EPA's recent determination not to limit the amount of perchlorate it allows in drinking water is a preliminary one, but it's garnering a lot of attention. The House Energy & Commerce Committee is launching an investigation, and environmental groups are preparing a lawsuit they will file against EPA as soon as the agency makes a final decision, which is expected in November or December. On Oct. 3, the agency announced it would not regulate the chemical in drinking water, arguing that there is not "a meaningful opportunity for health risk reduction" because levels of perchlorate are low in most public drinking-water systems. Perchlorate is a component of rocket fuel, although it also occurs naturally in some soils. The compound inhibits the thyroid's uptake of iodine and can lower the amount of thyroid hormone in the body. It has been found in water, food, breast milk, and cow's milk. EPA's decision not to regulate perchlorate is seen as a victory for the military, the Department of Energy, NASA, and their contractors, whose operations have tainted aquifers and rivers with the substance in more than 20 states.