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State Regulators Propose Lowering Arsenic Limit In Public Drinking Water By Half

Ceyhun (Jay) Isik

State regulators want to cut their limit on arsenic in drinking water in half – and their research shows the change could save lives.

A bill in the legislature last year suggested the Department of Environmental Services sharply lower its limit from the Environmental Protection Agency’s default 10 parts per billion to 4 parts per trillion.

But DES told lawmakers that might be infeasible, and suggested looking into a more moderate reduction instead, such as from 10 ppb to 5 ppb. 

Only one other state, New Jersey, has adopted that lower standard. 

Ultimately, lawmakers told the agency to come up with its own new number by Jan. 1.

Now, after months of research with the University of New Hampshire, regulators say lowering the arsenic standard to 5 ppb would be feasible.

(Click here to read the entire DES arsenic proposal, along with a related UNH study.) 

The UNH study that DES cites in its proposal says over a 70-year period, the decrease could prevent between 27 and 82 lung and bladder cancer cases, and between three and eight cancer deaths.

They say it would also prevent IQ and earnings loss and other health problems for hundreds of children who are currently drinking water that would be considered contaminated under the new standard.

UNH also found that residents would be willing to pay a little extra to avert all those risks.

The state says it would cost just under a million dollars for public water systems to comply with the lower limit.

Past studies have linked the prevalence of arsenic in northern New England’s groundwater – which feeds private wells and some public systems – to the region’s high rate of bladder cancer.

The roughly 40 percent of New Hampshire residents who use private wells would not be required to follow the lower standard. But the UNH researchers say in their study they hope a change in state law would spur more voluntary treatment.

Advocates for drinking water protection are lauding the proposal, which will now go to the legislature for review.

CORRECTION: An earlier version of this article incorrectly stated that DES had initially felt a 5 part-per-billion standard was infeasible. In fact, the agency worried an earlier legislative proposal of 4 parts per trillion would be infeasible, and suggested looking into a limit like 5 ppb instead.

An earlier version of this story also incorrectly stated that 1 part per billion was like a drop of ink in a bathtub; in fact, it is akin to a drop of ink inside an oil tanker truck.

This story has been updated to correct the errors. 

Annie has covered the environment, energy, climate change and the Seacoast region for NHPR since 2017. She leads the newsroom's climate reporting project, By Degrees.
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