Merphos

Synonyms

Butyl phosphorotrithioite; Butyl phosphorotrithioite ((BuS)3P); Chemagro B-1776; Deleaf defoliant; Easy off-D; Folex; Folex 6EC; Phosphorotrithious acid, S,S,S-tributyl ester; Phosphorotrithious acid, tributyl ester; S,S,S-Tributyl phosphorotrithioite; S,S,S-Tributyl trithiophosphite; Tributyl phosphorotrithioite; Tributyl trithiophosphite; Tributylthiofosfin [Czech]; [ChemIDplus]

Category

Organophosphate Insecticides

Description

Almost colorless liquid; [Hawley] Pale amber liquid; [HSDB] Colorless to pale yellow liquid; [MSDSonline]

Sources/Uses

Used as a cotton defoliant; [HSDB]

Comments

Cases of delayed neurotoxicity in agricultural workers via skin absorption have been reported; In one case a worker was exposed over a period of three days on his bare arms; Total facial diplegia developed two weeks after; Results of EMG include a decrease in muscle action potential and delayed conduction velocity in motor nerves; He fully recovered; No effects besides inhibition of cholinesterase observed in 90 day feeding studies with rats and dogs; Oral and dermal studies with hens demonstrated delayed neuropathy; [HSDB] “The average of two baseline respective cholinesterase activity determinations three days apart, with no exposures to enzyme inhibiting pesticides for at least 30 days, is recommended for each worker prior to exposure to cholinesterase inhibitors because of large inter-individual differences in published baseline values. To be established at least once a year. Removal from workplace exposures is recommended until the cholinesterase activity returns to within 20% of baseline.” [TLVs and BEIs]

Cancelled--no longer registered as a pesticide for use in the US; [HSDB]

Biomedical References

Acetylcholinesterase activity in red blood cells = 70% of individual's baseline; Butylcholinesterase activity in serum or plasma = 60% of individual's baseline; Sample at end of shift; [TLVs and BEIs]

2E-05 mm Hg

Predominantly motor

Other Poison

Organophosphate

Diseases

Occupational diseases associated with exposure to this agent:

• Organophosphates & carbamates, acute poisoning

Processes

Industrial Processes with risk of exposure:

• Farming (Pesticides)