United States
Environmental Protection
Agency
Prevention, Pesticides
and Toxic Substances
(7508C)
EPA738-F-00-018
July 2001
Temephos Facts
EPA has assessed the risks of temephos and reached a Reregi strati on Eligibility Decision
(RED) for this organophosphate (OP) pesticide. Provided that risk mitigation measures are
adopted, temephos is eligible for reregistration. A cumulative assessment is not warranted.
Temephos is one of a few
organophosphates registered to control mosquito
larvae, and is the only organophosphate with any
appreciable larvicidal use. It is an important
resistance management tool for mosquito
abatement programs. Temephos residues in food
and drinking water do not pose risk concerns
since temephos has no food uses and, because of
its limited use pattern, is not expected to be found
in drinking water. Residential risk is not of
concern since temephos has no residential use and
its use in mosquito abatement programs does not
result in residential exposure. With mitigation
measures, temephos' worker and ecological risks
will be eligible for reregistration.
EPA's next step under the Food Quality
Protection Act (FQPA) is to complete a
cumulative risk assessment and risk management
decision encompassing all the OP pesticides, which
share a common mechanism of toxicity. Because
temephos has no food uses, or other uses that
would result in exposure to children, it will not be
included in the cumulative assessment of OPs.
The OP Pilot Public Participation Process
The organophosphates are a group of
related pesticides that affect the functioning of the
nervous system. They are among EPA's highest
priority for review under the Food Quality
Protection Act.
EPA is encouraging the public to
participate in the review of the OP pesticides.
Through a six-phased pilot public participation
process, the Agency is releasing for review and
comment its preliminary and revised scientific risk
assessments for individual OPs. (Please contact
the OP Docket, telephone 703-305-5805, or see
EPA's web site,
http://www.epa.gov/pesticides/op/.)
EPA is exchanging information with
stakeholders and the public about the OPs, their
uses, and risks through Technical Briefings,
stakeholder meetings, and other fora. USDA is
coordinating input from growers and other OP
pesticide users.
Based on current information from
interested stakeholders and the public, EPA is
making interim risk management decisions for
most individual OP pesticides, and will make final
decisions through a cumulative OP assessment.
EPA is reviewing the OP pesticides to
determine whether they meet current health and safety standards. Older OPs need decisions about
their eligibility for reregistration under FIFRA. OPs with residues in food, drinking water, and
other non-occupational exposures also must be reassessed to make sure they meet the new FQPA
safety standard.
The temephos decision was made through the OP pilot public participation process, which
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increases transparency and maximizes stakeholder involvement in EPA's development of risk
assessments and risk management decisions. EPA worked extensively with affected parties to
reach the decisions presented in this decision document, which concludes the OP pilot process for
temephos.
Uses
Temephos is used to control mosquito, midge, gnat, punkie, and sandfly larvae in non-
potable water (stagnant, saline, brackish and temporary water bodies), waters high in
organic content, highly polluted water, including moist areas, woodland pools, shallow
ponds, edges of lakes, swamps, marshes, tidal waters, intertidal zones, catch basins, and
tire piles. It is an important resistance management tool for mosquito abatement
programs.
Annual usage is approximately 25,000 to 40,000 pounds of active ingredient per year.
Temephos' use has declined in recent years due to deletion of the use on citrus.
Health Effects
Temephos can cause cholinesterase inhibition in humans; that is, it can overstimulate the
nervous system causing nausea, dizziness, confusion, and at very high exposures (e.g.,
accidents or major spills), respiratory paralysis and death.
Risks
• Dietary risks from food and drinking water are not of concern since temephos has no food
uses. Because of its limited use pattern, it is not expected to be found in drinking water.
• Residential risk is not of concern since temephos has no residential use, and its use in
mosquito abatement programs does not result in residential exposure.
• EPA has risk concerns for workers who can be exposed both dermally and through
inhalation while mixing, loading, and/or applying temephos.
• Because temephos is applied directly to non-potable water, it is not expected to have a
direct impact on terrestrial animals. Risk quotients for freshwater fish exceed levels of
concern only for endangered species and restricted use. No acute toxicity data are
available for marine fish species. Risk quotients exceed levels of concern for aquatic
invertebrates.
Risk Mitigation
In order to support a reregistration eligibility decision for temephos the following risk
mitigation measures are necessary:
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• To mitigate risks to mixers, loaders, applicators and other handlers, either closed mixing
and loading systems or additional personal protective equipment (PPE) will be needed.
Where closed systems are not feasible or are not used, handlers will need to wear:
Cloth coveralls over long-sleeved shirt and long pants;
• Chemical-resistant gloves;
Chemical-resistant footwear plus socks;
• Chemical-resistant headgear (if overhead exposure).
See the temephos RED for application specific measures.
Temephos must be applied only by public health officials, personnel of mosquito
abatement districts and other similar government agencies or personnel under contract to these
entities.
• To mitigate ecological risks, temephos:
• May be applied only to non-potable water (stagnant, saline, brackish and
temporary water bodies), waters high in organic content, highly polluted water,
including moist areas, woodland pools, shallow ponds, edges of lakes, swamps,
marshes, tidal waters, intertidal zones, catch basins, and tire piles;
• May not be reapplied within 7 days of initial application unless monitoring
indicates that larval populations have reestablished, or weather conditions have
rendered initial treatments ineffective;
Limit use of high application rates to non-potable water (stagnant, saline, brackish
and temporary water bodies), high in organic matter content, highly polluted
water, and tire piles and where monitoring has confirmed a lack of control at
typical rates.
Next Steps
• The temephos RED contains a generic and a product-specific Data Call-In(s) (DCI) that
outline further data requirements for this chemical. A complete DCI, with all pertinent
instructions, is being sent to registrants under separate cover.
• The temephos RED also describes labeling amendments for end-use products and data
requirements necessary to implement the mitigation measures outlined in the document.
Instructions for registrants on submitting the revised labeling can be found in the set of
instructions for product-specific data that is being sent under separate cover.
Registrants are developing route-specific dermal toxicity data. If these data indicate lower
risk to workers than currently estimated, PPE requirements may be revised.
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For More Information
To obtain a copy of the RED document, please contact the OPP Public Regulatory
Docket (7502C), US EPA, Ariel Rios Building, 1200 Pennsylvania Avenue NW, Washington, DC
20460, telephone 703-305-5805. Electronic copies of the RED, the fact sheet, and supporting
documents are available on the Internet. See
http://www.epa.gov/pesticides/reregistration/status.htm or http://www.epa.gov/pesticides/.
Printed copies of the RED and fact sheet can be obtained from EPA's National Service
Center for Environmental Publications (EPA/NSCEP), PO Box 42419, Cincinnati, OH 45242-
2419, telephone 1-800-490-9198; fax 513-489-8695.
The temephos RED document also will be available from the National Technical
Information Service (NTIS), 5285 Port Royal Road, Springfield, VA 22161, telephone 1-800-
553-6847, or 703-605-6000.
For more information about EPA's pesticide reregi strati on program, the temephos RED,
or reregi strati on of individual products containing temephos, please contact the Special Review
and Reregistration Division (7508C), 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 Pesticide
Telecommunications Network (NPTN). Call toll-free 1-800-858-7378, from 6:30 am to 4:30 pm
Pacific Time, or 9:30 am to 7:30 pm Eastern Standard Time, seven days a week. Their Internet
address is http://ace.orst.edu/info/nptn/.
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