Cockroaches and Air Pollution Shouldn't Mix

Asthma linked to air pollution plus cockroach exposure

(RxWiki News) Most people try to steer clear of cockroaches. For children, however, avoiding these large, brown creepy crawlers is especially important.

Cockroach allergies are a major trigger for asthma in city kids. Another factor might make it even worse.

New research showed that early exposure to air pollution among pregnant women might increase kids’ risk of developing a cockroach allergy by age 7.

Researchers followed 349 mother-child pairs living in large housing projects in New York City. They measured how much air pollution the mothers were exposed to during their late pregnancies as well as how much cockroach exposure the children got in their early lives.

The results showed that children with the worst cockroach allergies had both high levels of cockroach exposure and mothers with high levels of air pollution exposure during pregnancy.

"Consult a pediatrician if your child has an allergic reaction."

Matthew S. Perzanowski, PhD, of the Mailman School of Public Health at Columbia University, and colleagues led the study to find out how a mother’s exposure to air pollution affected her child’s chances of developing cockroach allergies.

For their study, the researchers recruited 349 non-smoking, African-American or Dominican mother-child pairs from New York City.  

To measure what kind and how many allergens were in participants' homes, bed and kitchen dust samples were collected during the mother’s third trimester of pregnancy and again when the child was 1, 3 and 5 years old.

They also measured the amount of polycyclic aromatic hydrocarbons, or PAH, the women were breathing in during their third trimester of pregnancy. PAHs are especially harmful parts of air pollution. 

To measure PAHs, the participants wore a small backpack with an air filter that collected samples while they were awake and placed the sampler near their beds at night.

Blood samples were taken from the children at ages 2, 3, 5 and 7 years to test their exposure levels to cockroaches, mice, dust mites and cats. These tests showed how many allergies the children had developed.

The blood samples also allowed the researchers to test the children for a common kind of mutation in a specific gene called the GSTM.

Researchers suspect that this gene mutation makes it harder for people to get rid of the bad parts they breath in with air pollution.

The data analysis revealed that 279 (80 percent) of the participants’ New York City homes tested positive for high levels of cockroach allergen. By the age of 7, 82 of 264 children tested (31 percent) had a cockroach allergy.

However, the children with the highest cockroach allergy levels came from mothers that had been exposed to higher levels of PAH, or air pollution, during their pregnancies.

This link suggests that air pollution exposure during the third trimester of a mother’s pregnancy made her children more likely to develop cockroach allergies, the authors wrote.

The 27 percent of children that had the GSTM gene mutation and whose mothers were exposed to the higher levels of air pollution were even more likely to develop a cockroach allergy.

“Combined, these findings suggest that exposures in the home environment as early as the prenatal period can lead to some children being at much greater risk for developing an allergy to cockroach, which, in turn, heightens their risk of developing asthma," said Dr. Perzanowski.

The study results suggest that minimizing exposure to air pollution during pregnancy, and to cockroaches during early childhood, could be helpful in preventing cockroach allergies that can lead to asthma among city kids.

This study was published February 6 in The Journal of Allergy and Clinical Immunology.

The research was funded by the National Institute of Environmental Health Sciences, the US Environmental Protection Agency and several other foundations.

The authors reported no conflicts of interest.

Review Date: 
February 14, 2013