Thursday, April 12, 2012

Emerging Contaminants in Your Drinking Water

Chemicals are everywhere, they exist in pharmaceuticals, household products, personal care products, plastics, pesticides, industrial chemicals, human and animal waste; they are in short, all around us. These chemicals include organics, inorganic, polymers, complex reaction products, and biological materials. The technology used for chemical analysis has advanced to the point that it is possible to detect and quantify nearly any compound known to human kind down to less than a nanogram per liter or parts per trillion (1/1,000,000,000,000). This enhanced analytical ability has allowed scientists to discover that trace levels of pharmaceuticals, potential endocrine disrupting compounds (EDC) and other emerging contaminants exist in much of our surface water and is appearing in some groundwater and persists in the water through conventional and some advanced treatments to also appear in our finished drinking water. The list above have all been found by testing performed by Fairfax Water.

All water on earth is part of the hydraulic cycle and is reused over the course of time. These traces of chemicals have managed to slip through the earth’s natural filtration and some of them through treatment systems to be identified in finished drinking water at extremely low levels. Finished and source water (as well as food and beverages) have been found to have low levels of these emerging chemicals, but whether this low level of exposure can cause any health effects or developments effects is unknown. Some of the emerging chemicals are or maybe endocrine disruptors, a class of chemicals that can mimic, block, or otherwise alter animal hormone responses. Endocrine disruptos can sometimes affect reproduction, development, and behavior, this is actually, how some pest control treatments are designed to work. A diverse group of chemicals called endocrine disrupting chemicals (EDCs) come from a variety of sources. These chemical have diverse molecular structures. BPA is just one of these chemicals. These chemicals become of great concern when they are discovered to be potential human endocrine disruptors as DDT, dioxin, PCBs and the drug DES were found to be in the past. Traces of endocrine disrupting chemicals are seemingly found in every part of our world, including dust, soil, water, air, food, manufactured products, wildlife, and even ourselves.

 Findings in the Fourth National Report on Human Exposure to Environmental Chemicals by the Center for Disease Control (CDC) in December 2009 and updated in 2012 indicate widespread exposure to some commonly used industrial chemicals. This exposure may have existed for decades but our ability to identify parts per trillion has allowed us to become aware of the ubiquitous exposure. The CDC measured 212 chemicals in the blood and/or urine of the participants. The samples were collected from participants in CDC's National Health and Nutrition Examination Survey (NHANES), which is an ongoing survey that samples the U.S. population every two years. Each two year sample consists of about 2,400 people. What the report found was widespread exposure to some chemicals throughout the population tested. The implications of this ubiquitous exposure are unknown, but of concern. The detection of a chemical in a person’s blood or urine does not mean that it will cause health effects or disease. The guiding principal of toxicology is that there is a relationship between a toxic reaction (the response) and the amount of poison received (the dose). An important assumption in this relationship is that there is almost always a dose below which no response occurs or can be measured. So if the concentration of the contaminant was low enough there would be no toxic reaction, but that principal is being tested with endocrine disruption and advances in analysis.

The occurrence of intersex fish in the Potomac River, and in other areas of the US resulted in Congressional hearings in the fall or 2006 to inquire about the “State of the Science on EDCs in the Environment,” as well as the US EPA’s activities associated with EDCs. The hearings resulted in a White Paper; “AQUATIC LIFE CRITERIA FOR CONTAMINANTS OF EMERGING CONCERN” and validation of analytical methods. In 2009, a final list of 67 chemicals and the schedule for issuing Test Orders for Tier 1 screening was issued. EDSP Tier 1 screening requires a battery of assays tests to identify chemicals that have the potential to interact with the estrogen, androgen, or thyroid hormonal pathways. The battery consists of 11 assays that have been developed and validated by the Office of Chemical Safety Pollution and Prevention. EPA intends to evaluate the results of the Tier 1 screening assays to determine whether or not a chemical has the potential to interact with the estrogen, androgen or thyroid hormonal pathways and to assess the need for Tier 2 testing. The work proceeds slowly.

 Meanwhile, water utilities are left not knowing how to address findings of emerging contaminants in their source and finished drinking water. A study conducted by the Water Research Foundation concluded that using a combination of ozone and granular activated carbon in addition to coagulation, sedimentation, filtration and disinfection is effective in removing some of the broad categories of EDCs, personal care products and pharmaceuticals found in drinking water. The American Water Works Association Research Foundation developed an Acceptable Daily Intake level for many of the emerging contaminants that are being found in drinking water supplies. An Acceptable Daily Intake level or ADI is a measure of the amount of a specific substance in food or drinking water that can be ingested orally over a lifetime without an appreciable health risk. Unfortunately, the reference doses ADI levels were the historic levels established by the EPA based on non-endocrine toxicity and cancer risk. These screening levels were not developed to determine whether certain substances may have an effect in humans on estrogen, androgenic or thyroid-related pathways, but were developed to protect populations from acute toxicity or cancer.

 In addition to finding intersexed fish in the Potomac, researchers have found male amphibians with ovaries and female frogs with male genitalia and frogs with six legs and other mutations. The endocrine system of fish bears some similarity to the human endocrine system, but we do not live our lives in the waters of the Potomac. Two million people rely on the Washington Aqueduct for their drinking water and millions of people in other parts of the country drink source water with similar observed occurrences of endocrine disruption. The impact on human life and the ecosystem of these emerging contaminants is not known, but according to Dr. Robert Lawrence of the Johns Hopkins School of Public Health and other scientists there is the potential to for humans to develop premature breast cancer, have problems with reproduction, and develop congenital anomalies of the male genitalia. Some believe these kinds of impacts are happening at a broad and low level in society so that the occurrence is not alarming to the general public or easily noted without detailed statistics, other scientists can find no measurable risk. We can no longer live in the happy world where we believed that our water was contaminant free. In truth, we do not know these trace chemicals are hazardous and how pure water (and food) needs to be. More research is needed on these emerging contaminants. Resources are limited and we need to make wise use of our economic and natural resources that is impossible without information.

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