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EWG Statement, 03/10/2008

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NATIONAL SUMMARY

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Status: Regulated - EPA has established a maximum legal limit in tapwater for this contaminant.

Total trihalomethanes (TTHMs) is a measure of four disinfection by-products. Potential health impacts associated with Total trihalomethanes (TTHMs) include cancer. [read more]

Sources of Total trihalomethanes (TTHMs):

Water Treatment and Distribution Byproducts (pipes and fixtures, treatment chemicals and byproducts)

An Environmental Working Group analysis of Total trihalomethanes (TTHMs) tests reported by 28,082 public water suppliers in 41 states shows that between 1998 and 2003, 170 million people in 14,685 communities drank water contaminated with Total trihalomethanes (TTHMs). In 6,975 of these communities, tap water was contaminated at levels above health-based thresholds.

Exposure Summary

170,310,318 People drinking water contaminated with Total trihalomethanes (TTHMs) 14,685 Communities served water contaminated with Total trihalomethanes (TTHMs) 116,265,462 People drinking water contaminated with Total trihalomethanes (TTHMs) over health based limits 6,975 Communities served water with Total trihalomethanes (TTHMs) above health based limits

Table. Total trihalomethanes (TTHMs) Exposure by State

116 million Americans in 39 states were served tap water contaminated with Total trihalomethanes (TTHMs) at levels above health-based limits between 1998 and 2003.

State	Water suppliers with Total trihalomethanes (TTHMs) contamination		Water suppliers reporting Total trihalomethanes (TTHMs) above health-based limits
	Systems	Population	Systems	Population
Florida	557	15,642,210	439	14,259,875
Illinois	971	10,105,574	747	9,214,604
Ohio	674	9,634,334	456	9,163,021
Pennsylvania	445	9,280,273	336	8,827,090
California	702	25,627,979	223	7,302,045
North Carolina	1,697	6,395,581	846	5,814,678
Massachusetts	168	6,642,895	101	5,364,191
New Jersey	338	6,992,011	94	5,121,847
Virginia	293	4,847,485	166	4,749,452
Tennessee	285	4,708,489	188	4,115,236
Colorado	448	4,046,229	211	3,526,470
Texas	2,566	15,767,878	847	3,282,891
Washington	495	4,291,587	221	3,268,255
Arizona	234	4,401,600	68	3,018,011
Arkansas	468	2,994,620	263	2,562,838
Alabama	238	3,798,494	79	2,523,914
Indiana	356	3,809,844	113	2,451,488
Michigan	373	3,164,844	117	2,400,009
Utah	149	3,131,680	45	2,370,783
Minnesota	427	3,578,043	105	2,146,405
Oklahoma	356	2,695,477	217	1,939,087
Nevada	92	2,030,262	23	1,912,585
South Carolina	196	2,244,552	67	1,855,504
Missouri	357	2,106,849	204	1,597,394
Wisconsin	210	2,823,342	36	1,591,688
Iowa	129	1,420,870	60	1,037,257
New York	218	1,094,371	165	909,169
Nebraska	167	1,116,544	51	862,878
New Hampshire	195	620,179	75	491,847
Delaware	35	537,269	13	488,011
Montana	108	466,247	55	393,456
Maine	103	486,543	57	325,152
North Dakota	28	347,835	24	318,818
Oregon	29	720,008	25	252,145
New Mexico	179	1,214,395	35	226,818
Alaska	197	394,400	121	185,446
Wyoming	26	198,131	24	172,682
South Dakota	61	149,547	29	118,540
Idaho	105	585,180	29	103,882
Rhode Island	10	196,667	0	0
Total	14,685	170,310,318	6,975	116,265,462

Table. The most polluted communities

116 million Americans in 6,975 communities were served tap water contaminated with Total trihalomethanes (TTHMs) above health based limits between 1998 and 2003

Ranked by highest average Total trihalomethanes (TTHMs) level

Rank	System	Population Served	Positive test results of total reported tests	Average Level (Range)
1	Cadyville Water District Plattsburgh, NY	660	1 of 1	1500 ppb (1500 to 1500 ppb)
2	Black Brook Water Department No2 Ausable Forks, NY	77	1 of 1	1000 ppb (1000 to 1000 ppb)
3	Pleasant Acres Millsboro, DE	60	1 of 1	770 ppb (770 to 770 ppb)
4	Cedar Creek Estates Milford, DE	204	1 of 1	760 ppb (760 to 760 ppb)
5	Southpark Iowa Falls, IA	26	1 of 2	700 ppb (0 to 1400 ppb)
6	Sweet Briar Mobile Home Park Dover, DE	426	1 of 1	560 ppb (560 to 560 ppb)
7	Vaughn Cascade County Water and Sewer Di Vaughn, MT	500	1 of 1	530 ppb (530 to 530 ppb)
8	Rancho Oasis Apartments Las Vegas, NV	75	2 of 2	528.25 ppb (0.5 to 1056 ppb)
9	Tropic Breeze Port Richey, FL	100	1 of 1	512 ppb (512 to 512 ppb)
10	Keeseville Country Gardens Keeseville, NY	58	1 of 1	500 ppb (500 to 500 ppb)

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Health based limits for Total trihalomethanes (TTHMs)

Health Limit	Limit Value	Limit Description
Maximum Contaminant Limit (MCL)	80 ppb	The enforceable standard which defines the highest level of a contaminant that is allowed in drinking water. MCLs are set as close to health-based limits (Maximum Contaminant Level Goals, or MCLGs) as feasible using the best available analytical and treatment technologies and taking cost into consideration. Source: U.S. Environmental Protection Agency.
Maximum Contaminant Limit Goal (MCLG)	70 ppb	A non-enforceable health goal that is set at a level at which no known or anticipated adverse effect on the health of persons occurs and which allows an adequate margin of safety. Source: U.S. Environmental Protection Agency.
One in ten thousand (10-4) Cancer Risk	800 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	5.7 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	5000 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	4000 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	70 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	1000 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 Total trihalomethanes (TTHMs)

Water suppliers report an average of 1.6 Total trihalomethanes (TTHMs) tests per year. 11,669 water suppliers failed to report any Total trihalomethanes (TTHMs) tests at all.

Are tests routinely required for Total trihalomethanes (TTHMs) by federal law? Yes Water suppliers reporting tests for Total trihalomethanes (TTHMs) (1998-2003): 28,082 of 39,751 Average testing rate for water supplier reporting tests (1998-2003): 1.6 per year

Total trihalomethanes (TTHMs) Violations

Table. 0.9 percent of all water suppliers violated safe drinking water standards for Total trihalomethanes (TTHMs) between 1998 and 2003

Violation Type	Violations	Systems
Any Violation (1998-2003)	919	519
	(0.9% of all suppliers)
Testing violations (1998-2003)	385	277
	(0.5% of all suppliers)
Reporting violations (1998-2003)	6	6
	(< 0.1% of all suppliers)
Violations of tap water pollution standards (1998-2003)	528	247
	(0.4% of all suppliers)