Perchlorate is a natural product but also a synthetic chemical. It has many uses such a fertilzier, rocket fuel, fireworks, and explosives. It was once used as a pharmaceutical to treat hyperthyroidism (Graves' Disease). Perchlorate is a very powerful oxidizer.

Perchlorate occurs naturally especially in the SW United States, in soil and in water sources. It contaminates the soil around many military bases and defense plants. It has been found in food, and EPA has detected it in water supplies of at least half the states in the US.

In high concentrations, perchlorate can interfere with iodide uptake by the thyroid gland, reducing thyroid hormone production and interfering with normal growth and metabolism

Not regulated by EPA as a drinking water contaminant, but is on EPA’s Contaminant Candidate List. EPA recommends that people who prepare infant formula with water containing more than 15 ppb use water that is lower in perchlorate. EPA will look at further studies of perchlorate.

In 2011 the Obama adminsitration reversed a Bush ruling that perchlorate is of no health consequence and instructed the EPA to go about setting a MCL for perchlorate.

Two US states how have enforeable maximum limits for perchlorate. Califoria's is at 6 ppb and Massachusetts' is at 2 ppb.

Water treatment:

The best treatment is reverse osmosis. Also anion exchange, carbon adsorption and possibly distillation can be effective. NSF certifies reverse osmosis units for perchlorate reduction.