Perchlorate has been in the news for many years, chiefly because it has similarities to other toxins like fluorine, bromine, and radioactive iodine. Perchlorate is by no means a new substance. It has been used for decades by the military for rocket fuel, explosives and munitions. In addition, the substance is also used in airbag inflation systems, road flares, fertilizer and it also occurs naturally at low levels in the environment. At one time it as used to treat hypothyroidism but found to be toxic and is never used today.
The amount of perchlorate manufactured since the 1950s is over 870 million pounds and primarily used for rocket fuel. While this may be a source of cheap fuel for the aerospace industry, what is now becoming evident that this particular substance has leached into the waterways and into agricultural products. In more than half the US states, sampling of the soil and agriculture products has revealed contamination with perchlorate.
Even though perchlorate was first detected in groundwater more than half a century ago, it is only recently that its toxicity has been examined in more detail . The reason why perchlorate has become of concern is for the following reasons:
1. It is now widespread in the environment and may have deleterious effects on land and sea life.
2. It may have the potential to cause adverse effects on human health.
3. Removing it from the environment will be a costly project.
Perchlorate is both manmade and naturally occurring. The salts of perchlorate are very soluble in water and can easily be transferred by soil or water. While the substance is relatively inert in the environment, it can persist for a long time. The first news about perchlorate contamination appeared in the late 90s when levels of 4 ppb were found in water springs in the West. Since then, many water and soil samples from all over the country have revealed levels ranging from 1-28 ppb. Even though perchlorate has been reported in the soil in 49 states, high levels have only appeared in 28 states so far.
In most states, the source of perchlorate in the drinking water appears to be from manufacturers dumping their contaminants in water or where the contaminated water is used for irrigation or plants. The highest concentration of percolate are found in the western and north-western part of the USA. Highest levels of perchlorate have been reported in California, Texas, Massachusetts and New jersey but more recent studies show that moderately high levels are also common in the Midwest and Great Plains.
In some states like California, the maximal level of perchlorate allowed in drinking water is 6 microgram per liter but in many states the levels are many times higher. Further, no one really knows the level of perchlorate in industrial waters and in soil around military installations which use perchlorate as rocket fuel.
Contamination of the soil and waterways have been reported all over the US. Perchlorate has been shown to be harmful to the ecosystem and threatens both land and sea life. Today, in some parts of the world, there is significant contamination of lakes, rivers, and even groundwater with perchlorate. Environmental studies in the US show that perchlorate is found in tap water and even bottled water. Further, many of the plant foods we eat also have been found to have traces of perchlorate. In 2004, perchlorate was found in cow's milk, which may have entered after consumption of contaminated crops.
The thyroid gland takes up iodine to keep up its functions. Exposure to significantly higher levels of perchlorate has the potential to cause some health effects, primarily related to thyroid function. Perchlorate inhibits the transfer of iodide from the blood to the thyroid gland, which is required for the gland to produce hormones essential for metabolism and growth. Although short-term fluctuations in thyroid hormones are not a concern to healthy adults, long-term disruptions may result in hypothyroidism and related changes in metabolism, decreased mental performance, and altered development. This is of particular concern for people who are already experiencing hypothyroidism, as well as for pregnant women and children. Further, reports indicate that this lead to underactivity of the thyroid gland and make it susceptible to attack by the bodys own defensive cells.
In addition, there are reports that continuous perchlorate exposure may induce allergies, skin irritation, eczema, and even high blood pressure.
There is concern that perchlorate may not be safe for pregnant or breastfeeding women. Since perchlorate interferes with iodine absorption this may lead to deficiency in the fetus and lead to stunted growth and even mental retardation. In countries where iodine fortification does not take place, perchlorate in the environment may lead to developmental delays in infants. Perchlorate is also known to pass into breast milk and hence there is a risk that it may also affect the growth and development of the infant.
More important, perchlorate has also been found in processed milk formula for babies.
There are many reports indicating that perchlorate is found in varying amounts in the work place. Small amounts of perchlorate have been found in the urine and blood of work workers and so the question is how did it get there? It is believed that people who work in the construction and automobile industry may be exposed to high levels of perchlorate during manufacture of plastic products, munition, and airbags.
The EPA has admitted that it has botched up the investigation of perchlorate in the environment and in the drinking water. There have been a number of lawsuits filed against the agency for failing to set legal tap water limits for perchlorate. After these lawsuits in the mid 2000, EPA stated that it would establish safe levels for perchlorate and reinforce the standards in the nation- so far the agency has not done much. Today it is estimated that nearly 17-22 million Americans live in areas where the water may be contaminated with perchlorate. For several decades the aerospace industry and military have lobbied the EPA to block all regulations of perchlorate. It was only after relentless pressure from scientists and consumers that the EPA has finally decided to set limits on perchlorate in the environment but no set number has been published yet. More important, the EPA has also targeted other potent toxic agents like tetrachlorethylene and trichloroethylene. The chemicals are widely used in dry cleaning agents, are strongly associated with developmental problems in babies, as well as cancer.
At present more scientific studies and guidelines are being developed in relation to perchlorate are on going. In 2005, the American National Academy of Science published a report on the health implications of perchlorate ingestion, which has been used by the U.S. Environmental Protection Agency to establish a preliminary clean-up goal of 24.5 ppb for perchlorate in water. Unfortunately there are no enforceable national drinking water standards for perchlorate in the United States, although several states have implemented their own goals that range from 1 ppb to 18 ppb for perchlorate in drinking water.
So what should the consumer do in the face of the perchlorate threat in the drinking water? The first option is to find an alternative source of drinking water. Secondly, there are also some household treatment devices that may help lower the levels of perchlorate in the drinking water. Thirdly one should only obtain drinking water from certified private wells –unfortunately these options are not realistic or practical for most consumers. There are technologies for reducing perchlorate in the water supply available but the use of such technologies depends on the local municipality and affordability.
For those who are worried about the negative effects of perchlorate on the thyroid gland, it is important to ensure that there is an adequate intake of iodine in the diet. This prevents the perchlorate from taking over the thyroid gland.
More definitive research on the long-term toxicity of perchlorate are desperately needed. Scientists have started to examine levels of perchlorate in water supplies in many states and are evaluating the health effects. Some states have established sampling programs for perchlorate.
The bottom line is that perchlorate is not as safe as what the authorities suggest. Reports continue to appear that perchlorate is harmful even at very low levels. The best way to prevent perchlorate toxicity is to increase iodine in the foods, avoid drinking tap water and washing all foods thoroughly before consumption.
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