Subchronic toxicity

Irritation Sensitization Acute systemic toxicity Subchronic toxicity Local tolerance... 

The details of several other toxicological tests (namely, repeated-dose toxicity, subchronic toxicity, chronic toxicity, genotoxicity, mutagenicity, teratogenicity, carcinogenicity, neurotoxicity, and ecotoxicology) and the methods, purposes, and importance of safety evaluation studies to achieve human health have been discussed... 

See also Organochlorine Insecticides. Toxicity, Chronic Toxicity, Subchronic. 

See also Ames Test Analytical Toxicology Animal Models Biomarkers, Human Health Epidemiology Good Laboratory Practices (GLP) In Vitro Test In Vivo Test Risk Assessment, Human Health Risk Characterization Toxicity, Acute Toxicity, Chronic Toxicity, Subchronic. 

Acute inhalation toxicity Subchronic inhalation toxicity... 

See a/so Analytical Toxicology LD50/LC50 (Lethal Dosage 50/Lethal Concentration 50) Levels of Effect in Toxicological Assessment Occupational Toxicology Pollution, Air Respiratory Tract Toxicity, Acute Toxicity, Chronic Toxicity, Subchronic. 

Toxicity, Subchronic, Pages 343-347, Donald J. Ecobichon SummaryPlus Full Text + Links PDF (95 K)... 

Tier II Oncogenicity Toxicity subchronic oral, dermal, and inhalation Cellular Immune Response Teratogenicity... 

Adverse effects can also be classified as chronic, subchronic, snbacnte, or acute. Chronic toxicity refers to cumulative damage after months or years of exposure to a toxicant. Subchronic usually describes an incidence of exposnre that lasts several weeks or months. Subacute indicates an exposnre event that is limited, bnt repeated more than once. Acute toxicity is the term for an immediate and often severe effect that is apparent after a single dose. A single compound may exert different effects at different exposure levels. For example, one acnte effect of benzene is central nervous system depression, while chronic benzene exposnre may canse bone marrow toxicity. 

Toxicity studies on trifluoroethanol show acute oral LD q, 240 mg/kg acute dermal LD q, 1680 mg/kg and acute inhalation L(ct) Q, 4600 ppmh. Long-term subchronic inhalation exposure to 50—150 ppm of the alcohol has caused testicular depression in male rats, but no effects were noted at the 10 ppm level (32). Although the significance of the latter observations for human safety is unknown, it is recommended that continuous exposure to greater than 5 ppm or skin contact with it be avoided. 

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). 

Some nonmalignant respiratory effects have been observed in experimental animals during acute or subchronic exposures. Soluble and moderately soluble compounds were more toxic than were insoluble compounds and produced different effects. Sulfate and subsulftde produced fibrosis whereas nickel oxide did not. 

Inhalation is the chief route of worker exposure. Comparative data from acute or subchronic inhalation exposures with rats (98) indicate that nitromethane and nitroethane are the least toxic of the nitroparaffins by this route and do not induce methemoglobin formation. The nitropropanes are less well tolerated 2-nitropropane is more toxic than 1-nitropropane and is more likely to cause methemoglobinemia. 

A commercially interesting low calorie fat has been produced from sucrose. Proctor Gamble has patented a mixture of penta- to octafatty acid ester derivatives of sucrose under the brand name Olestra. It was approved by the FDA in January 1996 for use as up to 100% replacement for the oil used in preparing savory snacks and biscuits. Olestra, a viscous, bland-tasting Hquid insoluble in water, has an appearance and color similar to refined edible vegetable oils. It is basically inert from a toxicity point of view as it is not metabolized or absorbed. It absorbs cholesterol (low density Hpoprotein) and removes certain fat-soluble vitamins (A, D, E, and K). Hence, Olestra has to be supplemented with these vitamins. No standard LD q tests have been performed on Olestra however, several chronic and subchronic studies were performed at levels of 15% in the diet, and no evidence of toxicity was found. No threshold limit value (TLV), expressed as a maximum exposure per m of air, has been estabhshed, but it is estimated to be similar to that of an inert hpid material at 5 mg/m. ... 

Subchronic Studies. Although short-term repeated exposure studies provide valuable information about toxicity over this time span, they may not be relevant for assessment of ha2ard over a longer time period. For example, the minimum and no-effects levels determined by short-term exposure may be significantly lower if exposure to the test material is extended over several months. Also, certain toxic effects may have a latency which does not allow their expression or detection over a short-term repeated-exposure period for example, kidney dysfunction or disturbances of the blood-forming tissues may not become apparent until subchronic exposure studies are undertaken. 

Chronic Toxicity Studies. With the exception of tumorigenesis, most types of repeated exposure toxicity are detected by subchronic exposure conditions. Therefore, chronic exposure conditions are usually conducted for the following reasons if there is a need to investigate the tumorigenic potential of a material if it is necessary to determine a no-effects or threshold level of toxicity for lifetime exposure to a material and if there is reason to suspect that particular forms of toxicity are exhibited only under chronic exposure conditions. 

A number of antioxidants have been accepted by the FDA as indirect additives for polymers used in food appHcations. Acceptance is deterrnined by subchronic or chronic toxicity in more than one animal species and by the concentration expected in the diet, based on the amount of the additive extracted from the polymer by typical foods or solvents that simulate food in their extractive effects. Only materials of insignificant risk to the consumer are regulated by the FDA for use in plastics contacted by food stuffs. 

Daly, IW. 1989. A 13-week subchronic toxicity study of methyl parathion in dogs via the diet followed by a one-month recovery period. Stilwell, KS Mobay Corporation. 

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