Perchlorate Standard for US Drinking Water

Perchlorate in drinking water is known to suppress thyroid function by inhibiting uptake of iodide and its subsequent ability to produce hormones that are critical to development. Children and new born are particularly at risk. However, the exact safe dose of this compound is unknown. Link Link  In 2002 the US EPA suggested a limit of 1 ppb should be set, but in 2008 the Government decided not to regulate the compound but recommended drinking water concentrations should not exceed 15 ppb.

The US EPA has  now decided to regulate perchlorate under the Safe Drinking Water Act . Perclolrates are used to produce rocket fuel, fireworks and explosives, not activities associated with Ireland. However, they are also found in bleach, in some fertilizers and in nature making them universal. In the US it is estimated that between 5 to 17 million people may be exposed to perchlorate contaminated water with 153 supplies known to be contaminated. A standard is not expected to be set for at least 18-24 months. Link

Perchlorate In Irish Drinking Water a Potential Cause of Hyperthyroidism?

Attention is increasingly being focused on perchlorate in drinking water as prolonged exposure is known to suppress thyroid function. The sources of perchlorate in Ireland are quite limited but one area that urgently needs investigation is the use of sodium hypochlorite for water treatment. Other potential sources are household bleach and sodium hydroxide.

Sodium hypochlorite is a very common method of disinfecting water especially in smaller drinking water suppliers. The quality, storage and use of these chemicals varies considerably. When used it will dissociate to produce some perchlorate ions. Wherever sodium hypochlorite and sodium hydroxide are used there is a potential for perchlorate release into the environment.

A study carried out by NSF International in the US, and published in the Journal of the American Water Works Association found that perchlorate was found in 90% of sodium hypochlorite used at water treatment plants with the concentration increasing as the sodium hypochlorite aged. Their conclusions were: “For utilities that routinely use their sodium hypochlorite within 45 days of manufacture, the contribution of perchlorate is likely to be negligible, unless there is some contamination of the original ingredients. Utilities or small systems that store sodium hypochlorite for longer periods may encounter significant levels of perchlorate in the finished drinking water. To minimize the perchlorate risk, sodium hypochlorite should be stored in the dark, at cool temperatures, diluted if possible, and used within a few weeks of manufacture. Storage tanks and piping should also be emptied of aged material and flushed to minimize the potential for contamination.” Link