**UNITED STATES ENVIRONMENTAL PROTECTION AGENCY**

**WASHINGTON, D.C. 20460**

![](media/image1.png){width="5.330555555555556in"
height="0.4777777777777778in"}

August 1, 2006

**[MEMORANDUM]{.underline}**

SUBJECT: 2-(Thiocyanomethylthio) benzothiazole (TCMTB) Ecological Hazard
and Environmental Risk Assessment Chapter-Revised. D322611.

TO: Kathryn Avivah Jakob, Chemical Review Manager

Diane Isbell, Team Leader

Mark Hartman, Branch Chief

Regulatory Management Branch II

Antimicrobials Division (7510C)

FROM: Kathryn Montague, M.S., Biologist

Srinivas Gowda, Microbiologist

Siroos Mostaghimi, Environmental Engineer/Acting Team Leader

Risk Assessment and Science Support Branch

Antimicrobials Division (7510C)

THRU: Norm Cook, Branch Chief

Risk Assessment and Science Support Branch

Antimicrobials Division (7510C)

Attached are the TCMTB ecological hazard and environmental risk
characterization and environmental modeling chapters for incorporation
into the RED document.

**ECOLOGICAL HAZARD AND ENVIRONMENTAL**

**RISK ASSESSMENT CHAPTER - REVISED**

**2-(Thiocyanomethylthio)benzothiazole (TCMTB)**

**D322611**

**PC Code 035603**

**CASE No.: 2625**

**08/01/2006**

**Kathryn Montague**

**Srinivas Gowda**

**Siroos Mostaghimi**

**Richard Petrie**

**Antimicrobials Division**

**Office of Pesticide Programs**

**U.S. Environmental Protection Agency**

**1200 Pennsylvania Avenue, NW**

**Washington, DC 20460**

**Table of Contents**

I. Executive Summary. . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

II\. Ecological Hazard Assessment. . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

A. Toxicity to Terrestrial Animals . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . 4

1\. Birds, Acute and Subacute . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . 4

2\. Birds, Chronic. . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . 5

3\. Mammals, Acute and Chronic . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . 6

B. Toxicity to Aquatic Animals . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . 7

1\. Freshwater. . . . . . . . . . .. . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . 7

a\. Freshwater Fish, Acute. . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . 7

> b\. Freshwater Fish, Chronic. . . . . . . . . . . . . . . . . . . . .
> . . . . . . . . . . . . . . 8
>
> c\. Freshwater Invertebrates, Acute . . . . . . . . . . . . . . . . .
> . . . . . . . . . . . 10
>
> d\. Freshwater Invertebrates, Chronic. . . . . . . . . . . . . . . . .
> . . . . . . . . . . . 10
>
> e\. Freshwater Field Studies. . . . . . . . . . . . . . . . . . . . .
> . . . . . . . . . . . . . . .11

6\. Estuarine and Marine Organisms. . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .11

a\. Estuarine/Marine Fish, Acute. . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . .11

b\. Estuarine/Marine Fish, Chronic. . . . . . . . . . . . . . . . .. . .
. . . . . . . . . . 12

c\. Estuarine/Marine Invertebrates, Acute. . . . . . . . . . . . . . . .
. . . . . . . . .12

d\. Estuarine/Marine Invertebrates, Chronic . . . . . . . . . . . . . .
. . . . . . . . .12

e\. Estuarine/Marine Field Studies. . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . .13

7\. Bioaccumulation in Aquatic Organisms. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . 13

> 8\. Toxicity to Plants . . . . . . . . . . . . . . . . . . . . . . . .
> . . . . . . . . . . . . . . . . . . . . . . 13

III\. Environmental Fate and Exposure Assessment Summaries. . . . . . .
. . . . . . . . . . . . . . . . . . . 14

A.  Environmental Fate Assessment Summary. . . . . . . . . . . . . . . .
    .. . . . . . . . . . . . . . .14

B.  Environmental Exposure Assessment . . . . . . . . . . . . . . . . .
    . . . . . . .. . . . . . . . . . . 15

    1.  Terrestrial. . . . . . . . . . . . . . . . . . . . . . . .. . .
        . . . . . . . . . . . . . . . . . . . . . . . . 15

        a.  Seed Treatment.. . . .. . . . . . . . . . . . . . . . . . .
            . . . . . . . . . . . . 15

        b.  Antisapstain . . . . . . . . . . . . . . . . . . . . . . .
            .. . . . . . . . . . . . . 15

    2.  Aquatic . . . .. . . . . . . . . . . . . . . .. . . . . . . . .
        . . . . . . . . . . . . . . . . . . . . . . . . . 15

        a.  Seed Treatment. . . . . . . . . . . . . . . . . . . . . . .
            .. . . . . . . . . . . 15

        b.  Antisapstain. . . . . . . . . . . . . . . . . . . . . . . ..
            . . . . . . . . . . . . . 16

IV\. Risk Assessment and Risk Characterization . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . .19

A. Terrestrial Organisms.. . . . . . . . . . . . . . . .. . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . 21

B. Aquatic Organisms.. . . . . . . . . . . . . . . .. . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . .21

C. Endangered Species Considerations.. . . . . . . . . . . . . . . .. .
. . . . . . . . . . . . . . . . . . . 23

D. Label Hazard Statements and Use Recommendations.. . . . . . . . . . .
. . . . .. . . . . . . . .24

V. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

**I. EXECUTIVE SUMMARY**

2-(Thiocyanomethylthio)benzothiazole (TCMTB) is a pesticide that is used
as a seed treatment to prevent mold and fungus on cotton, wheat, barley,
oats, rice, sugar beets, and safflower. Additionally, it is used to
control algae, slime, mold, and fungus in industrial processing waters
in various applications, such as leather processing, recirculating
cooling towers, pulp and paper mills, storage tanks, secondary oil
recovery, and waste water systems. It is also used as a materials
preservative in various industrial applications. TCMTB is also used as a
wood preservative, primarily to control sapstain in cut lumber.

[]{.mark}

[Environmental Fate]{.underline}:

TCMTB shows pH-dependent hydrolytic degradation. While hydrolytically
stable at pH 5, the half-life at pH 9 is 1.8-2.1 days. TCMTB breaks down
rapidly by photolysis, with a half life of 1.5 hours. Biotic degradation
also occurs, with half-lives ranging from 1.4 days in soil under aerobic
conditions to 6.9 days in water/sediment systems under anaerobic
conditions. TCMTB is mobile-very mobile in various soils; however,
because of its tendency to biodegrade in water and soils, TCMTB is not
likely to contaminate surface and ground waters.

The Kow of TCMTB is 1995. A Kow \> 1000 indicates that a chemical may
potentially bioconcentrate; however, the results of a bioconcentration
study in fish indicate that bioconcentration of TCMTB will be minimal.

Several major metabolites are formed during the biotic degradation
processes of TCMTB, including Number range
CHAPTER2-benzothiazolesulfonic acid (BTSA) and Number range
CHAPTER2-mercaptobenzothiazole (2-MBT). BTSA not of toxicological
concern due to being completely excreted (sulfonic acid) and having
negligible toxicity. 2-MBT is generally less toxic than parent TCMTB
(see tables, below); therefore, mitigation of any risks from TCMTB
toxicity endpoints will be protective of any risks from 2-MBT.
Therefore, the environmental risk assessment was conducted for TCMTB
only.

[Ecological Effects]{.underline}:

TCMTB is slightly toxic and 2-MBT is practically non-toxic to birds on
an acute oral basis, and both TCMTB and 2-MBT are slightly toxic to
birds on a subacute dietary basis.

Based on the results of mammalian studies conducted to meet human
toxicity data requirements, TCMTB exhibits low acute oral and dermal
toxicity (toxicity category III). However, it is highly irritating to
the eyes and skin (toxicity category I and II, respectively) and is also
considered to be highly toxic via the inhalation route of exposure
(toxicity category I). TCMTB is a dermal sensitizer. The NOAEL
determined in a rat 2-generation reproduction study was 400 ppm.

Both TCMTB and 2-MBT are very highly toxic to freshwater fish on an
acute basis. Chronic testing indicates that TCMTB causes reproduction
and growth effects in fish at very low levels (\>0.34 ppb). TCMTB is
very highly toxic to estuarine/marine fish on an acute basis.

TCMTB is very highly toxic and 2-MBT is moderately toxic to freshwater
aquatic invertebrates on an acute basis, and TCMTB also shows very high
acute toxicity to marine/estuarine invertebrate species

TCMTB impairs growth of aquatic vascular plants at levels greater than
0.15 ppm (150 ppb).

Acute risks to birds and mammals from consuming TCMTB-treated seeds were
below Agency Levels of Concern (LOCs). Terrestrial risk from the wood
preservative uses of TCMTB were not addressed due to a lack of available
models to estimate terrestrial exposure from antisapstain treatments.

Risks to aquatic organisms from the seed treatment use of TCMTB are
below LOCs. However, based on the Tier I screening model used for the
antisapstain use, there are risks to aquatic organisms. Acute LOCs were
exceeded for all taxa except aquatic plants, and chronic LOCs for fish
were also exceeded. Chronic risk to invertebrates could not be addressed
due to a lack of chronic toxicity data. Precautions to limit leaching
and runoff from antisapstain treatment facilities areas (see Label
Hazard Statements and Use Recommendations section, below) should prevent
exposure to aquatic organisms. The aquatic monitoring study, described
below, will provide data on the effectiveness of the mitigation methods.

[Endangered Species Concerns]{.underline}:

Using Tier I screening modeling to assess potential exposure from
antisapstain wood preservation uses of TCMTB, risks to Listed Species
are indicated. Since the model is only intended as a screening-level
model, and, as such, has inherent uncertainties and limitations which
may result in inaccurate exposure estimations, further refinement of the
model is recommended before any regulatory action is taken regarding the
antisapstain uses of TCMTB. Potential impacts from the antisapstain use
can be mitigated in the interim with precautions to prevent leaching and
runoff when wood is stored outdoors. Due to these circumstances, the
Agency defers the Endangered Species Decision until additional data are
received regarding actual concentrations of TCMTB in waters receiving
runoff from antisapstain treatment facilities practicing the mitigation
methods described in this document (see Label Hazard Statements and Use
Recommendations section, below), as well as the other data described in
the data gaps section, below. When the additional data are received, the
environmental risk assessment of the antisapstain use of TCMTB will be
revised, and the risks to Listed Species will be reconsidered.

**Data Gaps:**

[Ecological Effects]{.underline}**:**

The following data requirements are outstanding for the currently
registered uses of TCMTB:

72-4b/850.1400 Aquatic invertebrate life-cycle study (wood preservation)

72-5/850.1500 Fish Life-Cycle Testing

123-1/850.4225 and 850.4250 Tier II seedling emergence and vegetative
vigor with rice (wood preservation)

122-1/850.4100 Tier I seedling emergence for 10 species of terrestrial
plant (seed treatment)

123-2/850.5400 Algal Toxicity (wood preservation and seed treatment)

\[No Guideline\] Residues in honey/beeswax and toxicity of treated wood
residues to bees - combination of Guidelines 171-4 and 850.3030 (see
attached information regarding residue data requirements for uses in
beehives. Numbers of bees used in this study and methods for
collection/introduction of bees into hives, feeding, and observations
for toxicity and mortality should be consistent with those described in
OPPTS Guideline 850.3030, "Honey Bee Toxicity of Residues on
Foliage.")**.** The toxicity portion of this study is in lieu of the
honeybee contact LD50 test. The residue and toxicity test can be waived
provided the label is amended to prohibit the use of treated wood for
beehive construction, with a statement such as, "Wood treated with TCMTB
shall not be used in the construction of beehives."

The following data requirements are reserved for TCMTB, pending the
results of other studies listed above:

Tier II seedling emergence (123-1/850.4100) with 10 species of
terrestrial plant (seed treatment)

\- may be required if Tier I study shows \>25% effect at concentration
tested

\- may be required if monitoring study shows concentrations at levels
known to cause adverse chronic effects in fish (as indicated in early
life-stage testing)

[Environmental Fate]{.underline}:

The following data requirements are outstanding for the currently
registered uses of TCMTB:

1.  Hydrolysis (wood preservation and seed treatment)

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1.  Aerobic soil metabolism (wood preservation and seed treatment)

2.  Anaerobic soil metabolism (wood preservation and seed treatment)

3.  Aerobic aquatic metabolism (wood preservation and seed treatment)

The following data requirements are reserved for TCMTB, pending the
results of lower tier testing and exposure modeling:

164-1 Terrestrial field dissipation (seed treatment and wood
preservation)

164-2 Aquatic field dissipation (wood preservation)

**Label Hazard Statements/Use Recommendations**

The following ecological effects/environmental risk statements are
required for TCMTB labels:

"This product is toxic to fish, aquatic invertebrates, oysters and
shrimp."

\"Do not discharge effluent containing this product into lakes, streams,
ponds, estuaries,

oceans, or other waters unless in accordance with the requirements of a
National Pollutant Discharge Elimination System (NPDES) permit and the
permitting authority has been

notified in writing prior to discharge. Do not discharge effluent
containing this product

to sewer systems without previously notifying the local sewage treatment
plant authority.

For guidance contact your State Water Board or Regional Office of the
EPA.\"

Antisapstain labels must state: \"Treated lumber must be stored under
cover, indoors, or at least 100 feet from any pond, lake, stream,
wetland, or river to prevent possible runoff of the product into the
waterway. Treated lumber stored within 100 feet of a pond, lake, steam,
wetland, or river must be either covered with plastic or surrounded by a
berm to prevent surface water runoff into the nearby waterway. If a berm
or curb is used around the site, it should consist of impermeable
material (clay, asphalt, concrete) and be of sufficient height to
prevent runoff during heavy rainfall events.\"

**II. ECOLOGICAL HAZARD ASSESSMENT**

A.  **Toxicity to Terrestrial Animals**

1**. Birds, Acute** **and Subacute**

An acute oral toxicity study using the technical grade of the active
ingredient (TGAI) is required under FIFRA to establish the toxicity of a
pesticide to birds. The preferred test species is either mallard duck (a
waterfowl) or bobwhite quail (an upland game bird). The results of

**Table 1. Acute Oral Toxicity of TCMTB and 2-MBT to Birds**

+---------+-------+------+--------+----+-----------+-------+-------+
| Study   | Sp    | Endp | To     | NO | Other     | EPA   | S     |
| type    | ecies | oint | xicity | EL | Effects   | ID    | tatus |
| (%a.i.) | T     | P    | Value  |    | Noted     | #     |       |
|         | ested | aram | (95%   |    |           | /Refe |       |
|         |       | eter | conf   |    |           | rence |       |
|         |       |      | idence |    |           |       |       |
|         |       |      | l      |    |           |       |       |
|         |       |      | imits) |    |           |       |       |
+---------+-------+------+--------+----+-----------+-------+-------+
| TCMTB   |       |      |        |    |           |       |       |
+---------+-------+------+--------+----+-----------+-------+-------+
| Avian   | Bob   | M    | LD~50~ | \  | Signs of  | 4178  | Accep |
| acute   | white | orta | =      | <2 | toxicity  | 09-01 | table |
| oral,   | quail | lity | 660.85 | 92 | and       | (Camp |       |
| 850.21  | (*Co  |      | (      | m  | reduction | bell, |       |
| 00/71-1 | linus |      | 541.09 | g/ | of body   | 1991) |       |
| (80.4%  | vir   |      | --     | kg | weight    |       |       |
| a.i.)   | ginia |      | 8      |    | and feed  |       |       |
|         | nus*) |      | 05.08) |    | co        |       |       |
|         |       |      | mg/kg, |    | nsumption |       |       |
|         |       |      | "sl    |    | at 292    |       |       |
|         |       |      | ightly |    | mg/kg     |       |       |
|         |       |      | toxic" |    |           |       |       |
+---------+-------+------+--------+----+-----------+-------+-------+
| 2-MBT   |       |      |        |    |           |       |       |
+---------+-------+------+--------+----+-----------+-------+-------+
| Avian   | Bob   | M    | LD50   | \< | Some      | 4226  | Accep |
| acute   | white | orta | \>     | 10 | evidence  | 71-01 | table |
| oral,   | quail | lity | 2150   | 00 | of        | (Ped  |       |
| 850.21  | (*Co  |      | mg/kg  | m  | dos       | ersen |       |
| 00/71-1 | linus |      |        | g/ | e-related | and   |       |
| (98.22% | vir   |      | "pract | kg | abno      | Hel   |       |
| a.i.)   | ginia |      | ically |    | rmalities | sten, |       |
|         | nus*) |      | non-   |    | upon      | 1     |       |
|         |       |      | toxic" |    | gross     | 992a) |       |
|         |       |      |        |    | necropsy  |       |       |
|         |       |      |        |    | (friable  |       |       |
|         |       |      |        |    | livers,   |       |       |
|         |       |      |        |    | resorbed  |       |       |
|         |       |      |        |    | eggs,     |       |       |
|         |       |      |        |    | flu       |       |       |
|         |       |      |        |    | id-filled |       |       |
|         |       |      |        |    | sacs in   |       |       |
|         |       |      |        |    | abdomen)  |       |       |
+---------+-------+------+--------+----+-----------+-------+-------+

These results indicate that TCMTB is slightly toxic and 2-MBT is
practically non-toxic to birds on an acute oral basis. The guideline
requirement (71-1/OPPTS 850.2100) is fulfilled.

Two subacute dietary studies using the technical grade of the active
ingredient are required to establish the toxicity of a pesticide to
birds. The preferred test species are mallard duck (a waterfowl) and
Northern bobwhite quail (an upland gamebird). Results of avian subacute
dietary tests are tabulated below.

+--------+------+---------+------+-------+--------+------+---------+
| *      |      |         |      |       |        |      |         |
| *Table |      |         |      |       |        |      |         |
| 2.     |      |         |      |       |        |      |         |
| Avian  |      |         |      |       |        |      |         |
| Su     |      |         |      |       |        |      |         |
| bacute |      |         |      |       |        |      |         |
| D      |      |         |      |       |        |      |         |
| ietary |      |         |      |       |        |      |         |
| To     |      |         |      |       |        |      |         |
| xicity |      |         |      |       |        |      |         |
| of     |      |         |      |       |        |      |         |
| TCMTB  |      |         |      |       |        |      |         |
| and    |      |         |      |       |        |      |         |
| 2      |      |         |      |       |        |      |         |
| -MBT** |      |         |      |       |        |      |         |
+========+======+=========+======+=======+========+======+=========+
| Test   | Chem | Species | Endp | Re    | Other  | R    | Status  |
| Type   | ical |         | oint | sults | E      | efer |         |
| (Ch    | (%   |         |      |       | ffects | ence |         |
| emical | a    |         |      |       | Noted  |      |         |
| and %  | .i.) |         |      |       |        |      |         |
| a.i.)  |      |         |      |       |        |      |         |
+--------+------+---------+------+-------+--------+------+---------+
| Avian  | T    | Mallard | M    | 8-day | Feed   | A    | Acc     |
| acute  | CMTB | duck    | orta | LC50  | consu  | cces | eptable |
| di     | (80  | (Anas   | lity | \>    | mption | sion |         |
| etary, | -83% | platyrh |      | 10000 | and    | #00  |         |
| 8      | a    | ynchos) |      | ppm   | 10%    | 9869 |         |
| 50.220 | .i.) |         |      |       | mor    | (Boo |         |
| 0/71-2 |      |         |      | "p    | tality | den, |         |
|        |      |         |      | racti | at     | 1    |         |
|        |      |         |      | cally | 5,000  | 974) |         |
|        |      |         |      | non-t | and    |      |         |
|        |      |         |      | oxic" | 10,000 |      |         |
|        |      |         |      |       | ppm    |      |         |
+--------+------+---------+------+-------+--------+------+---------+
| Avian  | T    | B       | M    | LC50  | Hu     | A    | Suppl   |
| acute  | CMTB | obwhite | orta | \>    | ddling | cces | emental |
| di     | (75  | quail   | lity | 10000 | and    | sion |         |
| etary, | %    | (       |      | ppm   | depr   | #09  |         |
| 8      | a    | Colinus |      |       | ession | 1624 |         |
| 50.220 | .i.) | virgi   |      | "P    | at     | (K   |         |
| 0/71-2 |      | nianus) |      | racti | levels | nott |         |
|        |      |         |      | cally | \>     | and  |         |
|        |      |         |      | non-t | 1000   | Wood |         |
|        |      |         |      | oxic" | ppm    | ard, |         |
|        |      |         |      |       |        | 19   |         |
|        |      |         |      |       |        | 68a) |         |
+--------+------+---------+------+-------+--------+------+---------+
| Avian  | T    | Mallard | M    | 8-day | NOEC   | 4    | Acc     |
| acute  | CMTB | duck    | orta | LC50  | \< 450 | 1595 | eptable |
| di     | (80% | (Anas   | lity | \     | pp     | 6-01 |         |
| etary, | a    | platyrh |      | >4496 | mbased | (    |         |
| 85     | .i.) | ynchos) |      | ppm   | on     | Long |         |
| 0.2200 |      |         |      | "Sli  | red    | et   |         |
| /71-2) |      |         |      | ghtly | uction | al., |         |
|        |      |         |      | t     | in     | 1    |         |
|        |      |         |      | oxic" | body   | 990. |         |
|        |      |         |      |       | weight |      |         |
|        |      |         |      |       | gain   |      |         |
|        |      |         |      |       | and    |      |         |
|        |      |         |      |       | food   |      |         |
|        |      |         |      |       | consu  |      |         |
|        |      |         |      |       | mption |      |         |
+--------+------+---------+------+-------+--------+------+---------+
| Avian  | T    | B       | M    | 8-day | NOEC = | 4    | Acc     |
| acute  | CMTB | obwhite | orta | LC50  | 450    | 1595 | eptable |
| di     | (80% | quail   | lity | \     | ppm,   | 6-02 |         |
| etary, | a    | (       |      | >4496 | based  | (    |         |
| 8      | .i.) | Colinus |      | ppm   | on     | Long |         |
| 50.220 |      | virgi   |      | "Sli  | red    | et   |         |
| 0/71-2 |      | nianus) |      | ghtly | uction | al., |         |
|        |      |         |      | t     | of     | 1990 |         |
|        |      |         |      | oxic" | a      |      |         |
|        |      |         |      |       | verage |      |         |
|        |      |         |      |       | body   |      |         |
|        |      |         |      |       | weight |      |         |
|        |      |         |      |       | gain   |      |         |
|        |      |         |      |       | at     |      |         |
|        |      |         |      |       | higher |      |         |
|        |      |         |      |       | levels |      |         |
+--------+------+---------+------+-------+--------+------+---------+
| Avian  | 2    | B       | M    | 8-day | NOEC = | 4    | Acc     |
| acute  | -MBT | obwhite | orta | LC50  | 3387   | 2428 | eptable |
| di     | (98  | quail   | lity | \     | ppm -- | 5-01 |         |
| etary, | .22% | (       |      | >3387 | no     |      |         |
| 85     | a    | Colinus |      | ppm   | signs  | (    |         |
| 0.2200 | .i.) | virg    |      | "Sli  | of     | Pede |         |
| /71-2) |      | inianus |      | ghtly | to     | rsen |         |
|        |      |         |      | t     | xicity | and  |         |
|        |      |         |      | oxic" | at any | Hels |         |
|        |      |         |      |       | level  | ten, |         |
|        |      |         |      |       |        | 19   |         |
|        |      |         |      |       |        | 92b) |         |
+--------+------+---------+------+-------+--------+------+---------+

These results indicate that both TCMTB and 2-MBT are slightly toxic to
birds on a subacute dietary basis. The guideline requirement (71-2/OPPTS
850.2200) is fulfilled.

> **2. Birds, Chronic**

Avian reproduction studies using the technical grade of the active
ingredient are 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. The currently registered uses of TCMTB
do not require avian reproduction testing.

> **3. Mammals**: (Excerpted from Toxicology Chapter)

Wild mammal testing was not required for TCMTB. In most cases, rodent
acute toxicity values obtained from studies conducted to support data
requirements for human health risk assessment substitute for wild mammal
testing. This information is discussed in the Toxicology chapter of this
RED document, from which the following is excerpted:

+-------------------------+---------+------------------------+--------+
| **Table 3. Acute        |         |                        |        |
| Toxicity Data on TCMTB  |         |                        |        |
| Technical (80% ai)**    |         |                        |        |
+-------------------------+---------+------------------------+--------+
| **Guideline No./ Study  | **MRID  | **Results**            | **To   |
| Type**                  | No.**   |                        | xicity |
|                         |         |                        | Cate   |
|                         |         |                        | gory** |
+-------------------------+---------+------------------------+--------+
| 870.1100 Acute oral     | 4       | LD~50~ = 750 mg/kg     | III    |
| toxicity                | 1583801 | (M+F); 80% ai          |        |
+-------------------------+---------+------------------------+--------+
| 870.1200 Acute dermal   | 4       | LD~50~ \> 2000 mg/kg   | III    |
| toxicity                | 1515401 | (M+F); 80% ai          |        |
+-------------------------+---------+------------------------+--------+
| 870.1300 Acute          | 4       | LC~50~=0.07 mg/L; 80%  | I      |
| inhalation toxicity     | 1640601 | ai                     |        |
+-------------------------+---------+------------------------+--------+
| 870.2400 Acute eye      | Acc No. | Diluted Busan 72 (60 % | I      |
| irritation              | 111991  | ai): primary           |        |
|                         |         | irritation score       |        |
|                         |         | (PIS)=2/110 (slight    |        |
|                         |         | conjunctival redness,  |        |
|                         |         | no corneal opacity);   |        |
|                         |         | undiluted Busan 72     |        |
|                         |         | (60% ai) PIS=34/110    |        |
|                         |         | (blanched              |        |
|                         |         | conjunctivae,          |        |
|                         |         | chemosis, corneal      |        |
|                         |         | opacity not reversible |        |
|                         |         | by day 7)              |        |
+-------------------------+---------+------------------------+--------+
| 870.2500 Acute dermal   | 4       | primary irritation     | II     |
| irritation              | 1583701 | index=7.42 with severe |        |
|                         |         | erythema and edema     |        |
|                         |         | observed at 72 hours;  |        |
|                         |         | 80% ai                 |        |
+-------------------------+---------+------------------------+--------+
| 870.2600 Skin           | MRID    | Busan 74 (80% ai)      | \--    |
| sensitization           | 4       | caused delayed contact |        |
|                         | 2349201 | hypersensitivity in    |        |
|                         |         | guinea pigs when       |        |
|                         | Acc No. | induced and challenged |        |
|                         | 259676  | by a 40% w/v aqueous   |        |
|                         |         | concentration of       |        |
|                         |         | active ingredient.     |        |
|                         |         | Sensitizer.            |        |
+-------------------------+---------+------------------------+--------+

TCMTB exhibits low acute oral and dermal toxicity (toxicity category
III). However, it is highly irritating to the eyes and skin (toxicity
category I and II, respectively) and is also considered to be highly
toxic via the inhalation route of exposure (toxicity category I). TCMTB
is a dermal sensitizer.

In a two-generation rat reproduction study, there were no treatment
related effects noted at the highest dose tested for parental toxicity
or on reproductive parameters examined in this study. Slight,
statistically significant effects were noted in mean body weight in the
high dose offspring in the second mating (F2B) around lactation day 21.
This must be considered as systemic toxicity as the litters began with
relatively equal mean body weights and around lactation day 14, the pups
began to consume diet while continuing to nurse.

The parental/systemic NOAEL = 400 ppm (38.4/45.5 mg /kg/day
\[males/females\]) and the parental/systemic LOAEL \> 400 ppm (\>
38.4/45.5 mg /kg/day \[males/females\]). The offspring NOAEL is 400 ppm.
The Reproductive toxicity NOAEL [\>]{.underline} 400ppm and the
Reproductive toxicity LOAEL \> 400 ppm.

1.  **Nontarget Insects - Honeybees**

Honeybees could potentially be exposed to pesticide residues if treated
wood is used to construct hives or hive components. These residues may
be toxic to the bees, or result in residues in honey or other hive
products intended for human use/consumption. Therefore, a special
honeybee study is required for all wood preservative unless a statement
prohibiting the use of treated wood in hive construction is added to the
label, such as, "Wood treated with TCMTB shall not be used in the
construction of beehives." This study is a combination of Guidelines
171-4 and 850.3030 (see information regarding residue data requirements
for uses in beehives in the residue chemistry section of 40 CFR part
158). Numbers of bees used in this study and methods for
collection/introduction of bees into hives, feeding, and observations
for toxicity and mortality should be consistent with those described in
OPPTS Guideline 850.3030, "Honey Bee Toxicity of Residues on
Foliage.")**.** The toxicity portion of this study is in lieu of the
honeybee contact LD50 test .

B.  **Toxicity to Aquatic Animals**

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1.  **Freshwater**

> **a. Freshwater Fish, Acute**

Two fish toxicity studies using the TGAI are required to establish the
toxicity of a pesticide to freshwater fish. The preferred test species
are rainbow trout (a coldwater fish) and bluegill sunfish (a warmwater
fish). The results of toxicity study are provided in the following
table.

**Table 4. Acute Toxicity of TCMTB to Freshwater Fish**

+----------+---------+------+----------+---------+--------+--------+
| Study    | O       | E    | Results  | Other   | Ref    | Status |
| Type/%   | rganism | ndpo |          | Effects | erence |        |
|          |         | ints |          | Noted   |        |        |
| Active   |         |      |          |         |        |        |
| In       |         |      |          |         |        |        |
| gredient |         |      |          |         |        |        |
|          |         |      |          |         |        |        |
| (a.i.)   |         |      |          |         |        |        |
+----------+---------+------+----------+---------+--------+--------+
| *        |         |      |          |         |        |        |
| *TCMTB** |         |      |          |         |        |        |
+----------+---------+------+----------+---------+--------+--------+
| Fr       | Rainbow | M    | 96-hr    | None    | TN     | Supple |
| eshwater | trout   | orta | static   | r       | 2437   | mental |
| fish     | (*Oncor | lity | LC50 =   | eported | (US    |        |
| acute    | hynchus |      | 55.2 (27 |         | EPA,   |        |
| t        | m       |      | --       |         | 1980)  |        |
| oxicity, | ykiss,* |      | 75)µg/L  |         |        |        |
| 850.1    |         |      | (ppb) )  |         |        |        |
| 075/72-1 |         |      | "very    |         |        |        |
|          |         |      | highly   |         |        |        |
| (90 %    |         |      | toxic"   |         |        |        |
| a.i.)    |         |      |          |         |        |        |
+----------+---------+------+----------+---------+--------+--------+
| Fr       | B       | M    | 96-hour  | None    | TN     | Supple |
| eshwater | luegill | orta | static   | r       | 2432   | mental |
| fish     | sunfish | lity | LC50 =   | eported | (US    |        |
| acute    | (*      |      | 32 (16   |         | EPA,   |        |
| t        | Lepomis |      | -- 45)   |         | 1979)  |        |
| oxicity, | macroc  |      | µg/L     |         |        |        |
| 850.1    | hirus*) |      | (ppb) )  |         |        |        |
| 075/72-1 |         |      | "very    |         |        |        |
|          |         |      | highly   |         |        |        |
| (90%     |         |      | toxic"   |         |        |        |
| a.i.)    |         |      |          |         |        |        |
+----------+---------+------+----------+---------+--------+--------+
| Fr       | B       | M    | 96-hour  | NOEC =  | 418    | Acce   |
| eshwater | luegill | orta | flow     | 5.1µg/L | 042-01 | ptable |
| fish     | sunfish | lity | -through | (ppb)   | (Ma    |        |
| acute    | (*      |      | LC50 =   | due to  | chado, |        |
| t        | Lepomis |      | 8.7 µg/L | signs   | 1991a) |        |
| oxicity, | macro   |      | (ppb);   | of      |        |        |
| 850.1    | chirus* |      | "very    | t       |        |        |
| 075/72-1 |         |      | highly   | oxicity |        |        |
|          |         |      | toxic"   | at      |        |        |
| (80.4    |         |      |          | higher  |        |        |
| a.i.)    |         |      |          | levels  |        |        |
+----------+---------+------+----------+---------+--------+--------+
| Fr       | Rainbow | M    | 96-hour  | NOEC =  | 418    | Acce   |
| eshwater | trout   | orta | flow     | 8.7     | 181-01 | ptable |
| fish     | (*Oncor | lity | -through | µg/L    |        |        |
| acute    | hynchus |      | LC50 =   | (ppb)   | (Ma    |        |
| t        | mykiss* |      | 20.12    | due to  | chado, |        |
| oxicity, |         |      | (17.77   | mo      | 1991b) |        |
| 850.1    |         |      | --       | rtality |        |        |
| 075/72-1 |         |      | 22.91)   | and     |        |        |
|          |         |      | µg/L     | l       |        |        |
| (80.4    |         |      | (ppb);   | ethargy |        |        |
| a.i.)    |         |      | "very    | and     |        |        |
|          |         |      | highly   | loss of |        |        |
|          |         |      | toxic"   | equi    |        |        |
|          |         |      |          | librium |        |        |
|          |         |      |          | in      |        |        |
|          |         |      |          | su      |        |        |
|          |         |      |          | rviving |        |        |
|          |         |      |          | fish at |        |        |
|          |         |      |          | higher  |        |        |
|          |         |      |          | levels  |        |        |
+----------+---------+------+----------+---------+--------+--------+
| Fr       | Rainbow | M    | 96-hour  | Loss of | ACC#   | Supple |
| eshwater | trout   | orta | static   | equi    | 091624 | mental |
| fish     | (*Oncor | lity | LC50 =   | librium | (Knott |        |
| acute    | hynchus |      | 29 (21   | and     | and    |        |
| t        | m       |      | -- 40)   | lying   | Wo     |        |
| oxicity, | ykiss,* |      | µg/L     | on      | odard, |        |
| 850.1    | f       |      | (ppb);   | sides   | 1968b) |        |
| 075/72-1 | ormerly |      | "very    | o       |        |        |
|          | *Salmo  |      | highly   | bserved |        |        |
| (75%     | gaird   |      | toxic"   |         |        |        |
| a.i.)    | ineri*) |      |          |         |        |        |
+----------+---------+------+----------+---------+--------+--------+
| Fr       | B       | M    | 96-hour  | Loss of | ACC#   | Supple |
| eshwater | luegill | orta | static   | equi    | 091624 | mental |
| fish     | sunfish | lity | LC50 =   | librium | (Knott |        |
| acute    | (*      |      | 47 (40   | and     | and    |        |
| t        | Lepomis |      | -- 55)   | lying   | Wo     |        |
| oxicity, | macro   |      | µg/L     | on      | odard, |        |
| 850.1    | chirus* |      | (ppb);   | sides   | 1968b) |        |
| 075/72-1 |         |      | "very    | o       |        |        |
|          |         |      | highly   | bserved |        |        |
| (75%     |         |      | toxic    |         |        |        |
| a.i.)    |         |      |          |         |        |        |
+----------+---------+------+----------+---------+--------+--------+
| *        |         |      |          |         |        |        |
| *2-MBT** |         |      |          |         |        |        |
+----------+---------+------+----------+---------+--------+--------+
| Fr       | Rainbow | M    | 96-hour  | NOEC =  | 422    | Acce   |
| eshwater | trout   | orta | static   | 310     | 322-01 | ptable |
| fish     | (*Oncor | lity | LC50 =   | µg/L    |        |        |
| acute    | hynchus |      | 730 µg/L | (ppb)   | (Co    |        |
| t        | mykiss* |      | (ppb)    | due to  | llins, |        |
| oxicity, |         |      | "very    | mo      | 1992)  |        |
| 850.1    |         |      | highly   | rtality |        |        |
| 075/72-1 |         |      | toxic"   | at      |        |        |
|          |         |      |          | higher  |        |        |
| (98.22%  |         |      |          | tr      |        |        |
| a.i.)    |         |      |          | eatment |        |        |
|          |         |      |          | levels  |        |        |
+----------+---------+------+----------+---------+--------+--------+

These results indicate that both TCMTB and 2-MBT are very highly toxic
to freshwater fish on an acute basis. The guideline requirement
(72-1/OPPTS 850.1075) is fulfilled.

**b. Freshwater Fish, Chronic**

**i. Early Life-Stage Testing**

A freshwater fish early life-stage test using the technical grade of the
active ingredient is required for a pesticide when it may be applied
directly to water or if the end-use product is expected to be
transported to water from the intended use site, and any of the
following conditions are met: (1) the pesticide is intended for use such
that its presence in water is likely to be continuous or recurrent
regardless of toxicity, (2) any aquatic acute LC50 or EC50 is less than
1 mg/l, (3) the EEC in water is equal to or greater than 0.01 of any
acute LC50 or EC50 value, or, (4) the actual or estimated environmental
concentration in water resulting from use is less than 0.01 of any acute
LC50 or EC50 value and any one of the following conditions exist:
studies of other organisms indicate the reproductive physiology of fish
may be affected, physicochemical properties indicate cumulative effects,
or the pesticide is persistent in water (e.g., half-life greater than 4
days). The preferred test species is rainbow trout, but other species
may be used.

**Table 5: Chronic Toxicity Values for Freshwater Fish Exposed to
TCMTB**

+---------+---------+---------+---------+---------+---------+---------+
| **Study | **Sp    | **End   | *       | *       | **MRID# | **S     |
| Type**  | ecies** | point** | *NOEC** | *LOEC** | (refer  | tatus** |
|         |         |         |         |         | ence)** |         |
|         |         |         | **g    | **g    |         |         |
|         |         |         | a       | a       |         |         |
|         |         |         | .i./l** | .i./l** |         |         |
+---------+---------+---------+---------+---------+---------+---------+
| Fre     | Rainbow | Reprod  | 0.34    | 0.56    | 42      | Acc     |
| shwater | trout   | uction, | ppb     | ppb     | 5959-01 | eptable |
| fish    | (*Oncor | pos     | based   | based   |         |         |
| Early   | hynchus | t-hatch | on      | on      | (       |         |
| lif     | m       | su      | growth  | growth  | Rhodes, |         |
| e-stage | ykiss*) | rvival, | and egg |         | 1992)   |         |
| t       |         | growth  | hatch   |         |         |         |
| oxicity |         |         | ability |         |         |         |
| (7      |         |         |         |         |         |         |
| 2-4a/85 |         |         |         |         |         |         |
| 0.1300) |         |         |         |         |         |         |
| (83.78% |         |         |         |         |         |         |
| a.i.)   |         |         |         |         |         |         |
+---------+---------+---------+---------+---------+---------+---------+

The results indicate that TCMTB causes reproduction and growth effects
in fish at very low levels (\>0.34 ppb). The guideline requirement
(72-4a/OPPTS 850.1300) is fulfilled.

Some reports in the published literature indicate that TCMTB may cause
sublethal effects in fish, which could result in an increase in
predation and a decreased ability to survive. This information was
submitted to the Agency under FIFRA §6(a)2 (MRID #424053-01). These
studies demonstrate that exposure to TCMTB at levels of 8-10 ppb caused
gill damage and behavioral changes, which could severely reduce the
ability of fish to survive in the wild. From [Proceedings of the
Seventeenth Annual Aquatic Toxicity Workshop, Nov. 5-7, 1990, Vancouver,
BC, Vol. 1]{.underline}. (edited by P. Chapman, F. Bishay, E. Power, K.
Hall, L. Harding, D. Mcleay, M. Nassichuk and W. Knapp). Canadian
Technical report of Fisheries and Aquatic Sciences, No. 1774 (vol 1).
Individual paper citations: (Kruzynski and Birtwell, 1990; Kruzynski et
al., 1990; Chew et al., 1990). The LC50 used in this risk assessment
(8.7 µg/L) is comparable to the levels at which these sublethal effects
occurred, however, so the risk assessment should be protective of those
effects.

**ii. Fish Life-Cycle Testing**

[]{.mark}

Fish life-cycle testing is required for a wood preservative if treated
wood will be used in the aquatic environment (including estuarine/marine
environments) or use of treated wood in aquatic environments is not
prohibited by product labeling, and any of the following conditions
apply:(i) the estimated environmental concentration (EEC) in water is
[\>]{.underline} 0.1 of the no-observed-effect-concentration/level
(NOEC/NOEL) determined in fish early life-stage studies; or

\(ii\) If studies with other organisms indicate the reproductive
physiology of fish may be affected; or, (iii) If the pesticide is
intended for use such that its presence in the aquatic environment is
likely to be continuous or recurrent, regardless of toxicity. Testing
should be conducted using the more sensitive of freshwater or
marine/estuarine species. The preferred freshwater test species is
fathead minnow (*Pimephales promelas*), and the preferred
estuarine/marine species is sheepshead minnow (*Cyprinodon variegatus*),
but other species may be used as per the Guidelines document
(72-4/850.1400). All of the above apply to TCMTB, so a fish life-cycle
test is indicated; however, since an aquatic monitoring study is
required to address the effectiveness of mitigation methods proposed in
this RED, fish life-cycle testing is **reserved**, pending the results
of the monitoring study.

**c. Freshwater Invertebrates, Acute**

A freshwater aquatic invertebrate toxicity test using the TGAI is
required to establish the toxicity of a pesticide to freshwater aquatic
invertebrates. The preferred test species is *Daphnia magna.*

**Table 6. Acute Toxicity of TCMTB and 2-MBT to Freshwater
Invertebrates**

+--------+---------+---------+---------+-------+----------+--------+
| Subst  | O       | En      | Results | Tox   | R        | Status |
| ance/% | rganism | dpoints |         | icity | eference |        |
|        |         |         |         |       |          |        |
| Active |         |         |         |       |          |        |
| Ingr   |         |         |         |       |          |        |
| edient |         |         |         |       |          |        |
|        |         |         |         |       |          |        |
| (AI)   |         |         |         |       |          |        |
+--------+---------+---------+---------+-------+----------+--------+
| TCMTB  | *       | Immobil | 48-hr   | Very  | TN 2427  | Supple |
| (90%   | Daphnia | ization | static  | h     | (US EPA, | mental |
| a.i.)  | magna*  |         | EC50 =  | ighly | 1979)    |        |
|        |         |         | 23 µg/L | toxic |          |        |
|        |         |         | (ppb)   |       |          |        |
+--------+---------+---------+---------+-------+----------+--------+
| TCMTB  | *       | Immobil | 48-hour | Very  | 4        | Acce   |
| (80.4% | Daphnia | ization | flow-   | h     | 18382-01 | ptable |
| a.i.)  | magna*  |         | through | ighly | (M       |        |
|        |         |         | EC50 =  | toxic | cNamara, |        |
|        |         |         | 22 µg/L |       | 1991)    |        |
|        |         |         | (ppb);  |       |          |        |
|        |         |         | NOEC =  |       |          |        |
|        |         |         | 8.7     |       |          |        |
|        |         |         | µg/L    |       |          |        |
|        |         |         | (ppb)   |       |          |        |
+--------+---------+---------+---------+-------+----------+--------+
| 2-MBT  |         |         |         |       |          |        |
+--------+---------+---------+---------+-------+----------+--------+
| 2-MBT  | *       | Immobil | 48-hour | Moder | 4        | Acce   |
| (100%  | Daphnia | ization | static  | ately | 22260-01 | ptable |
| a.i.)  | magna*  |         | EC50 =  | toxic |          |        |
|        |         |         | 2.9     |       | (        |        |
|        |         |         | mg/L    |       | Collins, |        |
|        |         |         | (ppm)   |       | 1992b)   |        |
+--------+---------+---------+---------+-------+----------+--------+

These studies indicates that TCMTB is very highly toxic and 2-MBT is
moderately toxic to aquatic invertebrates on an acute basis. The
guideline requirement (72-2/OPPTS 850.1010) is fulfilled.

> **d. Freshwater Invertebrates, Chronic**

A freshwater aquatic invertebrate life-cycle test using the technical
grade of the active ingredient is required for a pesticide if the
end-use product may be applied directly to water or expected to be
transported to water from the intended use site, and any of the
following conditions are met: (1) the pesticide is intended for use such
that its presence in water is likely to be continuous or recurrent
regardless of toxicity, (2) any aquatic acute LC50 or EC50 is less than
1 mg/l, or, (3) the EEC in water is equal to or greater than 0.01 of any
acute EC50 or LC50 value, or, (4) the actual or estimated environmental
concentration in water resulting from use is less than 0.01 of any
aquatic acute EC50 or LC50 value and any of the following conditions
exist: studies of other organisms indicate the reproductive physiology
of invertebrates may be affected, physicochemical properties indicate
cumulative effects, or the pesticide is persistent in water (e.g.,
half-life greater than 4 days). The preferred test species is *Daphnia
magna*.

One daphnid life-cycle study was submitted (MRID#425591-01), but was
invalidated due to high variablility in the test concentrations to which
the daphnids were exposed. **A new daphnid life-cycle study
(72-4b/850.1400) is required to support the currently registered uses of
TCMTB.**

> **e.** **Freshwater Field Studies**

An aquatic monitoring study is required, which will determine
concentrations of TCMTB in water and sediments exposed to runoff from
TCMTB antisapstain treatment facilities. A protocol for this study must
be approved by AD/RASSB prior to study initiation.

> **6. Toxicity to Estuarine and Marine Organisms**

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

Acute toxicity testing with estuarine/marine fish using the technical
grade of the active ingredient is required for a chemical 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.

  ----------------------------------------------------------------------------------------------------
  **Table 7. Acute                                                                        
  Toxicity of TCMTB                                                                       
  to                                                                                      
  Estuarine/Marine                                                                        
  Fish**                                                                                  
  ------------------ -------------- ----------- --------------- ---------- -------------- ------------
  Substance/% a.i.   Species        Endpoint    Results         Toxicity   Reference      Status

  TCMTB (80% a.i.)   Sheepshead     Mortality   96-hour static  Very       403636-01      Acceptable
                     minnow                     LC50 = 60 (36   highly     (Surprenant,   
                     (*Cyprinodon               -- 100) µg/L    toxic      1986a)         
                     variegatus*)               (ppb)                                     
  ----------------------------------------------------------------------------------------------------

The results indicate that TCMTB is very highly toxic to estuarine/marine
fish on an acute basis. The guideline requirement (72-3a/OPPTS 850.1025)
is fulfilled.

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

Estuarine/marine fish early life-stage testing is not required for the
currently registered uses of TCMTB. The freshwater fish early life-stage
test, which is required, should provide an adequate endpoint for use in
future risk assessments, since acute data indicate the freshwater fish
species tested are comparably sensitive or more sensitive to TCMTB than
the marine/estuarine species tested. Risks assessed using the freshwater
endpoint should therefore be protective of marine/estuarine species.

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

Acute toxicity testing with estuarine/marine invertebrates using the
technical grade of the active ingredient 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.

+-----------+---+----------+---------+-----+------+--------+--------+
| **Table   |   |          |         |     |      |        |        |
| 8: Acute  |   |          |         |     |      |        |        |
| Toxicity  |   |          |         |     |      |        |        |
| of TCMTB  |   |          |         |     |      |        |        |
| to        |   |          |         |     |      |        |        |
| Estuari   |   |          |         |     |      |        |        |
| ne/Marine |   |          |         |     |      |        |        |
| Invert    |   |          |         |     |      |        |        |
| ebrates** |   |          |         |     |      |        |        |
+===========+===+==========+=========+=====+======+========+========+
| Test      | \ | Species  | E       | R   | Toxi | Ref    | Status |
|           | % |          | ndpoint | esu | city | erence |        |
|           | a |          |         | lts |      |        |        |
|           | i |          |         |     |      |        |        |
|           | . |          |         |     |      |        |        |
+-----------+---+----------+---------+-----+------+--------+--------+
| Marine/   | 8 | Quahog   | Normal  | 4   | Very | 403    | Acce   |
| estuarine | 0 | clam,    | embryo  | 8-h | hi   | 636-03 | ptable |
| bivalve   | % | *Me      | -larvae | our | ghly | (Surpr |        |
| acute     |   | rcenaria | deve    | sta | t    | enant, |        |
| embr      |   | mer      | lopment | tic | oxic | 1986)  |        |
| yo-larvae |   | cenaria* |         | E   |      |        |        |
| toxicity, |   |          |         | C50 |      |        |        |
| 72-3b     |   |          |         | =   |      |        |        |
| /850.1055 |   |          |         | 1   |      |        |        |
|           |   |          |         | 3.9 |      |        |        |
|           |   |          |         | (   |      |        |        |
|           |   |          |         | 9.8 |      |        |        |
|           |   |          |         | --  |      |        |        |
|           |   |          |         | 16  |      |        |        |
|           |   |          |         | .1) |      |        |        |
|           |   |          |         | µ   |      |        |        |
|           |   |          |         | g/L |      |        |        |
|           |   |          |         | (p  |      |        |        |
|           |   |          |         | pb) |      |        |        |
|           |   |          |         | ;   |      |        |        |
|           |   |          |         | N   |      |        |        |
|           |   |          |         | OEC |      |        |        |
|           |   |          |         | \<  |      |        |        |
|           |   |          |         | 13  |      |        |        |
|           |   |          |         | 2   |      |        |        |
|           |   |          |         | 0.3 |      |        |        |
|           |   |          |         | µ   |      |        |        |
|           |   |          |         | g/L |      |        |        |
|           |   |          |         | (p  |      |        |        |
|           |   |          |         | pb) |      |        |        |
+-----------+---+----------+---------+-----+------+--------+--------+
| Marine/   | 8 | Mysid    | Mo      | 9   | Very | 403    | Acce   |
| estuarine | 0 | (*Amer   | rtality | 6-h | hi   | 636-02 | ptable |
| inv       | % | icamysis |         | our | ghly |        |        |
| ertebrate |   | bahia*,  |         | sta | t    | (Surpr |        |
| acute     |   | formerly |         | tic | oxic | enent, |        |
| toxicity, |   | *My      |         | L   |      | 1987)  |        |
| 72-3c     |   | sidopsis |         | C50 |      |        |        |
| /850.1035 |   | bahia*)  |         | =   |      |        |        |
|           |   |          |         | 2   |      |        |        |
|           |   |          |         | 0.3 |      |        |        |
|           |   |          |         | µ   |      |        |        |
|           |   |          |         | g/L |      |        |        |
|           |   |          |         | (pp |      |        |        |
|           |   |          |         | b); |      |        |        |
|           |   |          |         | N   |      |        |        |
|           |   |          |         | OEC |      |        |        |
|           |   |          |         | \<  |      |        |        |
|           |   |          |         | 7.8 |      |        |        |
|           |   |          |         | µ   |      |        |        |
|           |   |          |         | g/L |      |        |        |
|           |   |          |         | (p  |      |        |        |
|           |   |          |         | pb) |      |        |        |
+-----------+---+----------+---------+-----+------+--------+--------+

The results indicate that TCMTB is very highly toxic to marine/estuarine
invertebrate species. The guideline requirements (72-3b and 72-3c/OPPTS
850.1035 and 850.1045) are fulfilled.

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

An estuarine/marine invertebrate life-cycle toxicity test is required
for a pesticide if the end-use product may be applied directly to water
or expected to be transported to water from the intended use site, and
any of the following conditions are met: (1) the pesticide is intended
for use such that its presence in water is likely to be continuous or
recurrent regardless of toxicity, (2) any aquatic acute LC50 or EC50 is
less than 1 mg/l, or, (3) the EEC in water is equal to or greater than
0.01 of any acute EC50 or LC50 value, or, (4) the actual or estimated
environmental concentration in water resulting from use is less than
0.01 of any aquatic acute EC50 or LC50 value and any of the following
conditions exist: studies of other organisms indicate the reproductive
physiology of invertebrates may be affected, physicochemical properties
indicate cumulative effects, or the pesticide is persistent in water
(e.g., half-life greater than 4 days). A freshwater invertebrate life
cycle study (72-4b/850.1400) is required for TCMTB. Since the acute
invertebrate data indicate that daphnids are more sensitive to TCMTB
than clams and mysids, data from the freshwater invertebrate life cycle
test will be adequate to assess risk for marine/estuarine invertebrate
species.

e.  **Estuarine and Marine Field Studies**

This testing is currently reserved for TCMTB.

7.  **Bioaccumulation in Aquatic Organisms**

    a.  **Fish** (MRID #Number range CHAPTER424185-01, 424932-01, and
        467052-01): (see Environmental Fate chapter of this RED document
        for additional details regarding this study)

The log octanol-water coefficient (log Kow) of TCMTB is 3.30.
Bioconcentration testing is required for chemicals having a log Kow
[\>]{.underline} 3.00 if they are likely to result in exposure to
aquatic organisms, so this testing was required for TCMTB.

Number range CHAPTERRadiolabeled residues accumulated in bluegill
sunfish that were exposed to uniformly phenyl-ring labeled
\[^14^C\]TCMTB, at a nominal concentration of 0.40 g/L, under
flow-through aquarium conditions. Maximum bioconcentration factors
(BCF), based on total radioactivity were 302X for viscera, 64X for
fillet, and 184X for whole fish tissues. Seventy-five to 77%, 84-87%,
and 84-86% of the mean accumulated \[^14^C\] residues (exposure days
14-28) were eliminated from the fillet, viscera and whole fish tissues,
respectively, by days 21-35.

The results indicate that the bioaccumulation potential of TCMTB is
minimal.

This study was scientifically sound, and fulfills the requirements for
Guideline 165-1.

**8. Toxicity to Plants**

Phytotoxicity testing is required for pesticides other than herbicides
on a case-by-case basis (e.g., labeling bears phytotoxicity warnings,
incidents of plant damage have been reported, or literature indicating
phytotoxicity is available). Since many of the TCMTB product labels
state that the product controls algae, semi-aquatic (seed germination in
rice, 123-1/850.4225, and vegetative vigor in rice, 123-1/850.4250) and
aquatic plant testing (123-2/850.4400 and 850.5400) is required for
TCMTB. Additionally, since TCMTB is used as a seed treatment,
terrestrial plant testing (seed germination, 123-1/850.4225 and
vegetative vigor, 123-1/850.4250) is required for TCMTB.

No terrestrial or semi-aquatic plant toxicity data have been submitted
for TCMTB. These data are required to support the currently registered
uses of TCMTB. **Guidelines 123-1/850.4225 and 850.4250 (Tier II
seedling emergence and vegetative vigor) for rice are required to
support wood preservative uses. Guideline 122-1/850.4100 (Tier I
seedling emergence) for 10 species of terrestrial plants (to support
seed treatment uses) is also required. Guideline 123-1/850.4100 (Tier II
seedling emergence) is reserved for seed treatment uses, pending the
results of the Tier I test.**

A single aquatic plant study was submitted for TCMTB, the results of
which are summarized below. Additional aquatic phytotoxicity testing
with four species of algae are required to support the currently
registered uses of TCMTB.

**Table 9**: Toxicity of TCMTB to Aquatic Plants

  ------------------ --------------- ---------- ----------- ------------ ------------- ------------
  Test               Species/% a.i.  Endpoint   Toxicity    NOEC/other   MRID          Status
                                                            effects      (reference)   
                                                            noted                      

  Aquatic Vascular   Duckweed        Frond      14-day      0.15 mg/L    442009-01     Acceptable
  Plant Acute        *(Lemna         growth     static      (ppm)        (Thompson and 
  Toxicity, Tier II  gibba*)/83.5%              renewal                  Swigert,      
  (dose-response),   a.i.                       EC50 = 0.43              1996)         
  123-2/850.4400                                (0.29 --                               
                                                0.65) mg/L                             
                                                (ppm)                                  
  ------------------ --------------- ---------- ----------- ------------ ------------- ------------

The results indicate that TCMTB is impairs growth of aquatic vascular
plants at levels greater than 0.15 ppm (150 ppb). Guideline 850.4400 is
fulfilled; however, **Guideline 123-2/850.5400 is NOT fulfilled, as
additional testing with four algae species is required to support wood
preservative and seed treatment uses of TCMTB.**

**III. ENVIRONMENTAL FATE AND EXPOSURE ASSESSMENT SUMMARY**

> **A. Environmental Fate Assessment Summary (excerpted from the TCMTB
> Environmental Fate Chapter of this RED document)**:
>
> []{.mark}

Number range CHAPTERAs an antimicrobial pesticide,
2-(thiocyanomethylthio)benzothiazole (TCMTB) is used largely as a wood
preservative. It is also used as a microbiocide/microbiostat and
bacteriocide/bacteriostat in industrial processes and water system, as
well as in industrial materials, as a preservative. As an agricultural
pesticide, TCMB is used for seed treatment of crops; bulb and corm
treatment of flowers; and seed and soil treatment of trees. Buckman
Laboratories has submitted several guideline studies for an
environmental fate assessment; however, not all of these studies fulfill
Guidelines requirements. Additionally, a special leaching study is
required to support the antisapstain uses of TCMTB. For additional
information, please refer to the Environmental Fate Chapter of this RED.

An assessment of the various studies indicates the hydrolysis of TCMTB
is pH dependent. It is hydrolytically stable under abiotic and buffered
conditions at pH 5 and slowly degrades at pH 7. Under more alkaline
conditions, hydrolysis proceeds more rapidly with a calculated half-life
ranging from 1.8 to 2.1 days. Photolytically, TCMTB degrades in a pH 5
buffered aqueous solution with a calculated half-life of 1.5 hours.
Based on its degradation, TCMTB may not pose a concern for surface water
run-off.

Aquatic metabolism under aerobic and anaerobic conditions, as well as
aerobic soil metabolism, are major routes of dissipation for TCMTB.
TCMTB's calculated degradation half-life in flooded lake sediment is 6.9
days; however, the apparent half-life occurs between 2 and 4 days.
Similarly, TCMTB shows a tendency of degrading anaerobically in flooded
sediment within 2.7 days. Under aerobic conditions in sandy loam soil, a
representative agricultural soil, TCMTB degrades with a calculated
half-life of 1.4 days. Because of the biodegradation in water and soils,
TCMTB is not likely to contaminate surface and ground waters.

Number range CHAPTERTCMTB's tendency to bind with agricultural soils
varies according to soil type. TCMTB is mobile-very mobile in various
soils; however, because of its tendency to biodegrade in water and
soils, TCMTB is not likely to contaminate surface and ground waters.
TCMTB is very mobile in clay loam, sand, and sandy loam soil, and mobile
in clay and silt loam soil. K~d~s are 3.5 for clay loam soil, 0.99 for
sand soil, 9.9 for sandy loam soil, 22.1 for clay soil, and 62.7 for
silt loam soil. There may be a water/sediment partitioning issue and an
acute adverse impact on benthic organisms. However, TCMTB degrades
fairly rapidly in freshwater and soils and the impacts may be
short-lived.

Additional information on the aqueous availability of TCMTB from wood,
indicates that the use of TCMTB as a wood preservative may result in
minimal releases to the environment

**B. Environmental Exposure Assessment**

**1. Terrestrial:**

a.  **Seed Treatment**

The Terrestrial Residue Exposure Model (TREX) was used to calculate risk
quotients for birds and mammals consuming TCMTB-treated seeds. This is
discussed in the risk assessment section, below.

b.  **Antisapstain**

No model is available to estimate the exposure to terrestrial wildlife
from the use of TCMTB-treated wood. It is assumed that risk to aquatic
organisms from runoff of TCMTB from antisapstain treating facilities is
the greater concern from this use of TCMTB; therefore, the risk
assessment for the antisapstain uses of TCMTB focuses on aquatic
organisms.

**2. Aquatic:**

**a. Seed-Treatment**

Aquatic exposure from seed treatment uses of TCMTB was modeled by the
Environmental Fate and Effects Division (EFED) (USEPA, 2005). The
following section is a summary of that exposure assessment.

Number range CHAPTERThis aquatic exposure assessment provides the
estimated environmental concentrations (EEC) for the use of
2-(Thiocyanomethylthio)benzothiazole (TCMTB) as a seed treatment on
cotton, wheat, barley, oats, rice, sugar beets, and safflower. For this
action, EFED considered risk *only* from parent compound of TCMTB and
not any degradates associated with TCMTB.

> **TABLE 10: Application Rates for Seed Treatment Uses of TCMTB
> (revised 02/16/06)**

+---------+-----------------------+--------------------+--------------+
| > *     | > **Application Rate  | > **Max. Seeding   | **Rate (lbs  |
| *Crop** | > (fl oz/100 lbs)**   | > Rate (lbs/ac)**  | ai/ac)**     |
+---------+-----------------------+--------------------+--------------+
| >       | > 5                   | > 18               | 0.018        |
|  Cotton |                       |                    |              |
+---------+-----------------------+--------------------+--------------+
| > Sa    | > 2                   | > 100              | 0.041        |
| fflower |                       |                    |              |
+---------+-----------------------+--------------------+--------------+
| > Sugar | > 2                   | > 8                | 0.003        |
| > beets |                       |                    |              |
+---------+-----------------------+--------------------+--------------+
| > Rice  | > 1.25                | > 150              | 0.039        |
+---------+-----------------------+--------------------+--------------+
| > Wheat | > 1.25                | > 150              | 0.039        |
+---------+-----------------------+--------------------+--------------+
| > Oats  | > 1.25                | > 128              | 0.033        |
+---------+-----------------------+--------------------+--------------+
| >       | > 1.25                | > 100              | 0.026        |
|  Barley |                       |                    |              |
+---------+-----------------------+--------------------+--------------+

The maximum seeding rate information is based on EFED's Terrestrial
Residue Exposure model (TREX)
(<http://www.epa.gov/oppefed1/models/terrestrial/>). The application
rate ranges from 0.0018 lb ai/ac to 0.041 lb ai/ac.

[Modeling Approach]{.underline}

For this aquatic exposure assessment, the highest rate of 0.0128 lb
ai/ac is used for the screening purpose. We used the tier 1 models:
GENEEC (version 2.0; Aug. 1, 2001) and SCI-GROW (version 2.3;
Nov. 4, 2003) screening models to assess estimated concentrations of
TCMTB in surface water and ground water, respectively. These models and
their descriptions are available at the EPA internet site:

<http://www.epa.gov/oppefed1/models/water/> .

***Conclusions:** For surface water exposures, results from GENEEC
indicate that the TCMTB concentrations of 0.28 ppb (ug/L), 0.26 ppb,
0.20 ppb, 0.12 ppb, and 0.08 ppb, respectively, for peak, 4-day average,
21-day average, 60-day average, and 90-day average exposure. For ground
water, SCI-GROW indicates that TCMTB concentrations are not likely to
exceed 0.00014 g/L. Full model inputs and outputs are in provided in
USEPA, 2006.*

Since these models are not specifically designed to estimate
concentrations for pesticides used for seed treatment, there are
uncertainties in their predictive potential. However, these
uncertainties are not expected to substantially decrease the
conservativeness of the Tier 1 modeling results.

[Uncertainties in the Seed Treatment Modeling]{.underline}

Several factors suggests low environmental exposure from seed treatment,
including (1) seed treatment pesticides are applied at low rates; (2)
adjuvants are used to encourage pesticide binding to the seed coat; (3)
physicochemical properties of seed treatment pesticides generally
exhibit low mobility to retain the pesticide near the seed coat and root
zone; (4) seeds are normally incorporated, which is expected to limit
environmental exposure; and (5) seed treatments may have indoor use
patterns (e.g., seed storage). In additional to these factors, the main
uncertainty in our assessment for the use of TCMTB as a seed treatment
is that we have not accounted for the potential for sorption to, or
reaction on, the seed coat. Because of model limitations and because we
have no data to the contrary, we assumed that TCMTB does not sorb to the
seed coat, but only to soil. In effect, this assumption provides
conservative runoff and leaching scenarios.

SCI-GROW was developed using Koc values ranging from 32 -- 180 ml/g and
half-lives from 13 -- 1000 days. The input values for TCMTB are outside
these ranges, therefore, the extrapolation increases the uncertainty of
the ground water estimated concentrations.

a.  **[Antisapstain]{.underline}**

This section is a summary of the environmental exposure modeling
conducted to address the antisapstain uses of TCMTB. For additional
details, please refer to the Antisapstain Environmental Modeling Chapter
of this RED document.

Runoff concentrations of TCMTB were estimated for facilities that treat
wood with antisapstain chemicals. The concentrations were estimated
using an approach developed to determine runoff concentrations of
pesticides from antisapstain facilities in British Columbia, Canada
(Krahn and Strub, 1990).

Krahn and Strub (1990), in their protocol for a leaching study, suggest
that treated wood be stored outdoors, stacked into lumber packages 24" x
48" x 16', and placed over leachate collection trays (1.52 m x 5.2 m). A
total of 16 leaching cycles should be applied at a rate of 15 mm/day
every other day, with each rain duration lasting 5 hours and a target
intensity of 3 mm/hr. These values are based on the average
precipitation that occurs in British Columbia in the worst-case month of
the year.

No leaching studies were available for TCMTB. For lack of better data,
predictions of leaching behavior (as would be observed in a study
following the Krahn and Strub (1990) protocol) were made based on the
chemical properties of TCMTB and a number of assumptions (see
Antisapstain Environmental Modeling Chapter for details).

Aschacher and Gruendlinger (2000) have measured uptake of antisapstain
dipping solution by pine boards. Freshly sawn pine boards (2.3 x 10 x 50
cm, code R2 and R2 Ab) were dipped into a 1.5% Busan 30 L solution
(a.i.: 2-thiocyanomethylthio-benzthiazole, TCMTB). One set of samples
was treated in April 1997, and another set was treated in April 1998.
For each type of board treated each year, the uptake was measured based
on the average of 7 boards. The average uptake, based on the measurement
of 28 boards, was 163 g solution/m^2^.

Krahn and Strub (1990) assume that leachate entering the storm drain is
diluted with extra runoff water at a 1:15 ratio. This is based on
measurements of runoff in storm drains at facilities using antisapstain
chemicals in British Columbia. Use of the ratios 1:6 and 1:23 were also
suggested by Krahn and Strub (1990) to determine a "general industry
wide" predicted runoff concentration. These values were used in this
assessment. The estimated leachate concentration (0.196 ppm) was used in
conjunction with these dilution factors to estimate runoff
concentrations

**Table 11**. Estimated Runoff Concentrations

  ----------------------- ----------------------- -----------------------
  **Parameter**           **Dilution Factor**     **Estimated Runoff
                                                  Concentration
                                                  (ppm)^a^**

  High-end dilution       23.0                    0.00852

  Typical dilution        15.0                    0.0131

  Low-end dilution        6.00                    0.0327
  ----------------------- ----------------------- -----------------------

^a^Estimated Runoff Concentration = Estimated Leachate Concentration
(0.196 ppm) / Dilution Factor

# Uncertainties and Limitations

-   Krahn and Strub (1990) note that the concentrations of antisapstain
    chemical in runoff will be affected by numerous variables,
    including: chemical formulation, chemical retention in wood, rough
    vs. planed lumber cut, lumber packaging and stacking, drying time
    prior to exposure to precipitation, precipitation duration,
    precipitation intensity, precipitation frequency, precipitation pH,
    quantity of treated lumber on the storage site, species of lumber
    treated, general house keeping practices, whether the lumber is
    1^st^, 2^nd^, or 3^rd^ growth, solubility of the chemical in water,
    diffusion of the chemical into the wood, additives in the
    formulations, exposure and degradation due to ultraviolet light,
    microbial action, ambient temperatures, and affinity of the chemical
    to soils and to yard surfaces.

-   Information regarding the leaching behavior of TCMTB-treated wood is
    limited. It is unclear how well the method used above predicts the
    results of a study conducted using the protocol described by Krahn
    and Strub (1990).

-   It was assumed, for this assessment, that rain events are of equal
    intensity and duration. Variations in the intensities and durations
    of rain events would affect the results.

-   Krahn and Strub (1990) obtained a dilution factor of 15 based on a
    study of antisapstain facilities in British Columbia. The dilution
    factor is dependent on the intensity of rainfall events. There is no
    reason to expect that the average rainfall intensity in British
    Columbia would be representative of the average rainfall intensity
    of the United States; however, for lack of better data, the value
    was used.

-   Krahn and Strub (1990) assume that any batch of treated wood remains
    in the yard for 16 rain cycles. The frequency of rainfall events in
    British Columbia may not be representative of the frequency of
    rainfall events in the United States; therefore, the use of 16 rain
    cycles may not be an accurate description of treatment facilities in
    the United States.

-   The model is sensitive to the selection of the thickness of the
    leachable region, and the depth to which the antisapstain is assumed
    to penetrate. Although the value of 0.01 m is based on the value
    used in the Wood Leaching Model (WLM) (Lee, 2004), it is unclear how
    this value was derived and if use of the value is reasonable for a
    dipping treatment. The WLM is still under development, and has not
    yet been validated.

**IV. Risk Assessment and Characterization**

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 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). The
NOEC value is used as the ecotoxicity test value in assessing chronic
effects.

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. Environmental Risk Assessment for Terrestrial Organisms**:

Modeling was performed to address the exposure and risk to birds and
mammals consuming seeds treated with TCMTB. Using the Terrestrial
Residue Exposure Model (TREX)
(<http://www.epa.gov/oppefed1/models/terrestrial/>) for the seed
treatment on safflower, which has the highest application rate of 0.041
lb ai/A, the following RQs for seed treatment were calculated:

Avian: : 0.02 as (mg ai/kg/day)/LD50

The avian RQ was calculated with no toxicity scaling factor. Scaling
factors are used when it is likely that a pesticide will be
proportionally more toxic to smaller organisms than larger ones (e.g.,
the toxicity will not be directly correlated with body weight). TREX
recommends a default scaling factor of 1.15, based on Mineau et al.
(1996); however, that scaling factor was developed based on 37
conventional pesticides, most of which are cholinesterase inhibitors.
There is no information available indicating that such an adjustment is
necessary or appropriate for TCMTB.

Mammalian Acute: 0.05 as (mg ai/kg/day)/LD50,

0.02 as (mg ai/ft2)/(LD50\*BW)

Chronic: 0.53 as (mg/kg seed)/reproduction NOAEC

All of these are below any LOCs for avian or mammalian acute risk and
mammalian chronic risk. Avian chronic data are not available nor
required for the currently registered uses of TCMTB, therefore chronic
avian risk was not assessed.

**B. Environmental Risk Assessment for Aquatic Organisms**:

To develop RQs, the EECs determined by modeling were compared to the
most-sensitive endpoint for each taxa. For seed treatment, the peak EEC
was used for acute and endangered species risks, the 21-day average was
used for invertebrate chronic risk, and the 60 day average was used for
the fish chronic risk. For antisapstain uses, the worst-case scenario
(low dilution) and the "best-case" (high dilution) EECs were used for
acute and endangered species risks, and the typical dilution was used
for fish and invertebrate chronic risks. RQs exceeding one or more LOCs
(listed in the risk presumptions section, above) are in **bold** text.

**Table 12: Aquatic Organism Risk Quotients for Seed Treatment and
Antisapstain Uses of TCMTB**

+-------------------+------------+-------------+---------+-----------+
| **Taxa/Endpoint** | **Seed     | **Seed      | **Antis | **Ant     |
|                   | treatment  | Treatment   | apstain | isapstain |
|                   | EEC**      | RQ**        | EEC**   | RQ**      |
|                   |            |             |         |           |
|                   |            |             | **Low   |           |
|                   |            |             | dil     |           |
|                   |            |             | ution** |           |
|                   |            |             |         |           |
|                   |            |             | **High  |           |
|                   |            |             | dil     |           |
|                   |            |             | ution** |           |
+-------------------+------------+-------------+---------+-----------+
| Freshwater fish   | 0.28 ppb   | 0.03        | 32.7    | **3.76**  |
| Acute 8.7 µg/L    |            |             | ppb     |           |
|                   |            |             |         | **0.98**  |
|                   |            |             | 8.5 ppb |           |
+-------------------+------------+-------------+---------+-----------+
| Freshwater        | 0.28 ppb   | 0.01        | 32.7    | **1.49**  |
| Invertebrates     |            |             | ppb     |           |
| Acute 22 µg/L     |            |             |         | **0.39**  |
|                   |            |             | 8.5 ppb |           |
+-------------------+------------+-------------+---------+-----------+
| Marine/Estuarine  | 0.28 ppb   | 0.00        | 32.7    | **0.54**  |
| Fish Acute 60µg/L |            |             | ppb     |           |
|                   |            |             |         | **0.14**  |
|                   |            |             | 8.5 ppb |           |
+-------------------+------------+-------------+---------+-----------+
| Marine/Estuarine  | 0.28 ppb   | 0.02        | 32.7    | **2.35**  |
| Bivalve Acute     |            |             | ppb     |           |
| 13.9µg/L          |            |             |         | **0.61**  |
|                   |            |             | 8.5 ppb |           |
+-------------------+------------+-------------+---------+-----------+
| Marine/Estuarine  | 0.28 ppb   | 0.01        | 32.7    | **1.61**  |
| Invertebrate      |            |             | ppb     |           |
| Acute 20.3 µg/L   |            |             |         | **0.42**  |
|                   |            |             | 8.5 ppb |           |
+-------------------+------------+-------------+---------+-----------+
| Green Algae Acute | 0.28 ppb   | 0.00        | 32.7    | 0.08      |
| EC50 430 µg/L     |            |             | ppb     |           |
|                   |            |             |         | 0.02      |
|                   |            |             | 8.5 ppb |           |
+-------------------+------------+-------------+---------+-----------+
| Green Algae NOEC  | 0.28 ppb   | 0.00        | 32.7    | 0.22      |
| 150µg/L           |            |             | ppb     |           |
|                   |            |             |         | 0.06      |
|                   |            |             | 8.5 ppb |           |
+-------------------+------------+-------------+---------+-----------+
| Fish Chronic      | 0.12 ppb   | 0.35        | 13.1    | **38.53** |
| 0.34µg/L          |            |             | ppb     |           |
|                   |            |             |         | **25.00** |
|                   |            |             | 8.5 ppb |           |
+-------------------+------------+-------------+---------+-----------+
| Invertebrate      | 0.20 ppb   | \-\-\-\--   | 13.1    | \-\-\-\-- |
| Chronic -- DATA   |            |             | ppb     |           |
| GAP               |            |             |         |           |
+-------------------+------------+-------------+---------+-----------+

For seed treatment, no LOCs are exceeded, indicating that the use poses
minimal risk to aquatic organisms.

For the antisapstain use, the low dilution (worst-case) EECs exceed
acute high risk LOCs for all taxa, and chronic risk to fish. Even using
the high dilution ("best-case") EECs still results in exceedance of
acute high risk LOCs for freshwater fish and marine bivalves, and
restricted use LOCs for freshwater invertebrates, marine fish and marine
invertebrates, and chronic risk to fish.

Chronic risk to invertebrates cannot be assessed at this time due to the
lack of chronic invertebrate toxicity data.

The model used to estimate exposure from antisapstain uses is intended
as a Tier I screening model, and, as such, has inherent assumptions and
uncertainties that may result in over- or under-estimation of exposure
levels. Additional information, including, but not limited to, specific
leaching data for TCMTB used as an antisapstain wood preservative, and
aquatic monitoring data from waters receiving runoff from TCMTB
antisapstain treatment facilities, would remove some of the
uncertainties, and may result in more accurate exposure estimation.

Methods to reduce the amount of TCMTB potentially released from
antisapstain-treated wood would mitigate the risks. Possible mitigation
methods might include lowering the application rate or requiring
specific storage conditions to prevent exposure of recently treated wood
to weather (e.g., full covering) and/or prevent the release of any
associated runoff into aquatic habitats (e.g., drip pads). Number range
CHAPTERTCMTB is very mobile in soils, so any TCMTB leached outdoors will
likely reach aquatic habitats.

C.  **Endangered Species Considerations**

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

To facilitate compliance with the requirements of the Endangered Species
Act subsection (a)(2) the Environmental Protection Agency, Office of
Pesticide Programs has established procedures to evaluate whether a
proposed registration action may directly or indirectly reduce
appreciably the likelihood of both the survival and recovery of a listed
species in the wild by reducing the reproduction, numbers, or
distribution of any listed species (U.S. EPA 2004). After the Agency=s
screening-level risk assessment is performed, if any of the Agency=s
Listed Species LOC Criteria are exceeded for either direct or indirect
effects, a determination is made to identify if any listed or candidate
species may co-occur in the area of the proposed pesticide use. If
determined that listed or candidate species may be present in the
proposed use areas, further biological assessment is undertaken. The
extent to which listed species may be at risk then determines the need
for the development of a more comprehensive consultation package as
required by the Endangered Species Act.

Using Tier I screening modeling to assess potential exposure from
antisapstain wood preservation uses of TCMTB, risks to Listed Species
are indicated. Since the model is only intended as a screening-level
model, and, as such, has inherent uncertainties and limitations which
may result in inaccurate exposure estimations, further refinement of the
model is recommended before any regulatory action is taken regarding the
antisapstain uses of TCMTB. Potential impacts from the antisapstain use
can be mitigated in the interim with precautions to prevent leaching and
runoff when wood is stored outdoors. Due to these circumstances, the
Agency defers the Endangered Species Decision until additional data are
received regarding actual concentrations of TCMTB in waters receiving
runoff from antisapstain treatment facilities practicing the mitigation
methods described in this document (see Label Hazard Statements and Use
Recommendations section, below), as well as the other data described in
the data gaps section, below. When the additional data are received, the
environmental risk assessment of the antisapstain use of TCMTB will be
revised, and the risks to Listed Species will be reconsidered.

**D. Label Hazard Statements for and Use Recommendations:**

**TCMTB labels must state:**

"This product is toxic to fish, aquatic invertebrates, oysters and
shrimp."

\"Do not discharge effluent containing this product into lakes, streams,
ponds, estuaries,

oceans, or other waters unless in accordance with the requirements of a
National Pollutant

Discharge Elimination System (NPDES) permit and the permitting authority
has been

notified in writing prior to discharge. Do not discharge effluent
containing this product

to sewer systems without previously notifying the local sewage treatment
plant authority.

For guidance contact your State Water Board or Regional Office of the
EPA.\"

Antisapstain labels must state~~:~~

\"Treated lumber must be stored under cover, indoors, or at least 100
feet from any pond, lake, stream, wetland, or river to prevent possible
runoff of the product into the waterway. Treated lumber stored within
100 feet of a pond, lake, steam, wetland, or river must be either
covered with plastic or surrounded by a berm to prevent surface water
runoff into the nearby waterway. If a berm or curb is used around the
site, it should consist of impermeable material (clay, asphalt,
concrete) and be of sufficient height to prevent runoff during heavy
rainfall events.\"

**REFERENCES**

[Submitted Studies]{.underline}:

Accession #009869. Booden, R.M. 1974. Avian Dietary LC50, Mallard Duck,
Report #4043620. Unpublished data, conducted by Warf Institute for
Buckman Laboratories, Memphis, TN.

Accession #091624. Knott, W.B., and G. Woodard. 1968a. Busan 72 --
Safety Evaluation on Bobwhite Quail. Unpublished data, conducted by
Woodard Research Corp., for Buckman Laboratories, Inc., Memphis, TN.

Accession #091624. Knott, W.B., and G. Woodard. 1968b. Busan 72 --
Safety Evaluation on Bluegill Sunfish and Rainbow Trout. Unpublished
data, conducted by Woodard Research Corp., for Buckman Laboratories,
Inc., Memphis, TN

MRID #403636-01. Surprenant, D.C. 1986a. Acute Toxicity of TCMTB to the
Sheepshead Minnow, *Cyprinodon variegatus*. Unpublished data, conducted
by Springborn Bionomics, Inc., for Buckman Laboratories, Inc., Memphis,
TN

MRID #403363-02. Surprenant, D.C. 1987. Acute Toxicity of TCMTB to Mysid
Shrimp (*Mysidopsis bahia*). Unpublished data, conducted by Springborn
Bionomics, Inc., for Buckman Laboratories, Inc., Memphis, TN.

MRID #403636-03. Surprenant, D.C. 1986b. Acute Toxicity of TCMTB to
Embryo-Larvae of the Quahog Clam (*Mercenaria mercenaria*). Unpublished
data, conducted by Springborn Bionomics, Inc., for Buckman Laboratories,
Inc., Memphis, TN.

MRID #415956-01. Long, R.D., C.P. Driscoll, K.A. Hoxter, and G.J. Smith.
1990. TCMTB: A Dietary LC50 Study with the Mallard. Unpublished data,
conducted by Wildlife International, Ltd., for Buckman Laboratories,
Inc., Memphis, TN.

MRID \# 415956-02. Long, R.D., C.P. Driscoll, K.A. Hoxter, and G.J.
Smith. 1990. TCMTB: A Dietary LC50 Study with the Northern Bobwhite.
Unpublished data, conducted by Wildlife International, Ltd., for Buckman
Laboratories, Inc., Memphis, TN.

MRID #417809-01. Campbell, S. 1991. TCMTB: An Acute Oral Toxicity Study
with the Northern Bobwhite." Unpublished data, conducted by Wildlife
International, Ltd., for Buckman Laboratories, Memphis, TN

MRID #418042-01. Machado, M. W. 1991a. TCMTB -- Acute Toxicity to
Bluegill Sunfish (*Lepomis macrochirus*) under Flow-through Conditions.
Unpublished data, conducted by Springborn Laboratories, Inc., for
Buckman Laboratories, Inc., Memphis, TN.

MRID #418181-01. Machado, M. W. 1991b. TCMTB -- Acute Toxicity to
Rainbow Trout (*Oncorhynchus mykiss*) under Flow-through Conditions.
Unpublished data, conducted by Springborn Laboratories, Inc., for
Buckman Laboratories, Inc., Memphis, TN

MRID #418382-01. McNamara, P.C. 1991. TCMTB -- Acute Toxicity to
Daphnids (*Daphnia magna*) Under Flow-Through Conditions. Unpublished
data, conducted by Springborn Laboratories, Inc, for Buckman
Laboratories, Inc., Memphis, TN.

MRID #422260-01. Collins, M.K. 1992b. 2-Mercaptobenzothiazole (ROKON) --
Acute Toxicity to Daphnids (*Daphnia magna*) Under Static Conditions.
Unpublished data, conducted by Springborn Laboratories, Inc., for R.T.
Vanderbilt Ct., Inc., Norwalk, CT.

MRID #422322-01. Collins, M.K. 1992a. 2-Mercaptobenzothiazole (ROKON) --
Acute Toxicity to Rainbow Trout (*Oncorhynchus mykiss*) Under Static
Conditions. Unpublished data, conducted by Springborn Laboratories,
Inc., for R.T. Vanderbilt Ct., Inc., Norwalk, CT

MRID #422671-01. Pedersen, C.A., and B.R. Helsten. 1992a.
2-Mercaptobensothiazole (ROKON): 14-day Acute Oral LD50 Study in
Bobwhite Quail. Unpublished data, conducted by Bio-Life Associates,
Ltd., for R.T. Vanderbilt Co., Inc., Norwalk, CT.

MRID #424285-01. Pedersen, C.A., and B.R. Helsten. 1992b.
2-Mercaptobenziothiazol (ROKON): 8-Day Acute Dietary LC50 Study in
Bobwhite Quail. Unpublished data, conducted by Bio-Life Associates,
Ltd., for R.T. Vanderbilt Co., Norwalk, CT.

MRID #425929-01. Rhodes, J.E. 1992. Early Life-Stage Toxicity of
2-(Thiocyanomethylthio)benzothiazole (TCMTB) to the Rainbow Trout Under
Flow-Through Conditions. Unpublished data, conducted b ABC Laboratories,
Inc., for Buckman Laboratories International, Inc., Memphis, TN.

MRID #442009-01. Thompson, S.G., and J.P. Swigert. 1996. TCMTB: A 14-Day
Static-Renewal Toxicity Test with Duckweed (*Lemna gibba*). Unpublished
data, conducted by Wildlife International, Ltd., for Buckman
Laboratories International, Inc., Memphis, TN.

[Additional References]{.underline}:

Aschacher G and Gruendlinger R, 2000. Methods to evaluate the
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www.holzforschung.at/english/img_eng/ascha200.pdf.

Addinsoft, 2004. XLSTAT v7.5. http://www.xlstat.com.

.

Chew, G.L., G.M. Kruzynski, and I.K. Birtwell. Behavioural assessment of
exposure of juvenile Chinook salmon (*Oncorhynchus tshawtscha*) to
sublethal doses of a toxicant. In Proceedings of the Seventeenth Annual
Aquatic Toxicity Workshop, Nov. 5-7, 1990, Vancouver, BC, Vol. 1.
(edited by P. Chapman, F. Bishay, E. Power, K. Hall, L. Harding, D.
Mcleay, M. Nassichuk and W. Knapp). Canadian Technical report of
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Karickhoff SW, DS Brown, TA Scott, 1979. Sorption of Hydrophobic
Pollutants on Natural Sediments. Water Resources. 13:241-248.

Krahn P and Strub R, 1990. Standard Leaching Test for Antisapstain
Chemicals: Regional Program Report 90-10. Environment Canada,
Conservation and Protection, Pacific and Yukon Region North Vancouver,
BC.

Kruzynski, G.M., and I.K. Birtwell. 1990. Some Respiratory Responses of
Juvenile Pacific Salmon to the Antisapstain Chemical TCMTB. In
[Proceedings of the Seventeenth Annual Aquatic Toxicity Workshop, Nov.
5-7, 1990, Vancouver, BC, Vol. 1]{.underline}**.** (edited by P.
Chapman, F. Bishay, E. Power, K. Hall, L. Harding, D. Mcleay, M.
Nassichuk and W. Knapp). Canadian Technical report of Fisheries and
Aquatic Sciences, No. 1774 (vol 1).

Kruzynski, G.M., I.K. Birtwell, G.L. Chew, G.E. Piercey,and S. Spohn.
1990. An approach to testing for ecological relevance using behavioral
toxicology. . In [Proceedings of the Seventeenth Annual Aquatic Toxicity
Workshop, Nov. 5-7, 1990, Vancouver, BC, Vol. 1.]{.underline} (edited by
P. Chapman, F. Bishay, E. Power, K. Hall, L. Harding, D. Mcleay, M.
Nassichuk and W. Knapp). Canadian Technical report of Fisheries and
Aquatic Sciences, No. 1774 (vol 1).

Lee R, 2004. WLM recommendation regarding chemical generalization.
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Mineau, P., B.T. Collins, and A. Baril. 1996. On the Use of Scaling
Factors to Improve Interspecies Extrapolation of Acute Toxicity in
Birds. Regul Toxicol Pharmacol 24; 24-29.

USEPA. 2006. Office of Pesticide Programs internal memorandum, "Aquatic
Exposure Assessment for the Use of the Fungicide of
2-Thiocyanomethylthio)benzothiazole (TCMTB) as a Seed Treatment on
Cotton, Wheat, Barley, Oats, Rice, Sugar Beets, and Safflower," February
16, 2006.

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Office of Pesticide Programs U.S. Environmental Protection Agency -
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Biology Laboratory.

US EPA. 1979. TN 2427. Biological Report of Analysis, 90+ TCMTB, sample
MB618. Unpublished data, performed by US EPA Terrestrial and Aquatic
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