Contaminated water breeds low-weight babies, sometimes born prematurely

Pregnant women living in areas with contaminated drinking water may be more likely to have babies that are premature or with low birth weights (considered less than 5.5 pounds), according to a study based at Princeton University's Woodrow Wilson School of Public and International Affairs.

Featured in the Canadian Journal of Economics, the study shows that the effects of contaminated water—which include numerous cognitive and developmental impairments—are particularly significant for babies born to less-educated mothers. These mothers also are less likely to uproot from areas with contaminated water, which, the authors note, suggests a need for serious improvement in terms of communicating with people living in such areas.

"Fetuses are vulnerable to all types of pollution, including water contamination caused by chemicals and bacteria," said Janet Currie, the Henry Putnam Professor of Economics and Public Affairs at the Woodrow Wilson School of Public and International Affairs and director of the Center for Health and Wellbeing. "This contamination can lead to a host of problems, including low-birth-weight babies who can have lifelong cognitive struggles. It's a particular problem for less-educated women who also presumably have less options in terms of housing."

While past studies have focused on the effects of air pollution on infant health, Currie's is one of the first to evaluate the effects of water pollution on infants. Together with researchers from Columbia University and the University of California, San Diego, Currie examined ten years of New Jersey birth records and data on drinking-water quality collected from 1997 to 2007. All birth records contained information regarding the date of birth, an infant's health at birth and maternal characteristics such as race, education and marital status. To determine whether mothers relocated due to water contamination, the researchers studied sets of siblings and whether mothers moved between births.

Using data from the New Jersey Department of Environmental Protection (DEP), Currie and her team looked at violation records across 488 water districts in New Jersey and found that more than a quarter of districts had water contamination violations affecting more than 30,000 people. These violations included both chemical and bacterial contamination caused by such contaminants as dichloroethane—a solvent often used for plastics or as degreasers— as well as radon and coliform.

The researchers matched the birth records to the water systems that serve the infants' residences. Because weather can dictate the amount of water a person consumes, they also incorporated daily temperatures into their dataset.

"We found that infants exposed to contamination in utero tend to have mothers who are younger, less educated and less likely to be married than other mothers. They are also more likely to be African-American or Hispanic," Currie said. "The results also suggest that mothers who are less educated are less likely than other mothers to move in response to contamination, while older mothers are more likely to drink bottled water or move."

Currie notes that when a water district is affected, the DEP is required to send a notice to all residences. However, for renters, there may be routing difficulties.

"If someone puts something in your mailbox, do you even see it? Does your landlord pick it up?" said Currie. "Notices are being sent that people don't receive. There's an undercurrent here that the way information is sent isn't adequate. We need to get this information to people directly."

Currie suggests that health-care workers include literature about water contamination risks and hazards in clinics and exam rooms to reach more pregnant women.

"If it's going to be harmful for some groups, we need to at least let those groups know about them, so they can avoid it," said Currie.

In the future, Currie plans to continue studying environmental impacts on child health while also pursuing the relationship between home foreclosures and health.

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Maternal exposure to outdoor air pollution associated with low birth weights worldwide

Mothers who are exposed to particulate air pollution of the type emitted by vehicles, urban heating and coal power plants are significantly more likely to bear children of low birth weight.

The study, the largest of its kind ever performed, analyzed data collected from more than three million births in nine nations at 14 sites in North America, South America, Europe, Asia and Australia.

The researchers found that at sites worldwide, the higher the pollution rate, the greater the rate of low birth weight.

Low birth weight (a weight below 2500 grams or 5.5 pounds) is associated with serious health consequences, including increased risk of postnatal morbidity and mortality and chronic health problems in later life.

In the study, published on February 6th, 2013 in the journal Environmental Health Perspectives, the researchers assessed data collected from research centers in the International Collaboration on Air Pollution and Pregnancy Outcomes, an international research collaborative established in 2007 to study the effects of pollution on pregnancy outcomes. Most of the data assessed was collected during the mid-1990s to the late 2000s, and in some cases, earlier.

"What's significant is that these are air pollution levels to which practically everyone in the world is commonly exposed," said co-principal investigator Tracey J. Woodruff, PhD, MPH, professor of obstetrics and gynecology and reproductive sciences at UC San Francisco. "These microscopic particles, which are smaller than the width of a human hair, are in the air that we all breathe."

Woodruff noted that nations with tighter regulations on particulate air pollution have lower levels of these air pollutants. "In the United States, we have shown over the last several decades that the benefits to health and wellbeing from reducing air pollution are far greater than the costs," said Woodruff. "This is a lesson that all nations can learn from."

Particulate air pollution is measured in size (microns) and weight (micrograms per cubic meter). In the United States, federal regulations require that the yearly average concentration in the air to be no more than 12 µg/m3 of particles measuring less than 2.5 microns. In the European Union, the limit is 25 µg/m3, and regulatory agencies there are currently debating whether to lower it.

"This study comes at the right time to bring the issue to the attention of policy makers," said study co-author Mark Nieuwenhuijsen, PhD, of CREAL.

Nieuwenhuijsen observed that particulate air pollution in Beijing, China has recently been measured higher than 700 µg/m3.

"From the perspective of world health, levels like this are obviously completely unsustainable," he said.

Whether these pregnancy exposures can have effects later in life, currently is under investigation through an epidemiological follow-up of some of the children included in these studies.