Bromoethane, chloroethane and ethylene oxide induced uterine neoplasms in B6C3F1 mice from 2-year NTP inhalation bioassays: pathology and incidence data revisited.
Chloroethane, bromoethane and ethylene oxide represent a unique set of chemicals that induce endometrial neoplasms in the uterus of B6C3F1 mice following an inhalation route of exposure. The results of the NTP's chronic bioassays with these three compounds resulted in an unusually high incidence of uterine epithelial neoplasms in B6C3F1 mice (chloroethane 86%, bromoethane 56%) and a lower incidence for ethylene oxide (10%). The uterine neoplasms were classified as adenomas, adenocarcinomas, and squamous cell carcinomas for bromoethane, and as adenocarcinomas for both chloroethane and ethylene oxide. The adenocarcinomas and squamous cell carcinomas were invasive into the myometrium and the serosa, and metastasized to a wide variety of organs. Metastatic sites included most commonly the lung, lymph nodes, and ovary at unusually high rates of metastases (79% for chloroethane and 38% for bromoethane). Because of the dramatically high rates of uterine neoplasms (induced by chemicals given by the inhalation route) and metastases, a re-evaluation of the pathology and incidence data was undertaken. The earlier results were confirmed. The mechanism of uterine carcinogenesis by chloroethane, bromoethane and ethylene oxide is unclear.
Picut
Catherine A
CA
Biotechnics, Inc., Hillsborough, North Carolina, USA.
Aoyama
Hiroaki
H
Holder
James W
JW
Gold
Lois Swirsky
LS
Maronpot
Robert R
RR
Dixon
Darlene
D
D000230:Adenocarcinoma / Q000139:chemically induced* / Q000556:secondary; D000236:Adenoma / Q000139:chemically induced* / Q000473:pathology; D000280:Administration, Inhalation; D000818:Animals; D015197:Carcinogenicity Tests; D002273:Carcinogens / Q000008:administration & dosage / Q000633:toxicity*; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced* / Q000556:secondary; D004305:Dose-Response Relationship, Drug; D005018:Ethyl Chloride / Q000008:administration & dosage / Q000633:toxicity*; D005027:Ethylene Oxide / Q000008:administration & dosage / Q000633:toxicity*; D005260:Female; D006842:Hydrocarbons, Brominated / Q000008:administration & dosage / Q000633:toxicity*; D019570:Inhalation Exposure; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D015203:Reproducibility of Results; D014594:Uterine Neoplasms / Q000139:chemically induced* / Q000473:pathology
D002273:Carcinogens; D006842:Hydrocarbons, Brominated; D005018:Ethyl Chloride; D005027:Ethylene Oxide; C037311:bromoethane