Parathion

Synonyms

O,O-Diethyl-O-(p-nitrophenyl) phosphorothioate; Diethyl parathion; Ethylparathion; Parathion-ethyl; AC 3422; Alkron; Alleron; Aphamite; Corothion; E-605; Etilon; Fosferno 50; Niran;Orthophos; Panthion; Paramar; Paraphos; Parathene; Parawet; Phoskil; Rhodiatox; Soprathion; Stathion; Thiophos;

Category

Organophosphate Insecticides

Description

Pale-yellow to dark-brown liquid with a garlic-like odor. [Note: A solid below 43 degrees F.] [NIOSH]

Sources/Uses

In the U.S. parathion may be used only by licensed applicators on alfalfa, barley, corn, cotton, sorghum, soybeans, sunflowers, and wheat. [EXTOXNET]

Comments

Classified as "highly toxic," parathion has an LD50 in rats of 2 to 30 mg/kg; [EXTOXNET] A small number of the organophosphates (OPs) can Induce Delayed Neuropathy (OPIDN). OPIDN usually occurs after ingestion and is usually nonoccupational. [Levy, p. 431] "Toxic inhalation of parathion vapor is unlikely at ordinary temperatures because of its low volatility, but toxic effects can occur after inhalation of parathion sprays or dusts." [ATSDR Medical Management] “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]

Use on fruit, nut and vegetable crops cancelled by EPA in 1992; [EXTOXNET]

Reference Link #1

Biomedical References

Acetylcholinesterase activity in red blood cells = 70% of individual's baseline; Total p-nitrophenol in urine = 0.5 mg/g' Sample at end of shift; [ACGIH, 2020]]

Yes

0.05 mg/m3, inhalable fraction and vapor

0.1 mg/m3

0.1 mg/m3, inhalable fraction

10 mg/m3

4E-05 mm Hg

Explanatory Notes

2024 Notice of Intended Changes (NIC); [ACGIH TLVs and BEIs]

Elimination half-life of about 8 hours after inhalation; After dermal exposure, only 9.7% of dose eliminated in urine as p-nitrophenol within 5 days; [ACGIH]

Reference Link #2

Predominantly motor

Not classifiable

Not Classifiable

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)