Exposure levels diazinon

Most of the signs and symptoms resulting from diazinon poisoning are due to the inhibition of an enzyme called acetylcholinesterase in the nervous system. This enzyme is also found in your red blood cells and a similar enzyme (serum cholinesterase) is found in blood plasma. The most common test for exposure to many organophosphorus insecticides, including diazinon, is to determine the level of cholinesterase activity in the red blood cells or plasma. This test requires only a small amount of blood and is routinely available in your doctor s office. It takes time for this enzyme to completely recover to normal levels following exposure. Therefore, a valid test may be conducted a number of days following the suspected exposure. This test indicates only exposure to an insecticide of this type. It does not specifically show exposure to diazinon. 

Estimates of exposure levels posing minimal risk to humans (Minimal Risk Levels or MRLs) have been made for diazinon. An MRL is defined as an estimate of daily human exposure to a substance that is likely to be without an appreciable risk of adverse effects (noncarcinogenic) over a specified duration of exposure. MRLs are derived when reliable and sufficient data exist to identify the target organ(s) of effect or the most sensitive health effect(s) for a specific duration within a given route of exposure. MRLs are based on noncancerous health effects only and do not consider carcinogenic effects. MRLs can be derived for acute-, intermediate-, and chronic-duration exposures for inhalation and oral routes. Appropriate methodology does not exist to develop MRLs for dermal exposure. 

Table 2-1. Levels of Significant Exposure to Diazinon - Inhalation... 

Acute- and chronic-duration inhalation exposure MRLs for diazinon were not derived because of a lack of suitable studies in the literature. Since diazinon is not volatile, inhalation exposure near toxic waste sites is probably less likely than oral or dermal exposure. However, the potential risk of adverse health effects from inhalation exposure to diazinon cannot be assessed without information on the levels actually present in the air around the site. The MRL level of 0.009 mg diazinon/m3 should be protective for individuals living near waste sites. NIOSH has recommended a Permissible Exposure Level (PEL) of 0.1 mg diazinon/m3 to protect the health of individuals who regularly use diazinon in their work the MRL level of... 

Hepatic Effects. No hepatic effects were reported in humans from exposure to low doses of diazinon by any route. Hepatic effects reported in human studies were associated with acute high levels of diazinon such as are found in suicide attempts (Limaye 1966). The acute- and intermediate-duration oral exposure to diazinon in animals reduced the activity of a variety of hepatic enzymes (Anthony et al. 1986 Mihara et al. 1981). Liver pathology has also been observed in animals following chronic oral exposure to diazinon. The pathological changes reported in one study included fatty infdtrations, parenchymal atrophy,... 

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