United States Prevention, Pesticides EPA-738-F-94-024

Environmental Protection And Toxic Substances September 1994

Agency (7508W)

R.E.D. FACTS

Sodium and Zinc

Salts of 2-Mercapto- 

 benzothiazole

Pesticide

Reregistration

All pesticides sold or distributed in the United States must be

registered by EPA, based on scientific studies showing that they can be used

without posing unreasonable risks to people or the environment. Because of

advances in scientific knowledge, the law requires that pesticides which

were first registered years ago be reregistered to ensure that they meet

today's more stringent standards. 

In evaluating pesticides for reregistration, EPA obtains and reviews a

complete set of studies from pesticide producers, describing the human

health and environmental effects of each pesticide. The Agency imposes

any regulatory controls that are needed to effectively manage each

pesticide's risks. EPA then reregisters pesticides that can be used without

posing unreasonable risks to human health or the environment.

When a pesticide is eligible for reregistration, EPA announces this and

explains why in a Reregistration Eligibility Decision (RED) document. This

fact sheet summarizes the information in the RED document for

reregistration case 2380, the sodium and zinc salts of

2-mercaptobenzothiazole.

Use Profile This case includes two active ingredients, the sodium and zinc salts of

2-mercaptobenzothiazole, which are used as fungicides, microbiocides and

bacteriostats. These salts are used as preservatives for adhesives, latex and

oil paints, paper products, metal working cutting fluids and textile fibers. 

Sodium 2-mercaptobenzothiazole is used in the form of a soluble

concentrate or liquid to control mold, mildew, bacteria and fungi which

cause aqueous industrial products to degrade. The metal working cutting

fluid use of the sodium salt of 2-mercaptobenzothiazole is the only use

pattern where effluent containing the chemical is discharged into aquatic

environments, potentially exposing non-target aquatic organisms, including

endangered species. This use pattern exceeds the acute Level of Concern

(LOC) for endangered aquatic organisms. The Agency, therefore, has

determined that effluent containing sodium 2-mercaptobenzothiazole should
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not be discharged into streams and other waterways where endangered

aquatic organisms are known to reside. When the Agency completes its

Endangered Species Program, additional precautionary labeling may be

required to mitigate the risk to endangered species. 

Zinc 2-mercaptobenzothiazole is used in the form of a soluble

concentrate or liquid and wettable powder to control mold, mildew, bacteria

and fungi which degrade aqueous industrial products, fabrics, and yarns;

and slime-forming bacteria and fungi in industrial water systems. 

There are no registered food uses for either the sodium or zinc salts of

2-mercaptobenzothiazole.

Regulatory

History

Sodium 2-mercaptobenzothiazole was first registered as a pesticide in

the United States in 1949 in an industrial preservative product. Currently,

only one product is registered, for use in wood and paper/paperboard

treatment and as a preservative in metal working cutting fluids, emulsions,

textiles and pastes.

Zinc 2-mercaptobenzothiazole was first registered as a pesticide in the

United States in 1955 in an industrial preservative product. Currently, two

products are registered for use as preservatives in adhesives, textiles, paints,

coatings and paper products.

The parent compound, acid of 2-mercaptobenzothiazole, was

registered as a pesticide active ingredient in 1956. However, all products

containing that chemical have since been canceled.

Human Health

Assessment

Toxicity

Zinc 2-mercaptobenzothiazole has been placed in Toxicity Category

III, which indicates moderate to low acute toxicity, for acute skin and eye

effects. However, the sodium salt is placed in Toxicity Category I,

indicating the highest degree of acute toxicity, for skin and eye effects

because it is extremely acidic (with a Ph of 11.5).

The acid of 2-mercaptobenzothiazole is classified as a non-quantifiable

"Group C" carcinogen; a possible human carcinogen. A linear, multi-stage

model for cancer risk assessment was not appropriate because the use of this

pesticide is not likely to result in repeated human exposure over a significant

portion of the human life span. Margins of Exposure (MOEs) were

calculated to quantify the risk to applicators/mixers/loaders. The MOEs for

the preservative and metal working cutting fluid uses of zinc and sodium

2-mercaptobenzothiazole exceed 100 (the margin considered acceptable) by

several orders of magnitude. Therefore, additional exposure studies were

not warranted, and the Agency required data on acute, developmental and

subchronic toxicity and mutagenicity only. 

Occupational and Residential Exposure

The methods of application for products containing sodium or zinc

2-mercaptobenzothiazole that include open pouring of liquid concentrate,
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and open pouring of powder into adhesives and paints, present the potential

for dermal and inhalation exposure to applicators. Dermal exposure is the

primary route of exposure of sodium and zinc 2-mercaptobenzothiazole.

EPA was concerned about the risks of dermal and inhalation exposure

associated with the application of sodium 2-mercaptobenzothiazole for the

metal working cutting fluid use, and required a dermal exposure study to

assess the risks to workers. The study was designed to reflect typical work

practice involving the biocide in industrial use. The final assessment of the

study indicated that some absorption into the skin occurred. However, since

there are no special toxicological concerns about the sodium or zinc salts,

EPA is not imposing Personal Protective Equipment (PPE) requirements on

use of the products.

Post-application exposure from treated paint, adhesives, textiles and

other treated industrial products are not considered significant because of the

low concentration/dilution factor to the treated products. There are no

residential uses of sodium or zinc 2-mercaptobenzothiazole. Therefore, the

potential for any significant residential exposure is very low. 

Human Risk Assessment

The sodium and zinc salts are not registered for any food or feed

related uses, so no dietary risks are posed. The potential for residential

exposure and risk is very low. 

Workers (mixers, loaders and applicators) may be exposed to these

pesticides, especially during open pouring of liquid and powder

formulations. However, the Agency has determined that use of these

pesticides is not likely to result in repeated human exposure over a

significant portion of the human life span. The establishment of active

ingredient based PPE requirements is not warranted at this time. The PPE

for pesticide handlers will be based on the acute toxicity of the end-use

product. 

Environmental

Assessment

Environmental Fate

A hydrolysis study has been required on the technical grade of sodium

2-mercaptobenzothiazole for industrial use products where effluent is

potentially discharged into aquatic environments. While the Agency has

required the study to be based on the industrial use pattern, major

environmental exposure to the sodium salt is not expected. The Agency will

use the results of the study to confirm this assessment and the degradation

rate of the active ingredient and products formed during hydrolysis.

Ecological Effects Risk Assessment

2-Mercaptobenzothiazole is almost nontoxic to birds on an acute oral

basis and is only slightly toxic to birds on a dietary basis. However, it is

highly toxic to freshwater fish and moderately toxic to aquatic invertebrates. 

The use patterns of the sodium and zinc salts, except for sodium
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2-mercaptobenzothiazole's use in metal working cutting fluids, indicate that

they will not pose risks to avian and aquatic species.

Unlike agricultural situations, where aquatic organisms can be exposed

to pesticides via runoff or spray drift, nontarget aquatic organisms would be

exposed to industrial microbiocides through a point source discharge. The

metal working cutting fluids use of the sodium salt is the only use pattern

which may result in an effluent discharge into aquatic environments. It

therefore poses the potential for exposure to nontarget aquatic organisms,

including endangered species. 

EPA's aquatic risk assessment indicates that minimal risk is posed to

freshwater aquatic organisms in receiving streams at mean flow rates. 

However, under high exposure conditions, a high acute and chronic risk is

posed to freshwater aquatic organisms. The high exposure scenario also

exceeds the LOC for endangered freshwater fish and invertebrate species. 

Therefore, effluent containing sodium 2-mercaptobenzothiazole should not

be discharged into streams and other waterways where endangered aquatic

organisms are known to reside.

Additional Data

Required

A hydrolysis study has been required to confirm the environmental

assessment by determining the degradation rate of sodium 2-mercaptobenzothiazole and products formed during hydrolysis. EPA also is

requiring product-specific data including product chemistry and acute

toxicity studies, revised Confidential Statements of Formula (CSFs), and

revised product labeling for reregistration of products containing sodium or

zinc salts of 2-mercaptobenzothiazole.

Product Labeling

Changes Required

The labels of all registered pesticide products containing sodium and

zinc salts of 2-mercaptobenzothiazole must comply with EPA's current

pesticide labeling requirements. The following statement also must appear

on the labels of sodium 2-mercaptobenzothiazole end use products with the

metal working cutting fluid use:

Effluent Discharge Labeling Statement - "Do not discharge effluent

containing this product into lakes, streams, ponds, estuaries, oceans or

other waters unless in accordance with the requirements of a National

Pollutant Discharge Elimination System (NPDES) permit and the

permitting authority has been notified in writing prior to discharge. 

Do not discharge effluent containing this product to sewer systems

without previously notifying the local sewage treatment plant

authority. For guidance contact your State Water Board or Regional

Office of the EPA." 

When the Agency completes the Endangered Species Program,

additional precautionary labeling may be required to mitigate the risk to

endangered species. 
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Regulatory

Conclusion

The use of registered products containing sodium or zinc salts of

2-mercaptobenzothiazole will not pose unreasonable risks or adverse effects

to humans or the environment, provided that these products are used in

accordance with the restrictions on product labeling. Therefore, all uses of

these products are eligible for reregistration. Sodium or zinc salts of

2-mercaptobenzothiazole products will be reregistered once the confirmatory

generic data, the required product-specific data, Confidential Statements of

Formula and revised labeling are received and accepted by EPA.

For More

Information

EPA is requesting public comments on the Reregistration Eligibility

Decision (RED) document for sodium and zinc salts of

2-mercaptobenzothiazole during a 60-day time period, as announced in a

Notice of Availability published in the Federal Register. To obtain a copy

of the RED document or to submit written comments, please contact the

Pesticide Docket, Public Response and Program Resources Branch, Field

Operations Division (7506C), Office of Pesticide Programs (OPP), US

EPA, Washington, DC 20460, telephone 703-305-5805. 

Following the comment period, the sodium and zinc salts of

2-mercaptobenzothiazole RED document will be available from the National

Technical Information Service (NTIS), 5285 Port Royal Road, Springfield,

VA 22161, telephone 703-487-4650. 

For more information about EPA's pesticide reregistration program,

the sodium and zinc salts of 2-mercaptobenzothiazole RED, or reregistration

of individual products containing sodium and zinc salts of 

2-mercaptobenzothiazole, please contact the Special Review and

Reregistration Division (7508W), OPP, US EPA, Washington, DC 20460,

telephone 703-308-8000. 

For information about the health effects of pesticides, or for assistance

in recognizing and managing pesticide poisoning symptoms, please contact

the National Pesticides Telecommunications Network (NPTN). Call tollfree 1-800-858-7378, between 8:00 am and 6:00 pm Central Time, Monday

through Friday.