Chemical chronic

Finely divided aluminum dust is moderately flammable and explodes by heat or contact with strong oxidizing chemicals. Chronic inhalation of the powder can cause aluminosis, a type of pulmonary fibrosis. It is almost nontoxic by ingestion. 

The Environmental Criteria and Assessment Office in Cincinnati (ECAO-Cin) of the U.S. Environmental Protection Agency (EPA) has been preparing health risk assessment documentation and developing methods useful for assessment of health hazards for single chemical chronic exposure for several years (1,2). 

Risk Assessment for Single Chemical Chronic Exposure and Chemical Mixtures... 

Separate from the acute toxicity endpoints described above, one must be concerned about the long-term effects of exposure to chemicals. Chronic toxicity is particularly insidious because effects may not be felt by the individual(s) for years (or even decades) before serious effects such as cancer become apparent, which may by then be too late to treat. Cancer can result from many sources, cigarette smoking and genetic disorders being notable examples, but the public is also very concerned about cancer and other serious health effects which may result from exposure to synthetic chemicals. Repeated or continuous exposure to low levels of chemicals over an extended period ( chronic exposure ) is of primary concern and therefore a focus of the EPA under the TSCA. 

In the Green Screen the hazards of a chemical are defined by its potential to cause acute or chronic adverse effects in humans or wildlife, its fate in the environment, and certain physi-cal/chemical properties of concern to human health. Acute mammalian toxicity (lethality) and irritation of the skin or eye are examples of acute adverse effects that can result from inhalation, ingestion, or dermal contact with a chemical. Chronic effects occur after repeated exposures and include cancer and adverse effects to the reproductive, neurological, endocrine, or immune systems. 

Ghanei, M., Hosseini, A.R., Arabbaferani, Z., 2005. Evaluation of chronic cough in chemical chronic bronchitis patients. Environ. Toxicol. Pharmacol. 20 (1), 6-10. 

The third of the major hazards and the one with the greatest disaster potential is the release of toxic chemicals. The hazard posed by toxic release depends not only on the chemical species but also on the conditions of exposure. The high disaster potential from toxic release arises in situations where large numbers of people are briefly exposed to high concentrations of toxic material, i.e., acute exposure. However, the long-term health risks associated with prolonged exposure at low concentrations, i.e., chronic exposure, also present serious hazards. 

Workers in the metals treatment industry are exposed to fumes, dusts, and mists containing metals and metal compounds, as well as to various chemicals from sources such as grinding wheels and lubricants. Exposure can be by inhalation, ingestion, or skin contact. Historically, metal toxicology was concerned with overt effects such as abdominal coHc from lead toxicity. Because of the occupational health and safety standards of the 1990s such effects are rare. Subtie, chronic, or long-term effects of metals treatment exposure are under study. An index to safety precautions for various metal treatment processes is available (6). As additional information is gained, standards are adjusted. 

In additional EPA studies, subchronic inhalation was evaluated ia the rat for 4 and 13 weeks, respectively, and no adverse effects other than nasal irritation were noted. In the above-mentioned NTP chronic toxicity study ia mice, no chronic toxic effects other than those resulting from bronchial irritation were noted. There was no treatment-related increase ia tumors ia male mice, but female mice had a slight increase in bronchial tumors. Neither species had an increase in cancer. Naphthalene showed no biological activity in other chemical carcinogen tests, indicating Htde cancer risk (44). No incidents of chronic effects have been reported as a result of industrial exposure to naphthalene (28,41). 

Chemical Toxicity. Radiopharmaceuticals are subject to the same requirements for safety as are other pharmaceuticals, and are tested for chemical toxicity in much the same manner. It is generally understood, however, that patients are likely to receive relatively few doses of any given radiopharmaceutical so that the effects of long-term chronic exposure to the compound rarely need be assessed. Safety margins, that is, the ratio of the adininistered dose to the lowest dose that produces an observable effect, are usually on the order of 100 or more. 

Monoamine Oxidase Inhibitors. MAOIs inactivate the enzyme MAO, which is responsible for the oxidative deamination of a variety of endogenous and exogenous substances. Among the endogenous substances are the neurotransmitters, norepinephrine, dopamine, and serotonin. The prototype MAOI is iproniazid [54-92-2] (25), originally tested as an antitubercular dmg and a close chemical relative of the effective antitubercular, isoniazid [54-85-3] (26). Tubercular patients exhibited mood elevation, although no reHef of their tuberculosis, following chronic administration of iproniazid. In... 

The likelihood that materials will produce local effects in the respiratory tract depends on their physical and chemical properties, solubiHty, reactivity with fluid-lining layers of the respiratory tract, reactivity with local tissue components, and (in the case of particulates) the site of deposition. Depending on the nature of the material, and the conditions of the exposure, the types of local response produced include acute inflammation and damage, chronic... 

Along with increasing evidence of health benefits from consumption of vitamins at levels much higher than RE) A recommendations comes concern over potential toxicity. This topic has been reviewed (19). Like all chemical substances, a toxic level does exist for each vitarnin. Traditionally it has been assumed that all water-soluble vitamins are safe at any level of intake and all fat-soluble vitamins are toxic, especially at intakes more than 10 times the recommended allowances. These assumptions are now known to be incorrect. Very high doses of some water-soluble vitamins, especially niacin and vitamin B, are associated with adverse effects. In contrast, evidence indicates that some fat-soluble micronutrients, especially vitamin E, are safe at doses many times higher than recommended levels of intake. Chronic intakes above the RDA for vitamins A and D especially are to be avoided, however. 

Materials that on intense or continued hut not chronic exposure could cause temporary incapacitation or possible residual injury 2 Materials that must he moderately heated or exposed to relatively high ambient temperatures before ignition can occur 2 Materials that readily undergo violent chemical change at elevated temper atiires and pressures or which react violently with water or which may form explosive mixtures with water... 

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