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Water and Health on Long Island Study Frequently Asked Questions

Why is it that some chemicals don’t have standards?

Not all chemicals tested have a drinking water standard. This may be because the process for setting a standard takes a long time. Or, it might be that the safe level is not yet known. We think it is important to test these chemicals to generate new information, and there may be a standard in the future.

What if my water has an orange value for a chemical with a health-based standard?

Some water samples may have levels of a chemical greater than what is considered safe. In this case, a first step would be to have your water retested, because many factors influence chemical levels in drinking water, and levels can change over time. Or, you could take steps to reduce your exposure to these chemicals such as by drinking bottled water. If you have concerns about your drinking water, we recommend water testing by a state-certified water testing laboratory.

What if my blood sample has an above-average (“orange”) value for a chemical?

Some blood samples may have levels of a chemical greater than the US average. These chemicals have been detected at different levels across people throughout the US. This doesn’t mean that the levels are harmful. It is important to remember that this measurement is only a snapshot of time and may not reflect continuous exposure levels. A first step would be to do another test. Or, you could take steps to reduce your exposure to these chemicals such as by drinking bottled water or reducing your use of products that contain the chemical. It is difficult to identify products that contain 1,4-dioxane because it is not generally listed on the label. However, New York State recently set limits on the amount of this chemical that can be in home and personal care products. You can also talk to you doctor about any health concerns

What if my blood sample has a value for a liver marker outside the normal range?

Having a level above the normal range does not necessarily mean you have a medical issue. Levels of markers of liver health can vary with age, sex, medication use, and laboratory. If you have any questions or concerns about these test results, you should contact your physician. We have included some information that explains possible causes for abnormal test results.

Where were these samples measured?

The water and blood samples were analyzed for research purposes at Yale University.

Additional Resources

Drinking water quality

For more information about the EPA Maximum Contaminant Level water quality standards and development of drinking-water regulations under the Safe Drinking Water Act, visit: National Primary Drinking Water Regulations.


You can also call the EPA Safe Drinking Water Hotline toll free at 1-800-426-4791 to speak with an Information Specialist or call the EPA Region 2 toll-free from New Jersey, New York, Puerto Rico, or the US Virgin Islands at 877-251-4575.


For more information on protecting and managing your private well, visit: Private Drinking Water Wells.


For additional information on well water testing and treatment, visit: Private Wells: Protect Your Family's Water and Inspect & Maintain Your Well and Water System.


To search for state-accredited labs in New York (from the New York State Department of Health), visit: Search NY Accredited Environmental Laboratories.

1,4-Dioxane in consumer products

For information on 1,4-Dioxane in consumer products from the New York State Department of Conservation, visit: 1,4-Dioxane Limits For Household Cleansing, Personal Care, And Cosmetic Products.


For information on 1,4-Dioxane in consumer products from the FDA, visit: 1,4-Dioxane in Cosmetics: A Manufacturing Byproduct.

More information on chemicals tested

For more information on 1,1-dichloroethane from the EPA, visit: Ethylidene Dichloride (1,1-Dichloroethane).


For more information on 1,1,1-trichloroethane from the EPA, visit: Methyl chloroform (1,1,1-Trichloroethane).


For more information on 1,1,2-trichloroethylene from the EPA, visit: 1,1,2-Trichloroethane.


For more information on 1,4-Dioxane from the EPA, visit: 1,4-Dioxane (1,4-Diethyleneoxide).


For more information on 1,4-Dioxane from the Suffolk County Department of Health Services, visit: 1,4-Dioxane in our Water Resources – Fact Sheet.

Liver enzyme, health, and tumor marker tests

For more information on liver enzyme tests from the Cleveland Clinic, visit: Elevated Liver Enzymes.


For more information on ALT from the Cleveland Clinic, visit: Alanine Transaminase (ALT).


For more information on AST from the Cleveland Clinic, visit: Aspartate Transferase (AST).


For more information on AFP from Medline Plus published by the National Library of Medicine, visit: Tumor Marker Tests - Alpha Fetoprotein (AFP) Tumor Marker Test.


For more information on CEA from Medline Plus published by the National Library of Medicine, visit: Tumor Marker Tests - CEA Test.


For more information on CA 19-9 from the Cleveland Clinic, visit: Tumor Markers (see: "What are common cancer tumor markers?" 4th bullet point: "CA 19-9").