The safety and quality of our nation's drinking water sources are increasingly being questioned, after residents in Flint, Michigan, as well as other regions have recently been found to have contaminated water supplied to their homes. Now a new study has found that pharmaceutical drugs and chemicals found in every-day consumer products can find their way into private drinking wells via wastewater discharged into septic systems. The findings add to growing health concerns related to unregulated chemical pollutants commonly found in household drinking water.
While conducting the study, which was recently published online in Science of the Total Environment, scientists from the Silent Spring Institute discovered 27 unregulated chemical pollutants, including 12 different pharmaceutical drugs, chemical compounds used to manufacture flame retardants, non-stick coatings, and an artificial sugar-free sweetener.
It is estimated that around 44 million people in the US depend on private wells for their drinking water. Yet, unlike public water wells, private drinking wells are not regulated by water officials; instead, residents are solely responsible for ensuring that water quality within their wells meets federal safety standards. Not only are private wells monitored less frequently, they are typically also shallower than public drinking wells, and thus more vulnerable to contamination from farming activities, construction, and local landfills. Consequently, contamination of drinking water in private wells continues to present an ongoing health risk to residents in many areas of the country.
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Households that get their drinking water from private wells typically also make use of private septic systems for treating their wastewater. It is estimated that around 25% of all US homes make use of a septic system for treating household wastewater. Earlier studies conducted at Cape Cod by Silent Spring scientists revealed that hormone-disrupting pharmaceuticals and chemicals can leach through soils to contaminate both surface water and groundwater. According to lead author, Dr Laurel Schaider, a scientist at the Silent Spring Institute, the next step was to determine whether these contaminants could find their way from groundwater into household drinking water sources.
To find the answer to this key question, Dr Schaider and her research team took water samples from 20 private drinking water wells across Cape Cod and tested them for 117 pollutants. They found that around 70% of the wells tested positive for PFCs (perfluoroalkyl substances) — a class of fluorinated chemicals that are sometimes referred to as PFASs. PFCs are known endocrine-disrupters that are associated with developmental disorders and cancer. These chemicals are commonly found in every-day household products, such as non-stick frying pans, pizza boxes, stain-resistant rugs and carpets, and waterproof clothing.
The scientists found that 25% of all wells tested contained chemicals used in flame retardants, and found a staggering 60% of the tested wells contained pharmaceutical drugs. The antibiotic, sulfamethoxazole, which is commonly prescribed for infections of the urinary tract, together with carbamazepine, a pharmaceutical drug that is prescribed for the treatment of bipolar disorders, seizures and nerve pain, were amongst the more common drugs encountered.
The researchers also assessed nitrate concentrations in the wells, and discovered that water in wells that had higher nitrate levels also tended to have more contaminants, and these were found in higher concentrations. The researchers note that all water samples came from wells that were situated in areas that were served by septic wastewater treatment systems, and closer analysis revealed that these backyard septic systems were most likely the source of the contamination.
According to Schaider, this study is the first to show that septic systems can be a source of PFCs in private drinking wells, and considering that 85% of Cape Cod residents use septic treatment systems, the risk associated with contaminated drinking water is a serious health concern.
Nitrates are also a drinking water contaminant that pose a serious health risk at high concentrations. Yet, while the EPA has set standards for nitrate levels in drinking water, there are none for the chemical contaminants found during the course of this study. While the levels of pharmaceuticals found in this study were considered to be much lower than those typically prescribed for a therapeutic dose, that doesn't necessarily lessen the risk notes Schaider.
"Drugs are intended for specific uses and can have side effects," she says. "And we don't give certain medications to pregnant women or children because the developing body is very sensitive."
People may also be allergic to certain drugs, such as antibiotics; and endocrine disrupting chemicals, such as flame retardants and PFCs, may produce adverse effects at very low doses. Furthermore, little is known about the health effects of exposure to a concoction of different chemicals found in drinking water.
"People often don't think about where their tap water comes from," says Schaider. "But it's really important that they do and that they take steps to make sure it's safe."
Households that depend on private wells for their drinking water should have the water tested annually. While these tests typically assess nitrate and bacterial concentrations rather than unregulated chemicals originating from household wastewater, this study shows that high nitrate levels could indicate the presence of other chemical pollutants.
The current safety standard for nitrate in drinking water is set at 10 parts per million (ppm). However, the researchers found PFCs and pharmaceuticals in well water that had nitrate concentrations of less than 1 ppm. If you get your drinking water from a private well that has nitrate concentrations that are below the health standard set by the EPA, yet greater than 1 ppm, you should consider filtering your drinking water with a filter system to remove any pollutants that may contaminating your water. But as prevention is better than cure, to prevent these chemicals from making their way into the environment in the first place, we should limit our use of medications that contain toxic chemicals, refrain from flushing unused pharmaceuticals down the loo or drain, and where possible, move backyard septic systems away from drinking wells and ensure that they are well maintained.
Laurel A. Schaider, Janet M. Ackerman, and Ruthann A. Rudel. Septic systems as sources of organic wastewater compounds in domestic drinking water wells in a shallow sand and gravel aquifer. Science of the Total Environment. 2016. doi:10.1016/j.scitotenv.2015.12.081