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Methiocarb

Overview
 
CAS Number: 2032-65-7
Synonyms: Draza, Mercaptodimethur , Mesurol , Metmercapturon
Contaminant Type: Chemical

Methiocarb is an n-methyl carbamate pesticide used since the 1960s to control snails, slugs, mites, thrips, aphids, leafhoppers, fruit flies, & biting insects; & some soil pests of field crops. It is also used as a bird repellent on fruit crops [2116].  There currently are no food or feed uses for methiocarb.  Its IUPAC name is 4-methylthio-3,5-xylymethylcarbamate [2120]. 

  

Methiocarb was first registered as a pesticide in the U.S. in 1972 and EPA issued a Reregistration Eligibility Decision document for methiocarb in 1994.  Wettable powder formulations of methiocarb are restricted use pesticides available only to professional applicators.  One formulation of methiocarb is a general use pesticide which can be used by homeowners [2121]. 

 

The mechanism of toxicity for methiocarb is to inhibit the production of cholinesterase, an enzyme necessary for transmission of nerve impulses [2121]. 

 

National usage figures are not available for methiocarb; however, usage in California from 2005 to 2007 was over 6,000 pounds of active ingredient [2120].  

Methiocarb is highly toxic by the oral route and moderately toxic by the inhalation route. It is not an eye or skin irritant and does not cause delayed neurotoxicity [2121]. It is unclassifiable as a carcinogen based on insufficient data.  

 

Methiocarb is moderately persistent and relatively immobile in soil, and generally unlikely to contaminate groundwater [2121].  However, it has been detected in groundwaters in America, Australia, Mexico and Spain at concentrations ranging between 0.03 and 5.4 ug/L [2119].  The half life of methiocarb in water has been reported from 35 days at pH 7 to 6 hours at pH 9 [2116].

Methiocarb degradates include methiocarb sulfoxide, methiocarb sulfone, methiocarb phenol, methiocarb sulfoxide phenol, and methiocarb sulfone phenol [2119].  Based on oral LD50 values in rats, methiocarb sulfoxide has been found to be more toxic than methiocarb [2119].  

 

Methiocarb is not regulated in drinking water in the US. 

Date of Literature Search: March 2011



2116 United States National Library of Medicine; 2011; TOXNET - Toxicology Data Network; http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?HSDB; As posted on June 2011. United States National Library of Medicine
2119 Tian, F., Qiang, Z., Liu, C., Zhang, T. and Dong, B.; 2010; Kinetics and mechanism for methiocarb degradation by chlorine dioxide in aqueous solution; Chemosphere; 79:646
2120 USEPA; 2010; Methiocarb Summary Document Registration Review: Initial Docket; Document Number: EPA-HQ-OPP-2010-0278;
2121 USEPA; 1994; R.E.D. Facts: Methiocarb; EPA-738-F-94-002;



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