![](media/image1.png){width="1.4583333333333333in" height="1.15625in"}

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF

PREVENTION, PESTICIDES AND

TOXIC SUBSTANCES

July 27, 2006

Memorandum

SUBJECT: TCMTB \[2-(Thiocyanomethylthio)benzothiazole\]: Second Revision
of the Occupational and Residential Exposure Assessment for the
Reregistration Eligibility Decision Document.

PC Code: 035603 (TCMTB)

DP Barcode: D324013

FROM: Charles Smith

Reregistration Branch 2

Health Effects Division (7509C)

THROUGH: Alan Nielsen, Senior Scientist

Reregistration Branch 2

Health Effects Division (7509C)

TO: Kathryn Avivah Jakob, Chemical Review Manager

Regulatory Management Branch 2

Antimicrobials Division (7510C)

and

Deborah Smegal, Risk Assessor

> Reregistration Branch 1

Health Effects Division (7509C)

The attached assessment is the occupational and non-occupational
(residential) exposure and risk estimates for TCMTB to support the
Antimicrobial Division's reregistration eligibility decision (RED)
document. The assessment was reviewed by HED's Science Council for
Exposure (ExpoSAC) to ensure compliance with current HED policy as well
as ExpoSAC standard operating procedures (SOPs) for conducting
occupational and residential exposure (ORE) assessments.

**Table of Contents**

Executive Summary [4](#executive-summary)

1.0 Occupational and Residential Exposure/Risk Assessment
[5](#occupational-and-residential-exposurerisk-assessment)

1.1 Purpose [5](#purpose)

1.2 Criteria for Conducting Exposure Assessments
[5](#criteria-for-conducting-exposure-assessments)

1.3 Summary of Hazard Concerns for TCMTB
[5](#summary-of-hazard-concerns-for-tcmtb)

1.4 Incident Reports [8](#incident-reports)

1.5 Summary of Physical and Chemical Properties of TCMTB
[8](#summary-of-physical-and-chemical-properties-of-tcmtb)

1.6.1 End-Use Products [9](#end-use-products)

1.6.2 Registered Use Categories and Sites
[9](#registered-use-categories-and-sites)

1.6.3 Application Methods [9](#application-methods)

2.0 Occupational Exposures and Risks
[10](#occupational-exposures-and-risks)

2.1 Occupational Handler Exposures and Risks
[10](#occupational-handler-exposures-and-risks)

2.1.1 Data and Assumptions for Handler Exposure Scenarios
[12](#data-and-assumptions-for-handler-exposure-scenarios)

2.1.1.1 Assumptions for Handler Exposure Scenarios
[12](#assumptions-for-handler-exposure-scenarios)

2.1.1.2 Exposure Data for Handler Exposure Scenarios
[13](#exposure-data-for-handler-exposure-scenarios)

2.1.2 Noncancer TCMTB Handler Exposure and Assessment
[16](#noncancer-tcmtb-handler-exposure-and-assessment)

2.1.2.1 Noncancer TCMTB Handler Exposure and Risk Calculations
[16](#noncancer-tcmtb-handler-exposure-and-risk-calculations)

2.1.2.2 TCMTB Noncancer Risk Summary [17](#tcmtb-noncancer-risk-summary)

2.1.3 Cancer TCMTB Handler Exposure and Risk Assessment
[22](#__RefHeading___Toc131902218)

2.1.4 Summary of Risk Concerns/Data Gaps for Occupational Handlers
[22](#summary-of-risk-concernsdata-gaps-for-occupational-handlers)

2.1.4.1 Summary of Risk Concerns [22](#summary-of-risk-concerns)

2.1.4.2 Summary of Data Gaps [22](#summary-of-data-gaps)

2.1.5 Recommendations For Refining Handler Risk Assessment
[22](#recommendations-for-refining-handler-risk-assessment)

#   {#section .unnumbered}

# Executive Summary

TCMTB is a broad spectrum biocide used in commercial and on-farm seed
treatment settings. It is formulated as a liquid concentrate.

Hazard Concerns: The toxicological endpoints used to complete the
occupational and residential risk assessment were based on the best
professional judgment of AD toxicologists. Adverse effects were
identified at durations of exposure ranging from short-term (up to 30

days) to intermediate-term durations (\> 30 days up to 6 months) and
long-term durations (\> 6 months). No cancer endpoint was identified,
therefore, cancer risks are not assessed.

The short- and intermediate-term (noncancer) dermal risk assessment for
TCMTB is based on an NOAEL of 25 mg/kg/day from a dermal study. The
NOAEL was based on decreased body weight gain and food consumption in
males, in addition to significant hematalogical (increased neutrophils,
decreased hemoglobin, hematocrit and erythrocytes) and clinical
chemistry changes (increased urea nitrogen, glucose and globulins).
Long-term exposures to TCMTB (i.e., greater than 6 months) are not
expected for current registered uses. [HED's level of concern (LOC) for
occupational TCMTB dermal exposures is 100.]{.mark} The short- and
intermediate-term (noncancer) inhalation risk assessment for TCMTB is
based on an NOAEL of 16 mg/kg/day, which is based on an oral rabbit
development study. The NOAEL was based on reduced body weight gain and
food consumption. Long-term exposure to TCMTB (i.e., greater than 6
months) is not expected for current registered uses. [HED's level of
concern (LOC) for]{.mark} short- and intermediate-term [occupational
(and residential) TCMTB inhalation exposures is 100. The dermal and
inhalation margins of exposure were combined for the TCMTB risk
assessment because the toxicity endpoints for the dermal and inhalation
routes of exposure are based on the same toxicological effects.]{.mark}

The Health Effects Division Carcinogenicity Peer Review Committee (CPRC)
met on June 28, 1995 to discuss and evaluate the weight-of-the-evidence
on 2-(Thiocyanomethylthio) benzothiazole (TCMTB) with particular
reference to its carcinogenic potential. The CPRC concluded that TCMTB
should be classified as Group C - possible human carcinogen - and
recommended that for the purpose of risk characterization, the Reference
Dose (RfD) approach should be used for quantitation of human risk. This
was based on statistically significant increases in tumors in both sexes
of the Sprague-Dawley rat: testicular interstitial cell adenomas in
males and thyroid c-cell adenomas in females.

Use Patterns: TCMTB is a fungicide used for treating seeds in the United
States. It is used in commercial and on-farm settings.

Occupational Handler Risks: For commercial and on-farm seed treatment
scenarios, all dermal and inhalation MOEs met or exceeded the required
uncertainty factor of 100 at some level of mitigation. For commercial
and on-farm seed treatment scenarios, all combined dermal and inhalation
risks met or exceed the required uncertainty factor of 100 at some level
of mitigation.

# 1.0 Occupational and Residential Exposure/Risk Assessment

##  1.1 Purpose 

This document is the occupational and residential non-dietary exposure
and risk assessment for TCMTB from its use as a fungicide. In this
document, which is for use in EPA\'s development of the Antimicrobials
Division (AD) chapter of the TCMTB RED Document, EPA presents the
results of its review of the potential human health effects of
occupational and residential/non-occupational exposure to TCMTB.

##  1.2 Criteria for Conducting Exposure Assessments 

An occupational and/or residential exposure assessment is required for
an active ingredient if (1) certain toxicological criteria are triggered
and (2) there is a potential for exposure to handlers (mixers, loaders,
applicators) during use or to persons entering treated sites or exposed
to vapors after application is complete. Toxicological endpoints were
selected for short- and intermediate-term dermal and inhalation
exposures to TCMTB. There is a significant potential for exposure in a
variety of occupational agricultural and commercial seed treatment
settings. There are no residential uses currently registered for TCMTB.
Therefore, risk assessments are required for occupational handlers that
can occur as a result of TCMTB use.

##  1.3 Summary of Hazard Concerns for TCMTB 

*2-(Thiocyanomethylthio) benzothiazole (TCMTB) - Report of the
Antimicrobials Division Toxicity Endpoint Selection Committee (ADTC). M.
McMahon and M. Centra dated January 12, 2006.*

The toxicological endpoints used to complete the occupational and
residential risk assessment were based on the best professional judgment
of AD toxicologists. Adverse effects were identified at durations of
exposure ranging from short-term (up to 30 days) to intermediate-term
durations (\> 30 days up to 6 months) and long-term durations (\> 6
months). No cancer endpoint was identified, therefore, cancer risks are
not assessed.

TCMTB is a fungicide where the use patterns can vary widely ranging from
short-term through intermediate-term exposure durations. As such, when
the Antimicrobials Division Toxicity Endpoint Selection Committee (ADTC)
evaluated the TCMTB hazard database, endpoints were selected to address
the various durations of exposure. TCMTB exposures are expected to occur
only to occupational users.

[Dermal Route (noncancer)]{.underline}

The short- and intermediate-term (noncancer) dermal risk assessment for
TCMTB is based on an NOAEL of 25 mg/kg/day from a dermal study. The
NOAEL was based on decreased body weight gain and food consumption in
males, in addition to significant hematalogical (increased neutrophils,
decreased hemoglobin, hematocrit and erythrocytes) and clinical
chemistry changes (increased urea nitrogen, glucose and globulins).
Long-term exposures to TCMTB (i.e., greater than 6 months) are not
expected for current registered uses.

[Inhalation Route (noncancer)]{.underline}

The short- and intermediate-term (noncancer) inhalation risk assessment
for TCMTB is based on an NOAEL of 16 mg/kg/day, which is based on an
oral rabbit development study. The LOAEL was based on reduced body
weight gain and food consumption. Long-term exposure to TCMTB (i.e.,
greater than 6 months) is not expected for current registered uses.

[Incidental Oral Route (noncancer)]{.underline}

The short- and intermediate-term (noncancer) incidental oral risk
assessment for TCMTB is based on an NOAEL of 16 mg/kg/day, which is
based on an oral rabbit development study. The LOAEL was based on
reduced body weight gain and food consumption.

[Noncancer Level of Concern (LOC)]{.underline}

HED's level of concern (LOC) for occupational TCMTB dermal and
inhalation exposures is 100 (i.e., a margin of exposure (MOE) less than
100 exceeds HED's level of concern). The level of concern is based on a
10x for interspecies extrapolation and a 10x for intraspecies
extrapolation.

[Aggregation]{.underline}

The dermal and inhalation margins of exposure were combined for the
TCMTB risk assessment because the toxicity endpoints for the dermal and
inhalation routes of exposure are based on the same toxicological
effects.

[Cancer]{.underline}

Number range CHAPTERThe Health Effects Division Carcinogenicity Peer
Review Committee (CPRC) met on June 28, 1995 to discuss and evaluate the
weight-of-the-evidence on 2-(Thiocyanomethylthio) benzothiazole (TCMTB)
with particular reference to its carcinogenic potential. The CPRC
concluded that TCMTB should be classified as Group C - possible human
carcinogen - and recommended that for the purpose of risk
characterization, the Reference Dose (RfD) approach should be used for
quantitation of human risk. This was based on statistically significant
increases in tumors in both sexes of the Sprague-Dawley rat: testicular
interstitial cell adenomas in males and thyroid C-cell adenomas in
females.

[Acute Toxicity]{.underline}

TCMTB is classified as category II for acute oral toxicity, category III
for acute dermal toxicity, and category I for inhalation toxicity. It is
classified as category I for primary eye irritation potential and
category II for primary skin irritation potential. Results were positive
for dermal sensitization. The acute toxicity profile for TCMTB is
presented in Table 1.

[Body Weight]{.underline}

The adverse effects for the dermal and inhalation endpoint are observed
in the general population. Therefore, the body weight of an average
adult (i.e., 70 kg) was used to estimate dermal dose.

  ---------------------------------------------------------------------------------
  **Table 1.                                                           
  Acute                                                                
  Toxicity                                                             
  Profile -                                                            
  TCMTB**                                                              
  ------------- ----------------- ---------------- ------------------- ------------
  **Guideline   **Study Type**    **MRID(s)**      **Results**         **Toxicity
  No.**                                                                Category**

  81-1          Acute Oral        41583801         LD~50~ = 750 mg/kg  II

  81-2          Acute Dermal      41515401         LD~50~ \> 2000      III
                                                   mg/kg               

  81-3          Acute Inhalation  41640601         LC~50~ = 0.07 mg/L  I

  81-4          Primary Eye       Acc no. 111991                       I
                Irritation                                             

  81-5          Primary Skin      41583701         Severe erythema at  II
                Irritation                         72 hrs.             

  81-6          Dermal            42349201                             Sensitizer
                Sensitization                                          
  ---------------------------------------------------------------------------------

+------------+-------------+---------------+--------------------------+
| **Table 2. |             |               |                          |
| Summary of |             |               |                          |
| Tox        |             |               |                          |
| icological |             |               |                          |
| Doses and  |             |               |                          |
| Endpoints  |             |               |                          |
| for        |             |               |                          |
| TCMTB**    |             |               |                          |
+============+=============+===============+==========================+
| **         | **Dose Used | **Special     | **Study and              |
| Exposure** | in Risk     | FQPA SF\* and | Toxicological Effects**  |
|            | Assessment, | Level of      |                          |
| **         | UF**        | Concern for   |                          |
| Scenario** |             | Risk          |                          |
|            |             | Assessment**  |                          |
+------------+-------------+---------------+--------------------------+
| Acute      | NOAEL =     | FQPA SF = 1X  | Rat Developmental Study  |
| Dietary    | 25.1        |               |                          |
|            | mg/kg/day   | aPAD = [acute | LOAEL = 76.5 mg/kg/day   |
| (general   |             | RfD           | based on clinical signs  |
| p          | UF = 100    | ]{.underline} | of ventral toxicity      |
| opulation) |             |               | (alopecia, rough coat,   |
|            | Acute RfD = | FQPA SF       | dyspnea/wheezing, oral   |
|            | 0.25        |               | discharge,               |
|            | mg/kg/day   | aPAD = 0.25   | diarrhea/loose stool,    |
|            |             | mg/kg/day     | urine staining,          |
|            |             |               | piloerection and hunched |
|            |             |               | gait).                   |
+------------+-------------+---------------+--------------------------+
| Chronic    | LOAEL = 3.8 | FQPA SF = 1X  | One-year Dog Study       |
| Dietary    | mg/kg/day   |               |                          |
|            |             | PAD =         | LOAEL = 3.8 mg/kg/day    |
| (all       | UF = 300    | [chronic      | based on decreased body  |
| po         |             | RfD           | weight gain, white       |
| pulations) | Chronic RfD | ]{.underline} | cells, monocytes and     |
|            | = 0.013     |               | plasma ALT in males and  |
|            | mg/kg/day   | FQPA SF       | decreased plasma ALT and |
|            |             |               | uterine weight in        |
|            |             | cPAD = 0.013  | females.                 |
|            |             | mg/kg/day     |                          |
+------------+-------------+---------------+--------------------------+
| Incidental | NOAEL = 16  | MOE = 100     | Rabbit Developmental     |
| Oral       | mg/kg/day   |               | Study                    |
| Short- and |             |               |                          |
| Interme    | UF = 100    |               | LOAEL = 32 mg/kg/day     |
| diate-Term |             |               | based on reduced body    |
|            |             |               | weight gain and food     |
| (1 - 30    |             |               | consumption.             |
| days)      |             |               |                          |
+------------+-------------+---------------+--------------------------+
| Dermal     | Dermal      | MOE = 100     | 21-Day Dermal toxicity   |
|            | NOAEL = 25  |               | study in Rats            |
| Short-,    | mg/kg/day   |               |                          |
| Inte       |             |               | LOAEL = 100 mg/kg/day    |
| rmediate-, |             |               | for systemic toxicity    |
| and        |             |               | based on decreased body  |
| Long-Term  |             |               | weight gain and food     |
|            |             |               | consumption in males, in |
| (1 - 30    |             |               | addition to significant  |
| days)      |             |               | hematalogical (increased |
|            |             |               | neutrophils, decreased   |
|            |             |               | hemoglobin, hematocrit   |
|            |             |               | and erythrocytes) and    |
|            |             |               | clinical chemistry       |
|            |             |               | changes (increased urea  |
|            |             |               | nitrogen, glucose and    |
|            |             |               | globulins).              |
+------------+-------------+---------------+--------------------------+
| Inhalation | NOAEL = 16  | MOE = 100     | Rabbit Developmental     |
|            | mg/kg/day   |               | Study                    |
| Short-and  |             |               |                          |
| Interme    | (Inhalation |               | LOAEL = 32 mg/kg/day     |
| diate-Term | absorption  |               | based on reduced body    |
|            | rate =      |               | weight gain and food     |
| (1 - 30    | 100%)       |               | consumption.             |
| days)      |             |               |                          |
+------------+-------------+---------------+--------------------------+
| Inhalation | LOAEL = 3.8 | MOE = 1000    | One-year Dog Study       |
|            | mg/kg/day   |               |                          |
| Long-Term  |             |               | LOAEL = 3.8 mg/kg/day    |
|            | (Inhalation |               | based on decreased body  |
| (\> 6      | absorption  |               | weight gain, white       |
| months)    | rate =      |               | cells, monocytes and     |
|            | 100%)       |               | plasma ALT in males and  |
|            |             |               | decreased plasma ALT and |
|            |             |               | uterine weight in        |
|            |             |               | females.                 |
+------------+-------------+---------------+--------------------------+

##  1.4 Incident Reports

An analysis of incidence reports will be included in a separate memo.

##  1.5 Summary of Physical and Chemical Properties of TCMTB 

TCMTB (CAS registry number 21564-17-0) is a dark orange liquid with a
molecular formula of C~9~H~6~N~2~S~3~ and a molecular weight of 238.3
g/mole. It is has a faint, mild odor. TCMTB is miscible with most
organic solvents and can be formulated with a range of surface active
agents which can form stable emulsions when diluted further with water.

**1.6 Summary of Use Patterns and Formulations**

###  1.6.1 End-Use Products 

TCMTB is a fungicide used for treating seeds in the United States. It is
used in agricultural and commercial settings. TCMTB is formulated as a
liquid.

###  1.6.2 Registered Use Categories and Sites 

An analysis of the current labeling and available use information was
completed by HED. TCMTB is registered for use in agricultural and
commercial seed treating (see Table 3).

  --------------------------------------------------------------------------------
  **Table 3:                                                     
  Summary of                                                     
  Maximum                                                        
  Application Rates                                              
  for Registered                                                 
  TCMTB Commercial                                               
  and Agricultural                                               
  Uses**                                                         
  ----------------- -------- ---------------- ------------------ -----------------
  Crop              Target   Formulation^a^   Maximum            Application
                                              Application Rate   Equipment (Area
                                                                 Treated or Amount
                                                                 Handled Daily)

  Barley Seed, Oat  Seed     L                0.026 lbs ai/100   commercial
  Seed, Rice Seed,                            lbs of seed        treater
  Wheat Seed                                                     

  Cotton Seed       Seed     L                0.13 lbs ai/100    commercial
                                              lbs of seed        treater

                                              0.051 lbs ai/100   on-farm treater
                                              lbs of seed        

  Safflower Seed,   Seed     L                0.041 lbs ai/100   commercial
  Sugar beet Seed                             lbs of seed        treater
  --------------------------------------------------------------------------------

a L = Liquid concentrate

###  1.6.3 Application Methods 

TCMTB is applied to seeds during both on-farm and commercial seed
treatment. The following descriptions of seed treatment and planting
methods and equipment are based primarily on information provided in
HED's seed treatment SOP (SOP 14), which was developed in consultation
with industry specialists.

[Commercial Seed Treatment]{.underline}: Commercial seed treaters are
designed to apply accurately measured quantities of pesticides to a
given weight of seed. There are two primary methods for treating seeds:
the batch system and the continuous flow system. The batch system is
less automated and generates lower production volume than the continuous
flow system. Seed treatment in commercial facilities occurs primarily
via the highly automated continuous flow system. Treated seed is bagged
by a machine which picks up a bag, opens it, and lets it fill to a
predetermined weight. The bagger then folds the top of the bag, and
attaches the seed grade certificates and treatment tags. The sewer then
sews the bag shut using an automated sewing machine. The bag is then
moved by a conveyer belt to a pallet area where it is stacked for
shipping. Seed treatment workers may rotate duties to other areas. In
the smaller, less automated facilities in particular, one worker will
often have multiple duties within the plant.

[On-farm Seed Treatment & Planting of Treated Seed]{.underline}: There
are various pieces of equipment used for on-farm seed treatment, such as
drum mixers, homemade devices using augers, cement mixers, hand cranked
revolving drums, and gravity feed systems. The more sophisticated
on-farm treaters are essentially miniature versions of the commercial
treaters. Simpler units consist of reusable chemical containers, a power
source (vehicle battery), valve and pump or compressed air, and tubing
spray nozzles. These units are mounted directly on a truck box or wagon
to dispense seed treatment directly into an auger conveyance system.
Seed may be treated as it is augered from the grower's truck to the
storage bin or seeder or from the storage bin to the farmer's truck or
seeder. This type of enclosed on-farm treatment system is available only
for liquid formulations.

The treated seed can be planted with a wide range of equipment. Common
equipment types include: specialized drills with a box for small seeds
and disk openers with depth bands to place the seeds at the appropriate
depth followed by packer wheels to firm soil over and around seeds;
double corrugated roller seeders, which drop the seed between the
rollers followed by a second roller, which covers the seed and firms the
soil; and booms, delivery tubes, and air pressure that blow seed onto
the soil at properly spaced intervals followed by light packing,
dragging a chain or harrowing to cover the planted seed. Seeding rate is
determined by factors such as machine wear, seed size and shape, and
crop variety.

# 2.0 Occupational Exposures and Risks

There is a potential for exposure to TCMTB in occupational scenarios
from handling TCMTB products during the seed treating process (both
commercial and on-farm) and a potential for postapplication worker
exposure from handling seed previously treated with TCMTB. As a result,
risk assessments have been completed for occupational handler scenarios
as well as occupational postapplication scenarios.

##  2.1 Occupational Handler Exposures and Risks 

HED uses the term "handlers" to describe those individuals who are
involved in the pesticide application process. HED believes that there
are distinct job functions or tasks related to applications and that
exposures can vary depending on the specifics of each task. Job
requirements (e.g., amount of chemical to be used in an application),
the kinds of equipment used, the target being treated, and the level of
protection used by a handler can cause exposure levels to differ in a
manner specific to each application event.

HED uses exposure scenarios to describe the various types of handler
exposures that may occur for a specific active ingredient. The use of
scenarios as a basis for exposure assessment is very common as described
in the U.S. EPA Guidelines for Exposure Assessment (U.S. EPA; Federal
Register Volume 57, Number 104; May 29, 1992). Information from the
current labels, use and usage information, toxicology data, and exposure
data were all key components in the development of the exposure
scenarios. HED has developed a series of general descriptions for tasks
that are associated with pesticide applications. Tasks associated with
occupational pesticide handlers are categorized using one of the
following terms:

On-farm Loader/Applicator: The possible points of operator exposure for
an on-farm treatment are; transport of pesticide in mobile containers,
moving pesticide from storage in to seed treatment equipment,
introduction of pesticide into seed treatment equipment, and equipment
cleaning and maintenance. On-farm seed treatment with liquid
formulations is generally done with more automated equipment,
essentially miniature versions of commercial treaters. Seed may be
treated as it is augured from the grower's truck to the storage bin (at
the farmstead), or from the truck to the seeder (field) or from the
grower's storage bin into either a truck or seeder.

-   On-farm Planting of Treated Seed: Planting exposures occur during
    both the loading of hoppers and driving the equipment.

-   Commercial Mixer/Loader/Applicator for Seed Treatments: This
    scenario involves loading/applying of all formulations in a
    commercial operation.

-   Commercial Bagger for Seed Treatments: Seed is bagged by a machine
    which picks up a bag, opens it, slips it over a spout and lets it
    fill to a predetermined weight. The bagger then folds the top of the
    bag, attaches the seed grade certificates and treatment tags.

-   Commercial Sewer for Seed Treatments: After bagging the treated seed
    the sewer shuts the bag using an automatic sewing machine. The bag
    is then moved by a conveyer belt to a pallet area where it is
    stacked for shipping.

-   Multiple Commercial Activities for Seed Treatments: The SOP contains
    a scenario labeled "Multiple Activities" to address the potential
    for multiple types of exposure in small commercial operations.

A chemical can produce different effects based on how long a person is
exposed, how frequently exposures occur, and the level of exposure. HED
classifies exposures up to 30 days as short-term and exposures greater
than 30 days up to several months as intermediate-term. HED completes
both short- and intermediate-term assessments for occupational scenarios
in essentially all cases, because these kinds of exposures are likely
and acceptable use/usage data are not available to justify deleting
intermediate-term scenarios. Based on use data and label instructions,
HED believes that occupational TCMTB exposures may occur over a single
day or up to weeks at a time for many use-patterns and that intermittent
exposure over several weeks also may occur. Some applicators may apply
TCMTB over a period of weeks, because they are commercial seed treaters.
Long-term handler exposures are not expected to occur for TCMTB.

Other parameters are also defined from use and usage data such as
application rates and application frequency. HED always completes
noncancer risk assessments using maximum application rates for each in
order to ensure there are no concerns for each specific use.

Occupational handler exposure assessments are completed by HED using
different levels of risk mitigation. Typically, HED uses a tiered
approach. The lowest tier is designated as the baseline exposure
scenario (i.e., long-sleeve shirt, long pants, shoes, socks, and no
respirator). If risks are of concern at baseline attire, then increasing
levels of personal protective equipment or PPE (e.g., gloves,
double-layer body protection, and respirators) are evaluated. If risks
remain a concern with maximum PPE, then engineering controls (e.g.,
closed mixing/loading systems) are evaluated. This approach is used to
ensure that the lowest level of risk mitigation that provides adequate
protection is selected, since the addition of PPE and engineering
controls involves an additional expense to the user and -- in the case
of PPE -- also involves an additional burden to the user due to
decreased comfort and dexterity and increased heat stress and
respiratory stress.

###  2.1.1 Data and Assumptions for Handler Exposure Scenarios 

#### 2.1.1.1 Assumptions for Handler Exposure Scenarios

A series of assumptions and exposure factors served as the basis for
completing the occupational handler risk assessments. Each assumption
and factor is detailed below on an individual basis. The assumptions and
factors used in the risk calculations include:

-   Occupational handler exposure estimates were based on surrogate data
    from: the Health Effects Division Science Advisory Committee on
    Exposure (HED ExpoSAC) SOP #15: Amount of Seed Treated or Planted
    per Day, which was completed on March 2, 2004.

-   The toxicological endpoint of concern for dermal risks is from a
    dermal study; with the effects seen in males and females, therefore,
    the average body weight of an adult handler (i.e., 70 kg) is used to
    complete the dermal noncancer risk assessment. The toxicological
    endpoint of concern for inhalation risks is from an oral study; with
    the effects seen in males and females, therefore, the average body
    weight of an adult handler (i.e., 70 kg) is used to complete the
    inhalation noncancer risk assessment.

-   Generic protection factors (PFs) were used to calculate exposures
    when data were not available. For example, an 80 percent protection
    factor was assumed for the use of a respirator equipped with a
    quarter-face dust/mist filter.

-   On-farm treaters and planters are expected to have short-term
    exposure duration (less than 30 days) for all seed crops.

-   Personal protective equipment for on-farm and commercial
    mixer/loader/applicators and planter includes a single layer and
    gloves. Personal protective equipment for commercial baggers and
    sewers includes baseline attire only - no gloves. Personal
    protective equipment for performing multiple activities in a
    commercial operation includes a single layer of clothing and gloves

-   Exposure factors used to calculate daily exposures to handlers are
    based on applicable data, if available. For lack of appropriate
    data, values from a scenario deemed similar enough by the assessor
    might be used.

-   For noncancer assessments, HED assumes the maximum application rates
    allowed by labels in its risk assessments (see Table 3).

-   The average occupational workday is assumed to be 8 hours.

-   The daily pounds of seed treated per day were defined for each
    handler scenario by determining the amount that can be reasonably
    treated in a single day. These assumptions are taken from the HED's
    ExpoSAC SOP #15. The standard values in this SOP are based on the
    information obtained from the registrants, seed treatment equipment
    manufacturers, and Agency experts. The values listed are considered
    to be typical-to-high-end values. The default values may be modified
    by pesticide-specific knowledge that affects the amount of seed that
    can be treated or planted in a day (e.g., high amount of seed
    required per acre) but in the case of TCMTB, no such data is
    available. The values are as follows:

```{=html}
<!-- -->
```
-   for commercial seed treatment facilities it is assumed that for
    barley, rice, safflower, and wheat seed -- 718,000 lb seed is
    treated per day; for cotton seed -- 160,000 lb seed is treated per
    day; and for sugar beet seed -- 88,000 lb seed is treated per day.

-   for on farm treatments it is assumed that 200 acres is planted per
    day for cotton (18 lbs of seed per acre), oats (128 lbs of seed per
    acre), rice (150 lbs of seed per acre), and wheat (150 lbs of seed
    per acre) seeds; 80 acres is planted per day for safflower (100 lbs
    of seed per acre) and sugar beet (8 lbs of seed per acre) seeds; and
    35 acres is planted per day for barley (100 lbs of seed per acre)
    seeds.

There are data gaps that have been identified for some TCMTB
applications. Each is identified in the calculation tables and is also
noted in the summary of risk calculations.

#### 2.1.1.2 Exposure Data for Handler Exposure Scenarios

HED uses unit exposure to assess handler exposures to pesticides. Unit
exposures are estimates of the amount of exposure to an active
ingredient a handler receives while performing various handler tasks and
are expressed in terms of micrograms or milligrams of active ingredient
per pounds of active ingredient handled. HED has developed a series of
unit exposures that are unique for each scenario typically considered in
our assessments (i.e., there are different unit exposures for different
types of application equipment, job functions, and levels of
protection). The unit exposure concept has been established in the
scientific literature and also through various exposure monitoring
guidelines published by the U.S. EPA and international organizations
such as Health Canada and OECD (Organization for Economic Cooperation
and Development).

Exposure data used for the TCMTB seed treatment assessment are taken
primarily from HED's recently developed seed treatment standard
operating procedure (SOPs for Seed Treatment, 6/1/03) and also are based
on professional judgment. The seed treatment SOP contains representative
scenarios for worker exposure associated with seed treatment facilities
and planting treated seed. The data contained in the SOP are mostly
generated by industry sources. Exposure estimates are from actual seed
treatment studies and are based on exposure factors associated with
occupational handler scenarios (i.e., commercial seed treatment, on-farm
seed treatment, planting of treated seed). Eight seed treatment studies
were used in developing the SOP. Given the high level of variance in the
data, multiple statistical analyses were undertaken to help ensure
derivation of a statistically sound exposure value for the different
scenarios evaluated. For all selected seed treatment studies, replicates
were combined into sets of equivalent job functions. This process
resulted in four categories of commercial seed treatment activities
(loader/applicator, sewer, bagger, and multiple activities), and two
categories for on-farm activities (treater and planter).

[On-farm Seed Treatment and Planting]{.underline}

[On-farm Loader/Applicator]{.underline}: No studies were available to
address exposure to liquid formulations in an on-farm facility. On-farm
seed treatment with liquid formulations is generally done with more
automated equipment, essentially miniature versions of commercial
treaters.

[On-farm Planting of Treated Seed]{.underline}**:** Exposure estimates
for loading and planting of treated seed are based on 2 exposure studies
(MRID \# 42251901, 45654503). In one study, workers loaded and drilled
seed treated with Baytan at 13 different sites in the UK. The seed was
loaded into the drill hoppers from 0.5 or 1 ton super sacks or 50 kg
bags. The amount of seed handled ranged from 1100 to 12,100 lbs and the
amount of ai handled ranged from 0.35 to 4.72 lbs. The loading time
ranged from 19 to 83 minutes, while the planting time ranged from 155 to
487 minutes. The seed planting rate per acre was not given. The same
worker performed both the loading and planting. Dermal exposure was
measured with inner and outer whole body dosimeters which included a
cap, a jacket and trousers over a long sleeve T-shirt and long johns and
two sets of cotton gloves. The gloves were changed at the end of
loading. Inhalation exposures were measured with 37 mm glass fiber
filters and the filters were changed after loading. The dermal results
were adjusted by a clothing protection factor to account for the fact
that 5% of the outer residues were found on the inner dosimeters.

In the second study workers loaded and drilled canola seed treated with
Oftanol, which forms a hard shell coating. The 13 replicates for this
study were located at one site in Manitoba using four different planting
rigs. Four workers participated in the study and the replicates averaged
3.2 hours in duration. The seed was loaded into the drill hoppers from
25 kg bags. The amount of seed handled per replicate averaged 360 pounds
and the amount of ai handled averaged 4.33 lbs. The seed was planted at
a rate of 6 to 8 pounds per acre. The same worker performed both the
loading and planting. Dermal exposure was measured with patches located
both inside and outside the worker's coverall. Hand exposures were
measured by hand rinse. Inhalation exposures were measured with 37 mm
quartz microfiber filters.

[Commercial Seed Treatment]{.underline}

[Commercial Loader/Applicator]{.underline}: Exposure estimates are based
on a subset of 3 exposure studies (MRID Nos. 43080049, 42251902,
44904526). The loader/applicator activities in these 3 exposure studies
encompass a wide range of seed treaters, amounts of seed and amounts of
pesticides handled for seed treatment scenarios. The three studies
monitored an open loading/applying activity for various seed treatment
facilities. There is an average of 9 replicates per study (ranging from
1 to 20 replicates per study). Two of the three studies monitored dermal
exposures with patch dosimetry, hand rinses, and face wipes. The
methodology in the third study was whole body dosimetry, hand rinses and
face wipes.

[Commercial Bagger]{.underline}: Exposure estimates for bagging
activities for all formulations are based on data from 3 exposure
studies (MRID Nos. 43080049, 42251902, and 44904526). The studies
monitored bagging treated seed in various seed treatment facilities and
encompassed a wide range of bagging equipment, and amount of seed and
pesticides handled. The number of replicates ranged from 1 to 20 per
study. Two of the studies monitored dermal exposures with whole body
dosimeters, and face, neck and hand rinses. The third used dermal
patches and hand rinses to monitor exposure.

[Commercial Sewer]{.underline}: Exposure estimates for sewing activities
for all formulations are based on data from 2 exposure studies (MRID \#
430800-49, and449045-26). The two studies monitored sewing various bags
of treated seed in a number of seed treatment facilities. The number of
replicates ranges from 1 to 20 per study. Both of the studies monitored
dermal exposures with whole body dosimeters, and face, neck and hand
rinses.

[Multiple Commercial Activities]{.underline}: Exposure estimates for
multiple activities for all formulation are based on data from 4
exposure studies (MRID #s, 454427-01, 422519-02, 449045-26 and
447315-01). These studies encompass a variety of seed treatment activity
and a wide range of amount of seed pesticides handled. The four studies
in this scenario monitored multiple activities for various seed
treatment facilities. The number of replicates ranges from 3 to 45 per
study. Three of the five studies monitored dermal exposures with whole
body dosimeter, face and neck and hand rinses. The methodology in the
other studies was dermal patches and hand rinses.

**TCMTB Handler Exposure Scenarios**

It has been determined that exposure to pesticide handlers is likely
during the occupational use of TCMTB in a variety of occupational
environments. The anticipated use patterns and current labeling indicate
several occupational exposure scenarios based on the types of equipment
and techniques that can potentially be used for TCMTB applications. The
quantitative exposure/risk assessment developed for occupational
handlers is based on the following scenarios.

**[Seed treatment:]{.underline}**

> (S-1) loading and applying liquid formulations with commercial
> seed-treatment equipment,
>
> (S-2) commercial sewer stitching bags of seed,
>
> (S-3) bagging and otherwise handling treated seeds with commercial
> equipment,
>
> (S-4) multiple commercial seed treatment activities,
>
> (S-5) on-farm loading/applying seed treatment, and
>
> (S-6) on-farm loading/planting previously treated seeds.

###  2.1.2 Noncancer TCMTB Handler Exposure and Assessment 

#### 2.1.2.1 Noncancer TCMTB Handler Exposure and Risk Calculations 

**Daily Exposure:** Daily dermal or inhalation handler exposures are
estimated for each applicable handler task with the application rate,
the area treated in a day, and the applicable dermal or inhalation unit
exposure using the following formula:

Daily Exposure (mg ai/day) = Unit Exposure (mg ai/lb ai handled) \*
Application Rate (lbs ai/area) \*

> Daily Area Treated (area/day)

Where:

> Daily Exposure = Amount (mg ai/day) deposited on the surface of the
> skin that is available for dermal absorption or amount inhaled that is
> available for inhalation absorption;
>
> Unit Exposure = Unit exposure value (mg ai/lb ai handled) derived from
> August 1998 PHED data, from ORETF data;
>
> Application Rate = Normalized application rate based on a logical unit
> treatment, such as acres, square feet, or gallons. Maximum values are
> generally used (lb ai/cut weight); and
>
> Daily Area Treated = Normalized application area based on a logical
> unit treatment such as acres (A/day).

**Daily Dose:** The daily dermal or inhalation dose is calculated by
normalizing the daily exposure by body weight and adjusting, if
necessary, with an appropriate dermal or inhalation absorption factor.
For all exposure scenarios for TCMTB, an average adult body weight of 70
kilograms was used, since the toxicological endpoint of concern was
gender-specific. For dermal exposures, no dermal absorption factor was
necessary, since the toxicological endpoint is from a dermal study. For
inhalation exposures, an absorption factor of 100% was assumed.

Daily dose was calculated using the following formula:

Average Daily Dose (mg/kg/day) = [(Daily Exposure (mg ai/day) \*
(Absorption Factor (%)]{.underline}

> Body Weight (kg)

Where:

Average Daily Dose = Absorbed dose received from exposure to a pesticide
in a given scenario (mg pesticide active ingredient/kg body weight/day);

> Daily Exposure = Amount (mg ai/day) deposited on the surface of the
> skin that is available for dermal absorption or amount inhaled that is
> available for inhalation absorption;
>
> Absorption Factor = A measure of the amount of chemical that crosses a
> biological boundary such as the skin or lungs (% of the total
> available absorbed); and

Body Weight = Body weight determined to represent the population of
interest in a risk

> assessment (kg).

**Margins of Exposure:** Noncancer dermal and inhalation risks for each
applicable handler scenario are calculated using a Margin of Exposure
(MOE), which is a ratio of the daily dose to the toxicological endpoint
of concern. All MOE values were calculated separately for dermal and
inhalation exposure levels using the formula below:

MOE = (NOAEL (mg/kg/day) / Average Daily Dose (mg/kg/day)

Where:

MOE = Margin of Exposure, value used by HED to represent risk or how
close a

> chemical exposure is to being a concern (unitless);

ADD = Average Daily Dose or the absorbed dose received from exposure to
a pesticide

> in a given scenario (mg pesticide active ingredient/kg body
> weight/day); and

NOAEL = Dose level in a toxicity study, where no observed adverse
effects (NOAEL) occurred in the study

It is important to present risk estimates for each route of exposure
(i.e., dermal or inhalation) in each scenario because it makes
determining appropriate risk mitigation measures easier. For example, if
overall risks are driven by dermal exposures and not inhalation, it is
inadvisable to require respirators even though they may marginally
reduce overall risks.

A total MOE was calculated for TCMTB because common toxicity endpoints
were used to calculate dermal and inhalation risks for each exposure
duration. The dermal and inhalation MOEs were combined using the formula
below:

MOE TOTAL = \[1/((Dermal MOE ) + (1/Inhalation MOE))\]

#### 2.1.2.2 TCMTB Noncancer Risk Summary

All of the noncancer risk calculations for occupational TCMTB handlers
completed in this assessment are included in the appendices. A summary
of the short- and intermediate-term risks for each exposure scenario are
presented below in Tables 4 - 7.

**[Short- and Intermediate-term Dermal and Inhalation
Risks]{.underline}**

For commercial and on-farm seed treatment scenarios, all dermal and
inhalation MOEs met or exceeded the required uncertainty factor of 100
at some level of mitigation.

> **[Short- and Intermediate-term Total Risks]{.underline}**

For commercial and on-farm seed treatment scenarios, all combined dermal
and inhalation risks met or exceed the required uncertainty factor of
100 at some level of mitigation.

<table>
<colgroup>
<col style="width: 16%" />
<col style="width: 12%" />
<col style="width: 10%" />
<col style="width: 10%" />
<col style="width: 5%" />
<col style="width: 6%" />
<col style="width: 5%" />
<col style="width: 5%" />
<col style="width: 6%" />
<col style="width: 5%" />
<col style="width: 5%" />
<col style="width: 7%" />
</colgroup>
<tbody>
<tr class="odd">
<td colspan="12"><strong>Table 4. Estimated Worker Exposure and Risk
from Commercial Seed Treatment</strong></td>
</tr>
<tr class="even">
<td rowspan="4">Crop</td>
<td rowspan="4">Exposure Scenario</td>
<td rowspan="4"><p>Application Rate</p>
<p>(lb ai/100 lb)<sup>a</sup></p></td>
<td rowspan="4"><p>Amount Handled per Day</p>
<p>(lb ai/day)<sup>b</sup></p></td>
<td colspan="8">Short- and Intermediate-term MOEs <sup>c</sup></td>
</tr>
<tr class="odd">
<td colspan="2">Baseline</td>
<td colspan="4">Personal Protective Equipment</td>
<td colspan="2">Engineering Controls</td>
</tr>
<tr class="even">
<td rowspan="2">Dermal</td>
<td rowspan="2">Inhalation</td>
<td colspan="2">Dermal</td>
<td colspan="2">Inhalation</td>
<td rowspan="2">Dermal</td>
<td rowspan="2">Inhalation</td>
</tr>
<tr class="odd">
<td>SL w/ gloves</td>
<td>DL w/ gloves</td>
<td>80% R</td>
<td>90% R</td>
</tr>
<tr class="even">
<td rowspan="4">Barley, Oats Rice, Wheat Seeds</td>
<td>Loader/Applicator</td>
<td rowspan="4">0.026</td>
<td rowspan="4">187</td>
<td>ND</td>
<td>18000</td>
<td>410</td>
<td>520</td>
<td>88000</td>
<td>180000</td>
<td>1100</td>
<td>72000</td>
</tr>
<tr class="odd">
<td>Sewer</td>
<td>1500</td>
<td>26000</td>
<td>ND</td>
<td>ND</td>
<td>13000</td>
<td>260000</td>
<td>NF</td>
<td>NF</td>
</tr>
<tr class="even">
<td>Bagger</td>
<td>1000</td>
<td>37000</td>
<td>ND</td>
<td>ND</td>
<td>190000</td>
<td>370000</td>
<td>NF</td>
<td>NF</td>
</tr>
<tr class="odd">
<td>Multiple Activities</td>
<td>ND</td>
<td>3700</td>
<td>220</td>
<td>ND</td>
<td>19000</td>
<td>37000</td>
<td>NF</td>
<td>NF</td>
</tr>
<tr class="even">
<td rowspan="4">Cotton Seeds</td>
<td>Loader/Applicator</td>
<td rowspan="4">0.13</td>
<td rowspan="4">208</td>
<td>ND</td>
<td>16000</td>
<td>370</td>
<td>470</td>
<td>79000</td>
<td>160000</td>
<td>980</td>
<td>65000</td>
</tr>
<tr class="odd">
<td>Sewer</td>
<td>1400</td>
<td>23000</td>
<td>ND</td>
<td>ND</td>
<td>120000</td>
<td>230000</td>
<td>NF</td>
<td>NF</td>
</tr>
<tr class="even">
<td>Bagger</td>
<td>920</td>
<td>34000</td>
<td>ND</td>
<td>ND</td>
<td>170000</td>
<td>340000</td>
<td>NF</td>
<td>NF</td>
</tr>
<tr class="odd">
<td>Multiple Activities</td>
<td>ND</td>
<td>3400</td>
<td>200</td>
<td>ND</td>
<td>17000</td>
<td>34000</td>
<td>NF</td>
<td>NF</td>
</tr>
<tr class="even">
<td rowspan="4">Safflower Seeds</td>
<td>Loader/Applicator</td>
<td rowspan="4">0.041</td>
<td rowspan="4">294</td>
<td>ND</td>
<td>11000</td>
<td>260</td>
<td>330</td>
<td>56000</td>
<td>110000</td>
<td>690</td>
<td>46000</td>
</tr>
<tr class="odd">
<td>Sewer</td>
<td>960</td>
<td>17000</td>
<td>ND</td>
<td>ND</td>
<td>83000</td>
<td>170000</td>
<td>NF</td>
<td>NF</td>
</tr>
<tr class="even">
<td>Bagger</td>
<td>650</td>
<td>24000</td>
<td>ND</td>
<td>ND</td>
<td>120000</td>
<td>240000</td>
<td>NF</td>
<td>NF</td>
</tr>
<tr class="odd">
<td>Multiple Activities</td>
<td>ND</td>
<td>2400</td>
<td>140</td>
<td>ND</td>
<td>12000</td>
<td>24000</td>
<td>NF</td>
<td>NF</td>
</tr>
<tr class="even">
<td rowspan="4">Sugar Beet Seeds</td>
<td>Loader/Applicator</td>
<td rowspan="4">0.041</td>
<td rowspan="4">36</td>
<td>ND</td>
<td>91000</td>
<td>2100</td>
<td>2700</td>
<td>460000</td>
<td>910000</td>
<td>5600</td>
<td>370000</td>
</tr>
<tr class="odd">
<td>Sewer</td>
<td>7800</td>
<td>130000</td>
<td>ND</td>
<td>ND</td>
<td>670000</td>
<td>1300000</td>
<td>NF</td>
<td>NF</td>
</tr>
<tr class="even">
<td>Bagger</td>
<td>5300</td>
<td>190000</td>
<td>ND</td>
<td>ND</td>
<td>970000</td>
<td>1900000</td>
<td>NF</td>
<td>NF</td>
</tr>
<tr class="odd">
<td>Multiple Activities</td>
<td>ND</td>
<td>19000</td>
<td>1200</td>
<td>ND</td>
<td>97000</td>
<td>190000</td>
<td>NF</td>
<td>NF</td>
</tr>
</tbody>
</table>

ND = No Data; NF = Not Feasible

a Application rates are the maximum application rates determined from
EPA registered labels for TCMTB

b Amount handled per day calculated from the maximum application rate
and the lbs of seed treated or planted/day and: for barley, rice,
safflower, and wheat seed - 718000 lb/day; for cotton seed -- 160000
lb/day; and sugar beet seed -- 88000 lb/day.

c Baseline Dermal: Long-sleeve shirt, long pants, no gloves.

Baseline Inhalation: no respirator.

PPE Dermal SL with gloves: Single layer plus chemical-resistant gloves.

PPE Dermal DL and gloves: Coveralls worn over long-sleeve shirt and long
pants plus chemical-resistant gloves.

PPE 80% R inhalation: assumes a dust/mist removing filtering face piece
style respirator providing an 80% protection factor.

PPE 90%R inhalation: assumes a dust/mist removing half-face style
respirator providing a 90% protection factor.

Eng Controls Dermal and Inhalation: Closed System.

  ------------- ------------------- --------- --------- ---------- ------ ------ ------ ------ ------ ------ ---------
  **Table 5.                                                                                                 
  Combined                                                                                                   
  Estimated                                                                                                  
  Worker Dermal                                                                                              
  and                                                                                                        
  Inhalation                                                                                                 
  Risk from                                                                                                  
  Commercial                                                                                                 
  Seed                                                                                                       
  Treatment**                                                                                                

  Crop          Exposure Scenario   App       Amount    Combined                                             
                                    Rate^a^   Handled   MOEs ^c^                                             
                                    (lb       per Day                                                        
                                    ai/lb)    ^b^ (lb                                                        
                                              ai/day)                                                        

                                                        Baseline   SL,    DL,    SL +   SL,    SL +   SL, G+ Eng
                                                                   G + NR G + NR 80% R  G +    90% R  90% R  Control
                                                                                        80% R                

  Barley, Oats, Loader/Applicator   0.026     187       ND         400    510    ND     410    ND     410    1000
  Rice, Wheat                                                                                                
  Seeds                                                                                                      

                Sewer                                   1400       ND     ND     1500   ND     1500   ND     NF

                Bagger                                  970        ND     ND     990    ND     1000   ND     NF

                Multiple Activities                     ND         210    ND     ND     220    ND     220    NF

  Cotton Seeds  Loader/Applicator   0.13      208       ND         360    450    ND     360    ND     360    920

                Sewer                                   1300       ND     ND     1400   ND     1400   ND     NF

                Bagger                                  900        ND     ND     910    ND     920    ND     NF

                Multiple Activities                     ND         190    ND     ND     200    ND     200    NF

  Safflower     Loader/Applicator   0.041     294       ND         250    320    ND     260    ND     260    650
  Seeds                                                                                                      

                Sewer                                   910        ND     ND     950    ND     950    ND     NF

                Bagger                                  630        ND     ND     650    ND     650    ND     NF

                Multiple Activities                     ND         130    ND     ND     140    ND     140    NF

  Sugar Beet    Loader/Applicator   0.041     36        ND         2100   2600   ND     2100   ND     2100   5300
  Seeds                                                                                                      

                Sewer                                   7400       ND     ND     7700   ND     7800   ND     NF

                Bagger                                  5200       ND     ND     5300   ND     5300   ND     NF

                Multiple Activities                     ND         1100   ND     ND     1100   ND     1100   NF
  ------------- ------------------- --------- --------- ---------- ------ ------ ------ ------ ------ ------ ---------

ND = No Data; NF = Not Feasible

a Application rates are the maximum application rates determined from
EPA registered labels for TCMTB

b Amount handled per day calculated from the maximum application rate
and the lbs of seed treated or planted/day and: for barley, rice,
safflower, and wheat seed - 718000 lb/day; for cotton seed -- 160000
lb/day; and sugar beet seed -- 88000 lb/day.

c Baseline = No gloves and no respirator

SL, G = Single layer w/gloves is baseline attire plus chemical-resistant
gloves.

DL, G = Double layer w/gloves is coveralls worn over long-sleeve shirt
and long pants, plus chemical-resistant gloves.

80% R = 80% Respirator is dust/mist removing filtering face piece style
respirator (that provides an 80% protection factor).

90% R = 90% Respirator is half-face dust/mist respirator (that provides
a 90% protection factor).

Eng Control = Engineering control is closed mixing/loading system,
enclosed cab, or enclosed cockpit.

<table style="width:100%;">
<colgroup>
<col style="width: 7%" />
<col style="width: 5%" />
<col style="width: 6%" />
<col style="width: 7%" />
<col style="width: 6%" />
<col style="width: 7%" />
<col style="width: 6%" />
<col style="width: 6%" />
<col style="width: 6%" />
<col style="width: 6%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 6%" />
<col style="width: 5%" />
<col style="width: 5%" />
</colgroup>
<thead>
<tr class="header">
<th colspan="15"><strong>Table 6. Estimated Worker Exposure and Risk
from On-farm Seed Treatment</strong></th>
</tr>
<tr class="odd">
<th rowspan="4">Crop</th>
<th rowspan="4"><p>Acres treated/</p>
<p>day</p></th>
<th rowspan="4"><p>App Rate</p>
<p>(lb ai/</p>
<p>100 lb)<sup>a</sup></p></th>
<th rowspan="4"><p>Amount Handled per day<sup>b</sup></p>
<p>(lb ai/day)</p></th>
<th colspan="7">Unit Exposures</th>
<th colspan="4">Short- and Intermediate-term MOEs</th>
</tr>
<tr class="header">
<th colspan="2">Baseline</th>
<th colspan="3">Personal Protective Equipment</th>
<th colspan="2">Engineering Controls</th>
<th>Baseline</th>
<th colspan="3">Personal Protective Equipment</th>
</tr>
<tr class="odd">
<th rowspan="2"><p>Dermal<sup>c</sup></p>
<p>(mg/lb ai)</p></th>
<th rowspan="2"><p>Inhalation<sup>d</sup></p>
<p>(g/lb ai)</p></th>
<th><p>Dermal</p>
<p>(mg/lb ai)</p></th>
<th colspan="2"><p>Inhalation</p>
<p>(ug/lb ai)</p></th>
<th rowspan="2"><p>Dermal<sup>h</sup></p>
<p>(mg/lb ai)</p></th>
<th rowspan="2"><p>Inhalation<sup>i</sup></p>
<p>(ug/lb ai)</p></th>
<th rowspan="2">Inhalation</th>
<th>Dermal</th>
<th colspan="2">Inhalation</th>
</tr>
<tr class="header">
<th>SL w/ gloves<sup>e</sup></th>
<th>80% R<sup>f</sup></th>
<th>90% R<sup>g</sup></th>
<th>SL w/ gloves</th>
<th>80% R</th>
<th>90% R</th>
</tr>
</thead>
<tbody>
<tr class="odd">
<td colspan="15"><strong>LOADING/APPLYING LIQUID SEED
TREATMENTS</strong></td>
</tr>
<tr class="even">
<td>Cotton</td>
<td>125</td>
<td>0.051</td>
<td>0.64</td>
<td colspan="11">ND<sup>j</sup></td>
</tr>
<tr class="odd">
<td colspan="15"><strong>LOADING/PLANTING PREVIOUSLY TREATED
SEEDS</strong></td>
</tr>
<tr class="even">
<td>Barley</td>
<td>35</td>
<td>0.026</td>
<td>0.64</td>
<td rowspan="7">ND</td>
<td rowspan="7">3.4</td>
<td rowspan="7">0.25</td>
<td rowspan="7">0.68</td>
<td rowspan="7">0.34</td>
<td rowspan="7">NF</td>
<td rowspan="7">NF</td>
<td>360000</td>
<td>7700</td>
<td>1800000</td>
<td>3600000</td>
</tr>
<tr class="odd">
<td>Beet; Sugar</td>
<td>80</td>
<td>0.041</td>
<td>0.26</td>
<td>1300000</td>
<td>27000</td>
<td>6300000</td>
<td>13000000</td>
</tr>
<tr class="even">
<td>Cotton</td>
<td>200</td>
<td>0.13</td>
<td>4.68</td>
<td>70000</td>
<td>1500</td>
<td>350000</td>
<td>700000</td>
</tr>
<tr class="odd">
<td>Oats</td>
<td>200</td>
<td>0.026</td>
<td>6.66</td>
<td>49000</td>
<td>1100</td>
<td>250000</td>
<td>490000</td>
</tr>
<tr class="even">
<td>Rice</td>
<td>200</td>
<td>0.026</td>
<td>7.80</td>
<td>42000</td>
<td>900</td>
<td>210000</td>
<td>420000</td>
</tr>
<tr class="odd">
<td>Safflower</td>
<td>80</td>
<td>0.041</td>
<td>3.28</td>
<td>100000</td>
<td>2100</td>
<td>500000</td>
<td>1000000</td>
</tr>
<tr class="even">
<td>Wheat</td>
<td>200</td>
<td>0.026</td>
<td>7.80</td>
<td>42000</td>
<td>900</td>
<td>210000</td>
<td>420000</td>
</tr>
</tbody>
</table>

ND = No Data; NF = Not Feasible

a Application rates are the maximum application rates determined from
EPA registered labels for TCMTB.

b Amount handled per day calculated from the acres treated/day and the
maximum lb of seed planted per acre.

c Baseline Dermal: Long-sleeve shirt, long pants, no gloves.

d Baseline Inhalation: no respirator.

e PPE Dermal SL with gloves: Single layer plus chemical-resistant
gloves.

f PPE 80% R inhalation: assumes a dust/mist removing filtering face
piece style respirator respirator providing an 80% protection factor.

g PPE 90%R inhalation: assumes a dust/mist removing half-face style
respirator providing a 90% protection factor.

h Eng Controls Dermal: Closed System.

i Eng Controls Inhalation: Closed System.

j On-farm seed treatment with liquid formulations is generally done with
automated equipment, essentially miniature versions of commercial
treaters.

  -------------------- ------------- --------- --------- ---------- ------- ------ ------ ------- ------ ------- ---------
  **Table 7. Combined                                                                                            
  Estimated Worker                                                                                               
  Dermal and                                                                                                     
  Inhalation Risk from                                                                                           
  On-farm Seed                                                                                                   
  Treatment**                                                                                                    

  Crop                 Acres         App       Amount    Combined                                                
                       treated/day   Rate^a^   Handled   MOEs ^c^                                                
                                     (lb       per                                                               
                                     ai/lb)    day^b^                                                            
                                               (lb                                                               
                                               ai/day)                                                           

                                                         Baseline   SL, G + SL +          SL, G + SL +   SL, G+  Eng
                                                                    NR      80% R         80% R   90% R  90% R   Control

  **LOADING/APPLYING                                                                                             
  LIQUID SEED                                                                                                    
  TREATMENTS**                                                                                                   

  Cotton               125           0.051     0.64      ND^d^                                                   

  **LOADING/PLANTING                                                                                             
  PREVIOUSLY TREATED                                                                                             
  SEEDS**                                                                                                        

  Barley               35            0.026     0.64      ND         7500           ND     7700    ND     7700    NF

  Beet; Sugar          80            0.041     0.26      ND         26000          ND     27000   ND     27000   NF

  Cotton               200           0.13      4.68      ND         1500           ND     1500    ND     1500    NF

  Oats                 200           0.026     6.66      ND         1100           ND     1100    ND     1100    NF

  Rice                 200           0.026     7.80      ND         880            ND     900     ND     900     NF

  Safflower            80            0.041     3.28      ND         2100           ND     2100    ND     2100    NF

  Wheat                200           0.026     7.80      ND         880            ND     900     ND     900     NF
  -------------------- ------------- --------- --------- ---------- ------- ------ ------ ------- ------ ------- ---------

ND = No Data; NF = Not Feasible

a Application rates are the maximum application rates determined from
EPA registered labels for TCMTB

b Amount handled per day calculated from the acres treated/day and the
maximum lb of seed planted per acre.

c Baseline = No gloves and no respirator

SL, G = Single layer w/gloves is baseline attire plus chemical-resistant
gloves.

DL, G = Double layer w/gloves is coveralls worn over long-sleeve shirt
and long pants, plus chemical-resistant gloves.

80% R = 80% Respirator is dust/mist removing filtering face piece style
respirator (that provides an 80% protection factor).

90% R = 90% Respirator is half-face dust/mist respirator (that provides
a 90% protection factor).\`

Eng Control = Engineering control is closed mixing/loading system,
enclosed cab, or enclosed cockpit.

d On-farm seed treatment with liquid formulations is generally done with
automated equipment, essentially miniature versions of commercial
treaters.

[]{#__RefHeading___Toc131902218 .anchor}**2.1.3 Cancer TCMTB Handler
Exposure and Risk Assessment**

The Health Effects Division Carcinogenicity Peer Review Committee (CPRC)
met on June 28, 1995 to discuss and evaluate the weight-of-the-evidence
on 2-(Thiocyanomethylthio) benzothiazole (TCMTB) with particular
reference to its carcinogenic potential. The CPRC concluded that TCMTB
should be classified as Group C - possible human carcinogen - and
recommended that for the purpose of risk characterization, the Reference
Dose (RfD) approach should be used for quantitation of human risk. This
was based on statistically significant increases in tumors in both sexes
of the Sprague-Dawley rat: testicular interstitial cell adenomas in
males and thyroid c-cell adenomas in females.

###  2.1.4 Summary of Risk Concerns/Data Gaps for Occupational Handlers 

There are several occupational handler scenarios for TCMTB that have
risks associated with them that are above HED's level of concern for
noncancer risk assessments, even at the highest level of risk
mitigation. However, there are also some occupational handler scenarios
for TCMTB that have data gaps.

#### 2.1.4.1 Summary of Risk Concerns 

The short- and intermediate-term dermal and inhalation handler risk
assessment for TCMTB indicates risk concerns for a number of seed
treatment scenarios, even with maximum risk mitigation. See Section
2.1.3.2 for a detailed summary.

#### 2.1.4.2 Summary of Data Gaps 

One data gap was identified for TCMTB. On-farm seed treatment with
liquid formulations is generally done with automated equipment,
essentially miniature versions of commercial treaters. Currently, HED
has no exposure data to assess this particular exposure scenario.

###  2.1.5 Recommendations For Refining Handler Risk Assessment

The values presented in the Health Effects Division Science Advisory
Committee on Exposure SOP #15: Amount of Seed Treated or Planted per Day
are most relevant to commercial seed treaters and growers planting
treated seed. When assessing growers who do on-farm seed treatment, the
values may, in some cases, be overestimates or underestimates, depending
on the crop type, geographic location and toxicity endpoint. Likewise,
because of limitations on farm size/crop type specific to the pesticide
being assessed, the volume given in the tables may not be appropriate.
These are cases when more detailed information regarding the pesticide
application rates, geographical/cultural characteristics of the crop and
other relevant information should be considered and modifications made
to the table values on a case-by-case basis. For TCMTB, no chemical
specific data regarding applications to seeds is currently available. In
order to refine this occupational risk assessment, data on actual use
patterns including rates, timing, and seeds treated per day would better
characterize TCMTB risks.