Every five years the U.S. Environmental Protection Agency designates 30 contaminants that all large water suppliers and a sampling of smaller ones must test for in their drinking water wells.
These contaminants are unregulated, meaning there are no set national safe drinking water standards.
The intent is to see what is in the nation’s drinking water and if the contaminants pose a health risk. If widespread, the agency can decide to regulate the contaminants if it serves a public health need.
In its latest round, water suppliers were required to undertake sampling during a 12-month period between 2013 and 2015. The results of the survey, which covers about 80 percent of the population in the United States, were released in August.
On Long Island, 25 large and three small water districts took part in the survey. State health records show those districts supply water to about 2.97 million people.
Water suppliers here either did not detect, or found concentrations below a minimum reporting threshold for 14 compounds, according to EPA data. Other contaminants were discovered but, in addition to 1,4-dioxane, only three were at levels that could post health risks, each under circumstances that lessened reasons for concern.
Chlorate, which is used as a bleaching agent, for agricultural pesticides and in explosives, was found in samples in eight water districts in concentrations higher than established health safety levels. Persistent consumption of high concentrations by infants and young children can cause anemia and low oxygen levels in blood.
But unlike for 1,4-dioxane, no complex treatment is required.
High chlorate levels are typically associated with chlorine being added to the system as a disinfectant to prevent bacterial growths, said Stan Carey, chairman of the Long Island Water Conference.
High levels of chlorate can show when a well is not often used, and sometimes all that is required is flushing out a well or changing how chlorine is stored.
“Most of the time you’re not looking at the treatment,” Carey said. “You’re looking at operational changes.”
The most extreme reading for chlorate was up to 1,200 parts per billion in a South Farmingdale well, nearly six times the EPA yardstick for chromic exposure of 210 parts per billion. But South Farmingdale Water District Superintendent Frank Koch said the well was under construction and not in use when the test took place. Six months later, the chlorate levels were at 140 parts per billion, well below the level of concern, EPA data shows.
Levels of 1,2,3-trichloropropane, labeled a probable carcinogen by the EPA were also found in at least 10 water district wells at concentrations that pose a 1-in-a-million cancer risk after prolonged exposure. It’s unclear how many wells showed concentrations at the 1-in-10,000 risk because that threshold is below what sample methods can detect , EPA said. But running a granulated activated carbon system — which is used widely on Long Island — will remove the chemical from water supplies.
One sample for cobalt showed up at 84 parts per billion in Franklin Square, though a later sample from the same well tested six months later measured 1.7 parts per billion. H2M Water president Dennis Kelleher, whose firm represents the water district, said they believe the initial results were an error or an outlier. Ill health effects are predicted to occur at intermediate exposure to 70 parts per billion, according to EPA. Exposure to this naturally occurring element can damage the heart and lungs.
The EPA survey also found hexavalent chromium in samples taken from 36 of 38 public water supply districts on Long Island. The compound was made famous by Erin Brockovich’s crusade against Pacific Gas and Electric Co. of California for allowing hexavalent chromium to leak into one town’s water supply. It led to a $333 million settlement. State officials say they are unconcerned about the samples taken on Long Island because they are at safe levels. The limit is set at 100 parts per billion for all forms of chromium combined, which would include hexavalent, and levels on Long Island did not exceed 7.3 parts per billion.
“All results we have seen would still be below standards,” said Dr. Roger Sokol, director of the New York Department of Health’s Drinking Water Protection Program.