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A water contaminant messing with your thyroid

On February 2011, The Environmental Protection Agency (EPA) declared that "perchlorate may have an adverse effect on the health of persons and is known to occur in public drinking water systems with a frequency and at levels that present a public health concern".

Perchlorate is commonly used as an oxidizer in rocket propellants, munitions, fireworks, airbag initiators for vehicles, matches, explosives and batteries. Perchlorate-like chemicals are widely applied as herbicides and fertilizers. Sodium chlorate acts as a soil sterilant, leaving the soil unusable for a period of time.


Sodium hypochlorite is widely used to disinfect water and as household bleach. Perchlorate found in drinking water and swimming pools may find its origins in these commonly used chemicals.

Perchlorate reduces thyroid hormone production in the thyroid gland, resulting in various adverse health effects.

Routes of exposure

Perchlorate has often been detected in water supplies in arid southwest US, and in close proximity to potash ore and sites where solid rocket fuel is manufactured or used. There are also locations in the United States lacking a clearly defined source.

Perchlorate can be carried over from fertilizers to plants and therefore to plant-based foods too. It can also find its way into the environment through the use of industrial chemicals, rocket fuels and fireworks. Perchlorate enters foods in the course of their production and/or processing, when in contact with water which has been treated with chlorinated biocidal products for disinfection purposes.

On 2005, the FDA has approved perchlorate to be used in food packaging, as an anti-static agent or as a sealant. However, it seems that perchlorate is leaching to food items from the packages. Perchlorate use in food contact materials may well explain the observed increase in perchlorate levels measured in foods sampled in recent years.

Health effects

Perchlorate can interfere with the human body's ability to absorb iodine into the thyroid gland, which is a critical element in the production of thyroid hormones.

Perchlorate can disrupt the normal function of the thyroid gland in both children and adults. In adults, the thyroid plays an important role in metabolism, making and storing hormones that help regulate the heart rate, blood pressure, body temperature, and the rate at which food is converted into energy. In fetuses and infants, thyroid hormones are critical for normal growth and development of the central nervous system.

People with thyroid disorders or an iodine deficiency can be particularly affected by undesired effects, as can newly born babies and other children. Another critical group comprises expectant mothers who already have a thyroid function disorder.


Perchlorate enters the body mostly through drinking and eating. The blood stream carries perchlorate to all parts of the body, where a few internal organs like the thyroid, breast tissue, and salivary glands take up most of it. Perchlorate generally leaves these organs in a few hours and eliminated through the kidneys.

However, the presence of perchlorate in many foods and in some drinking water sources means that exposure may continue to occur on a daily basis.

Because it is neither stored nor metabolized, effects of perchlorate on the thyroid gland are reversible, though effects on brain development from lack of thyroid hormone in fetusesnewborns, and children are not.

How to reduce the risk from exposure to perchlorate

Contact your local water supplier to find out if perchlorate is in your drinking water and what steps your utility is taking to reduce your exposure.

Water filters using ion exchange or reverse osmosis can remove perchlorate from your drinking water. Perchlorate cannot be removed by heating or boiling water.

Avoid using disinfectants containing sodium chlorine directly on food, or was it thoroughly right after.

Consumers should maintain a balanced and varied diet. The health benefits of fruit and vegetables remain undisputed.

Make sure you take the adequate daily iodine intake. Using an iodine-enriched table salt is a good source for iodine. 

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