title: Inhalation toxicity studies of aqueous dispersion resin.
abstract: Aqueous dispersion resin (ADR) is a water-based acrylate copolymer designed to allow a range of ethanol concentrations for hair-spray formulations. A series of inhalation (whole-body) aerosol toxicity studies, including acute, 9-day, and 90-day exposures, was conducted to determine any toxicological effects for ADR. An acute study of ADR was conducted for 4 h with a 14-day observation period. The maximum ADR aerosol concentration was 1.07 (+/- 0.04) mg/L with a mass medium aerodynamic diameter (MMAD) value of 1.46 microm and a geometric mean (sigma(g)) of 1.42. No deaths or exposure-related lesions were observed. Thus, the LC50 value was greater than 1.07 mg/L. For the 9-day study, each group contained 10 animals/sex and was exposed for 2 h/day. The mean exposure concentrations (+/- standard deviation) were 244 (+/- 39.6), 543 (+/- 71.9), and 843 (+/- 186.2) mg/m(3) for the 250-, 500-, and 1000-mg/m(3) groups, respectively. The mean MMADs were 2.83, 2.90, and 4.09 microm for the 250-, 500-, and 1000-mg/m(3) groups, respectively, with sigma(g) values ranging from 3.15 to 6.22. Unkempt fur and alopecia in the males and females from the 1000-mg/m(3) group at sacrifice were the only exposure-related clinical signs observed. Increased lung weights in the 500- and 1000-mg/m(3) exposure groups were found. Histopathological effects, such as alveolar histiocytosis and interstitial pneumonitis, were also noted in these two exposure groups. For the 90-day study, 10 animals per sex were included in each group with a 6-wk recovery group of 5 female rats/group. Exposures were conducted for 2 h/day. The mean exposure concentrations were 30.4 (+/- 2.3), 102 (+/- 11.6), and 308 (+/- 19. 3) mg/m(3) with mean MMADs of 3.09, 2.64, and 2.67 microm and sigma(g) values ranging from 3.54 to 3.90 for exposure concentrations of 30, 100, and 300 mg/m(3), respectively. The only findings at the 90-day sacrifice were increased lung weights for the males and females in the 300-mg/m(3) group and males in the 100-mg/m(3) group. For the 6-wk recovery sacrifice of the females, the lung weights for the 300- and 100-mg/m(3) groups were increased. Histopathological effects at the 90-day sacrifice included alveolar histiocytosis and lymphadenitis in the mediastinal lymph nodes in the 100- and 300-mg/m(3) exposure groups for males and females, while alveolar histiocytosis, intraalveolar cellular debris, lymphadenitis in the mediastinal lymph nodes, and/or interstitial pneumonitis were noted in these 2 exposure groups of the females after the 6-wk recovery period. Animals exposed for 90 days to 100 and 300 mg/m(3) for 2 h had increased lung weights. However, no effects were observed in the 30-mg/m(3) exposure group. Thus, under the conditions of the present 90-day study, a no-observable-effect level (NOEL) was found to be 30 mg/m(3).
authors.affiliation: Norris Consulting Services, 6 West Grove, Harrogate, North Yorkshire HG1 2AD, United Kingdom.
authors.forename: J C
authors.initials: JC
authors.lastname: Norris
authors.forename: T R
authors.initials: TR
authors.lastname: Tyler
mesh_terms: D000179:Acrylates / Q000008:administration & dosage / Q000633:toxicity*; D000280:Administration, Inhalation; D000336:Aerosols / Q000008:administration & dosage / Q000633:toxicity; D000818:Animals; D001273:Atmosphere Exposure Chambers; D001835:Body Weight / Q000187:drug effects; D019963:Clinical Chemistry Tests; D004655:Emulsions / Q000008:administration & dosage / Q000633:toxicity; D005260:Female; D008168:Lung / Q000187:drug effects / Q000473:pathology; D008198:Lymph Nodes / Q000187:drug effects / Q000473:pathology; D008199:Lymphadenitis / Q000139:chemically induced / Q000473:pathology; D008297:Male; D008482:Mediastinum / Q000473:pathology; D019055:No-Observed-Adverse-Effect Level; D009929:Organ Size / Q000187:drug effects; D011009:Pneumoconiosis / Q000209:etiology / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D023382:Toxicity Tests, Acute
chemical_list: D000179:Acrylates; D000336:Aerosols; D004655:Emulsions