AWWA JAW69180

Perchlorate is a contaminant of health concern because exposure to high levels over extended periods may adversely affect thyroid activity. In response to recent findings of perchlorate in sodium hypochlorite, NSF International surveyed sodium hypochlorite products used to treat drinking water to better understand the occurrence of perchlorate as a contaminant. Perchlorate contamination was found to occur in more than 90% of sodium hypochlorite samples from production facilities across North America. Results also indicated a trend of increasing perchlorate concentration as the hypochlorite aged. The duration and conditions of storage can affect the levels of the contaminant in a utility's hypochlorite supplies and ultimately its drinking water. The investigation provided a basis for recommendations to minimize perchlorate formation and lower the potential for its unintended addition to drinking water. Sodium hypochlorite should be stored in the dark at cool temperatures, diluted if possible, and used within a few weeks of manufacture. Includes 10 references, tables, figures.