EXPOSURE-BASED

Exposures of Children. Data need to be developed to properly assess the exposure of infants who eat processed baby foods containing residues of pesticides such as endosulfan. Several studies have estimated exposure based on endosulfan concentration found in foods typically eaten by infants however, no studies that directly studied infant exposure could be located. Attention should also be given to infant formulas and to the tap water used to prepare infant formulas from condensed or powdered forms. More data are also required to properly assess endosulfan exposure to children who live, play, or attend school near farmlands that are treated with endosulfan. Maps that catalog endosulfan use on crops and present average application rates would better allow an assessment of the potential for children in farming communities to be exposed. The possibility that farming parents work clothes and shoes may carry endosulfan residues into the home also should be studied. In addition, home use of endosulfan, which may result in exposure of children, needs to be investigated. 

The potential for, and location of, exposure based on assigned worker duties, activities, and functions... 

Hydrogen sulfide is primarily absorbed through the lungs. It can also be absorbed through the gastrointestinal tract and the skin. Hydrogen sulfide is widely distributed in the body after inhalation exposure. Based on analyses of tissues from humans who died after accidental exposure, sulfides have... 

Interroute extrapolation. The values for pharmacokinetic variables in the Leggett Model are independent of the route of exposure. Based on the description of the inputs to the model provided by Leggett (1993), lead intake from different exposure routes is defined as a total lead intake from all routes of exposure. 

Oberst et al. (1956) exposed nine male Wistar rats to aniline at 5 ppm for 6 h/d, 5 d/ w for up to 26 w. Exposed rats developed a mild hemoglobinemia (0.6%) with some blueness of the skin during w 23 of exposure. Based on the slight increase of methemoglobin content and the absence of spleen toxicity, U.S. EPA (1994) considered this concentration a free-standing no-observed-adverse-effect level (NOAEL). 

The Dow indexes are useful for determining equipment spacing requirements. The F EI uses an empirical correlation based entirely on the F EI value to estimate the radius of exposure. It is assumed that any equipment located outside this distance would not be damaged by a fire or explosion. The CEI estimates the hazard distance for chemical exposure based on the emergency response planning guideline (ERPG) values for the particular material released. 

Figure 7 in the Dow index booklet provides the radius of exposure based on the F EI value. For this case the radius is 90 ft. Thus the unloading station must be located a minimum of 90 ft from any other equipment or processes. 

Gerberick, G. F., et al., Understanding fragrance allergy using an exposure-based risk assessment approach, Contact Derm. 45, 333-340, 2001. 

Hexachloroethane has been found in the plasma of workers wearing protective clothing and respiratory protection suggesting that hexachloroethane can be absorbed following inhalation and/or dermal exposure. Based on the minimal effects seen on target tissues (liver and kidney) in animal studies, absorption from the lungs seems to be limited. Dermal absorption was also estimated to be low based on calculated dermal penetration rates. 

Absorption, Distribution, Metabolism, and Excretion. There are no mechanistic or quantitative studies of hexachloroethane absorption from the lungs or across the gastrointestinal tract or skin. However, absorption does occur following oral exposure based on the appearances of hexachloroethane and its metabolites in blood, urine, and exhaled air (Fowler 1969b Gorzinski et al. 1985 Jondorf et al. 1957 Mitoma... 

Neurobehavioral changes were observed in rats (Clark and Pearson 1973) and mice (Clark et al. 1971) exposed orally for intermediate durations. Necrosis and atrophy of the optic nerve and retina in dogs (Uga et a1. 1977) were observed after oral exposure. Based on the results of the human and animal studies, neurological effects (subtle and/or overt) may occur regardless of the route of exposure. Additional animal studies do not seem to be warranted at this time. 

No information exists on reproductive effects in humans or animals after oral exposure. Based on the inhalation studies in animals which indicate the testes are a target tissue, it would be valuable to include histological examination of the testes in any intermediate- or chronic-duration oral studies in animals. In addition, tests of male reproductive success would be valuable in assessing the functional significance of any testicular lesions. 

Specific Sociai Anxiety Disorder, Acute Phase Treatment. Different strategies have evolved for treating specific social anxiety disorder versus generalized social anxiety disorder. Less complicated is the management of the specific subtype. Exposure-based psychotherapy is a mainstay of treatment, and as-needed medication doses prior to scheduled performances are also widely used. Preferred agents for performance anxiety are alprazolam or propranolol. 

Despite the uncertainty at which concentration BP A shows toxic effects, it is important to conclude that current human exposure, based on biomonitoring studies, is still far below the current TDI for the general population [224]. 

Pronounced increases were seen for total cancer, lymphatic and hematopoietic cancers, and leukemia in a mortality study of chlorohy-drin production workers." The investigators attributed the excesses to ethylene dichloride exposure based on probable exposures of the workers however, concomitant exposure to other chemicals precludes identifying the etiologic agent(s). 

Reproductive Toxicity. No data are available on the reproductive toxicity of hexachlorobutadiene in humans. Hexachlorobutadiene did not cause adverse reproductive effects in mice or rats after inhalation or oral exposures, even at dose levels causing kidney and liver damage (Harleman and Seinen 1979 Kociba etal. 1977a NIOSH 1981 NTP 1991 Saillenfait et al. 1989 Schwetzetal. 1977). No data are available on the reproductive toxicity of hexachlorobutadiene after dermal exposure. Based on existing data in animals, it does not appear that exposure to the compound would pose any significant risk to human reproduction. 

Chlorine dioxide is a strong oxidizing agent that is not likely to be widely distributed in biological systems or excreted as parent compound. Chlorite may be detected in tissues, blood, urine, and feces, which may serve as an indication of exposure to chlorine dioxide or chlorite. However, no information was located regarding the quantification of exposure based on measured levels of chlorite in biological samples. 

When the CS is presented repeatedly in the absence of the US, a reduction in the condition fear response occurs. This process is called extinction. It forms the basis for exposure-based psychotherapies for the treatment of anxiety disorders characterized by exaggerated fear responses. Individuals who show an abihty to quickly attenuate learned fear through a powerful and efficient extinction processes are hkely to fimction more effectively under dangerous conditions. 

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