When rats ate enough atrazine to almost kill them, they had increased activity followed by slowing, incoordination, and muscle spasms. Atrazine does not easily pass through the skin. In a study with monkeys, atrazine was highest in blood plasma within 1 hour. The plasma half-life was 4 hours. Metabolites of atrazine had half-lives of 2. It is excreted in the urine and feces. Urinary excretion of atrazine peaked days after exposure. Atrazine does not alter or damage genes in humans and animals.
However, these tumors were not considered relevant to humans by a scientific advisory panel. This was because of differences in rat and human female reproductive systems. They also lost weight and had difficulty moving. They also had enlarged hearts with fluid inside the heart's membrane. This started when they were 8 weeks old.
After 3 months, half the rats in each group were then fed a high-fat diet instead of regular rat chow. Rats who drank the treated water used less energy when they were sitting still. They also gained weight and became insulin resistant. This happened even though their food intake and activity level did not change. The high-fat diet made the weight gain and insulin resistance worse. They lost more pregnancies than rabbits who did not get atrazine.
The rabbit litters had fewer and smaller babies. They also showed slower bone formation. However, the mothers and pups weighed less. More infant rats died than when their mothers were not fed atrazine. Benchmark Dose: The benchmark dose is based on the benchmark response. The benchmark response represents some set percent change from baseline or controls. Scientists look at two factors to decide how much change is of concern.
They look at both the pesticide's potential negative effect and the strength of evidence. They consider both short-term and long-term exposures. The threshold is set at the lowest dose that led to a negative effect in tested animals. EPA does not expect any harm to come from exposures below the benchmark dose.
Their daughters reached puberty later than expected. Reproductive cycles were disrupted in female rats after eating low doses of 3. It also happened in rats fed 3. Puberty was delayed in young male rates fed low doses of The EPA uses a benchmark dose to set a limit of 2. This hormone normally affects embryo development. It also affects fertility by leading to the release of eggs from ovaries. A reference dose of 0. Epidemiology looks at what has happened to people and what health problems they have to see if the two are related.
A number of epidemiology studies have looked at possible human health effects from exposure to atrazine. Some studies found effects on human health, but others have not. These studies help guide more research. They may also provide information about possible risk. They do not prove that exposure leads to harm. A study in Texas found that mothers who lived in areas where more atrazine was used had a greater chance of giving birth to children with birth defects in their faces and skulls than mothers who did not.
The more atrazine used in the county, the greater the chance of birth defects. Researchers collected urine from pregnant women in France. They tested the urine for atrazine or its metabolites to estimate exposure to atrazine.
Babies whose mothers were exposed to atrazine while they were pregnant grew more slowly. They had a smaller head circumference than babies whose mothers were not exposed to atrazine during pregnancy.
Women living in areas in Illinois where atrazine is heavily used had more irregular menstrual periods than women living in Vermont, where less atrazine is used. Atrazine measured in the residential water was 0. Information on atrazine levels at a given site, in conjunction with other environmental factors, can help explain why a particular waterbody may experience lower productivity and less diversity in plant and wildlife communities than expected.
Skip to main content. National Aquatic Resource Surveys. Contact Us. Indicators: Atrazine. What is atrazine? The highest levels of contamination are in the Midwest where it is widely used on corn fields. USGS monitoring shows drinking water concentrations typically spike during the spring and early summer as rains flush the freshly applied herbicide into streams — and into local water supplies. Data from the EPA's Atrazine Monitoring Program show that atrazine levels in drinking water can spike above the legal limit of 3 parts per billion in some U.
Although the EPA bases its limit on an annual average not seasonal peaks , the monitoring results reveal alarming levels of human exposure. According to NRDC's analysis of the most recent EPA data, drinking water in 67 public systems had peak atrazine levels above 3 parts per billion ppb , with one as high as 60 ppb in Ohio.
Six water systems had average annual atrazine concentrations that exceeded the EPA limit entirely. And these figures are for treated drinking water — raw water samples contained even higher concentrations.
Exposure to atrazine does not kill right away. For sensitive species however, atrazine's sublethal effects can be almost as devestating. Fish and amphibians are most vulnerable. A growing body of research shows that atrazine exposure--even to trace levels of the herbicide--can adversely impact a number of species.
Tyrone Hayes and other scientists have conducted research to show that exposing frogs to as little as 0. Atrazine exposure from contaminated surface water is also known to compromise fish and amphibian growth, behavior, immune function, and gonadal development. Strikingly, the level of atrazine used in the study — 2. There are many viable ways of producing corn and growing food without relying on atrazine.
0コメント