Toxicity report series
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Toxicity report series · Aug 2006
NTP Toxicity Study Report on the atmospheric characterization, particle size, chemical composition, and workplace exposure assessment of cellulose insulation (CELLULOSEINS).
Cellulose insulation (CI) is a type of thermal insulation produced primarily from recycled newspapers. The newspapers are shredded, milled, and treated with fire-retardant chemicals. The blowing process for installing CI generates a significant quantity of airborne material that presents a potential inhalation hazard to workers. CI was selected for study based upon the high production volume, the potential for widespread human exposure, and a lack of toxicity data; insufficient information was available to determine whether inhalation studies in laboratory animals were technically feasible or necessary. Studies were conducted to characterize the chemical and physical properties of CI aerosols, to evaluate the potential acute pulmonary toxicity of CI, and to assess occupational exposure of CI installers. Workplace exposure assessments were conducted in collaboration with the National Institute for Occupational Safety and Health (NIOSH, 2001). ⋯ Chemical analyses of the four bulk CI samples revealed only minor differences in additives. The major elemental components detected were aluminum, boron, calcium, sodium, and sulfur, but they were attributed to the fire retardants aluminum sulfate, boric acid, and sodium sulfate. For all four CI samples, less than 0.1% by weight was collected as the small respirable particle fraction. The fractions consisted mainly of fire retardants and smaller quantities of clays and did not contain cellulose material. Intratracheal instillation of the respirable fraction in rats produced minimal to mild inflammatory responses in the lungs with no increase in severity by 28 days after dosage. Although a significant increase in lung collagen was detected at day 28 in treated rats, microscopic evaluation revealed only a minimal to mild increase in collagen fibrils associated with granulomatous nodules. The results of these studies indicated that few respirable particles or fibers are generated during the aerosolization of CI, and that even at very high doses of respirable CI particles, acute pulmonary toxicity is minimal. These results are supported by the NIOSH workplace exposure assessment conducted on CI workers. Based on the air sample data collected from the 10 contractor site visits, there is a potential for overexposure to CI; however, respirable dust concentrations were typically low. There was increased potential for 8-hour TWAs exceeding the OSHA PEL for total and respirable dust when employees were involved in CI application activities for longer periods of time. There was evidence of work-related eye and mucous membrane irritation among some workers, which were possibly caused by the additives present in CI, such as boric acid. There was little evidence of lower respiratory system health conditions associated with CI exposure. Based upon the results of the CI chemical characterization studies, the pulmonary toxicity study, and the worksite exposure assessment, the NTP concluded that additional studies of CI in laboratory animals are not warranted at this time. However, the animal pulmonary toxicity studies and worker health surveys focused on acute CI exposures and do not preclude the possibility of toxicity resulting from chronic exposure. Although exposure concentrations of respirable CI particulate matter were low, additional information is needed on the biodurability and reactivity of CI particles and fibers in the respiratory tract. CI should continue to be regarded as a nuisance dust, and workers should continue to wear protective masks to prevent inhalation exposure to CI dusts.
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Toxicity report series · Jul 2006
Comparative StudyNTP Technical Report on the comparative toxicity studies of allyl acetate (CAS No. 591-87-7), allyl alcohol (CAS No. 107-18-6) and acrolein (CAS No. 107-02-8) administered by gavage to F344/N rats and B6C3F1 mice.
Allyl acetate, allyl alcohol, and acrolein are used in the manufacture of detergents, plastics, pharmaceuticals, and chemicals and as agricultural agents and food additives. Male and female F344/N rats and B6C3F(1) mice received allyl acetate, allyl alcohol, or acrolein by gavage for 14 weeks. Genetic toxicology studies were conducted in Salmonella typhimurium, Drosophila melanogaster, cultured Chinese hamster ovary cells, rat bone marrow erythrocytes, and mouse peripheral blood erythrocytes. ⋯ No increases in the frequencies of micronucleated normochromatic erythrocytes were observed in the peripheral blood of male or female mice administered allyl alcohol or acrolein by gavage for 14 weeks. Acrolein induced sister chromatid exchanges in cultured Chinese hamster ovary cells in the absence, but not the presence, of S9; it did not induce chromosomal aberrations, with or without S9. Results of three independent Drosophila melanogaster sex linked recessive lethal tests in which acrolein was administered to adult flies via feeding or injection and to larvae via feeding were negative.
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Toxicity report series · Nov 2002
NTP technical report on the toxicity studies of p-tert-butylcatechol (CAS No. 98-29-3) administered in feed to F344/N rats and B6C3F1 mice.
[molecular structure: see text] p-tert-Butylcatechol is used as an antioxidant, stabilizer, and polymerization inhibitor for styrene, butadiene, neoprene, and other olefins and reactive monomers. p-tert-Butylcatechol was nominated by the National Cancer Institute and the U. S. Food and Drug Administration for testing based on reports of its increasing levels of production and use and to compare the toxicity of p-tert-butylcatechol with that of similar antioxidants, butylated hydroxyanisole and butylated hydroxytoluene, which are added to food. ⋯ In summary, the primary toxicity of p-tert-butylcatechol was to the forestomach of rats and mice. In the 14-week study in rats, forestomach toxicity was observed at all exposure concentrations, and the no-observed-adverse-effect level (NOAEL) was not reached for this effect. In the 14-week study in mice, the NOAEL for forestomach toxicity was 1,562 ppm.
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Toxicity report series · Apr 1995
NTP technical report on the toxicity studies of Dibutyl Phthalate (CAS No. 84-74-2) Administered in Feed to F344/N Rats and B6C3F1 Mice.
Dibutyl phthalate is a phthalate ester with extensive use in industry in such products as plastic (PVC) piping, various varnishes and lacquers, safety glass, nail polishes, paper coatings, dental materials, pharmaceuticals, and plastic food wrap. Concomitant with this extensive worldwide use is the high potential for human exposure to dibutyl phthalate in the workplace and the home environment through direct sources as well as indirectly, through contamination of water, air, and foodstuffs. Because existing toxicity information was considered inadequate, the effects of exposure to dibutyl phthalate were examined in male and female F344/N rats and B6C3F1 mice in 13-week feed studies. ⋯ Trade Names: Celluflex DBP; Elaol; Ergoplast FDB; Ersoplast FDA; Genoplast B; Hexaplas M/B; Palatinol C; Polycizer DBP; PX 104; RC Plasticizer DBP; Staflex DBP; Uniflex DBP; Unimoll DB; Witcizer 300; Witicizer 300. (NOTE: These studies were supported in part by funds from the Comprehensive Environmental Response, Compensation, and Liability Act trust fund (Superfund) by an interagency agreement with the Agency for Toxic Substances and Disease Registry, U. S. Public Health Service.)
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Toxicity report series · Dec 1993
NTP technical report on the toxicity studies of Riddelliine (CAS No. 23246-96-0) Administered by Gavage to F344 Rats and B6C3F1 Mice.
Riddelliine is a naturally occurring pyrrolizidine alkaloid, a class of compounds occurring in rangeland plants of the genera Crotalaria, Amsinckia, and Senecio. Two-week and 13-week rodent toxicity studies of riddelliine were conducted because riddelliine can be a contaminant of foodstuffs, such as meat, grains, seeds, milk, herbal tea, and honey. In addition to histopathology, evaluations included clinical pathology and reproductive toxicity. ⋯ The liver was the primary target of riddelliine-induced injury that resulted in lesions characterized by cytomegaly and cytologic alteration in rats and mice and also by marked necrotic and proliferative changes in rats. Riddelliine is carcinogenic to female F344/N rats, based on the occurrence of hepatocellular adenomas. Synonyms: 13,19-didehydro-12,18-dihydroxy senecionan-11,16- dione; trans-15-ethylidine-12b-hydroxy-12a-hydroxymethyl-13-methylenesenec-1-enine; 3-ethylidine-3,4,5,6,9,11,13,14,14a,14b-decahydro-6-hydroxy-6-(hydroxymethyl)-5-methylene (1,6)di-oxacyclododecino(2,3,4-gh)-pyrrolizidine-2,7-dione.