The use of hematological effects in the development of minimal risk levels.
ABSTRACT The Agency for Toxic Substances and Disease Registry (ATSDR) derives minimal risk levels (MRLs) to assist in evaluating risk of adverse health effects in individuals exposed to hazardous substances. MRLs are derived from published values identifying no-observed-adverse-effect levels (NOAELs) or lowest-observed-adverse-effect levels (LOAELs) in animal or human studies. The most sensitive end points are used. To date, 4 inhalation MRLs and 13 oral MRLs have been derived from hematological end points for 12 substances. This paper provides a brief overview of the hematological system, examples of hematological end points, and the MRL for substances with hematological end points.
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ABSTRACT: Nitrites and nitrates possess a unique position in human toxicology. They are both ubiquitous in the environment and can be formed from nitrogenous compounds. Water, vegetables and meat are important sources of nitrite exposure. Nitrites have several detrimental effects on health. The primary health concern regarding nitrate and nitrite exposure is the formation of methemoglobinemia. Baby food and infant formulas can be important sources of nitrite and infants younger than six months are the most susceptible population. Furthermore, nitrites react with primary, secondary, or tertiary amines in an acid medium and form nitrosamines many of which are known to cause cancer. Health care providers, governments and health authorities should be aware of the routes of nitrite exposure and must have knowledge to assess the hazards. This review will focus on the detrimental effects of nitrite exposure, the possible outcomes and standards put by regulatory authorities to prevent high nitrite exposure especially for susceptible populations.Gazi University Journal of Science GU J Sci. 01/2010; 23:261-270.
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ABSTRACT: A study was undertaken within the context of the U.S. EPA HPV Chemical Challenge Program to 1) characterize relationships between PAC content and repeat-dose toxicities of high-boiling petroleum substances (HBPS) and 2) develop statistical models that could be used to predict the repeat-dose toxicity of similar untested substances. The study evaluated 47 repeat-dose dermal toxicity and 157 chemical compositional studies. The four most sensitive endpoints of repeat-dose toxicity were platelet count, hemoglobin concentration, relative liver weight and thymus weight. Predictive models were developed for the dose-response relationships between the weight percent concentration of each of seven ring classes of aromatic compounds (the "ARC profile") and specific effects, with high correlations (r = 0.91-0.94) between the observed and model-predicted data. The development of the mathematical models used to generate the results reported in this study is described by Nicolich et al. (2013). Model-generated dose-response curves permit the prediction of either the effect at a given dose or the dose that causes a given effect. The models generate values that are consistent with other standard measures. The models, using compositional data, can be used for predicting the repeat-dose toxicity of untested HBPS.Regulatory Toxicology and Pharmacology 06/2013; · 2.13 Impact Factor
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ABSTRACT: Contamination of the environment with antimony compounds may affect human health through the persistent exposure to small doses over a long period. Sixty growing male albino rats, weighing 43-57 grams, utilized in this study. The animals were divided into 3 groups; each of 20 rats: animals of group I served as control, animals of group II received 6 mg/kg body weight antimony trisulfide daily for 8 weeks with drinking water, and those of group III received the same dose by the same route for 12 weeks. The Malpighian renal corpuscles showed distortion, destruction and congestion of glomerular tuft, vacuoles in the glomeruli, peritubular haemorrhage, obliteration of Bowman's space, and thickening with irregularity of Bowman's membrane. The proximal convoluted tubules demonstrated patchy loss of their brush border, thickening of the basement membrane with loss of its basal infoldings, disarrangement of the mitochondria, pleomorphic vacuoles in the cytoplasm, apical destruction of the cells, apical migration of the nuclei, and absence of microvilli. On the other hand, peri-tubular hemorrhage, apical vacuolation, small atrophic nuclei, swelling of mitochondria, obliteration of the lumina, destruction of cells, and presence of tissue debris in the lumina, were observed in the distal convoluted tubules. The present work demonstrated the hazardous effect of antimony on the renal function as evidenced by the significant increase of the level of blood urea, serum creatinine, and serum sodium and potassium. In conclusion, this study proposed that continuous oral administration of antimony for 8 and 12 weeks has hazardous toxic effect on the structure and function of the kidney in growing albino rat. Based on the results of the present study, it is recommended to avoid the use of any drinking water contaminated with antimony compounds and forbidden its use in infants and children foods.International journal of clinical and experimental pathology 01/2013; 6(8):1467-80. · 1.78 Impact Factor