take of pesticides. Generally, the FDA monitoring studies conclude that the U.S. food supply contains only very small amounts of pesticides that are not a concern. For more information, see Section 1.7 and Chapter 6.
How can malathion enter and leave my body?
For the general population, the most likely way that malathion can enter the body is by eating or drinking contaminated food or water or through dermal contact with contaminated plants, soils, or surfaces such as playground equipment or pavements. It can also enter your body if you breathe air containing malathion during or after it has been sprayed for public health uses. By any means of exposure, malathion enters your body quickly and passes into the bloodstream.
Once in your bloodstream, malathion can go to many organs and tissues. Most of the malathion is broken down in your liver into other substances, called metabolites. One of these metabolites is more harmful than malathion. Malathion and its metabolites do not tend to accumulate in the body, and leave mostly in your urine within a few days.
See Chapter 3 for more information on how malathion enters and leaves the body.
How can malathion affect my health?
Malathion interferes with the normal function of the nervous system. Because the nervous system controls many other organs, malathion indirectly can affect many additional organs and functions. Exposure to high amounts of malathion in the air, water, or food may cause difficulty breathing, chest tightness, vomiting, cramps, diarrhea, watery eyes, blurred vision, salivation, sweating, headaches, dizziness, loss of consciousness, and death. If persons who are exposed accidentally or intentionally to high amounts of malathion are rapidly given appropriate treatment, there may be no long-term harmful effects. If people are exposed to levels of malathion below those that affect the function of the nervous system, few or no health problems seem to occur. This has been shown in studies with volunteers who inhaled or swallowed small known amounts of malathion. There is no evidence that malathion affects the ability of humans to reproduce. There is also no conclusive proof that malathion causes cancer in humans, although some studies have found increased incidence of some cancers in people who are regularly exposed to pesticides, such as farmers and pesticide applicators. The International Agency for Research on Cancer (IARC) has determined that malathion is unclassifiable as to carcinogenicity to humans.
To protect the public from the harmful effects of toxic chemicals and to find ways to treat people who have been harmed, scientists use many tests.
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.
Studies in animals have observed the same effects that occur in humans after exposure to malathion. This is because malathion also affects the nervous system of animals. Some studies in animals suggest that malathion may produce subtle changes in the immune system, but there was no evidence indicating that those animals were more susceptible to infections than animals that were not given malathion. Some studies in male rats observed temporary alterations in the testes following short-term exposure to malathion, but there is no evidence that exposure to malathion affected the reproductive ability of these animals. A longer-term study that evaluated the ability of rats to reproduce did not detect any harmful effects. Most studies of cancer in animals have not shown evidence of carcinogenicity for malathion, or have shown evide