Asthma more likely in kids with prenatal exposure to plasticizers

The following article was originally published by Environmental Health News

New York City children exposed in the womb to moderate levels of two plasticizers had a 72- to 78-percent higher chance of developing asthma, according to a new study.

The study is the first to link childhood asthma, which has been increasing in recent decades, to prenatal exposure to phthalates.

“These results suggest that phthalates may be one of the factors associated with that increase,” said Robin Whyatt, a Columbia University environmental-health scientist who led the study. She added, however, that more studies are needed to understand how important a risk factor these chemicals may be.

Pthalates previously linked to other health problems

Phthalates, used in the manufacture of vinyl and some cosmetics, have been connected to a number of health effects in lab animal and human studies, including airway inflammation, altered male genitalia, attention and learning problems, and premature births.

Nationally, one in every 11 children has asthma, according to the U.S. Centers for Disease Control and Prevention. Asthma rates more than doubled between 1980 and the mid-1990s and have remained high.

“We don’t have a good answer for why asthma and allergies have increased dramatically. Looking at the role of environmental exposures is an interesting and important question,” said Dr. David Bernstein, an allergist at the University of Cincinnati and spokesperson for the American College of Allergy, Asthma, and Immunology.

Study first to look at womb exposures

Previous studies reported an association between childhood exposures to phthalates and asthma, but no one until now had examined risk related to exposures before birth. “The prenatal period is likely the greatest window of susceptibility for lung development,” Whyatt said.

The researchers measured four phthalate metabolites in the urine of 300 pregnant women in the South Bronx and Northern Manhattan between 1998 and 2006. All of the women were African American or of Dominican descent.

Just over half of the study children visited a doctor for asthma symptoms between the ages of 5 and 11. Of those, 94 children, or 31 percent of the entire group, were diagnosed with the disease.

Subjects' asthma rate three times national average

The children in the study had asthma at a rate three times higher than the U.S. average and roughly double the national average for black children. They likely have such a high rate for a multitude of reasons, including cigarette smoke and vehicle exhaust.

“We don’t know how applicable these [phthalate] findings are to groups with much lower rates of asthma,” Whyatt said.

Kids whose mothers had the highest levels of di-n-butyl phthalate (DnBP) were 78 percent more likely to have an asthma diagnosis than kids whose mothers had the lowest levels. In addition, kids with mothers who had high levels of butyl benzyl phthalate (BBzP) were 72 percent more likely to have asthma. Children also were 39 to 44 percent more likely to have asthma symptoms, such as wheeze, if their mothers had higher levels of DnBP and BBzP during pregnancy. No association was found between asthma and two other phthalates used in cosmetics and food packaging.

Similar mother phthalate levels found throughout U.S.

The phthalate levels measured in study mothers are comparable to levels found in adults throughout the United States, Whyatt said.

The findings “raise new concerns that the presence of relatively ubiquitous environmental exposures may have deleterious respiratory effects”, according to the study published in the journal Environmental Health Perspectives.

BBzP, used to soften plastics, is commonly found in PVC plastics such as vinyl floor tiles and artificial leather. DnBP is used in food packaging and some cosmetics.

Levels of two chemicals dropping

A 2013 study reported that levels of both chemicals are dropping in Americans. They were banned from some children’s products in 2008. DnBP, once widely used in nail polishes, has been removed from most formulations.

The new study builds on 2012 studies of the same group that reported that children exposed to BBzP or diethyl phthalate (DEP) had elevated risk of asthma-related airway inflammation. Prenatal exposure to BBzP also was associated with elevated risk of childhood eczema.

While the new study, taken alone, isn’t conclusive, “there is mounting evidence linking phthalates to a number of diseases and chronic conditions,” said Kenneth Spaeth, director of the Occupational and Environmental Medicine Center at the North Shore University Hospital in Manhasset, N.Y., who was not involved in the study.

It’s unclear how phthalates may be increasing asthma risk. One theory, Whyatt said, is that they may make airways overly sensitive—essentially programming them to respond to common environmental stimuli, such as pollen or animal dander.

Chemical companies declined comment

Representatives of plastics and chemical manufacturers declined to comment on the new findings.

Based on a handful of studies conducted between 2003 and 2009, the American Chemistry Council, which represents manufacturers of phthalates and other chemicals, concluded that “phthalates do not cause, and are not likely to exacerbate, asthma.”

But Whyatt said that conclusion is “remarkably incomplete” and misses more recent findings.

Nearly everyone in the U.S. is exposed to phthalates. Whyatt said pregnant women can reduce their exposures by avoiding numbers 3 and 7 plastics, storing food in glass containers, and never microwaving food in plastic containers.