Contaminants of Emerging Concern in Drinking Water Sources

Scientific advances have produced numerous compounds that facilitate everyday life, cure diseases, and save lives through human and veterinary medicine.  One byproduct of these advances is the entry of chemicals into the environment, including pharmaceuticals, synthetic fragrances, detergents, disinfectants, plasticizers, preservatives, and others that can be present in wastewater, or agricultural and urban runoff.  New information has shown that these contaminants may pose a threat, but the detailed facts needed to establish the need for a regulatory standard have yet to be developed.

Some emerging contaminants have been used for a long time but have only recently been discovered in lakes, rivers, and ground water - our drinking water sources.  Advances in detection methods have made it possible to measure these chemicals in very small concentrations.  Traces of these contaminants have been  found in drinking water sources across the country, including in Maryland. 

To protect our drinking water, the U.S. Environmental Protection Agency (EPA) regulates more than 90 specific contaminants in public drinking water supplies because of their known or suspected human health effects.   An additional 40 or so "unregulated contaminants" are monitored at public drinking water systems in order to determine if they need to be regulated.  In addition, there are a large number of contaminants that exist at trace levels or have only recently come under study. 

How do contaminants of emerging concern get into the water?

Emerging contaminants are of many types and have many sources.  One large group consists of the pharmaceuticals and personal care products (PPCPs) that we purchase and use regularly.  Other categories include certain pesticides, nanomaterials, flame retardants, and plasticizers. 

These compounds can make their way to the waste stream, but wastewater treatment processes are not always effective at removing them.   Consequently, some are  found in surface water bodies that receive treated wastewater, and their concentrations are higher near discharge points.    Some compounds reach the ground water through onsite sewage disposal systems or improper disposal of unwanted materials.  Agricultural wastes can also be a source.  For example, livestock are given antibiotics that sometimes find their way into our rivers and streams.

What are the health impacts?

These contaminants are at low concentrations in drinking water and have not been established as causes of human illness, but more research is needed.  We know more about their effects on wildlife.  One example is the change observed in male fish, indicating that their sex organs have been influenced by unidentified endocrine-active chemicals in the water.  Other examples include egg-shell thinning, masculinization of snails, and changes in immune function. 

What is being done?

Researchers are attempting to measure the impacts of emerging contaminants, detect their presence in water supplies, and improve water treatment methods.  EPA is developing laboratory methods to facilitate the monitoring of these compounds. 

All of us have an opportunity to help by disposing of unused medicines in the trash rather than down the sink or toilet.  The federal government recommends the following actions:

  • Take unused, unneeded, or expired prescription drugs out of their original containers and throw them in the trash
  • Mix prescription drugs with an undesirable substance, such as used coffee grounds or kitty litter, and put them in non-descript containers, such as empty cans or bags, to further ensure that the drugs are not diverted
  • Flush prescription drugs down the toilet only if the label or accompanying patient information specifically instructs doing so
  • Check to see if your community has a pharmaceutical take-back program or solid waste program that allows the public to bring unused drugs to a central location for proper disposal

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