sed to dangerous amounts if they go into fields too soon after spraying. The people most likely to be exposed to malathion can be protected by wearing special clothing and breathing equipment and by staying out of sprayed fields for the appropriate amount of time for the job that they are going to do in the field; this amount of time can be up to 6 days.
Individuals can also be exposed to malathion if they live near landfills where malathion has been dumped or near water containing malathion that washes off nearby land or that is accidentally spilled. The greatest amounts of malathion are expected to be present near or on the farms where malathion is used. After spraying, some malathion can be transported by the wind or fog to areas away from where it is used, but the amounts present at these locations are not expected to be at dangerous levels. In a collection of data gathered by the EPA for the years 1971-1991, it was reported that malathion was only found in a total of 12 groundwater monitoring wells in three states. The most that was found in any of the wells was 6.17 parts of malathion per billion parts of water (ppb); this was found in a county in Virginia that is made up mainly of agricultural and forested land. More recent studies of water samples taken near where malathion was sprayed indicate that malathion is not usually found in groundwater. The risk of exposure to malathion from drinking groundwater appears to be low. For more information, see Chapter 6.
Malathion is approved for use on crops, in homes and gardens, in urban/residential areas where mosquitos or medflies pose a problem, and at agricultural sites. The maximum amount of malathion residue allowed by the FDA and EPA on crops used as food is 8 ppm of malathion. The FDA has monitored the food supply for pesticides for a number of years. FDA purchases many kinds of foods through Total Diet Studies (also called Market Basket Surveys) and analyzes them for residue levels of pesticides. These FDA studies allow scientists to estimate the daily intake 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 malathi