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EWG Statement, 03/10/2008

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NATIONAL SUMMARY

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Status: Unregulated - EPA has not established a maximum legal limit in tapwater for this contaminant.

Isophorone is a solvent for lacquers, plastics, oils, fats, gums, resins, nitrocellulose, vinyl resins and other chemicals; intermediate in chemical manufacturing; occurs naturally in cranberries. Potential health impacts associated with Isophorone include cancer, developmental toxicity, gastrointestinal or liver toxicity, kidney toxicity, neurotoxicity, respiratory toxicity, and skin sensitivity.

Sources of Isophorone:

	Agriculture (pesticides, fertilizer, factory farms)
	Industry

An Environmental Working Group analysis of Isophorone tests reported by 265 public water suppliers in 6 states shows that between 1998 and 2003, 1.2 million people in 6 communities drank water contaminated with Isophorone. Isophorone remains unregulated in tap water, without a maximum legal limit.

Exposure Summary

1,217,547 People drinking water contaminated with Isophorone 6 Communities served water contaminated with Isophorone

Table. Isophorone Exposure by State

1.2 million Americans in 2 states were served tap water contaminated with Isophorone between 1998 and 2003.

State	Water suppliers with Isophorone contamination
	Systems	Population
Nevada	3	1,124,779
Rhode Island	3	92,768
Total	6	1,217,547

Table. The most polluted communities

1.2 million Americans in 6 communities were served tap water contaminated with Isophorone between 1998 and 2003

Ranked by highest average Isophorone level

Rank	System	Population Served	Positive test results of total reported tests	Average Level (Range)
1	Mount Rose Water Company Reno, NV	1,650	1 of 2	0.64 ppb (0 to 1.28 ppb)
2	Las Vegas Valley Water District Las Vegas, NV	1,115,500	1 of 4	0.33 ppb (0 to 1.3 ppb)
3	Desert Springs Utility Company Reno, NV	7,629	1 of 2	0.32 ppb (0 to 0.63 ppb)
4	Heritage Park Home Co - Operative Tiverton, RI	100	1 of 4	0.04 ppb (0 to 0.16 ppb)
5	Bristol County Water Authority Warren, RI	48,859	1 of 5	0.04 ppb (0 to 0.19 ppb)
6	Newport - City of Newport, RI	43,809	1 of 11	0.01 ppb (0 to 0.14 ppb)

Health based limits for Isophorone

Health Limit	Limit Value	Limit Description
One in ten thousand (10-4) Cancer Risk	4000 ppb	The concentration of a chemical in drinking water corresponding to an excess estimated lifetime cancer risk of 1 in 10,000. Source: U.S. Environmental Protection Agency.
EPA Human Health Water Quality Criteria	35 ppb	Water quality criteria set by the US EPA provide guidance for states and tribes authorized to establish water quality standards under the Clean Water Act (CWA) to protect human health. These are non-enforceable standards based upon exposure by both drinking water and the contribution of water contamination to other consumed foods. Source: U.S. Environmental Protection Agency.
Children's health-based limit for 1-day exposure	15000 ppb	Concentration of a chemical in drinking water that is not expected to cause any adverse, noncarcinogenic health effects for up to one day of exposure. The One-Day health-based limit (or Health Advisory, HA) is typically set to protect a 10-kg child consuming 1 liter of water per day. Source: U.S. Environmental Protection Agency.
Children's health-based limit for 10-day exposure	15000 ppb	Concentration of a chemical in drinking water that is not expected to cause any adverse, noncarcinogenic effects for up to ten days of exposure. The Ten-Day health-based limit (or Health Advisory, HA) is typically set to protect a 10-kg child consuming 1 liter of water per day. Source: U.S. Environmental Protection Agency.
Lifetime health-based limit, non-cancer risk	100 ppb	Concentration of a chemical in drinking water that is not expected to cause any adverse, noncarcinogenic health effects for a lifetime of exposure. The Lifetime health-based limit (or Health Advisory, HA) is based on exposure for a a 70-kg adult consuming 2 liters of water per day. Source: U.S. Environmental Protection Agency.
Drinking Water Equivalent Level	7000 ppb	A lifetime exposure concentration protective of adverse, noncarcinogenic health effects, that assumes all of the exposure to a contaminant is from drinking water. Source: U.S. Environmental Protection Agency.

Testing Summary for Isophorone

Water suppliers report an average of 0.4 Isophorone tests per year. 39,486 water suppliers failed to report any Isophorone tests at all.

Are tests routinely required for Isophorone by federal law? No Water suppliers reporting tests for Isophorone (1998-2003): 265 of 39,751 Average testing rate for water supplier reporting tests (1998-2003): 0.4 per year

Isophorone Violations

Because Isophorone is unregulated in tap water, no violations are recorded in EPA's violations database, the Safe Drinking Water Information System. Under the federal tap water law, water suppliers are not required to routinely test for Isophorone, and any level is legal in tap water.