Trace Compounds In Groundwater A Growing Concern
By: Elise R. Hugus
Every time you drink a cup of coffee, pop an aspirin, or shampoo your hair, some of the chemicals in those products could end up in your drinking water.
One would have to drink an Olympic-sized pool of that water in order to get a “therapeutic” dose, said experts from the Silent Spring Institute, speaking to an audience of 70 people at the Unitarian Universalist Fellowship in East Falmouth Wednesday night. As techniques for measuring these trace compounds improve, so does understanding of their effects on human health and the environment.
“These are not really emerging chemicals. They’ve been around for years,” said Nicholas Anastas, an environmental toxicologist and a self-described “green chemist.” “But they’re an emerging concern because now we can identify them.”
A groundbreaking study by the US Geological Survey in 2002, and another published by the Associated Press in 2008, found significant concentrations of pharmaceuticals and other chemicals in drinking water across the country. Other compounds topping the list were DEET, the main ingredient in bug spray; caffeine; flame retardant; and an active ingredient found in soaps, fertilizers, and detergents.
“In terms of the human health effect, there are many unanswered questions,” said Laurel Schraider, a researcher with the Silent Spring Institute. “The levels are very low, but there are reasons to study their effects as endocrine disruptors. Mixtures can have a greater effect than if you look at each [chemical] separately. Drinking contaminated water over a lifetime raises concern.”
In 2005, Silent Spring did a similar study of wastewater and drinking water on Cape Cod. The researchers found 13 of 85 chemicals they tested for, but most commonly found were tetrachlorethylene, a byproduct of chemicals used in dry cleaning; acetominophin, the active ingredient in Tylenol; sulfamethanoxol, found in antibiotics; and carbamezapine, a mood stabilizing drug. In a similar study in 1998, Silent Spring researchers found the chemical breakdowns of detergents and plastic in drinking water and wastewater.
These chemicals are known to break down slowly, said Dr. Schraider, which is one reason why their incidence was so high. One reason why they are not biodegrading is because once the wastewater is discharged back into the ground, there is relatively little oxygen to cause aerobic bacteria to “eat up” the chemicals.
In 2008, Silent Spring researchers tested the relationship between population density and contaminant levels in ponds across Cape Cod. Three hormones and six chemicals were commonly found, suggesting that pharmaceuticals and hormones are migrating in the groundwater, Dr. Schraider said. Silent Spring is working on a new study of nine water supply districts and 20 groundwater wells across the Cape, testing for pharmaceuticals, hormones, personal care products, fragrances, herbicides, flame retardants, and other chemical residues. The results of that study will be ready for release later this year, she said.
While the human health effect is not completely understood, researchers have found serious ecological implications downstream from wastewater treatment plants. In lab studies, researchers found that estrogen at 10 parts per trillion led to a “feminization of fish,” said Dr. Schraider. While no ponds were found to contain those levels in the wild, a Canadian field study showed that an entire fathead minnow population crashed at 5 parts per trillion.
Greater understanding of the issues posed by endocrine disruptors in drinking water will lead to better wastewater treatment planning, said David A. Reckhow, a drinking water specialist and biochemist at the University of Massachusetts Amherst. “If we knew which [chemicals] were most important to remove, that would make our lives a lot easier. We’d know which treatment method to pick,” he said.
Some treatment processes work better than others at breaking down the compounds, reverting them to harmless carbon dioxide and water, he said. “Large treatment plants tend to be more successful at removal. It seems that, the older the bacteria, the more effective they are. Just like us, the older you are, the better you get,” he said, eliciting laughter from around the room.
Bacteria are an essential process in wastewater treatment, and are recycled as biomass at the end of the treatment cycle. “Recycling allows them to become more diverse and biodegrade a greater range of compounds,” Dr. Reckhow said. In studies, 5-day-old bacteria were able to break down chemicals found in sunscreen. More complex chemicals, such as galaxolide, a component of fragrances, required bacteria over 15 days old to biodegrade.
The researchers also found that ultraviolet light, often used to disinfect wastewater at the tertiary treatment stage, is able to destroy the chemicals that escaped biological breakdown.
Dr. Reckhow outlined the benefits of various advanced treatment methods, analyzed in a recent study of wastewater in the Puget Sound area. There are four levels that are able to break down increasing numbers of chemical compounds. The most advanced system includes, after secondary treatment, coagulation and filtration, bionutrient removal and membrane filtration, and chemical coagulation.
Due to the combination of both aerobic and anaerobic breakdown processes, as well as chlorine treatment, close to 100 percent of the chemicals were removed from the wastewater stream, Dr. Reckhow said. However, they were found concentrated in the sludge, a byproduct of wastewater treatment that is usually disposed of by incineration.
Gerald C. Potamis, the Falmouth wastewater superintendent, asked the speakers if they thought treatment for total organic carbon (TOC) is an appropriate surrogate for capturing endocrine disruptors and other contaminants. In Falmouth, the wastewater treatment facility treats water to a standard of three TOC per liter.
Dr. Reckhow said that using the TOC standard is “a blunt tool” for removing potentially harmful compounds. Carbon comes from a variety of natural sources, including tree leaves, he said. In some places, boron is used as a tracer for pharmaceuticals, making them easier to identify. However, using boron would be problematic on the Cape, where most of the disposed wastewater winds up eventually in the ocean. Dr. Schraider added that even if the TOC content is reduced, it would not necessarily remove all the chemicals.
Jonathan R. Todd, president of John Todd Ecological Design in Woods Hole, asked if decentralized wastewater treatment plants could be just as effective in removing nutrients and chemicals. “If we could more rapidly deploy decentralized systems, wouldn’t it make just as much sense [as a central facility], and be much cheaper?” he asked.
Dr. Reckhow said he thinks decentralized systems have a lot of merit, but they require constant monitoring. One benefit, he said, is that the discharge would also not be centralized, resulting in lower concentrations of contaminants.
Mr. Todd pointed out that there could be natural attenuation in the soil as well, to which a member of the audience asked if that possibility has been studied. George R. Heufelder, director of the Barnstable County Department of Health and Environment, said that he is about to begin a study of the chemical breakdown of wastewater through soil and air dispersal systems.
A woman in the audience asked if her Brita water filter would be able to remove endocrine disruptors from her tap water. Dr. Reckhow said that the charcoal filter could be very effective, provided that it is new. As the filter ages, he said, it could actually release the concentrated contaminants right into the glass.
State Representative Matthew C. Patrick (D-Falmouth) asked if boiling water would work, to which Dr. Reckhow responded with a negative.
Dr. Anastas pointed out that residents can do a lot to reduce their contribution to the problem by properly disposing of unused medications and personal care products. Some cities have take-back programs through pharmacies or municipal fire departments and police stations. Through these programs, the products are incinerated at 2,000 degrees Fahrenheit, the only sure method of destroying the chemicals.
Several people in the audience questioned why the US Environmental Protection Agency is not regulating the chemicals in products that eventually end up in their drinking water. Dr. Anantas said that the EPA is in the process of reviewing the Toxic Substances Control Act, which he said has not been an effective tool in keeping potentially harmful chemicals out of consumers’ hands. He pointed out that, of the nearly 100,000 chemicals used regularly in industry, there are drinking water standards for only 100. “We need more uniform, transparent standards. We have some work to do,” he said.
Ruthann A. Rudel, director of the Silent Spring Institute, said that there is a growing grassroots movement to understand the chemicals commonly found in consumer products. She pointed to the “unintended consequences” of using asbestos or lead paint as an example of how citizens have changed industry’s practices in the past. She added that Silent Spring is engaging in research to determine whether products labeled as “safe” or “natural” really are what they claim.
“Exposures [to these chemicals] from drinking water are much smaller than the [exposure] in the products we’re using in our homes. We need to do a better job screening chemicals before they appear in commerce,” she said.
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