Exposure general population

Chromium Exposure Levels and U.S. Government Regulations. The level of exposure to chromium compounds for employees in industry and for the general population via waste disposal and industrial emissions is the subject of much regulation, research, and controversy. Some U.S. Government regulations, such as the Comprehensive Environmental Response, Compensation, and LiabiUty Act (CERCLA), also known as the Superfund Act, make no distinction as to the oxidation state of chromium (144). However, there is valence distinction in other regulations. 

The radiological hazard of tritium to operating personnel and the general population is controlled by limiting the rates of exposure and release of material. Maximum permissible concentrations (MPC) of radionucHdes were specified in 1959 by the International Commission on Radiological Protection (79). For purposes of control all tritium is assumed to be tritiated water, the most readily assimilated form. The MPC of tritium ia breathing air (continuous exposure for 40 h/wk) is specified as 185 kBq/mL (5 p.Ci/mL) and the MPC for tritium in drinking water is set at 3.7 GBq/mL (0.1 Ci/mL) (79). The maximum permitted body burden is 37 MBq (one millicurie). Whenever bioassay indicates this value has been exceeded, the individual is withdrawn from further work with tritium until the level of tritium is reduced. 

The harmful effects of industrial emissions are not confined to the workers but extend beyond the plant boundary line. Chemically-induced diseases among workers exposed to industrial chemicals are a warning sign of the risks to which a larger population is also being exposed usually the chemical hazards are in principle similar in the occupational and general environment. However, occasionally environmental exposures can be qualitatively different from the occupational environment and may also cause deleterious health effects in the general population. 

In densely populated areas, traffic is responsible for massive exhausts of nitrous oxides, soot, polyaromatic hydrocarbons, and carbon monoxide. Traffic emissions also markedly contribute to the formation of ozone in the lower parts of the atmosphere. In large cities, fine particle exposure causes excess mortality which varies between one and five percent in the general population. Contamination of the ground water reservoirs with organic solvents has caused concern in many countries due to the persistent nature of the pollution. A total exposure assessment that takes into consideration all exposures via all routes is a relatively new concept, the significance of which is rapidly increasing. 

GENERAL POPULATION AND OCCUPATIONAL EXPOSURE EXPOSURES OF CHILDREN... 

The greatest potential for exposure of the general population to methyl parathion is by consumption of food containing residues from spray applieations of the inseetieide. In a 10-year study, methyl parathion was found at an average concentration of 0.0035 ppm in a few examples of ready-to-eat foods. Concentrations in the range of 0.05-2.0 ppm were reported in 0.5% of the samples of domestie and... 

Dermal exposure to methyl parathion is not likely to be a health concern to the general population, with the possible exception of individuals in the immediate vicinity of a field during application of the pesticide. Dermal exposure, however, is a major source of exposure for workers directly involved in the manufacture, application, and cleanup of the chemical, and for field workers. Laundry workers cleaning the clothing of such workers may also be exposed. 

Due to a nascent understanding of the use and interpretation of biomarkers, implementation of biomarkers as tools of exposure in the general population is very limited. A biomarker of exposure is a xenobiotic substance or its metabolite(s), or the product of an interaction between a xenobiotic agent and some target molecule(s) or cell(s) that is measured within a compartment of an organism (NAS/NRC 1989). The preferred biomarkers of exposure are generally the substance itself or substance-specific metabolites in readily obtainable body fluid(s) or excreta. However, several factors can confound the use and... 

Unusually susceptible populations are those groups of individuals who respond more quickly or at lower exposure levels than the general population to the toxic effects of methyl parathion. These responses may be genetic in origin or may be due to differences in development or life style factors such as nutrition or behavior, or due to preexisting disease states. 

There are insufficient data to determine potential daily inhalation and dermal exposure levels. However, based on the information presented in Seetions 6.3 and 6.4, exposure levels for the general population are probably very low by these routes. Inhalation exposure is not important for the general population, with the possible exception of those individuals living near areas where methyl parathion is frequently sprayed. Since methyl parathion is readily adsorbed through the skin, dermal eontact may be the most relevant exposure pathway. Dermal eontaet is most likely to oeeur in people who are occupationally exposed. 

Exposure of the general population to higher concentrations of methyl parathion may result from contact with, or ingestion of, contaminated hazardous waste site media, principally soils and water. No information was found in the available literature regarding the size of the human population potentially exposed to methyl parathion through contact with contaminated waste site media. 

Exposures of Children. More studies are needed to assess the exposures of children living in agricultural areas to methyl parathion residues in air, soil, or water. More studies are also needed to assess the exposures of children in the general population to residues of methyl parathion that might be present in food, milk, or water, or on contaminated clothing and skin from occupationally exposed household members. 

The limited toxicity data available for endosulfan suggest that several subgroups of the population may be more susceptible to endosulfan exposure than the general population. These subgroups include the unborn and neonates the elderly and people with liver, kidney, or neurological diseases, - effects that have been better characterized in animal studies. 

The most important routes of exposure to endosulfan for the general population are ingestion of food and the use of tobacco products with endosulfan residues remaining after treatment. Farmers, pesticide applicators, and individuals living in the vicinity of hazardous waste disposal sites contaminated with endosulfan may receive additional exposure through dermal contact and inhalation. 

Exposure to endosulfan residues in tobacco products could be another important source of general population exposure. Endosulfan residues in tobacco leaves and finished tobacco products were reviewed by EPA (1982a). Eor example, auction market tobacco had a mean residue of <0.2-14 ppm endosulfan and endosulfan sulfate in the early 1970s, and cigarettes sold in 1973 contained a mean residue of 0.83 ppm endosulfan. No information was found in the available literature regarding endosulfan concentrations in cigarette smoke. 

In addition to individuals who are occupationally exposed to endosulfan (see Section 5.5), there are several groups within the general population that have potentially high exposures (higher than background levels) to endosulfan. These populations include individuals living in proximity to sites where endosulfan was produced or sites where endosulfan was disposed of, and individuals living near one of the 162 NPL hazardous waste sites where endosulfan has been detected in some environmental media (HazDat 2000). 

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