CRAG HERBICIDE

OSHA comments from the January 19, 1989 Final Rule on Air Contaminants Project extracted from 54FR2332 et. seq. This rule was remanded by the U.S. Circuit Court of Appeals and the limits are not currently in force.

CAS: 136-78-7; Chemical Formula: C₈H₇Cl₂NaO₅S

OSHA formerly applied a TWA limit of 15 mg/m³ for the total particulate of crag herbicide; this was the Agency’s generic total particulate limit for all particulates. The ACGIH has a total-dust TLV-TWA of 10 mg/m³ for this colorless, odorless, non combustible solid. The proposed PEL for crag herbicide was 10 mg/m³ (total particulate), and the final rule promulgates this limit; the 5-mg/m³ limit for the respirable fraction is retained. NIOSH (Ex. 8-47, Table N4) concurs with OSHA in the selection of these limits.

An early study reported an oral LD(50) in rats of 1500 mg/kg for this herbicide (Smyth 1956/Ex. 1-759). At high concentrations, crag herbicide is a gastrointestinal irritant (NIOSH 1984, as cited in ACGIH 1986/Ex. 1-3, p. 519). Rats fed a diet containing 60 mg sesone/100 gm of diet experienced minor liver damage; when fed 20 mg sesone/100 gm of diet for two years, rats showed no adverse effects (ACGIH 1986/Ex. 1-3, p. 519). In 1984, NIOSH reported the oral LD(50) in rats to be 730 mg/kg (NIOSH 1984, as cited in ACGIH 1986/Ex. 1-3, p. 519). There are no reported incidents of human poisoning associated with the use of sesone. NIOSH submitted the only comment on this substance.

OSHA is reducing the 8-hour TWA PEL for crag herbicide (total particulate) to 10 mg/m³ and retaining the 5-mg/m³ (respirable particulate) limit. OSHA concludes that these limits will protect workers from eye, skin, gastrointestinal, and other forms of irritation caused by exposure to crag herbicide.