Agent Name

Paraquat dichloride

CAS Number

1910-42-5

Formula

C12-H14-N2.2Cl

Major Category

Pesticides

Synonyms

1,1'-Dimethyl-4,4'-bipyridinium dichloride; N,N'-Dimethyl-4,4'-bipyridinium dichloride; Paraquat chloride; Paraquat dichloride [Note: Paraquat is a cation (C12H14N2++; 1,1-Dimethyl-4,4-bipyridinium ion); the commercial product is the dichloride salt of paraquat.]; [NIOSH] Bipyridinium, 1,1'-dimethyl-4,4'-, dichloride; Cekuquat; Crisquat; Dexuron; Dimethyl viologen chloride; Dwuchlorek 1,1'-dwumetylo-4,4'-dwupirydyniowy [Polish]; Esgram; Galokson; Goldquat 276; Gramixel; Gramoxone; Gramoxone D; Gramoxone S; Gramoxone W; Gramoxone dichloride; Gramuron; Herbaxon; Herboxone; Methyl viologen; Methyl viologen (reduced); Methyl viologen dichloride; Methylviologen chloride; OK 622; Ortho paraquat CL; Parakwat [Polish]; Paraquat CL; Pathclear; Pillarquat; Pillarxone; Toxer total; Viologen, methyl-; [ChemIDplus]

Category

Herbicides, Bipyridyl

Description

Yellow solid with a faint, ammonia-like odor. [herbicide] [Note: Paraquat may also be found commercially as a methyl sulfate salt C12H14N2+2CH3SO4.]; [NIOSH]

Sources/Uses

Used as a contact herbicide on weeds; [EXTOXNET] Used in animal experiments as a model of Parkinson's syndrome at doses several orders of magnitude greater than occupational exposure levels; [PMID 16217247]

Comments

Classified as "highly toxic," paraquat may be used only by certified applicators. [EXTOXNET] Prolonged contact will cause blistering of skin. Poisoning usually occurs after toxic ingestion, e.g., attempted suicide. [EPA Pesticides] Acute poisoning causes pulmonary edema, liver injury, and renal failure. Pulmonary fibrosis, starting one to three weeks after ingestion, may be seen in survivors. [ACGIH] Allergic and photoallergic contact dermatitis reported in farmworkers; [Kanerva, p. 1823] Paraquat causes fetal losses in high-dose reproductive studies of animals. In studies of Mallard embryos, it causes birth defects. [Frazier, p. 242-3] "Among the many herbicides in use, only the bipyridyl compounds have appeared to produce hepatic injury in humans. Even these agents have produced hepatic injury only as the result of ingestion of large amounts, not because of environmental contamination and questionably as the result of occupational exposures." [Zimmerman, p. 415] Paraquat has a chemical structure similar to MPTP, but animal studies have failed to show that paraquat causes parkinsonism. [Rosenstock, p. 1111] See "Paraquat."

Reference Link

EXTOXNET PIP - PARAQUAT

Exposure Assessment
Skin Designation (ACGIH)

Insufficient data

TLV (ACGIH)

0.5 mg/m3, as the cation (0.1, respirable fraction, as the cation)

PEL (OSHA)

0.5 mg/m3, respirable dust

MAK

0.1 mg/m3, inhalable fraction

IDLH (NIOSH)

1 mg/m3

Excerpts from Documentation for IDLHs

Human data: It has been stated that the high acute inhalation toxicity of paraquat is dependent wholly on the size of the particulate, with respirable sizes (i.e., <5 micrometer mass median diameter) found to be 5 to 6 times more toxic than nonrespirable dusts [McElligo 1965]. It has been reported that under paraquat spraying conditions particle sizes appear to be nonrespirable [Swan 1969].

Vapor Pressure

1.0E-7 mm Hg

Lethal Concentration

LCLo (rat) = 1 mg/m3/6H for respirable dust;

Explanatory Notes

ACGIH has TLV for paraquat (4685-14-7) = 0.5 mg/m3 ( total particulate) and 0.1 (respirable fraction); LCLo (rats) = 6400 mg/m3/6H for nonrespirable dust; See "2017 Notice of Intended Changes." [TLVs and BEIs]

Half Life

Animal studies: less than 6 hours; other animal studies have found measurable paraquat 26 days after ingestion; [TDR, p. 991]

Reference Link

Phototoxic contact dermatitis with toxic hepatitis due to the percutaneous absorption of paraquat

Adverse Effects
Skin Sensitizer

Yes

Toxic Pneumonitis

Yes

Fibrogenic

Yes

Hepatotoxin

Hepatotoxin, Secondary

Nephrotoxin

Yes

Reproductive Toxin

Yes

Dermatotoxin

Skin Burns

Links to Other NLM Databases
Health Studies

Human Health Effects from Hazardous Substances Data Bank:

Toxicity Information

Search TOXNET

Chemical Information

Search ChemIDplus

Related Information in HazMap
Diseases

Occupational diseases associated with exposure to this agent:

Processes

Industrial Processes with risk of exposure: