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Terbufos

Overview
 
CAS Number: 13071-79-9
Synonyms: AC 92100, Aragran, Contraven, Counter
Contaminant Type: Chemical

Terbufos [S-tert-butylthiomethyl O,O-diethyl phosphorodithioate] is an organothiophosphate insecticide-nematicide applied to corn, sugar beets and grain sorghum to control wireworms, seedcorn maggots, white grubs, corn rootworm larvae, and other pests. It is classified as toxicity class I (highly toxic).

Products containing 15 percent or more terbufos are classified as Restricted Use Pesticides (RUPs), which may be purchased and used only by certified applicators [1938].  Terbufos can be introduced in humans through oral, inhalation or dermal routes but has not been found to accumulate in body tissues [1940].  It has acute effects a cholinestrase inhibitor with nervous system effects.  It is not likely a human carcinogen.

Terbufos was first registered in 1974; the average domestic use was reported to be approximately 7.5 million pounds of active ingredient per year for 1987 to 1996 [1947]. It is not registered for use in residential settings. An estimated 87% is used on corn [1948].

Terbufos is considered to be low to moderately persistent in soil; it converts rapidly to its metabolites, which then persist in the soil. Reported half-lives are 5 to 30 days, while its metabolites persist 2 to 3 times longer [1938]. Its dissipation is faster in soils with low organic carbon content and higher temperatures. Due to its immobility and low water solubility, terbufos is not expected to impact groundwater supplies. Terbufos does hydrolyze quickly, with half lives of 4.5 to 8.5 days at pH in range of 5-9 [1938]. Vapor pressure and Henry's constant suggest terbufos may volatilize.  Principal degradates are its sulfone, sulfoxide and oxon sulfone metabolites. 

Although not currently regulated by the USEPA in drinking water, it is included on the USEPA's Contaminant Candidate List 3 [620].  USGS NAWQA monitoring found terbufos infrequently (<1%) detected in surface and ground waters below 1 ug/L.

Date of Literature Search: September 2010

 



620 USEPA Office of Ground Water and Drinking Water; 2008; Contaminant Candidate List 3 (CCL3); USEPA Office of Ground Water and Drinking Water; http://www/epa.gov/OGWDW/ccl/ccl3.html
1938 Extension Toxicology Network (Extoxnet); 1996; Terbufos; Pesticide Information Profiles; pp. 1-4
1939 Dogheim, S.; 2005; Terbufos Fact Sheet; Central Laboratory of Residue Analysis of Pesticides and Heavy Metals in Food, Agriculture Research Centre, Ministry of Agriculture, Cairo, Egypt.; pp. 1059-1060
1940 Unknown; 1987; Terbufos; Unknown; p. 1-2
1947 USEPA; 2006; Finalization of Interim Reregistration Eligibility Decisions (IREDs) and Interim Tolerance Reassessment and Risk Management Decisions (TREDs) for the Organophosphate Pesticides, and Completion of the Tolerance Reassessment and Reregistration Eligibility P; Memorandum; pp. 14-17, USEPA Office of Prevention, Pesticides, and Toxic Substances, Washington, DC.
1948 USEPA; 2010; Terbufos IRED Facts; C:\Documents and Settings\hasan\Desktop\Terbufos\1948_Terbufos IRED Facts Pesticide US EPA.mht; As posted on September 22, 2010. USEPA , Washington, DC.



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