the risk assessment was only based on exposure to CCA
components in soil. A quantitative assessment of the risks to birds and
mammals from direct contact with CCA-treated lumber was not conducted
due to the lack of exposure and toxicity data available. As a result,
the potential risks from direct contact with CCA-treated wood were not
evaluated. Additional uncertainties associated with the assessment are
discussed in the Uncertainty section of the report.

**3. Insects**

Exposure to CCA components from treated lumber and the surrounding soil
may result in adverse effects to insects such as honey bees. The
potential risks to insects could not be quantitatively evaluated,
however, since exposure data for insects were not readily available. Bee
hives constructed from treated wood have been shown to cause toxicity to
bees and result in residues of wood preservatives in honey (Kalnins and
Detroy, 1984).

> **B. Exposure and Risk to Nontarget Freshwater and Marine/Estuarine
> Aquatic Organisms**

Freshwater and marine/estuarine aquatic organisms could potentially be
exposed to the components of CCA via residues leached from treated wood
into the aquatic environment, either as runoff from land-based
structures, such as utility poles, or from CCA-treated structures which
stand directly in aquatic habitats, such as docks, piers, pilings, and
bulkheads.

A risk assessment for copper as a component of inorganic arsenical wood
preservatives is not included in this RED, as explained in the Executive
Summary, above. However, copper is known to be highly toxic to aquatic
organisms. While CCA-treated wood does leach copper into aquatic
environments (Hobson, 2000), other copper-containing wood preservatives
have been shown to leach greater amounts of copper (Townsend et al.,
2001), and the copper-containing wood preservatives that do not contain
arsenic are likely to be more toxic to marine organisms than CCA (Weis
and Weis, 1996). Additionally, copper is found in aquatic habitats from
a variety of other pesticidal uses, such as marine antifoulants and
agricultural applications. The forthcoming copper RED will address all
of the pesticidal uses of copper, and will provide a complete assessment
of the risks they pose to aquatic organisms.

There are two major ways in which the components of CCA can reach
aquatic habitats:

1\. The metals can leach directly from CCA-treated structures installed
in or above the water, such as docks, piers, pilings or bulkheads. There
are numerous published studies which provide data on the leaching of CCA
components from these types of structures \[Brooks, 1997; Hobden, 2000;
Townsend et al, 2001\]; however the data are extremely variable because
leaching rates of the metals depend on many factors, such as the
salinity and pH of the water or leaching solution, age of the wood, type
of wood, and retention time. Additionally, much of the data are reported
as losses of metals from the wood as opposed to metal concentrations of
the leachate. There is also a lack of validated methods for estimating
the dispersion of the metals into the larger aquatic environment
surrounding the treated structures, so developing a realistic estimation
of risk from these structures is difficult.

Lee et al (1993) examined freshwater leaching of CCA components in a
laboratory test, involving exposing 2.5 cm2 yellow pine cubes to a water
bath for 14 days and measuring the leachate concentrations of the
metals. The range of values for chromium and arsenic from these studies
are summarized in the table below. Townsend et al (2001) performed
leaching tests with CCA-treated wood using a variety of methods:
deionized water, salt water, Synthetic Precipitation Leaching Procedure
(SPLP),and Toxicity Characteristic Leaching Procedure (TCLP). The range
of values from these tests is also reported in the table below.

**Table 25. Maximum and Minimum Leaching Values from Lee et al, 1993 (as
cited in Hobden, 2000 and Brooks, 1997) and Townsend et al, 2001.**

  ------- --------------- ------------ ----------------- ------------------
          Lee et al., min Lee et al.,  Townsend et al,   Townsend et al,
          (mg/L)          max (mg/L)   min (mg/L)        max (mg/L)

  As      19              28           3.6               8.9

  Cr      3               28           1.8               3.4
  ------- --------------- ------------ ----------------- ------------------

2\. The metals can leach from CCA-treated structures into soil, and
reach aquatic habitats via surface runoff.. Since the model typically
used by OPP to determine EECs from surface runoff \[e.g., the Generic
Expected Environmental Concentrations (GENEEC) model (USEPA, 2001)\] was
developed for organic compounds, it is not appropriate to use it to
model the runoff of metals leached from CCA-treated structures. Cooper
(1990, as cited in Brooks, 1997) examined the concentration of metals in
run-off water from CCA-treated poles and lumber exposed to natural rain;
these values are provided in the table below.

**Table 26. Maximum and Minimum Runoff Values from Cooper, 1990 (as
cited in Brooks, 1997).**

  ------------- ------------------------- --------------------------------
                Cooper, poles (mg/L)      Cooper, lumber (mg/L)

  As            0.300                     1.1 - 7.3

  Cr            0.400                     0.080 - 1.0
  ------------- ------------------------- --------------------------------

Attempting to estimate realistic EECs for arsenic and chromium leaching
from CCA-treated wood is extremely difficult. Water-column
concentrations of these metals in aquatic habitats would likely be much
lower than the values obtained in the leaching studies discussed above,
due to dispersion in the water body and partitioning into biota and
sediment; however, there are no methods currently available to OPP to
reliably quantify these effects and estimate realistic water-column
EECs. Calculating risk quotients (RQ ) using the published values as
"worst-case" EECs is not useful, given the variability of the values and
the high degree of uncertainty in

extrapolating the results to "real-world" conditions. Therefore, a
numerical risk assessment for aquatic organisms will not be performed at
this time.

Published literature on effects to aquatic organisms from the use of
CCA-treated wood has shown that the metals leached from it are taken up
by biota and can have adverse effects (Weis and Weis, 1995). The most
affected aquatic community appears to be the epibiotic , or "fouling,"
community, which grows in direct contact with treated structures (Weis
and Weis, 1996), but effects on benthic community diversity were also
observed, and were correlated with elevated levels of metals in
sediments adjacent to treated wood (Weis and Weis, 1996). Copper leaches
the most of the three metals (Weis and Weis, 2002), and it is known to
be the most toxic of the three metals to aquatic organisms. The leaching
of metals and the corresponding toxic effects are greatest when the wood
is new (Weis et al, 1991).

**C. Endangered Species**

The results of the terrestrial risk assessment indicate that threatened
and endangered birds may be adversely affected by arsenic residues
leached from CCA-treated structures. Birds may also be adversely
affected on a chronic basis by chromium leached from those structures.
These estimates are based on maximum exposure estimates, however.
Average estimated levels of arsenic and chromium are not likely to
impact sensitive avian species. Maximum exposure estimates indicate that
arsenic may cause adverse acute effects to endangered and threatened
mammal species, and both arsenic and chromium may adversely affect
mammals from chronic exposure. Average predicted exposure levels for
both metals are still high enough to cause concern for chronic adverse
effects to mammals.

Since it is not possible to quantify the risk to aquatic organisms from
arsenic and chromium leached from treated wood, it is not known whether
Endangered Species Levels of Concern are exceeded. Literature data do
suggest that the components of CCA do cause adverse effects to aquatic
organisms, particularly epibiotic and benthic organisms, including
impacts on species richness and diversity as well as pathological and
genotoxic effects and reduced growth in individual organisms (Weis and
Weis, 2002). Based on these observed effects, and considering the known
toxicity of the component metals, particularly copper, to aquatic
organisms, it is possible that the component metals of CCA could
adversely impact endangered or threatened aquatic organisms,
particularly those in epibiotic or benthic communities which cannot move
away from treated wood leachate.

The Agency has developed a program (the Endangered Species Protection
Program) to identify pesticides whose use may result in adverse impacts
to endangered and threatened species, and to implement mitigation
measures that will eliminate the adverse impacts. At present, the
program is being implemented on an interim basis as described in a
Federal Register notice (54 FR 27984-28008, July 3, 1989), and is
providing information to pesticide users to help them protect these
species on a voluntary basis. As currently planned, the final program
will call for label modifications referring to required limitations on
pesticide uses, typically as depicted in county-specific bulletins or by
other site-specific mechanisms as specified by state partners. A final
program, which may be altered from the interim program, will be
described in a future Federal Register notice. The Agency is not
imposing label modifications through the RED process at this time.
Rather, any requirements for product use modifications will occur in the
future under the Endangered Species Protection Program.

**D. Uncertainties in the Risk Assessment**

Many of the toxicity values used in the assessment were from the ECOTOX
database or the open literature rather than submitted studies that meet
the pesticide guideline requirements. Toxicity studies conducted with
components of CCA according to guideline requirements would remove some
of the uncertainty in this risk assessment. Toxicity data were not
identified for terrestrial plants, as a result the risks to terrestrial
plants could not be evaluated

Also, many of the toxicity values used in the assessment were based on
the evaluation of different metal compounds than the forms used to
manufacture CCA (e.g., arsenic acid and chromic acid). These compounds
may have different levels of toxicity for the receptor species, which
would increase the level of uncertainty for those specific endpoints.
For example, chromium III toxicity data were used to evaluate risks to
avian receptors since chromium VI toxicity data were not available.
Because chromium VI and chromium III often have different levels of
toxicity, the risk levels estimated based on chromium III toxicity data
are uncertain relative to exposure to chromium VI.

The toxic effects of the combined components of CCA are unknown. The
toxicity of the three metals when received as a combined dose may be
greater than any of their individual toxicities. Toxicity testing with
CCA formulations would address the potential for additive or synergistic
toxic effects from arsenic, chromium and copper in combination.

In general, the toxicity of metals to terrestrial receptors will depend
on many site-specific factors such as the soil type (e.g., sand, loam,
clay, etc.), soil pH, organic content of the soil, and soil moisture
which will affect the availability of the metals to the receptors.
Similarly, the toxicity of metals to aquatic receptors will depend on
site-specific conditions such as surface water pH, sediment
characteristics, and surface water flow patterns (e.g., tidal or river
current) that will affect the metal concentrations and availability of
the metals to aquatic receptors.

Another source of uncertainty regarding the toxicity data used in the
assessment is that most of the toxicity studies were conducted in a
laboratory environment and therefore may not accurately reflect field
conditions experienced by ecological receptors. Toxicity studies also
frequently use different terrestrial or aquatic species than those
expected to occur in the natural environment. As a result, the toxicity
endpoints may be inaccurate with regard to the species of interest.

There are several uncertainties associated with the exposure assessment
for CCA in terrestrial and aquatic environments. The terrestrial
exposure assessment assumed that birds and mammals were only exposed to
CCA in soil since toxicity and exposure data were not readily available
for direct contact with CCA-treated wood. The model also included many
assumptions regarding the indicator species such as diet, food ingestion
rate and home range size that may not accurately reflect actual
conditions in the environment.

Finally, there are numerous uncertainties regarding the estimated
environmental concentrations (EECs) used in the risk assessment.
Concentrations of CCA components in soil and surface water may vary
extensively depending on the type of exposure. The leaching of metals
from treated wood is influenced by a variety of factors, such as the age
and type of wood, the pH of the soil or water contacting the wood, the
retention time used in the treatment process, and environmental
conditions. EECs used in the assessment were based on monitoring and
modeled data based on the leachate of metals from CCA-treated structures
such as decks and telephone poles. The level of uncertainty associated
with the EECs directly affects the uncertainty regarding the estimated
risk levels.

**REFERENCES**

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*APPENDIX A*

***CCA: Arsenic, Chromium and Copper Exposure Assessment for Avian and
Mammalian Species***

*The meadow vole (Microtus pennsylvanicus) was selected as the mammalian
receptor species for evaluating potential effects of the components of
CCA to mammals. The meadow vole is primarily herbivorous and is widely
distributed in the United States (EPA, 1993). The northern bobwhite
(Colinus virginianus) was selected as the avian receptor species for
evaluating potential effects of the components of CCA to avian species.
The northern bobwhite feeds mainly on seeds and low-lying vegetation.
The bobwhite range includes the eastern and central U.S. as well as
portions of the Rocky Mountains and the southwest. The mouse and
bobwhite were selected because a relatively large proportion of the diet
of both species is comprised of vegetation and there is an extensive
amount of toxicity data available for these species, particularly for
the bobwhite.*

*The following discussion presents the methods used to calculate the
potential ingestion of chemicals by the mouse and bobwhite via the
ingestion of food (i.e., terrestrial plants) and surface soil. The
equations presented below were derived based on equations presented by
EPA (1989). The following equation was used to calculate the dose of
chemicals that a mouse or bobwhite would be expected to obtain from the
ingestion of terrestrial plants:*