1. Use of sodium bromide in swimming pools resulting in exposure to bromate Kevin Cox Senior Research Toxicologist NSF International

2. Sodium bromide Sodium bromide uses include: –Active ingredient in numerous products used in the control of bacteria, fungi and algal slimes –Industrial uses include treatments of cooling water systems, wastewater treatment systems, fruit and vegetable washes –Residential uses include disinfection of hot tubs, spas, decorative fountains and non-potable water. Sodium bromide is of low acute oral and dermal toxicity –Causes mild eye and skin irritation Per U.S. EPA, there are no toxicological endpoints of concern for sodium bromide

3. Bromate In aqueous environments in the presence of sunlight, oxidizing agents and/or alkaline conditions, bromide is repeatedly oxidized to form bromate Bromate is classified as a Probable Human Carcinogen –U.S. EPA MCL of 10 ppb, NSF 60/61 TAC of 10 ppb –Multiple cancer sites found in chronic studies in animals exposed to bromate in drinking water In 2005, U.S. EPA received an inquiry regarding potential risks of sodium bromide use in pools –Investigated both sodium bromide as well as BCDMH and DBDMH (review of BCDMH and DBDMH is not covered in this presentation)

4. U.S. EPA (2005) Investigation U.S. EPA received data regarding bromate formation in swimming pools from a study by Arch Chemicals (2005) –Arch assessed the amount of bromate formation in outdoor swimming pools when dosed with sodium bromide at 250 mg/L –The selected dose rate of 250 mg/L significantly exceed label application rates of 6 mg/L –The highest conversion rate was ~50% bromide to bromate U.S. EPA assessed cancer risks based on the 6 mg/L application rate with either a 50% or 100% conversion to bromate assumed –A 1 x 10 -6 (1 in 1,000,000 risk) was back calculated to be 0.01 ppm

5. U.S. EPA (2005) Investigation Using SWIMODEL equations and assumptions, Cancer Risk values were estimated for swimmers exposed to bromate –When assuming 100% conversion, lifetime cancer risk levels ranged from approximately 4 x 10 -4 (4 in 10,000) to 9 x 10 -4 (9 in 10,000) –When assuming 50% conversion, lifetime cancer risk levels ranged from approximately 2 x 10 -4 (2 in 10,000) to 5 x 10 -4 (5 in 10,000) –For comparison, NSF derives drinking water limits based on 1 x 10 -5 (TAC) and 1 x 10 -6 (SPAC) cancer risks Due to the exaggerated dose level used in the Arch study (2005), the U.S. EPA considered the data to be insufficient to accurately characterize the risk

6. U.S. EPA (ongoing) Investigation NSF contacted U.S. EPA regarding any further activities that were conducted as follow-up to the 2005 memorandum –Notified that this issue is being investigated as part of the FIFRA registration review of inorganic halides (including sodium bromide) –It is noted that a call for data will be issued to obtain more accurate data on the conversion of bromide to bromate in outdoor swimming pools –At this time the call for data has not yet been issued pending the internal review of associated registration actions

7. Summary The U.S. EPA (2005) memorandum suggests that the use of sodium bromide in outdoor swimming pools may present a significant cancer risk based on conversion to bromate The U.S. EPA has indicated that they intend to further investigate this safety concern and they are planning to obtain additional data on the conversion of bromide to bromate in outdoor pools in order to better characterize the risk

8. Questions?