Chemical testing health effects

A list of danger categories is given in Table 14.2. Note that chemicals may possess several hazards, e.g. nitric acid is classed as both an oxidizer and a conosive. If a chemical is not in one of these categories it is not generally considered to be dangerous. If the hazards of a new chemical have not been established it should be labelled Caution - substance not yet fully tested . Mixtures can be classified either from results from tests on the preparation, or by calculation to predict the healtli effects of the product based on the properties of individual components and tlieu concentration in the mixture. Preparations need to be classified for both physico-chemical and health effects but, to date, not for environmental effects. 

This database contains unpublished test data which is submitted to EPA by industries. It includes tests pertaining to a chemical s health effects, environmental effects, and environmental fate. 

One way to see if a chemical will hurt people is to learn how the chemical is absorbed, used, and released by the body for some chemicals, animal testing may be necessary. Animal testing may also be used to identify health effects such as cancer or birth defects. Without laboratory animals, scientists would lose a basic method to get information needed to make wise decisions to protect public health. Scientists have the responsibility to treat research animals with care and compassion. Laws today protect the welfare of research animals, and scientists must comply with strict animal care guidelines. 

Several medical tests can determine whether you have been exposed to methyl parathion. The first medical test measures methyl parathion in your blood or measures 4-nitrophenol, which is a breakdown product of methyl parathion, in your urine. These tests are only reliable for about 24 hours after you are exposed because methyl parathion breaks down quickly and leaves your body. These tests cannot tell whether you will have harmful health effects or what those effects may be. The next medical test measures the levels of a substance called cholinesterase in your blood. If cholinesterase levels are less than half of what they should be and you have been exposed to methyl parathion, then you may get symptoms of poisoning. However, lower cholinesterase levels may also only indicate exposure and not necessarily harmful effects. The action of methyl parathion may cause lower cholinesterase levels in your red blood cells or your blood plasma. Such lowering, however, can also be caused by factors other than methyl parathion. For example, cholinesterase values may already be low in some people, because of heredity or disease. However, a lowering of cholinesterase levels can often show whether methyl parathion or similar compounds have acted on your nerves. Cholinesterase levels in red blood cells can stay low for more than a month after you have been exposed to methyl parathion or similar chemicals. For more information, see Chapters 3 and 7. 

However, a sample taken in the doctor s office can be properly packed and shipped to a special laboratory, if necessary. Because endosulfan leaves the body fairly quickly, these methods are useful only for finding exposures that have occurred within the last few days. At this time, these methods can only be used to prove that a person has been exposed to endosulfan. The test results cannot be used to predict if you wiU have any adverse health effects. Exposure to other chemicals at the same time at hazardous waste sites could cause some confusion in understanding these results. More information about tests to find endosulfan in the body is presented in Chapters 2 and 6. 

Since simultaneous health effect surveys were conducted in the Love Canal area, environmental test results In the homes adjoining the Canal were examined in an effort to demonstrate the presence or absence of correlations between environmental chemical levels and frequencies of particular health abnormalities. This effort was largely unsuccessful, since the total exposed population proved to be too small for meaningful interpretation of most health endpoints of Interest and since difficulties in controlling for subjective reporting of health symptoms made it difficult to Interpret health survey results O, ). 

TSCATS is an online index to unpublished, nonconfidential studies covering chemical testing results and adverse effects of chemicals on health and ecological systems. The studies are submitted by US industry to EPA under several sections of the Toxic Substance Control Act (TSCA). There are four types of documents in the database Section 4 chemical testing results, Section 8(d) health and safety studies, Section 8(e) substantial risk of injury to health or the environment notices, and voluntary documents submitted to EPA known as a For Your Information (FYI) notice. 

The literature emphasizes that arsenic metabolism and toxicity vary greatly between species and that its effects are significantly altered by numerous physical, chemical, and biological modifiers. Adverse health effects, for example, may involve respiratory, gastrointestinal, cardiovascular, and hematopoietic systems, and may range from reversible effects to cancer and death, depending partly on the physical and chemical forms of arsenic tested, the route of administration, and the dose. 

The lack of information is well illustrated by trying to examine the costs and benefits of TSCA. The major benefits of the act are the adverse health effects avoided by whatever actions are taken under the act s authority or because of the act s existence. But for many actions, such as voluntary testing by industry, we are not sure whether to attribute the action to TSCA s existence. We also are not sure how to relate such actions to reduced exposure to potentially hazardous chemicals. Insofar as exposure is reduced, we usually do not have any precise idea of the health consequences of such reduced exposure. And even if we knew the health consequences we would not know how to place a dollar value on them. 

Specific contaminants that are components of total petroleum hydrocarbons, such as BTEX (benzene, toluene, ethylbenzene, and xylene), n-hexane, jet fuels, fuel oils, and mineral-based crankcase oil have been studied and a number of toxicological profiles have been developed on individual constituents and petroleum products. However, the character of the total petroleum hydrocarbons has not been studied extensively and no profiles have been developed. Although several toxicological profiles have been developed for petroleum products and for specific chemicals found in petroleum, the total petroleum hydrocarbon test results have been too nonspecific to be of real value in the assessment of its potential health effects. 

A) The study of the types of adverse health effects produced by chemicals under various conditions of exposure. Epidemiologists are similarly engaged in their studies of exposed human populations. Toxicologists are usually in the laboratory, carrying out experiments in animals and other test systems. 

Although we can measure the amount of chloroform in the air that you breathe out, and in blood, urine, and body tissues, we have no reliable test to determine how much chloroform you have been exposed to or whether you will experience any harmful health effects. The measurement of chloroform in body fluids and tissues may help to determine if you have come into contact with large amounts of chloroform. However, these tests are useful only a short time after you are exposed to chloroform because it leaves the body quickly. Because it is a breakdown product of other chemicals (chlorinated hydrocarbons), chloroform in your body might also indicate that you have come into contact with those other chemicals. Therefore, small amounts of chloroform in the body may indicate exposure to these other chemicals and may not indicate low chloroform levels in the environment. From blood tests to determine the amount of liver enzymes, we can tell whether the liver has been damaged, but we cannot tell whether the liver damage was caused by chloroform. 

A few days after exposure, blood levels of heptachlor and heptachlor epoxide decrease and can no longer be measured. Therefore, blood tests for these chemicals must be done within a short period after exposure. Levels in fat can be measured for a much longer period after exposure. If heptachlor or heptachlor epoxide is found in your fat, it is not possible to tell when you were exposed to these chemicals or if harmful health effects will occur. See Chapters 2 and 6 for more information on detecting these chemicals in the environment or in human tissues. 

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