Emerging Compounds in Drinking Water

 

Pharmaceuticals and Personal Care Products

Nitrate-nitrogen, besides being a contaminant itself, can also indicate the possible presence of other wastewater contaminants such as disease causing organisms, solvents, cleaners, petroleum compounds, PPCP’s (pharmaceuticals and personal care products) and other emerging contaminants.

“Emerging contaminants” are chemicals or microorganisms that are not commonly monitored or regulated in the environment, but are suspected of having potentially adverse ecological and/or human health effects. They can include hormones, human and veterinary pharmaceuticals, and household products like soaps and lotions, insect repellents, perfumes and other fragrances, sunscreens, and hand sanitizers.

There have been numerous national studies done to investigate and document the occurrence of these emerging compounds in wastewater, surface, and groundwater.  In 1999 and 2000, the U.S. Geological Survey conducted a national stream reconnaissance, testing 139 streams in 30 states for 95 organic wastewater compounds (OWC). Eighty-two of the 95 compounds were detected in at least one sample, and 80% of the streams had at least one OWC detected. (Barnes, et al 2002).  In 2000, USGS sampled 47 groundwater sites across 18 states. Ninety-eight percent of the sites sampled had detections of emerging contaminants, with 46 of the 83 contaminants being found at least once. (Barnes et al.2008).  During 2001, USGS analyzed 25 ground and 49 surface-water untreated public drinking water supply sources in 25 states and Puerto Rico.  Ninety-six percent of the samples showed at least one emerging contaminant.

The emerging contaminants were more frequently detected in surface-water than ground-water sources. (Focazio et al. 2008)  Generally, all of these studies have detected the presence of a variety of organic wastewater contaminants and PCPP’s. The detections were more common in the stream samples (86%) and surface water samples than in groundwater (35%).  Mixtures of chemicals were common and the concentrations measured were generally at low levels (often less than 1microgram /liter) – just slightly above detection levels.

In June 2004, the U.S. Geological Survey and the Barnstable County Health Department (Zimmerman 2005), sampled wastewater sources and public, semipublic, and private drinking water supplies on Cape Cod that were thought to be affected by wastewater because of previously high nitrate-nitrogen concentrations.  Forty-three of the eighty-five PPCP and organic wastewater contaminant compounds that were analyzed for were detected in the wastewater samples. Thirteen were detected in low concentrations (less than 1 microgram/liter) in the private and semipublic drinking water supplies and three (an antibiotic, an antidepressant, and a solvent) were detected in the public water supply.

Although the ability to detect these emerging compounds at extremely low levels in drinking water has been greatly improved, the human health effects from these low level concentrations are not well documented.

In the absence of better information about the actual occurrence of these compounds and need to provide a level of protection, DEP recently incorporated very stringent performance standards for proposed wastewater discharges in Zone IIs.  DEP has adopted a Total Organic Carbon Concentration of 3 mg/l.  TOC is a surrogate for PPCP.  Some studies have documented that PPCP will be absorbed on to particulates of carbon. Therefore, removing this carbon will provide a level of protection to the underlying aquifer and public supply wells.  However, removing TOC to this level will require an extremely high level of treatment with 20-30% higher capital treatment costs and higher annual operation and maintenance.  Investigations into the transport of PPCP have found that the majority of these compounds do not travel very far in the groundwater.  In fact, monitoring wells downgradient of existing wastewater disposal sites on Cape Cod have found concentrations of TOC below the 3 ppm concentration.  The Massachusetts Environmental Trust has recently funded a study by Silent Spring Institute to sample and test public supplies for these emerging compounds.  The RWMP recommends a regional review of the findings of the SSI study and further review of the DEP regulations for cost-effectiveness.

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