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
PGStJCJdG All pesticides sold or distributed in the United States must be
RGTGClistration 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.
USG ProfilG 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
(LOG) for endangered aquatic organisms. The Agency, therefore, has
determined that effluent containing sodium 2-mercaptobenzothiazole should
-------
Regulatory
History
Human Health
Assessment
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.
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/paper board
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.
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,
-------
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 Environmental Fate
AsSGSSITIGnt 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
-------
Additional Data
Required
Product Labeling
Changes Required
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 LOG 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.
A hydrolysis study has been required to confirm the environmental
assessment by determining the degradation rate of sodium 2-mercapto-
benzothiazole 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.
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.
-------
Regulatory
Conclusion
For More
Information
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.
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 toll-
free 1-800-858-7378, between 8:00 am and 6:00 pm Central Time, Monday
through Friday.
------- |