**HIGH PRODUCTION VOLUME (HPV)**

**CHEMICAL INITIATIVE**

**FINAL SUBMISSION**

**For**

**DITHIOPHOSPHATE ALKYL ESTERS CATEGORY**

**Prepared by**

**The American Chemistry Council**

**Petroleum Additives Panel**

**Health, Environmental and Regulatory Task Group**

**December 2005**

LIST OF MEMBER COMPANIES IN THE

HEALTH, ENVIRONMENTAL AND REGULATORY TASK GROUP

The Health, Environmental, and Regulatory Task Group (HERTG) of the
American Chemistry Council Petroleum Additives Panel includes the
following member companies:

Afton Chemical Corporation (formerly Ethyl Corporation)

Chevron Oronite Company, LLC

ExxonMobil Chemical Company

Infineum

The Lubrizol Corporation

SNPE

**EXECUTIVE SUMMARY**

The American Chemistry Council Petroleum Additives Panel Health,
Environmental and Regulatory Task Group (HERTG), and its member
companies, hereby submit for review this Final Submission for the
*"Dithiophosphate Alkyl Esters"* category of chemicals under the United
States Environmental Protection Agency High Production Volume (HPV)
Chemical Challenge Program. This final submission should be read in its
entirety in order to obtain a complete understanding of the category and
fulfilled testing requirements.

*Dithiophosphate Alkyl Esters Category.* Relying on several factors
specified in EPA's guidance document on "Development of Chemical
Categories in the HPV Challenge Program," in which use of chemical
categories is encouraged, the following nine closely related chemicals
constitute a chemical category:

-   Phosphorodithioic acid, mixed O,O-bis (1,3-dimethylbutyl and
    iso-propyl) esters -- (CAS \# 84605-28-7), referred to as "mixed
    1,3-dimethylbutyl and iso-propyl derivative"

```{=html}
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```
-   Phosphorodithioic acid, mixed O,O-bis(iso-butyl and pentyl) esters
    -- (CAS \# 68516-01-8), referred to as "mixed isobutyl and pentyl
    derivative"

```{=html}
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```
-   Phosphorodithioic acid, mixed O,O-bis(sec-butyl and 1,3
    dimethylbutyl) esters -- (CAS \# 68784-30-5), referred to as "mixed
    sec-butyl and 1,3-dimethylbutyl derivative"

```{=html}
<!-- -->
```
-   Phosphorodithioic acid mixed O,O-bis(sec-butyl and isooctyl) mixed
    esters -- (CAS \# 113706-14-2), referred to as "mixed sec-butyl and
    isooctyl derivative"

```{=html}
<!-- -->
```
-   Phosphorodithioic acid, mixed 0,0-bis(2-ethylhexyl and iso-butyl)
    esters -- (CAS \# 68784-32-7), referred to as "mixed 2-ethylhexyl
    and isobutyl derivative"

```{=html}
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```
-   2-Pentanol, 4-methyl-hydrogen phosphorodithioate -- (CAS \#
    6028-47-3), referred to as "1,3-dimethylbutyl derivative"

```{=html}
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```
-   Phosphorodithioic acid, 0,0-bis(2-ethylhexyl) esters -- (CAS#
    5810-88-8), referred to as "2-ethylhexyl derivative"

-   Phosphorodithioic acid, O,O-dioctyl ester, branched -- (CAS#
    68649-43-4), referred to as "branched isooctyl derivative"

-   Phosphorodithioic acid, O,O-diisooctyl ester -- (CAS# 26999-29-1),
    referred to as "isooctyl derivative".

An additional chemical that is not a part of the HPV Challenge Program
but which is an analogue of these chemicals and fits into the
Dithiophosphate alkyl esters category was used in the data review:
Phosphorodithioic acid, mixed O,O-bis(iso-Bu and isooctyl and pentyl)
esters. The alkyl chains in this derivative (C4-C8) are within the range
of the nine chemicals in the HPV category (C3-C8). This analogue has no
CAS# because the substance was originally nominated as confidential to
the U.S. TSCA Inventory and will be referred to as "mixed isobutyl,
isooctyl and pentyl derivative".

***Structural Similarity.*** A key factor supporting the classification
of these chemicals as a category is their structural similarity. All
substances in this category consist of a phosphorodithioic acid
structure with alkyl ester substituent groups.

*Fate and Transport Characteristics.* Based on biodegradation test data
for two members of the zinc dialkyldithiophosphate category, members of
this category are expected to be poorly biodegradable. The members of
the category are resistant to hydrolysis at room temperature because
they lack readily hydrolyzable moieties. One member of this category was
shown to be stable with respect to hydrolysis at room temperature. This
makes hydrolysis modeling unnecessary and no further hydrolysis testing
was conducted for this category. Photodegradation is not expected to
cause significant physical degradation of Dithiophosphate alkyl esters.
However, computer-modeled data was developed to adequately characterize
the potential atmospheric oxidation for members of this category.
Although these substances are not expected to partition to water or air
if released into the environment due to their low water solubility and
low vapor pressure, computer-modeled environmental partitioning data is
calculated on the members of this category.

*Aquatic Toxicity.* The 96-hour LL~50~ for the rainbow trout
(*Oncorhynchus mykiss)* exposed to the mixed 1,3-dimethylbutyl and
iso-propyl derivative (CAS \# 84605-28-7) is greater than 100 mg/l
loading rate WAF (Water Accommodated Fractions) and the No Observed
Effect Loading rate (NOEL) is 100 mg/l loading rate WAF . The 48-h
EL~50~ for *Daphnia magna* exposed to the mixed 1,3-dimethylbutyl and
iso-propyl derivative (CAS \# 84605-28-7) is 36 mg/l loading rate WAF.
The 72-hour E~b~L~50~ for the green alga (*Scenedesmus subspicatus)*
exposed to the mixed 1,3-dimethylbutyl and iso-propyl derivative (CAS \#
84605-28-7) is 55 mg/l loading rate WAF; the E~r~L~50~ (0-72 h) is 87
mg/l loading rate WAF and the NOEL is 25 mg/l loading rate WAF. These
data are bridged to other members of the category.

***Mammalian Toxicity*.** Acute mammalian toxicity tests are available
on a lower molecular weight analogue for this category. The molecular
weight range of this category is fairly narrow (C3-C8) and the alkyl
groups similar. Bridging is used to all Dithiophosphate alkyl esters
based on the C3-C8 Dithiophosphate Ester analogue derivative data.
Dithiophosphate alkyl esters are extremely corrosive to tissue; there is
low risk of human exposure and test animals will experience extreme pain
and suffering with additional testing. Therefore, in order to minimize
stress to test animals, no repeat dose or reproductive/developmental
testing was considered necessary.

*Genotoxicity.* An *in vitro* bacterial gene mutation assay was
conducted for the mixed 1,3-dimethylbutyl and iso-propyl derivative (CAS
\# 84605-28-7). This substance does not demonstrate mutagenic activity
in either the presence or absence of metabolic activation. The *in
vitro* chromosomal aberration assay on the mixed 1,3-dimethylbutyl and
iso-propyl derivative (CAS \# 84605-28-7) showed that this substance is
non-clastogenic to human lymphocytes *in vitro*. This derivative is the
lowest molecular weight component of this category and hence represents
the "worst case" genetic toxicity of the chemicals in this category.
Therefore, data from this substance is bridged to other members of the
category.

*Conclusion.* Based on the physiochemical, environmental fate, aquatic
toxicology and mammalian toxicology studies completed for this
submission and the data reviewed, the HERTG concludes that the
Dithiophosphate alkyl esters do not readily pose a risk to the aquatic
and mammalian environments. As this final submission was completed,
careful consideration was given to the number of animals required for
tests and conditions to which the animals would be exposed.

TABLE OF CONTENTS

**[LIST OF MEMBER COMPANIES IN THE HEALTH, ENVIRONMENTAL AND REGULATORY
TASK GROup 1]{.smallcaps}**

Executive Summary 2

1.0 INTRODUCTION 5

2.0 General Substance Information 7

2.1 Exposure information 9

3.0 **physiochemical properties** 10

4.0 ENVIRONMENTAL FATE DATA 11

4.1 Biodegradability 11

4.2 Hydrolysis 11

4.3 Photodegradation 12

4.4 Fugacity Modeling 12

5.0 AQUATIC TOXICITY DATA 16

5.1 Fish Acute Toxicity 16

5.2 Daphnia Acute Toxicity 16

**5.3 Algae Acute
Toxicity......................................................................................................16**

6.0 mammalian Toxicity Data 17

6.1 Acute Mammalian Toxicity 17

6.2 Repeated Dose & Reproductive/Developmental Toxicity 17

6.3 Genotoxicity 19

6.3.1 Bacterial Gene Mutation Assay 19

6.3.2 Chromosomal Aberrations Assay 19

**TABLE 1. Chemical Structures and CAS numbers of Dithiophosphate alkyl
ester**s **Category Members...............................
................................................................................................7**

**TABLE 2. Physico-chemical properties of Dithiophosphate alkyl ester**s
**Category Members..................\...11**

**TABLE 3. Evaluation of Environmental Fate Data of Dithiophosphate
alkyl ester**s **Category
Members.............................................................................................................................12**

**TABLE 4. Distribution data for Dithiophosphate alkyl ester**s
**Category
Members..............................................................................\................................................15**

**TABLE 5. Evaluation of Aquatic Toxicity of Dithiophosphate alkyl
ester**s **Category Members
Members.............................................................................................................................16**

**TABLE 6. Evaluation of Acute Mammalian Toxicity of Dithiophosphate
alkyl ester**s **Category Members Category
Members............................................................................................................\...\...18**

**TABLE 7. Evaluation of Genotoxicity of Dithiophosphate alkyl ester**s
**Category Members.......................19**

**TABLE 8. Summary of Data for Dithiophosphate alkyl ester**s **Category
Members ...\..........................\.....21**

**1.0 INTRODUCTION**

In March 1999, the American Chemistry Council (formerly the Chemical
Manufacturers Association) Petroleum Additives Panel Health,
Environmental, and Regulatory Task Group (HERTG), and its participating
member companies committed to address certain chemicals listed under the
Environmental Protection Agency (EPA) High Production Volume (HPV)
Chemical Challenge Program. This final submission follows up on that
commitment.

Specifically, this final submission illustrates how the HERTG addressed
testing requirements for the following nine substances (structures are
representative in Table 1):

-   Phosphorodithioic acid, mixed O,O-bis (1,3-dimethylbutyl and
    iso-propyl) esters -- (CAS \# 84605-28-7), referred to as "mixed
    1,3-dimethylbutyl and iso-propyl derivative"

```{=html}
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```
-   Phosphorodithioic acid, mixed O,O-bis(iso-butyl and pentyl) esters
    -- (CAS \# 68516-01-8), referred to as "mixed isobutyl and pentyl
    derivative"

```{=html}
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```
-   Phosphorodithioic acid, mixed O,O-bis(sec-butyl and 1,3
    dimethylbutyl) esters -- (CAS \# 68784-30-5), referred to as "mixed
    sec-butyl and 1,3-dimethylbutyl derivative"

```{=html}
<!-- -->
```
-   Phosphorodithioic acid mixed O,O-bis(sec-butyl and isooctyl) mixed
    esters -- (CAS \# 113706-14-2), referred to as "mixed sec-butyl and
    isooctyl derivative"

```{=html}
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```
-   Phosphorodithioic acid, mixed 0,0-bis(2-ethylhexyl and iso-butyl)
    esters -- (CAS \# 68784-32-7), referred to as "mixed 2-ethyl hexyl
    and isobutyl derivative"

```{=html}
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```
-   2-Pentanol, 4-methyl-hydrogen phosphorodithioate -- (CAS \#
    6028-47-3), referred to as "1,3-dimethylbutyl derivative"

```{=html}
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```
-   Phosphorodithioic acid, 0,0-bis(2-ethylhexyl) esters -- (CAS#
    5810-88-8), referred to as "2-ethylhexyl derivative"

-   Phosphorodithioic acid, O,O-dioctyl ester, branched -- (CAS#
    68649-43-4), referred to as "branched isooctyl derivative"

-   Phosphorodithioic acid, O,O-diisooctyl ester -- (CAS# 26999-29-1),
    referred to as "isooctyl derivative"

An additional chemical (Phosphorodithioic acid, mixed O,O-bis(iso-Bu and
isooctyl and pentyl) esters) is used in the data review. This chemical
is not a part of the HPV Challenge Program but is an analogue of these
chemicals and fits into the Dithiophosphate alkyl esters category. The
alkyl chain in this derivative (C4-C8) is within the range of the nine
chemicals in the HPV category (C3-C8). This analogue has no CAS# and
will be referred to as "mixed C3-C8 Dithiophosphate Ester analogue
derivative\".

**Table 1**

**Chemical Structures and CAS Numbers of Dithiophosphate Akly Ester
Category Members**

**(In estimated lowest to highest molecular weight order)**

+-----+-------------------------------------+-------------------------+
| CAS | Structure                           | Simplified Chemical     |
| \#  |                                     | Name                    |
+-----+-------------------------------------+-------------------------+
| 8   | ![](media/image1.wmf)               | mixed 1,3-dimethylbutyl |
| 460 |                                     | and iso-propyl          |
| 5-2 | Phosphorodithioic acid, mixed       | derivative              |
| 8-7 | O,O-bis (1,3-dimethylbutyl and      |                         |
|     | iso-propyl) esters                  |                         |
+-----+-------------------------------------+-------------------------+
| 6   | ![](media/image2.wmf)               | mixed isobutyl and      |
| 851 |                                     | pentyl derivative       |
| 6-0 | Phosphorodithioic acid, mixed       |                         |
| 1-8 | O,O-bis(iso-butyl and pentyl)       |                         |
|     | esters                              |                         |
+-----+-------------------------------------+-------------------------+
| 6   | ![](media/image3.wmf)               | mixed sec-butyl and     |
| 878 |                                     | 1,3-dimethylbutyl       |
| 4-3 | Phosphorodithioic acid, mixed       | derivative              |
| 0-5 | O,O-bis(sec-butyl and 1,3           |                         |
|     | dimethylbutyl) esters               |                         |
+-----+-------------------------------------+-------------------------+
| mi  | ![](media/image4.wmf)               | mixed isobutyl,         |
| xed |                                     | isooctyl and pentyl     |
| iso | Phosphorodithioic acid, mixed       | derivative              |
| but | O,O-bis(iso-Bu and isooctyl and     |                         |
| yl, | pentyl) esters                      |                         |
| is  |                                     |                         |
| ooc |                                     |                         |
| tyl |                                     |                         |
| and |                                     |                         |
| pen |                                     |                         |
| tyl |                                     |                         |
| d   |                                     |                         |
| eri |                                     |                         |
| vat |                                     |                         |
| ive |                                     |                         |
| (NO |                                     |                         |
| CAS |                                     |                         |
| #)  |                                     |                         |
+-----+-------------------------------------+-------------------------+

+------+--------------------------------------+------------------------+
| 113  | ![](media/image5.wmf)                | mixed sec-butyl and    |
| 706- |                                      | isooctyl derivative    |
| 14-2 | Phosphorodithioic acid mixed         |                        |
|      | O,O-bis(sec-butyl and isooctyl)      |                        |
|      | mixed esters                         |                        |
+------+--------------------------------------+------------------------+
| 68   | ![](media/image6.wmf)                | mixed 2-ethyl hexyl    |
| 784- |                                      | and isobutyl           |
| 32-7 | Phosphorodithioic acid, mixed        | derivative             |
|      | 0,0-bis(2-ethylhexyl and iso-butyl)  |                        |
|      | esters                               |                        |
+------+--------------------------------------+------------------------+
| 6    | ![](media/image7.wmf)                | 1,3-dimethylbutyl      |
| 028- |                                      | derivative             |
| 47-3 | 2-Pentanol, 4-methyl-hydrogen        |                        |
|      | phosphorodithioate                   |                        |
+------+--------------------------------------+------------------------+
| 5    | ![](media/image8.wmf)                | 2-ethylhexyl           |
| 810- |                                      | derivative             |
| 88-8 | Phosphorodithioic acid,              |                        |
|      | 0,0-bis(2-ethylhexyl) esters         |                        |
+------+--------------------------------------+------------------------+
| 68   | ![](media/image9.wmf)                | branched isooctyl      |
| 649- |                                      | derivative             |
| 43-4 | Phosphorodithioic acid, O,O-dioctyl  |                        |
|      | ester, branched                      |                        |
+------+--------------------------------------+------------------------+
| 26   | ![](media/image10.wmf)               | isooctyl derivative    |
| 999- |                                      |                        |
| 29-1 | Phosphorodithioic acid,              |                        |
|      | O,O-diisooctyl ester                 |                        |
+------+--------------------------------------+------------------------+

The only structural variable that influences the molecular weight of the
category members and consequently their bioavailability and toxicity is
the length of the alkyl side chain, which may vary from C3 to C8. The
length and extent of branching of the alkyl side chain also affects the
water solubility of these substances.

In preparing this final submission the following steps have been
undertaken:

Step 1: A review of the literature and confidential company data was
conducted on the physiochemical properties, mammalian toxicity endpoints
and environmental fate and effects for the nine dithiophosphate alkyl
esters derivatives in this category. Searches included the following
sources: MEDLINE, BIOSIS, CANCERLIT, CAPLUS, CHEMLIST, EMBASE, HSDB,
RTECS, EMIC, and TOXLINE databases; the TSCATS database for relevant
unpublished studies on these chemicals; and standard handbooks and
databases (e.g., Sax, CRC Handbook on Chemicals, IUCLID, Merck Index,
and other references) for physiochemical properties.

Step 2: The compiled data was evaluated for adequacy in accordance with
the EPA guidance documentation. Where additional data was needed,
testing was completed to fulfill the Screening Information Data Sets
requirements.

**2.0 General Substance Information**

Dithiophosphate alkyl esters consist of a phosphorodithioic acid
structure with alkyl ester substituent groups. The alkyl groups are
saturated hydrocarbon chains that vary in length and extent of
branching. An idealized structure is below:

![](media/image11.wmf){width="1.1in" height="0.89375in"}

The chemical structures and CAS numbers for the members of the
Dithiophosphate Esters category and analogue chemical are presented in
Table 1 and the chemical names in Table 2. These substances are prepared
by reacting phosphorous pentasulfide with one or more primary or
secondary alcohols to form the phosphorodithioic acid ester. Residual
phosphorus pentasulfide is removed and stored as a closed system
intermediate. These esters are not transported to other sites but are
converted to the commercial zinc dialkydithiophosphates in a subsequent
in-line step at the same manufacturing site.

**2.1 Exposure Information**

> Dithiophosphate alkyl esters are closed system intermediates. They are
> used by the member companies of the HERTG to produce components for
> lubricating oils by subsequent neutralization to form metal salts such
> as zinc dialkyldithiophosphates. In all HERTG manufacturing sites in
> the United States, these materials are neutralized in the reaction
> vessel in which they are produced or stored in on-site facilities
> until neutralized. They are not transported to other manufacturing
> sites by members of the HERTG. Since the neutralization reactions that
> are used to produce the lubricating oil components use an excess of
> metal oxide or hydroxide, dithiophosphate alkyl esters are not present
> in any end products at analytically detectable concentrations.
> Therefore, under prescribed conditions of use, the potential for
> exposure to the environment or to humans is extremely low.

**3.0 PHYSICOCHEMICAL PROPERTIES**

Selected physicochemical properties of the members of the
Dithiophosphate alkyl esters category are presented in Table 3. The
members of this category are all amber colored viscous liquids at
ambient temperature. The physicochemical properties of these substances,
which are described below, are very similar as would be expected based
upon the similarity in their chemical structures. All members of this
category are within a narrow molecular weight range (256 - 354 daltons)
and are highly acidic. In addition, based on modeling data, they have
similar melting and boiling points, low water solubility, low vapor
pressure and are lipophilic in nature. These properties provide support
to the justification of this group of chemicals as a category within the
HPV Challenge Program.

######### 3.1 Molecular Weight and Alkyl Side Chain Length

> The members of the category range in molecular weight from 256 to 354
> daltons (Table 3).

######### 3.2 pH

Dithiophosphate alkyl esters are strong acids. This acidity makes the
members of this category corrosive.

######### 3.3 Boiling Point

> The Dithiophosphate alkyl esters differ only in the alkyl chain(s)
> present in the molecule. Therefore, the boiling points generally
> follow a pattern based upon their molecular weight and the extent of
> branching of the alkyl side chain. Modeling data indicates that the
> boiling point of these substances could range from 289 to 385^o^C
> (Table 3).

######### 3.4 Vapor Pressure

> Modeling data indicates that the vapor pressure of these substances
> range from 3.46 x 10^-3^ to 1.9 x 10^-5^ mm Hg at 25^o^C and generally
> follow a pattern based upon their molecular weight and the extent of
> branching of the alkyl side chain (Table 3).

######### 3.5 Water Solubility

> The low water solubility is consistent with the high lipophilic nature
> of these substances. The category member containing the shortest alkyl
> chain, mixed 1,3-dimethylbutyl and isopropyl derivative (CAS#
> 84605-28-7) was tested for water solubility and was determined to be
> 19.6 g/l of solution with a nominal loading rate of 100 g/l at 20.0 ±
> 0.5 °C.

6.  Octanol Water Coefficient

> Modeling data indicates that these substances have low water
> solubility and that the log of the octanol-water partition coefficient
> (log K~o/w~) of these substances range from 4.48 to 7.99 (Table 3).

##### Table 2

#####  Physicochemical Properties of Dithiophosphate alkyl esters

+-------------+--------+--------+--------+--------+--------+--------+
| CAS Number  | Mol    | MP^1^  | BP^1^  | Vapor  | Water  | Log    |
|             | ecular |        |        |        | Solu   | K~     |
|             | Weight | ^o^C   | ^o^C   | Pr     | bility | ow~^1^ |
|             |        |        |        | essure |        |        |
|             |        |        |        |        | m      |        |
|             |        |        |        | mm     | g/L^1^ |        |
|             |        |        |        | Hg^1^  |        |        |
+-------------+--------+--------+--------+--------+--------+--------+
| 84605-28-7  | 256    | -39    | 289    | 0      | 3.277  | 4.48   |
|             |        |        |        | .00346 |        |        |
+-------------+--------+--------+--------+--------+--------+--------+
| 68516-01-8  | 256    | -18    | 307    | 0      | 2.454  | 4.62   |
|             |        |        |        | .00134 |        |        |
+-------------+--------+--------+--------+--------+--------+--------+
| 68784-30-5  | 270    | -29    | 304    | 0      | 1.04   | 4.97   |
|             |        |        |        | .00157 |        |        |
+-------------+--------+--------+--------+--------+--------+--------+
| 113706-14-2 | 298    | 0      | 339    | 0.     | 0      | 6.02   |
|             |        |        |        | 000246 | .08998 |        |
+-------------+--------+--------+--------+--------+--------+--------+
| 68784-32-7  | 298    | 0      | 339    | 0.     | 0      | 6.02   |
|             |        |        |        | 000246 | .08998 |        |
+-------------+--------+--------+--------+--------+--------+--------+
| 6028-47-3   | 298    | -19    | 323    | 0      | 0.1201 | 5.88   |
|             |        |        |        | .00056 |        |        |
+-------------+--------+--------+--------+--------+--------+--------+
| 5810-88-8   | 354    | -13    | 385    | 1.9 x  | 0.0    | 7.99   |
|             |        |        |        | 10^-5^ | 008768 |        |
+-------------+--------+--------+--------+--------+--------+--------+
| 68649-43-4  | 354    | 16     | 353    | 0.     | 0.     | 7.69   |
|             |        |        |        | 000113 | 001573 |        |
+-------------+--------+--------+--------+--------+--------+--------+
| 26999-29-1  | 354    | -13    | 385    | 1.9 x  | 0.0    | 7.99   |
|             |        |        |        | 10^-5^ | 008768 |        |
+-------------+--------+--------+--------+--------+--------+--------+

^1^Data derived from modeling

4.  **ENVIRONMENTAL FATE DATA**

    1.  **Biodegradability**

> Adequate biodegradation data existed for two of twelve substances in
> the zinc dialkyldithiophosphate category including the lowest
> molecular weight (CAS# 84605-29-8) and the highest molecular weight
> (CAS# 54261-67-5) members. These data are similar and indicate a
> narrow range of biodegradability irrespective of molecular weight and
> alkyl chain type. The hydrocarbon portion of these compounds that is
> susceptible to biodegradation is present in both the zinc
> dialkyldithiophosphates and the dithiophosphate alkyl esters. It is
> expected that the dithiophosphate alkyl esters would behave similarly
> to the corresponding zinc derivatives. Therefore, data from the zinc
> dialkyldithiophosphate category is bridged to the members of the
> dithiophosphate alkyl esters category.

**[4.2]{.smallcaps} Hydrolosis**

> The members of the category are resistant to hydrolysis at room
> temperature because they lack readily hydrolyzable moieties.
>
> Adequate data exists on hydrolytic evaluations on the 2-ethylhexyl
> derivative (CAS# 5810-88-8) member of the Dithiophosphate alkyl esters
> category performed at room temperature and at 80 degrees C. At room
> temperature, hydrolysis does not readily occur. When heated to 80
> degrees C, hydrolytic degradation results in the formation of the
> phosphorothioic acid ester and hydrogen sulfide. Continued heating at
> high temperatures results in the formation of the mono-ester and
> eventually, phosphorothioic acid itself.
>
> Data from the 2-ethylhexyl derivative (CAS# 5810-88-8) is used to
> bridge to the other members of the category.

**4.3 Photodegradation**

> The Atmospheric Oxidation Potential (AOP) for category members was
> evaluated using the modeling program AOPWIN. The AOP data for
> representative structures of the category was evaluated to estimate
> (1) rate constants for the atmospheric, gas phase reaction as mediated
> by photochemically produced hydroxyl radicals and (2) atmospheric
> half-lives based on hydroxyl radical attack. The data is presented in
> Table 4.

**4.4 Fugacity**

> The relative distribution of substances within this category among
> environmental compartments was evaluated using a Level III fugacity
> model. Data developed using this model can be used for simple
> comparative purposes across several substances. The data presented in
> Table 5 indicate the likely environmental compartment into which a
> chemical will tend to partition and an indication of the distribution
> in each medium.

**Table 3**

**EVALUATION OF ENVIRONMENTAL FATE Data for DITHIOPHOSPHATE ALKYL ESTERS
CATEGORY Members**

+-----------+-----------------+-----------------+--------------------+
| **CAS     | **BIO           | **HYDROLYSIS**  | **                 |
| Number**  | DEGRADABILITY** |                 | PHOTODEGRADATION** |
+-----------+-----------------+-----------------+--------------------+
|           | Available Data  | Available Data  | Available Data &   |
|           | & Testing       | & Testing       | Testing            |
+-----------+-----------------+-----------------+--------------------+
| 8         | Bridging^1^     | Bridging^2^     | [Direct            |
| 4605-28-7 |                 |                 | Photodegrada       |
|           |                 |                 | tion]{.underline}: |
|           |                 |                 |                    |
|           |                 |                 | Dithiophosphate    |
|           |                 |                 | alkyl esters are   |
|           |                 |                 | not subject to     |
|           |                 |                 | photolytic         |
|           |                 |                 | reactions          |
|           |                 |                 |                    |
|           |                 |                 | [Indirect          |
|           |                 |                 | Photodegrada       |
|           |                 |                 | tion]{.underline}: |
|           |                 |                 |                    |
|           |                 |                 | Calculated OH^-^   |
|           |                 |                 | Rate Constant      |
|           |                 |                 | (cm^3^/molec-sec)  |
|           |                 |                 | = 146.3228 E-12    |
|           |                 |                 |                    |
|           |                 |                 | Calculated         |
|           |                 |                 | Half-life in Air   |
|           |                 |                 | (hrs) = 0.877 Hrs  |
+-----------+-----------------+-----------------+--------------------+
| 6         | Bridging^1^     | Bridging^2^     | [Direct            |
| 8516-01-8 |                 |                 | Photodegrada       |
|           |                 |                 | tion]{.underline}: |
|           |                 |                 |                    |
|           |                 |                 | Dithiophosphate    |
|           |                 |                 | alkyl esters are   |
|           |                 |                 | not subject to     |
|           |                 |                 | photolytic         |
|           |                 |                 | reactions          |
|           |                 |                 |                    |
|           |                 |                 | [Indirect          |
|           |                 |                 | Photodegrada       |
|           |                 |                 | tion]{.underline}: |
|           |                 |                 |                    |
|           |                 |                 | Calculated OH^-^   |
|           |                 |                 | Rate Constant      |
|           |                 |                 | (cm^3^/molec-sec)  |
|           |                 |                 | = 105.5599 E-12    |
|           |                 |                 |                    |
|           |                 |                 | Calculated         |
|           |                 |                 | Half-life in Air   |
|           |                 |                 | (hrs) = 1.216 Hrs  |
+-----------+-----------------+-----------------+--------------------+
| 6         | Bridging^1^     | Bridging^2^     | [Direct            |
| 8784-30-5 |                 |                 | Photodegrada       |
|           |                 |                 | tion]{.underline}: |
|           |                 |                 |                    |
|           |                 |                 | Dithiophosphate    |
|           |                 |                 | alkyl esters are   |
|           |                 |                 | not subject to     |
|           |                 |                 | photolytic         |
|           |                 |                 | reactions          |
|           |                 |                 |                    |
|           |                 |                 | [Indirect          |
|           |                 |                 | Photodegrada       |
|           |                 |                 | tion]{.underline}: |
|           |                 |                 |                    |
|           |                 |                 | Calculated OH^-^   |
|           |                 |                 | Rate Constant      |
|           |                 |                 | (cm^3^/molec-sec)  |
|           |                 |                 | = 156.6187 E-12    |
|           |                 |                 |                    |
|           |                 |                 | Calculated         |
|           |                 |                 | Half-life in Air   |
|           |                 |                 | (hrs) = 0.820      |
+-----------+-----------------+-----------------+--------------------+
| 11        | Bridging^1^     | Bridging^2^     | [Direct            |
| 3706-14-2 |                 |                 | Photodegrada       |
|           |                 |                 | tion]{.underline}: |
|           |                 |                 |                    |
|           |                 |                 | Dithiophosphate    |
|           |                 |                 | alkyl esters are   |
|           |                 |                 | not subject to     |
|           |                 |                 | photolytic         |
|           |                 |                 | reactions          |
|           |                 |                 |                    |
|           |                 |                 | [Indirect          |
|           |                 |                 | Photodegrada       |
|           |                 |                 | tion]{.underline}: |
|           |                 |                 |                    |
|           |                 |                 | Calculated OH^-^   |
|           |                 |                 | Rate Constant      |
|           |                 |                 | (cm^3^/molec-sec)  |
|           |                 |                 | = 135.3242 E-12    |
|           |                 |                 |                    |
|           |                 |                 | Calculated         |
|           |                 |                 | Half-life in Air   |
|           |                 |                 | (hrs) = 0.948 Hrs  |
+-----------+-----------------+-----------------+--------------------+
| 6         | Bridging^1^     | Bridging^2^     | [Direct            |
| 8784-32-7 |                 |                 | Photodegrada       |
|           |                 |                 | tion]{.underline}: |
|           |                 |                 |                    |
|           |                 |                 | Dithiophosphate    |
|           |                 |                 | alkyl esters are   |
|           |                 |                 | not subject to     |
|           |                 |                 | photolytic         |
|           |                 |                 | reactions          |
|           |                 |                 |                    |
|           |                 |                 | [Indirect          |
|           |                 |                 | Photodegrada       |
|           |                 |                 | tion]{.underline}: |
|           |                 |                 |                    |
|           |                 |                 | Calculated OH^-^   |
|           |                 |                 | Rate Constant      |
|           |                 |                 | (cm^3^/molec-sec)  |
|           |                 |                 | = 111.8908 E-12    |
|           |                 |                 |                    |
|           |                 |                 | Calculated         |
|           |                 |                 | Half-life in Air   |
|           |                 |                 | (hrs) = 1.147 Hrs  |
+-----------+-----------------+-----------------+--------------------+
| 6028-47-3 | Bridging^1^     | Bridging^2^     | [Direct            |
|           |                 |                 | Photodegrada       |
|           |                 |                 | tion]{.underline}: |
|           |                 |                 |                    |
|           |                 |                 | Dithiophosphate    |
|           |                 |                 | alkyl esters are   |
|           |                 |                 | not subject to     |
|           |                 |                 | photolytic         |
|           |                 |                 | reactions          |
|           |                 |                 |                    |
|           |                 |                 | [Indirect          |
|           |                 |                 | Photodegrada       |
|           |                 |                 | tion]{.underline}: |
|           |                 |                 |                    |
|           |                 |                 | Calculated OH^-^   |
|           |                 |                 | Rate Constant      |
|           |                 |                 | (cm^3^/molec-sec)  |
|           |                 |                 | = 159.4364 E-12    |
|           |                 |                 |                    |
|           |                 |                 | Calculated         |
|           |                 |                 | Half-life in Air   |
|           |                 |                 | (hrs) = 0.805 Hrs  |
+-----------+-----------------+-----------------+--------------------+
| 5810-88-8 | Bridging^1^     | Does not        | [Direct            |
|           |                 | readily occur   | Photodegrada       |
|           |                 |                 | tion]{.underline}: |
|           |                 |                 |                    |
|           |                 |                 | Dithiophosphate    |
|           |                 |                 | alkyl esters are   |
|           |                 |                 | not subject to     |
|           |                 |                 | photolytic         |
|           |                 |                 | reactions          |
|           |                 |                 |                    |
|           |                 |                 | [Indirect          |
|           |                 |                 | Photodegrada       |
|           |                 |                 | tion]{.underline}: |
|           |                 |                 |                    |
|           |                 |                 | Calculated OH^-^   |
|           |                 |                 | Rate Constant      |
|           |                 |                 | (cm^3^/molec-sec)  |
|           |                 |                 | = 118.2384 E-12    |
|           |                 |                 |                    |
|           |                 |                 | Calculated         |
|           |                 |                 | Half-life in Air   |
|           |                 |                 | (hrs) = 1.086 Hrs  |
+-----------+-----------------+-----------------+--------------------+
| 6         | Bridging^1^     | Bridging^2^     | [Direct            |
| 8649-43-4 |                 |                 | Photodegrada       |
|           |                 |                 | tion]{.underline}: |
|           |                 |                 |                    |
|           |                 |                 | Dithiophosphate    |
|           |                 |                 | alkyl esters are   |
|           |                 |                 | not subject to     |
|           |                 |                 | photolytic         |
|           |                 |                 | reactions          |
|           |                 |                 |                    |
|           |                 |                 | [Indirect          |
|           |                 |                 | Photodegrada       |
|           |                 |                 | tion]{.underline}: |
|           |                 |                 |                    |
|           |                 |                 | Calculated OH^-^   |
|           |                 |                 | Rate Constant      |
|           |                 |                 | (cm^3^/molec-sec)  |
|           |                 |                 | = 57.4989 E-12     |
|           |                 |                 | Calculated         |
|           |                 |                 | Half-life in Air   |
|           |                 |                 | (hrs) = 2.232 Hrs  |
+-----------+-----------------+-----------------+--------------------+
| 2         | Bridging^1^     | Bridging^2^     | [Direct            |
| 6999-29-1 |                 |                 | Photodegrada       |
|           |                 |                 | tion]{.underline}: |
|           |                 |                 |                    |
|           |                 |                 | Dithiophosphate    |
|           |                 |                 | alkyl esters are   |
|           |                 |                 | not subject to     |
|           |                 |                 | photolytic         |
|           |                 |                 | reactions          |
|           |                 |                 |                    |
|           |                 |                 | [Indirect          |
|           |                 |                 | Photodegrada       |
|           |                 |                 | tion]{.underline}: |
|           |                 |                 |                    |
|           |                 |                 | Calculated OH^-^   |
|           |                 |                 | Rate Constant      |
|           |                 |                 | (cm^3^/molec-sec)  |
|           |                 |                 | = 116.8475 E-12    |
|           |                 |                 |                    |
|           |                 |                 | Calculated         |
|           |                 |                 | Half-life in Air   |
|           |                 |                 | (hrs) = 1.098 Hrs  |
+-----------+-----------------+-----------------+--------------------+

^1^Bridging from zinc dialkyldithiophosphates category data**.**

^2^Bridging from CAS# 5810-88-8 data**.**

**Table 4**

**distribution data for selected chemical components for DITHIOPHOSPHATE
ALKYL ESTERS CATEGORY Members**

+-----------------+------------+------------+------------+------------+
| **CAS**         | **PERCENT  |            |            |            |
|                 | DIST       |            |            |            |
| **Number**      | RIBUTION** |            |            |            |
+-----------------+------------+------------+------------+------------+
|                 | **Air**    | **Water**  | **Soil**   | **         |
|                 |            |            |            | Sediment** |
|                 | **(%)**    | **(%)**    | **(%)**    |            |
|                 |            |            |            | **(%)**    |
+-----------------+------------+------------+------------+------------+
| 84605-28-7      | 0.135      | 8.75       | 84.9       | 6.27       |
+-----------------+------------+------------+------------+------------+
| 68516-01-8      | 0.389      | 16         | 80.4       | 3.22       |
+-----------------+------------+------------+------------+------------+
| 68784-30-5      | 0.107      | 7.39       | 76.7       | 15.8       |
+-----------------+------------+------------+------------+------------+
| 113706-14-2     | 0.0576     | 3.52       | 43.2       | 53.2       |
+-----------------+------------+------------+------------+------------+
| 68784-32-7      | 0.161      | 6.76       | 42.5       | 50.6       |
+-----------------+------------+------------+------------+------------+
| 6028-47-3       | 0.0557     | 3.95       | 47.2       | 48.8       |
+-----------------+------------+------------+------------+------------+
| 5810-88-8       | 0.0823     | 3.79       | 28.2       | 67.9       |
+-----------------+------------+------------+------------+------------+
| 68649-43-4      | 0.0196     | 0.767      | 39.7       | 59.5       |
+-----------------+------------+------------+------------+------------+
| 26999-29-1      | 0.0334     | 1.92       | 28.2       | 69.8       |
+-----------------+------------+------------+------------+------------+

**5.0 AQUATIC TOXICITY [DATA ]{.smallcaps}**

**5.1 Fish Acute Toxicity**

> An acute toxicity test with Rainbow trout (*Oncorhynchus mykiss)* was
> conducted with the mixed 1,3-dimethylbutyl and iso-propyl derivative
> (CAS# 84605-28-7). The 96-hour LL~50~ based on nominal loading rates
> was greater than 100 mg/l loading rate WAF and correspondingly the No
> Observed Effect Loading rate was 100 mg/l loading rate WAF.

.

**5.2 Invertebrate Acute Toxicity**

> An acute invertebrate toxicity test with *Daphnia magna* was conducted
> with the mixed 1,3-dimethylbutyl and iso-propyl derivative (CAS#
> 84605-28-7). A 48-h EL~50~ based on nominal loading rates was 36 mg/L
> loading rate WAF. The No Observed Effect Loading rate was 18 mg/l
> loading rate WAF.

**[5.3]{.smallcaps} Alga Acute Toxicity**

> An algal inhibition test was conducted to assess the effect of the
> mixed 1,3-dimethylbutyl and iso-propyl derivative (CAS# 84605-28-7) on
> the growth of the green alga *Scenedesmus subspicatus.* The 72-h
> E~b~L~50~ was 55 mg/l loading rate WAF and the E~r~L~50~ (0-72 h) was
> 87 mg/l loading rate WAF. The No Observed Effect Loading rate was 25
> mg/l loading rate WAF.

**Table 5**

**Aquatic Toxicity Data for DITHIOPHOSPHATE ALKYL ESTERS CATEGORY
Members**

  ------------- ------------------ -------------------- --------------------
  **CAS         **ACUTE TOXICITY   **ACUTE TOXICITY TO  **TOXICITY TO
  Number**      TO FISH**          INVERTEBRATES**      ALGAE**

                **Available data** **Available data**   **Available data**

  84605-28-7    96-hr LL~50~ \>    48-hr EL~50~ = 36    72-hr E~b~L~50~ = 55
                100 mg/l           mg/L                 mg/l

  68516-01-8    Bridging^1^        Bridging^1^          Bridging^1^

  68784-30-5    Bridging^1^        Bridging^1^          Bridging^1^

  113706-14-2   Bridging^1^        Bridging^1^          Bridging^1^

  68784-32-7    Bridging^1^        Bridging^1^          Bridging^1^

  6028-47-3     Bridging^1^        Bridging^1^          Bridging^1^

  5810-88-8     Bridging^1^        Bridging^1^          Bridging^1^

  68649-43-4    Bridging^1^        Bridging^1^          Bridging^1^

  26999-29-1    Bridging^1^        Bridging^1^          Bridging^1^
  ------------- ------------------ -------------------- --------------------

^1^Bridging from CAS# 84605-28-7 data**.**

**6.0 MAMMALIAN TOXICOLOGY DATA**

**6.1 Acute Mammalian Toxicity**

> Acute mammalian toxicity tests were available on a lower molecular
> weight analogue for this category (Mixed isobutyl, isooctyl and pentyl
> derivative). The molecular weight range of this category is fairly
> narrow (C3-C8) and the alkyl groups similar. Therefore, the acute
> toxicity was not expected to vary greatly. Due to the corrosivity of
> these chemicals, as seen in the eye and skin irritation studies, to
> spare animals from unnecessary pain and suffering, no additional acute
> mammalian toxicity testing was conducted on the Dithiophosphate alkyl
> esters category constituents. Bridging was used to all Dithiophosphate
> alkyl esters based on the C3-C8 Dithiophosphate Ester analogue
> derivative data.

**6.2 Repeated Dose Toxicity and Reproductive/Developmental Toxicity**

> The exposure profile of Dithiophosphate alkyl esters offers assurance
> that there is minimal risk for repeated dose toxicity. The exposure
> potential to production workers is very low due to process,
> engineering and personal protection equipment controls. For
> concentrated component, the only practical type of exposure would be
> acute and only occur in the rare case of an accidental spill. The
> dermal route would be the principle route of exposure. Oral or
> inhalation exposure is expected to be rare.
>
> Additionally, Dithiophosphate alkyl esters are corrosive. Therefore,
> the handling and storage conditions lead to a limited potential for
> long-term exposure. Since exposures resulting from chemical accidents
> are likely to be of relatively short versus chronic duration,
> repeated-dose toxicity, developmental or reproduction/developmental
> toxicity testing was not conducted.
>
> In addition to the arguments outlined above, HERTG believes that
> additional testing of Dithiophosphate alkyl esters will cause
> unnecessary distress to experimental animals since previously
> conducted experimental studies demonstrate Dithiophosphate alkyl
> esters are corrosive to skin, eye and mucosal membranes.
>
> Based on scientific review and the limited potential for intentional
> or accidental human exposure, the sponsoring companies of HERTG would
> be unable to conduct additional mammalian toxicity testing on
> Dithiophosphate alkyl esters without imparting unnecessary distress
> and suffering to the experimental animal. The HERTG believes that by
> not conducting mammalian toxicity tests on chemicals known to be
> corrosive and that have limited risk of exposure to the environment
> and to humans, we are supporting the spirit of this commitment.

##### Table 6

##### Evaluation of Acute Mammalian Toxicology of Dithiophosphate alkyl esters

  -----------------------------------------------------------------------------------------
  CAS Number    ACUTE ORAL    ACUTE DERMAL  ACUTE INHALATION PRIMARY DERMAL   EYE
                TOXICITY^1^   TOXICITY^1^   TOXICITY^2^      IRRITATION       IRRITATION
  ------------- ------------- ------------- ---------------- ---------------- -------------
                Available     Available     Available Data & Available Data   Available
                Data &        Data &        Testing                           Data
                Testing       Testing                                         

  84605-28-7    Bridging      Bridging      Bridging                          

  68516-01-8    Bridging      Bridging      Bridging                          

  68784-30-5    Bridging      Bridging      Bridging                          

  mixed         Bridging      \>2,000 mg/kg \>0.198 mg/L     Severe damage to Maximum
  isobutyl,                                 (nominal         the skin. Edema, irritation
  isooctyl and                              concentration)   erythema and/or  score of
  pentyl                                                     eschar formation 78.5/110.0
  derivative                                                 was observed at  (day 1). All
                                                             the test sites   rabbits
                                                             of all rabbits   exhibited eye
                                                             at all scoring   irritation
                                                             intervals.       and recovery
                                                             Necrosis was     was not
                                                             evident on days  complete in
                                                             1, 3, and 7      any rabbit by
                                                             following        day 21. One
                                                             chemical         rabbit
                                                             application. The euthanized at
                                                             primary dermal   day 14 due to
                                                             irritation score the severe
                                                             was 8.0/8.0.     ocular
                                                                              reaction.

  113706-14-2   Bridging      Bridging      Bridging                          

  68784-32-7    Bridging      Bridging      Bridging                          

  6028-47-3     Bridging      Bridging      Bridging                          

  5810-88-8     2140 ml/kg^3^ 1250 ml/kg^3^ Bridging                          

  68649-43-4    Bridging      Bridging      Bridging                          

  26999-29-1    Bridging      Bridging      Bridging                          
  -----------------------------------------------------------------------------------------

^1^Toxicity endpoints are expressed as median lethal dose (LD~50~) for
dermal toxicity**.**

^2^Toxicity of endpoint is expressed as median lethal concentration
(LD~50~) for inhalation toxicity

^3^Smyth, Henry F., Charles P. Carpenter, Carrol S. Weil, Urbano C.
Pozzani, and Jean A. Striegel. "Range-Finding Toxicity Data: List VI."
[American Industrial Hygiene Association Journal]{.underline} 1962.
23:95.

**6.3 [Genotoxicity]{.smallcaps}**

6.3.1 [Bacterial Gene Mutation Assay]{.underline}

> An *in vitro* bacterial gene mutation assay was conducted for the
> mixed 1,3-dimethylbutyl and iso-propyl derivative (CAS \# 84605-28-7).
> This substance does not demonstrate mutagenic activity in either the
> presence or absence of metabolic activation. This derivative is the
> lowest molecular weight component of this category and hence
> represents the "worst case" genetic toxicity of the chemicals in this
> category. Therefore data from this substance is bridged to other
> members of the category (Table 7).

6.3.2 [Chromosome Aberration Assay]{.underline}

> The *in vitro* chromosomal aberration assay on the mixed
> 1,3-dimethylbutyl and iso-propyl derivative (CAS \# 84605-28-7) showed
> that the material was non-clastogenic to human lymphocytes *in vitro*.
> This derivative is the lowest molecular weight component of this
> category and hence represents the "worst case" genetic toxicity of the
> chemicals in this category. Therefore data from this substance was
> bridged to other members of the category.

**Table 7**

**Evaluation of Genotoxicity of Dithiophosphate alkyl esters**

+----------+-------------------------+--------------------------------+
| CAS      | GENE MUTATION ASSAY     | CHROMOSOMAL ABERRATION ASSAY   |
| Number   |                         |                                |
+==========+=========================+================================+
| 84       | *In vitro* Bacterial    | *In vitro* Chromosome          |
| 605-28-7 | Reverse Mutation Assay  | Aberration Assay in Human      |
|          | --                      | Lymphocytes--                  |
|          |                         |                                |
|          | With and Without S-9 -- | Non-Clastogenic                |
|          |                         |                                |
|          | Not Mutagenic           |                                |
+----------+-------------------------+--------------------------------+
| 68       | Bridging^1^             | Bridging^1^                    |
| 516-01-8 |                         |                                |
+----------+-------------------------+--------------------------------+
| 68       | Bridging^1^             | Bridging^1^                    |
| 784-30-5 |                         |                                |
+----------+-------------------------+--------------------------------+
| 113      | Bridging^1^             | Bridging^1^                    |
| 706-14-2 |                         |                                |
+----------+-------------------------+--------------------------------+
| 68       | Bridging^1^             | Bridging^1^                    |
| 784-32-7 |                         |                                |
+----------+-------------------------+--------------------------------+
| 6        | Bridging^1^             | Bridging^1^                    |
| 028-47-3 |                         |                                |
+----------+-------------------------+--------------------------------+
| 5        | Bridging^1^             | Bridging^1^                    |
| 810-88-8 |                         |                                |
+----------+-------------------------+--------------------------------+
| 68       | Bridging^1^             | Bridging^1^                    |
| 649-43-4 |                         |                                |
+----------+-------------------------+--------------------------------+
| 26       | Bridging^1^             | Bridging^1^                    |
| 999-29-1 |                         |                                |
+----------+-------------------------+--------------------------------+
| ^1^      |                         |                                |
| Bridging |                         |                                |
| from CAS |                         |                                |
| #84      |                         |                                |
| 605-28-7 |                         |                                |
+----------+-------------------------+--------------------------------+

Table 8

**Summary of Data for Dithiophosphate alkyl esters**

  ----------------------------------------------------------------------------------------------------------------------------------------------------------------------
  CAS Number    Environmental                                               Ecotoxicity                         Human                                          
                Fate                                                                                            Health                                         
                                                                                                                Effects                                        
  ------------- --------------- ---------- ------------ ---------- -------- ------------- ---------- ---------- ---------- ----------- --------- ------------- ---------
                Physical Chem   Photodeg   Hydrolysis   Fugacity   Biodeg   Acute Fish    Acute      Algal      Acute      Point       Chrom     Sub-chronic   Repro/
                                                                            Toxicity      Invert     Toxicity   Toxicity   Mutations   Effects                 Develop
                                                                                          Toxicity                                                             

  84605-28-7    A               C          B            C          B        A             A          A          B          A           A         I             I

  68516-01-8    A               C          B            C          B        B             B          B          B          B           B         I             I

  68784-30-5    A               C          B            C          B        B             B          B          B          B           B         I             I

  113706-14-2   A               C          B            C          B        B             B          B          B          B           B         I             I

  68784-32-7    A               C          B            C          B        B             B          B          B          B           B         I             I

  6028-47-3     A               C          B            C          B        B             B          B          B          B           B         I             I

  5810-88-8     A               C          A            C          B        B             B          B          A          B           B         I             I

  68649-43-4    A               C          B            C          B        B             B          B          B          B           B         I             I

  26999-29-1    A               C          B            C          B        B             B          B          B          B           B         I             I
  ----------------------------------------------------------------------------------------------------------------------------------------------------------------------

A Adequate data available

C Computer modeling

B Bridging

I Inappropriate due to corrosivity of chemical and risk and exposure
analysis