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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.

Molybdenum is a by-product of copper and tungsten mining, used as a alloy for various metals, occurs naturally in soil and rock. Potential health impacts associated with Molybdenum include neurotoxicity and reproductive toxicity.

Sources of Molybdenum:

	Sprawl and Urban Areas (road runoff, lawn pesticides, human waste)
	Industry

An Environmental Working Group analysis of Molybdenum tests reported by 1,183 public water suppliers in 9 states shows that between 1998 and 2003, 24.6 million people in 134 communities drank water contaminated with Molybdenum. In 84 of these communities, tap water was contaminated at levels above health-based thresholds. Molybdenum remains unregulated in tap water, without a maximum legal limit.

Exposure Summary

24,622,018 People drinking water contaminated with Molybdenum 134 Communities served water contaminated with Molybdenum 5,073,250 People drinking water contaminated with Molybdenum over health based limits 84 Communities served water with Molybdenum above health based limits

Table. Molybdenum Exposure by State

5.1 million Americans in 3 states were served tap water contaminated with Molybdenum at levels above health-based limits between 1998 and 2003.

State	Water suppliers with Molybdenum contamination		Water suppliers reporting Molybdenum above health-based limits
	Systems	Population	Systems	Population
California	54	22,810,007	19	4,912,114
Illinois	61	98,591	61	98,591
Ohio	9	134,282	4	62,545
Nevada	8	1,573,458	0	0
Minnesota	1	3,930	0	0
Nebraska	1	1,750	0	0
Total	134	24,622,018	84	5,073,250

Table. The most polluted communities

5.1 million Americans in 84 communities were served tap water contaminated with Molybdenum above health based limits between 1998 and 2003

Ranked by highest average Molybdenum level

Rank	System	Population Served	Positive test results of total reported tests	Average Level (Range)
1	Arden Shores Estates Subdivision Libertyville, IL	66	1 of 1	76 ppb (76 to 76 ppb)
2	Ohio - American Water Company - Timberbr Westerville, OH	865	1 of 1	64 ppb (64 to 64 ppb)
3	Hindsboro Hindsboro, IL	375	2 of 2	54 ppb (52 to 56 ppb)
4	Grandwood Park Subdivision Libertyville, IL	4,810	2 of 2	52 ppb (24 to 80 ppb)
5	Richgrove Mwc Richgrove, CA	3,723	1 of 1	47 ppb (47 to 47 ppb)
6	Manteno Manteno, IL	6,100	2 of 2	42.5 ppb (33 to 52 ppb)
7	Willoway Terrace Mhp Arlington Heights, IL	450	2 of 2	42 ppb (37 to 47 ppb)
8	Hainesville Hainesville, IL	1,150	1 of 1	40 ppb (40 to 40 ppb)
9	Highland Lake Subdivision Libertyville, IL	303	1 of 1	39 ppb (39 to 39 ppb)
10	Ohio - American Water Company - Lake Dar Westerville, OH	4,495	1 of 1	37 ppb (37 to 37 ppb)

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Health based limits for Molybdenum

Health Limit	Limit Value	Limit Description
Children's health-based limit for 1-day exposure	80 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	8 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	40 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	200 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 Molybdenum

Water suppliers report an average of 0.4 Molybdenum tests per year. 38,568 water suppliers failed to report any Molybdenum tests at all.

Are tests routinely required for Molybdenum by federal law? No Water suppliers reporting tests for Molybdenum (1998-2003): 1,183 of 39,751 Average testing rate for water supplier reporting tests (1998-2003): 0.4 per year

Molybdenum Violations

Because Molybdenum 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 Molybdenum, and any level is legal in tap water.