Accidental exposures acute toxicity

Most organophosphates are readily absorbed by oral, inhalational, and dermal routes of exposure. Acute toxicity is generally related to either accidental or deliberate ingestion or to occupational exposure. It is accepted that low-level exposure on foods and in the environment is not sufficient to cause human health signs of nervous system toxicity such as described above. This is true even... 

Dihydroxybenzenes (DHBs) are slightly more acutely toxic than phenol (Table 5). Contact with dihydroxybenzene through oral, dermal, or respiratory routes can induce significant systemic exposure. Skin or eye effects have been demonstrated during chronic or accidental professional exposure. No systemic effect has been described in such circumstances. 

Data on acute exposures of humans to both isomers of dimethylhydrazine are limited to case reports of accidental exposures. Signs and symptoms of exposure include respiratory irritation, pulmonary edema, nausea, vomiting, and neurologic effects. However, definitive exposure data (concentration and duration) were unavailable for these accidents. The limited data in humans suggest that the nonlethal toxic response to acute inhalation of dimethylhydrazine is qualitatively similar to that observed in animals. No information was available regarding lethal responses in humans. In the absence of quantitative data in humans, the use of animal data is considered a credible approach for developing AEGL values. 

Threshold Limit Value-Short Term Exposure Limit (TLV-STEL) - the concentration to which workers can be exposed continuously for a short period of time without suffering from (1) irritation (2) chronic or irreversible tissue damage or (3) narcosis of sufficient degree to increase the likelihood of accidental injury, impair self-rescue, or materially reduce work efficiency, provided that the daily TLV-TWA is not exceeded. It is not a separate independent exposure limit rather, it supplements the TWA limit where there are recognized acute toxic effects from a substance whose toxic effects are primarily of a chronic nature. STELs are recommended only where toxic effects have been reported from high short-term exposures in either humans or animals. 

Workers exposed to an airborne fluoride concentration of 5mg/m complained of eye and respiratory tract irritation and nausea. The lethal oral dose of sodium fluoride for humans has been estimated to be 32-65 mg F/kg of body weight. Effects from ingestion are diffuse abdominal pain, diarrhea, and vomiting excessive salivation, thirst, and perspiration painful spasms of the limbs and sometimes albuminuria." Gastrointestinal effects produced after the acute ingestion of toxic amounts of fluoride likely arise from the corrosive action of hydrofluoric acid, which is produced within the acidic environment of the stomach. Cardiac arrest after accidental exposure to high levels of fluoride has been attributed to the development of hypocalcemia and/or hyperkalemia. ... 

Deaths from occupational exposure have been reported, usually after massive accidental exposures. Data from human poisonings by methyl parathion are not sufficiently detailed to identify the range between the doses producing first symptoms and those producing severe or fatal intoxication.The probable oral lethal dose is 5-50mg/kg. Most animal data and limited human data indicate that methyl parathion is somewhat less acutely toxic than parathion. ... 

Exposure to toxicants can vary, producing what is known as acute or chronic poisoning. Poisoning can also be classified according to the intent of use. Poisoning can either be suicidal (non-accidental) or accidental in nature. Recreational poisoning, such as substance abuse, can be a source of harmful intoxication and, in some cases, can lead to addiction and withdrawal symptoms. Intentional harm is observed when there is criminal doping with sedative-hypnotic medicines, often associated with robberies. 

Acute Toxicity Associated with Occupational Exposure in Humans and Accidental Exposure of Domestic Animals... 

Effects of PTE are summarised in Table 11.6, together with the maximum concentration limits (MCL) in drinking water (source EPA and WHO). PTE at high concentrations are acutely toxic to humans. High concentrations are rare in urban wastewater, but could possibly result from accidental spills, although there is limited exposure from this route. The major concern is exposure to low concentrations over longer time periods. This is chronic exposure and may have more subde effects. 

The National Advisory Committee for Acute Exposure Guideline Levels for Hazardous Substances (NAC/AEGL Committee) was established to develop scientifically credible short-term exposure limits for approximately 400 to 500 acutely toxic substances. These short-term exposure limits, referred to as acute exposure guideline levels, or AEGLs, are essential for emergency planning, response, and prevention of accidental releases of chemical substances. Further, it is important that the values developed be scientifically credible so that effective planning, response, and prevention can be accomplished. 

Acute dermal toxicity Rat Accidental exposure or skin... 

Most of the examples presented so far have concerned ingestion — the oral route of exposure. Acute exposures by other routes can also lead to toxicity. Animal or insect venoms may be injected directly into the blood as a result of biting or stinging. Accidental releases to the air of volatile agents can lead to toxicity in the airways or lungs, and there... 

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