Acute Toxic Concentration

Health nd Safety Factors. Isophorone is considered moderately toxic by ingestion and skin contact. Some rat tumor formation evidence has been found (264), but no demonstration as a human carcinogen has been proven. Isophorone is considered an Environmental Protection Agency (EPA) priority pollutant, and has a permissible acute toxicity concentration of 117, 000 ///L to protect freshwater aquatic life, 12, 900 ///L to protect saltwater aquatic life, and 5, 200 ///L to protect human life (265). Isophorone is mildly toxic by inhalation, but because of its low volatiUty it is not a serious vapor hazard. 

The results of metabolism studies with laboratory animals and livestock indicate that endosulfan does not bioconcentrate in fatty tissues and milk. Lactating sheep administered radiolabeled endosulfan produced milk containing less than 2% of the label. Endosulfan sulfate was the major metabolite in milk (Gorbach et al. 1968). A half-life of about 4 days was reported for endosulfan metabolites in milk from survivors of a dairy herd accidentally exposed to acutely toxic concentrations of endosulfan endosulfan sulfate accounted for the bulk of the residues detected in the milk (Braun and Lobb 1976). No endosulfan residues were detected in the fatty tissue of beef cattle grazed on endosulfan-treated pastures for 31-36 days (detection limits of 10 ppm for endosulfan, 40 ppm for endosulfan diol) the animals began grazing 7 days after treatment of the pastures. Some residues were detected in the fatty tissue of one animal administered 1.1 mg/kg/day of endosulfan in the diet for 60 days. No endosulfan residues were... 

The New Jersey Department of Environmental Protection uses the TXDS method of consequence analysis to estimate potentially catastrophic quantities of toxic substances, as required by the New Jersey Toxic Catastrophe Prevention Act (TCPA). An acute toxic concentration (ATC) is defined as the concentration of a gas or vapor of a toxic substance that will result in acute health effects in the affected population and 1 fatality out of 20 or less (5% or more) during a 1-hr exposure. ATC values, as proposed by the New Jersey Department of Environmental Protection, are estimated for 103 extraordinarily hazardous substances and are based on the lowest value of one of the following (1) the lowest reported lethal concentration (LCLO) value for animal test data, (2) the median lethal concentration (LC50) value from animal test data multiplied by 0.1, or (3) the IDLH value. 

In terms of organic food quality, the question is then whether high, acutely toxic concentrations occur in the relevant plant foods and if so, what production factors are important to predict and preferably prevent this from happening, or if other measures can be used to alleviate the harmful effects. 

Exposure to acutely toxic concentrations of nerve agents can result in excessive bronchial, salivary, ocular and intestinal secretions, sweating, miosis, bronchospasm, intestinal hypermotility, bradycardia, muscle fasciculations, twitching, weakness, paralysis, loss of consciousness, convulsions, depression of the central respiratory drive, and death (Grob and Harvey, 1953 Grob, 1956 Marrs, 2007 Sidell, 1997 Yanagisawa et al, 2006 many others). Minimal effects observed at low vapor concentrations... 

Studies of occupational exposures to sulfur mustard indicate an elevated risk of respiratory tract and skin tumors following long-term exposure to acutely toxic concentrations. Overall, several factors are important regarding the assessment of the carcinogenicity of sulfur mustard. Increased cancer incidence in humans appears to be associated only with exposures that caused severe acute effects, and occupational exposures tended to involve repeated exposures and repeated injury of the same tissues. Because the therapeutic use of the sulfur mustard analog nitrogen mustard is associated with an increased incidence of CML, the reports of CML in HD-exposed individuals appear to be relevant to the eareinogenicity of sulfur mustard. 

Acutely toxic concentration/levels (New Jersey/Delaware)... 

For its Toxic Catastrophe Prevention Act (TCPA), New Jersey defined the Acutely Toxic Concentration as the lowest of ... 

The Acute Toxicity Concentration (ATC) as used by the State of Delaware is defined as being the lowest reported concentration of the substance that will cause death or permanent disability from an exposure of 1 hour. The order of preference for determining ATC is ... 

EVP is the substance s vapor pressure in mmHg at 20°C ATC (which has the same value as ERPG-3) is its acute toxicity concentration in ppm, defined as the lowest reported concentration based on recognized scientific test protocols that can cause death or permanent injury to humans after a single exposure of 1 hour or less. The constant 760 converts the vapor pressure from mmHg to atmospheres. 

Within the context of the EPA s statement, it is now usehil to examine the minimum database that the EPA beheves is needed to determine acutely toxic concentrations. The rationale behind estabhshing a minimum database is as follows ... 

A total of 29.8 5.31 ig sulfur mustard per animal was absorbed, 90% of which remained in the skin. This result agrees with an in vitro study by Hattersley et al. (2008) using human skin samples, which confirmed that a depot of sulfur mustard existed for at least 24 h following dermal exposure, and estimated concentrations in skin is at least 20 times above the acutely toxic concentration. 

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