Health risk analysis limitations

It is not surprising that the data produced as total petroleum hydrocarbons (EPA 418.1) suffer from several shortcomings as an index of potential ground-water contamination or health risk. In fact, it does not actually measure the total petroleum hydrocarbons in the sample but rather, measures a specific range of hydrocarbon compounds. This is caused by limitations of the extraction process (solvents used and the concentration steps) and the reference standards used for instrumental analysis. The method specifically states that it does not accurately measure the lighter fractions of gasoline [benzene-toluene-ethylbenzene-xylenes fraction (BTEX)], which should include the benzene-toluene-ethylbenzene-xylenes fraction. Further, the method was originally a method for water samples that has been modified for solids, and it is subject to bias. 

Many methods are available for analysis of petroleum hydrocarbon products, particularly in water and soil matrices. The current literature includes a number of studies that document the performance and limitations of the commonly used methods. Method modifications and new methods are being investigated to provide better information about the petroleum component content of environmental samples. However, the available analytical methodology alone may not provide adequate information for those who evaluate the movement of petroleum components in the environment or evaluate the health risks posed to humans (Heath et al. 1993a). 

There are clear ethical constraints that prevent human research that could definitively answer the questions of concern regarding the military operational and civilian health risks of exposure to low-levels of chemical warfare nerve agents. Only three sources of relevant human data are available for analysis. These data are from either past human volunteer studies, reports based on accidental exposures, or reports of the consequences of malicious releases of the agents. While these sources are valuable, the data have some limitations for deriving dose-response relationships because of inferior analytical and clinical methods or the lack of precise estimates of exposure. 

Approximately 70% of evaluated companies store a dangerous substance classified as toxic or highly toxic. In approximately 25% of evaluated companies, the toxic substances are treated in such an amoimt and in such a physical form (gas, liquefied gas and highly volatile hquid) to be considered as possible threat for human health in the vicinity of the evaluated source of risk. Figure 2 shows the percentage occurrence of the use of individual software and methods in which acute toxicity limits are used. The versions of modeling software were not distinguished in the evaluation, because they were not always stated in risk analysis documents. The most often used software include TEREX (T-Soft 2000), SAVE II, ROZEX (TLP 2001), EFFECTS (TNO 2003), ALOHA (US ERA 2007) and CEI method (AIChE 1994). 

The detection of ammonium perchlorate, an important constituent of solid rocket propellants, in the ground waters of some U.S. federal states is alarming. Significant amounts have been measured in areas where rocket fuel, ammunition, or pyrotechnic articles are developed, tested, or manufactured. Even in low concentrations, perchlorate represents a health risk for human beings, because it affects hormone production in the thyroid. Initial investigations by the U.S. EPA indicate a health risk at perchlorate concentrations above 4-18 Hg/L. In California, perchlorate has been detected in more than 100 drinking water wells 20 of them had to be closed because they exceed the above-mentioned limit. Trace analysis of perchlorate is a difficult analytical task. Ion chromatogra-... 

Mineral Oil Hydraulic Fluids and Polyalphaolefin Hydraulic Fluids. Limited information about environmentally important physical and chemical properties is available for the mineral oil and water-in-oil emulsion hydraulic fluid products and components is presented in Tables 3-4, 3-5, and 3-7. Much of the available trade literature emphasizes properties desirable for the commercial end uses of the products as hydraulic fluids rather than the physical constants most useful in fate and transport analysis. Since the products are typically mixtures, the chief value of the trade literature is to identify specific chemical components, generally various petroleum hydrocarbons. Additional information on the properties of the various mineral oil formulations would make it easier to distinguish the toxicity and environmental effects and to trace the site contaminant s fate based on levels of distinguishing components. Improved information is especially needed on additives, some of which may be of more environmental and public health concern than the hydrocarbons that comprise the bulk of the mineral oil hydraulic fluids by weight. For the polyalphaolefin hydraulic fluids, basic physical and chemical properties related to assessing environmental fate and exposure risks are essentially unknown. Additional information for these types of hydraulic fluids is clearly needed. 

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