California Environmental Protection Agency Department of Pesticide Regulation Medical Toxicology Branch Summary of Toxicology Data Fenthion

An acute neurotoxicity study in the rat is on file. Note, Toxicology one-liners are attached In the one-liners below: ** indicates acceptable study Bold face indicates possible adverse effect File name: T971202 Revised by C. Aldous, 12/23/93, 10/20/95 and by J. Gee, 12/2/97 All records on file as of 12/2/97 for the above study types have been examined. This includes record numbers through 155670 (Document 214-117) plus some record numbers of the series DPR Medical Toxicology FENTHION T971202 2 900000+. II. TOXICOLOGY ONE-LINERS AND CONCLUSIONS These pages contain summaries only. Individual worksheets may identify additional effects. **214-097 098227 "Combined chronic toxicity/oncogenicity study of technical grade fenthion (Baytex) with rats", (Fenthion technical, purity 97%, administered in the feed at nominal concentrations of 0 (Corn oil), 5, 20, or 100 ppm to 50 Fischer 344 rats/sex/group for 2 years. An additional 20/sex were treated at 0 and 100 ppm for 1 year as a satellite study. Cholinesterase inhibition NOEL < 5 ppm: brain ChE was inhibited significantly at all doses in both sexes; plasma ChE was clearly inhibited in all doses of females and at 20 ppm and above in males [and marginally (7-19%) in 5 ppm males]. RBC ChE was clearly inhibited at 20 ppm and marginally at 5 ppm in both sexes. NOEL (other than ChE enzyme inhibition) = 5 ppm [modest suppression of electroretinogram (ERG) in females, vacuolar degeneration of the nasolacrimal duct in females, and granulomatous pneumonia in males]. Prominent features at 100 ppm included: modest body weight decrements (both sexes); skin lesions of tail and hindlimbs (both sexes, considered chronic active inflammation); other signs of unthrifty animals including urine stained ventrum and rough coat (both sexes); ocular effects, including retinal atrophy and cataract formation (females), focal corneal scarring (both sexes), and atrophy of the optic nerve (elevated in both sexes, but definitively treatment-related in females only): some of these morphological changes were reflected in undetectable electroretinogram responses in 100 ppm females. Other findings at 100 ppm were respiratory changes, including vacuolar degeneration of the nasolacrimal duct, foreign material in the nasal passageway, and granulomatous pneumonia (all in both sexes); and mineralization of the muscularis externa of the stomach (both sexes). Effects on eyes, respiratory system, skin, and epididymides are considered Possible adverse effects. No oncogenicity response. Study is acceptable. Kishiyama and Aldous, 4/9/92. (See Record No. 122320 below, which did not change study acceptability status). This record …