The inhalation toxicity of di- and triethanolamine upon repeated exposure.

Systemic and respiratory tract (RT) toxicity of triethanolamine (TEA) was assessed in a 28-day nose-only inhalation study in Wistar rats (10animals/sex, concentrations: 0, 20, 100, 500mg/m3; 5 days/week, 6h/day). In two nose-only 90-day inhalation studies, with similar exposure design, Wistar rats were exposed to 0, 15, 150, 400mg/m3 diethanolamine (DEA) (DEA Study 1:13animals/sex, general subchronic study) and to 0, 1.5, 3, 8mg/m3 (DEA Study 2:10animals/sex) to specifically investigate respiratory tract toxicity. Only DEA induced systemic toxicity at or above 150mg/m3 (body and organ weight changes, clinical- and histo-pathological changes indicative for mild blood, liver, kidney and testicular effects). Neurotoxicity was not observed for both substances. Exposure to both substances resulted in laryngeal epithelial changes starting from 3mg/m3 for DEA (reversible metaplasia at the base of the epiglottis, inflammation at higher concentrations extending into the trachea) or from 20mg/m3 for TEA (focal inflammation, starting in single male animals). TEA appears to be less potent with respect to systemic toxicity and RT irritancy than DEA. The 90-day no adverse effect concentration" (NOAEC) for changes due to TEA exposure in the respiratory tract was 4.7mg/m3 derived by extrapolation from the NOAEC of the 28day study.

Investigations on cell proliferation in B6C3F(1) mouse liver by diethanolamine.

Diethanolamine (DEA) has been shown to induce liver tumours in B6C3F(1) mice in a previous 2-year dermal study. To elucidate the mode of action groups of eight male and eight female B6C3F1 mice were dermally exposed to daily DEA doses of 0 or 160 mg/kg body weight/day for 1 week. Reversibility was assessed after a 3-week treatment-free recovery period. Subsequently groups of 10 male B6C3F(1) mice were dermally exposed to daily DEA doses of 0 or 160 mg/kg body weight for 1, 4 or 13 weeks. Finally, groups of 8 male B6C3F(1) mice were dermally exposed to daily DEA doses of 0, 10, 20, 40, 80, and 160 mg/kg body weight for 1 and 13 weeks. Following a 1-week treatment, DEA caused increased cell proliferation (5-bromo-2'-deoxyuridine (BrdU) method) in zone 3 (central vein region) of the liver lobules at 160 mg/kg body weight. Reversibility of liver cell proliferation was demonstrated in the recovery phase. In the subsequent studies increased cell proliferation was observed at 10 mg/kg body weight or higher after 13 weeks of treatment. These results support the hypothesis that sustained liver cell proliferation is a potential non genotoxic mode of action by which DEA promotes liver tumours in B6C3F(1) mice.

Chemical substances and contact allergy--244 substances ranked according to allergenic potency.

From 1985 to 2001 a group consisting of thirty experts including dermatologists from universities, representatives from the chemical industry and from regulatory authorities elaborated and consequently decided on the potency ranking of chemicals with contact allergenic properties. These chemicals were defined either as synthetic chemicals or as chemicals identified as ingredients in natural products. On 244 substances clinical and experimental data on humans and results of animal tests as documented in the scientific literature were carefully collected and evaluated. This careful evaluation and assessment of these chemicals clearly demonstrate that ranking of substances according to their allergenic potency is possible and justified. It was decided to rank the most potent contact allergens in Category A of substances having significant allergenic properties. Substances with a solid-based indication of a contact allergenic potential and substances with the capacity of cross-reactions were listed in Category B and substances with insignificant or questionable allergenic effects were listed in Category C. An assessment of these compiled data is published here. Three Appendices give a comprehensive overview of the 98 substances listed in Category A, the 77 substances listed in Category B and the 69 substances listed in Category C.

A review of potential human carcinogenicity of the chlorophenoxy herbicides MCPA, MCPP, and 2,4-DP.

For the purpose of assessing the human carcinogenic potential of the chlorophenoxy herbicides MCPA, MCPP, and 2,4-DP, the relevant epidemiological and toxicological evidence is reviewed. These compounds have not produced tumours in animal studies conducted under current test guidelines, giving no reason to predict that they would be carcinogenic to humans. Epidemiological studies have been conducted on three continents; greater emphasis is placed on the studies reported from western Europe, however, as this has been the area of more use. Although several of these studies provide suggestive evidence of associations between exposure to chlorophenoxy compounds and increased risks for some uncommon cancers, it is inconsistent and far from conclusive. None of the evidence specifically implicates MCPA, MCPP, or 2,4-DP as human carcinogens.

X-ray microanalysis and chlorotetracycline staining of calcium vesicles in the green alga Mougeotia.

Calcium ions have been proposed to play a key role in the sensory transduction of phytochrome-governed chloroplast movement in the green alga Mougeotia. To test this hypothesis, the intracellular pattern of calcium distribution was studied in this alga by two independent techniques, namely, X-ray microanalysis of fixed and of unfixed frozen-hydrated cells, as well as in vivo fluorescence by chlorotetracycline. Both methods of detection reveal a significant compartmentation of calcium in vesicles close to the chloroplast edge and, less frequently, in the cortical cytoplasm. Microfilaments, presumably actin, which could function in driving chloroplast movement, have been observed running between the chloroplast edge and the cortical cytoplasm (Wagner, G., Klein, K. (1978) Photochem. Photobiol. 27, 137). The vesicular calcium concentration is stable and decays only slowly in the absence of extracellular calcium much in the same way as the ability of the chloroplast to perform movements decreases. A functional relationship between vesicular calcium compartmentation and phytochrome-governed chloroplast movement in the green alga Mougeotia seems indicated.