Mapped Data Offers Insights about Water Quality and Birth Defects
Aggregated data about metals in North Carolina’s well water indicate some disturbing connections between birth defects and well water in some parts of the state.
By Gabe Rivin
First, pull up a state map. Next, gather six years’ worth of childbirth records from across the state. Top it off with a surplus of data about the state’s drinking-water wells.
Confused what to do next?
If the connection isn’t immediately clear, you might want to ask Rebecca Fry, a professor at UNC-Chapel Hill and an expert in the harms wrought by heavy metals, such as arsenic and cadmium. Fry, along with researchers from UNC and the state’s government, recently combined these disparate data sets while studying the connections between well water and birth defects.
What they found, Fry said, was striking.
Water wells throughout the center of the state are saturated with manganese, they found. And babies in North Carolina were more likely to have heart defects if their mothers drank water from these manganese-rich wells.
In recent years, health researchers have increasingly turned their attention to heavy metals – such as cadmium, mercury, chromium and arsenic – particularly for their effects on unborn children. Fry and others have shown that cadmium can potentially harm newborns’ health and that the heavy metal has accumulated in mothers’ blood.
So it’s not entirely novel that a metal has been implicated in a health problem. But what is new, according to Fry, is that researchers have turned to data-rich maps to make these findings.
“Just being able to map those metals across the state is very new,” said Fry.
Mapping big data
Fry said she and her colleagues had a surfeit of data to work with.
For their study, published in September, the researchers gathered six years’ worth of childbirth data from across the state, captured by the state’s Birth Defects Monitoring Program. That program is part of the N.C. Department of Health and Human Services and keeps records on newborns’ birth defects in all 100 state counties.
The researchers gathered data from about 20,000 babies born with birth defects. As a control, they also considered about 668,000 born without defects.
The babies were born in counties in all regions of the state. And that meant that the babies’ mothers lived in counties across the state where water quality can vary dramatically from well to well.
The researchers wanted to know whether well water had anything to do with newborns’ birth defects. But they were limited, Fry said, since they couldn’t measure the mothers’ actual water consumption.
“We don’t have active environmental monitoring in everyone’s home,” she said.
So, to estimate the water that the mothers drank, the researchers instead relied on geocoding, a technique that allows different types of data to be plotted on maps.
It’s a technique that’s gaining momentum in public health research, according to Tzy-Mey May Kuo, a research associate at UNC’s Lineberger Comprehensive Cancer Center.
“This is not new, but it’s a technique that’s become popular,” she said, noting that geocoding is used in popular websites like Google Maps, whose maps are enriched with street-level images and information about businesses.
For the study’s authors, geocoding helped explain what was in the water that the mothers drank.
Using state records about well water, the researchers mapped out the different quality of the water across the state. They then combined this water data and another key data set – the locations of mothers’ homes while they were pregnant – in order to predict, on average, what sorts of heavy metals were entering the women’s bodies and potentially the bodies of their unborn children.
This complex method allowed them to answer three simpler questions: Where in the state is well water a problem, where are children being born with defects and is there a connection between the two?
The need for biomonitoring
When the data crunching was done, the picture was clear.
Manganese is highly concentrated in many North Carolina wells, the researchers found, especially in the central counties of the state, which sit above the Carolina slate belt, a cross-state geologic formation with an abundance of manganese. In fact, about 20 percent of private water wells exceeded the EPA’s suggested limit for the metal.
And the manganese appeared to be causing harm. Newborns had a higher chance of being born with heart defects if their mothers drank the manganese-rich water, the study found.
Manganese toxicity follows a basic principle: the dose makes the poison. The body needs a small amount of the metal to function properly. But excessive amounts can be harmful.
Health researchers have known since the 1800s that manganese, which is used to harden steel, can cause neurological disorders in humans who’ve had high enough doses. Its effects, in fact, can emulate those of Parkinson’s disease. Among children, it’s also suspected of causing problems with neurological development.
But while their finding is worrisome, the researchers admit that their study had several significant limitations.
Though their sample size was large, the researchers were hampered by a lack of data about the mothers’ actual water consumption.
The study’s authors say their lack of individual measurements points to the need for biomonitoring, or chemical measurements of study participants’ bodies. But North Carolina currently doesn’t have any biomonitoring programs for pregnant women, they add.
They also note that until 2008 state government did not require residents to test well water – and even then, the tests were only made mandatory for new wells. So while the study relied on data from 1998 to 2010, the pre-2008 data would have come from residents who chose to have their wells tested. And that could have biased the data, the researchers say.
What well users can do
The UNC and government researchers used a sophisticated method to calculate health risks for newborns. But for residents concerned about their water, the solution can be much simpler. County health departments offer tests of private water wells, including tests for a number of heavy metals, including manganese.
In Montgomery County, well tests run between $35 and $85, and can measure pesticides, inorganic chemicals and petroleum. Teresa Davis, an environmental health coordinator with the county, said that most people seek out the county’s services on their own.
“Being such a small community, people know to call the health department,” she said.
Fry said that this is a good idea since federal and state regulations don’t cover the quality of well water. Residents can also install technology to remove heavy metals if they’re having an issue, she added.
But those filters can be more expensive than conventional water filters, like those made by Brita, Fry said. One, manufactured by Apyron, removes about 92 percent of arsenic from water but costs about $500. A reverse-osmosis system made by Certex costs about $300 and removes about 86 percent of arsenic.
The N.C. Department of Health and Human Services also collects water samples from newly drilled wells.
“The wells are sampled and the resident is given a list of contaminants (if any), possible remedies for such contaminants, as well as any health risks associated with consuming the water,” said Alexandra Lefebvre, a press officer with DHHS, in an email interview. “We recommend to all new well owners to sample their well annually after the first samples are collected.”