By Paul A. Atrazine is the most widely used herbicide in Texas corn and grain sorghum production. With its widespread use, atrazine has been discovered in minute quantities in Texas ground and surface waters. Because of this, it is important to understand atrazine behavior in the environment and the potential for adverse effects on human and animal health and on other non-target organisms.
Atrazine kills plants by disrupting photosynthesis. Photosynthesis— unique to green, living plants—happens when light energy is converted to chemical energy needed for food production.
Simply put, when food production stops, plants eventually starve to death. Atrazine selectively kills non-desirable plants weeds that compete for water and nutrients with desirable plants crops, turf- grass.
Therefore, it is a useful tool for both agricultural and urban sites. Atrazine is generally applied to soil or turfgrass surfaces in a uniform, broadcast manner to ensure adequate distribution over the area in which weed control is desired. Rainfall or irrigation shortly after application transports atrazine into the upper soil profile where plant seedlings germinate.
These seedlings take up the herbicide through the roots and, depending on their tolerance, they may or may not survive. If rainfall or irrigation water accumulates at the soil surface faster than it can percolate into the upper soil profile, this standing water might run off the site of application, carrying some of the atrazine. Farmers regularly atrazine because it kills off grassy weeds. It is also deadly to grasses such as fescue grass and bahia grass.
The rate of kill will vary with the type of grass, but atrazine has about a 75 percent success ratio when killing fescue. Why is atrazine banned in Europe? Although the U. Environmental Protection Agency EPA approved its continued use in October , that same month the European Union EU announced a ban of atrazine because of ubiquitous and unpreventable water contamination.
How dangerous is atrazine? Atrazine Threatens Amphibians The chemical is a potent endocrine disruptor that causes immunosuppression, hermaphroditism and even complete sex reversal in male frogs at concentrations as low as 2. Will atrazine kill emerged weeds? Atrazine Uses Atrazine kills emerged weeds by absorption of the chemical into the plants' leaves and stems and absorption through its roots of chemical that seeps into the ground.
In the soil, atrazine is an effective preemergence herbicide, preventing weeds from sprouting. What does atrazine do to frogs? A restricted herbicide, atrazine is used primarily on crops, not around the home, and can be purchased and applied only by certified applicators. The herbicide also lowers levels of the male hormone testosterone in sexually mature male frogs by a factor of 10, to levels lower than those in normal female frogs.
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. The more water women in Illinois drank, the more likely they were to have delayed periods. Farmers have reported information on their health and use of pesticides in the Agricultural Health Study.
Spring water could also be contaminated depending on the source. What does atrazine do to frogs? A restricted herbicide, atrazine is used primarily on crops, not around the home, and can be purchased and applied only by certified applicators.
The herbicide also lowers levels of the male hormone testosterone in sexually mature male frogs by a factor of 10, to levels lower than those in normal female frogs. What is the half life of atrazine? Atrazine degrades in soil primarily by the action of microbes.
The half-life of atrazine in soil ranges from 13 to days. What is the source of atrazine? Pure Atrazine is found as white cystals. Under normal conditions, Atrazine is stable. It dissolves fairly well in water and organic carbon-containing solvents. The main sources of release of Atrazine are to soils and surface waters due to its application to land as a herbicide. What is eating my plumeria leaves? What was the strategy that Fabius came up with in order to deal with Hannibal?
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