Perchlorates play havoc with thyroid glands.

The EPA has established an oral reference dose (RfD) of 0.7 µg/kg/day of perchlorate.

That translates to a drinking water equivalent level (DWEL) of 25 ppb.

This analysis calculates how 25 ppb is 19x too high.

That amount exposes pregnant women to amounts that will affect their babies.

90% of nursing infants will exceed this dose.

More than half will exceed it by ~ 3x.

Perchlorate contamination has been found in water and soil at ~ 400 sites in the U.S.

Concentration levels range from 4 ppb to more than 1,000,000 ppb.

Other contaminated sites probably exist.

State and federal agencies are not required to report perchlorate findings to the EPA.

Perchlorate contamination is often linked to military bases, defense contractors and industrial sites.

The human thyroid gland depends on iodide to produce T3 and T4.

T3 and T4 affect almost every physiological process in the body, for example

Basic metabolism

Protein synthesis

Body temperature

Heart rate

Insulin potency

Neural growth and development

Regulation of neurotransmitters

The thyroid gets iodide via a mechanism known as the sodium-iodide symporter (NIS).

The NIS has a 30x higher affinity for perchlorate than for iodide.

It's a double-whammy.

Perchlorate is transported into thyroid cells, and iodide is not.

This leads to metabolic disorder, abnormal neurodevelopment during gestation, and more.

Roughly 40% of U.S. women receive insufficient iodine.

That's more than 100 million women.

Close to 44 million women risk perchlorate exposure.

Millions of women have both.

During the 1st trimester, a developing fetus is completely dependent on its mother for thyroid hormone.

During the 2nd and 3rd trimesters, the fetus receives approximately 30% of its thyroid hormone from the mother.

Any deficiency has an adverse effect on the fetus.

Drinking water with 5 ppb perchlorate can reduce maternal thyroid to a level that causes abnormal fetal brain development.

Newborns must produce thyroid hormone on their own because breast milk provides almost none.

Also, infants use up their thyroid hormone quickly and have very little in reserve.

These factors make infants especially vulnerable to disruptions.

But perchlorates are found in the breast milk of at least 99% of mothers sampled.

Most have levels greater than 10 ppb.

Levels greater than 100 ppb are common.

It is logical to conclude that infants are incurring developmental damage.

Mild hypothyroidism during pregnancy has been linked to cognitive deficits in children.

A baby who is severely iodide deficient during fetal development can suffer hearing impairment and severe learning disabilities.

Note that insufficient thyroid has been associated with symptoms of 'autism'.

Anila Jacob, MD, gave this congressional subcommittee testimony.

It explains how perchlorate impacts thyroid function to cause developmental harm.

All of the symptoms and consequences of hypothyroidism and hypothyroxinemia apply.

A survey of medical research concerning perchlorates further reveals

• The NIS is also a signaling pathway for estrogen.

    Perchlorate inhibits this pathway.

    Chemicals that disrupt estrogen have been proven to cause cancer.

• Long-term exposure to perchlorate impairs reproductive capacity.

• High levels of exposure produce strong endocrine disrupting (androgenic) effects.

Some species of fish are naturally hermaphroditic — they have aspects of both genders.

When exposed to perchlorate, fish that are not naturally hermaphroditic looked and behaved like males.

But genetically they were female — they became ripe with eggs.

Perchlorate is synergistically toxic with



Thiocyanate (common in tobacco smoke)

Hexavalent chromium (Cr VI)

Additional research is likely to reveal other synergistic relationships.

Ammonium perchlorate is a major component of rocket fuel.

Perchlorates are also commonly used in


Car airbag propellants

Chemical reagents



Fireworks and pyrotechnics





Oxygen as generators

Other uses exist, but they are generally hidden behind proprietary formulas, corporate trade secrets, and classified military documents.

Almost 100 perchlorate chemicals are reportable under under the Toxic Substances Control Act (TSCA).

More than 500 varieties are commercially available.

By far the most common are

Ammonium perchlorate NH4ClO4
Sodium perchlorate NaClO4
Potassium perchlorate KClO4
Perchloric acid HClO4

Experimentally, potassium perchlorate has been tested as an animal fattening agent.

It was added to cattle feed to slow the animals' thyroid function.

The result was rapid fattening.

Other mammals develop extra adipose (fat) tissue when exposed to perchlorate.

This implicates perchlorate as a factor in human obesity.

Fireworks release significant amounts of perchlorate into local water systems

This study examined what happened to perchlorate in the wake of lakeside firework displays.

Perchlorate levels skyrocketed more than 1000x after some events.

Levels returned to baseline after ~ 2 months, but it was unclear exactly why or how.

Microbes appeared to feed on perchlorate but had a preference for nitrate when available.

The perchlorate may have simply dispersed into the lake.

Studies like this demonstrate how perchlorate exposure can begin unexpectedly.

There are many 'transient' sources constantly at play.

Specific levels of exposure are difficult to pin down.

But they add up.

This study found perchlorate in 20 out of 31 dietary supplements tested.

Concentrations up to 2400 ppb were detected.

Almost half the products were specifically marketed for pregnant women and children.

A person taking the recommended dose could ingest 18 µg perchlorate daily.

For an average adult female weighing 74 kg ( 163 lb) that calculates to 243 ppb — 350x the EPA RfD.

For an average 10 year old boy weighing 32 kg (70 lb) that calculates to 563 ppb — 800x the EPA RfD.

Perchlorate was also found in 4 products marketed for the enhancement of food flavor.

Perchlorate is a reaction byproduct of common household bleach (NaClO, sodium hypochlorite).

Levels increase the longer bleach sits on the shelf.

A 'fresh' bottle can yield ~ 400 ppb.

A two-year old bottle can yield ~ 8000 ppb.

California in 2007 set the perchlorate limit at 6 ppb for drinking water.

In Los Angeles County alone, 67 water sources exceeded 6 ppb during a 5-year monitoring period.

Massachusetts in 2006 adopted a limit of 2 ppb.

The EPA estimates perchlorate contamination exists in at least 25 states.

Exposure to perchlorate is ubiquitous in the U.S.

Children have higher levels than adults.

Perchlorates are widely detected in

Drinking water

Forage crops





How perchlorate gets into food is not entirely certain.

Contaminated irrigation water is one source.

Food made from animals that drank contaminated groundwater water is another.

But these sources cannot account for the widespread detection of perchlorates in the food supply.

Perchlorate information is comparatively sparse.

You can gather more at

The National Tap Water Quality Database can help you find out whether perchlorates have been reported in your area.