Superfund Research Program

Particulate matter pollution: A particular problem for the young?

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Release Date: 03/07/2012

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More than a quarter of the United States population is exposed to harmful levels of airborne particulate matter (PM) pollution, which is made up of soot, dust, and liquid particles, according to the Environmental Protection Agency. Now scientists at the University of California, Davis NIEHS Superfund Research Program have shown that newborns and infants may be more susceptible to harm from PM than adults.

Transmission electron microscope image of carbonaceous ultrafine particles that were used in the exposure studies.

"This study adds to the evidence that young children may be uniquely susceptible to PM," said Ian Kennedy, Ph.D., professor of mechanical and aeronautical engineering and co-author of the study. "Extensive development of the conducting airways happens in the postnatal period. Exacerbation of many airway diseases, such as bronchitis and asthma, has been linked to either acute or chronic exposures to PM in young children."

The researchers exposed 7-day-old rats and adult rats to either filtered air or to a low dose of ultrafine PM for six hours. The dose was below the average level of ultrafine PM in the United States and was approximately the same as the level found in downtown Fresno, Calif.

The neonatal rats were more susceptible to the pollution than the adult rats, as indicated by the very different biological changes they showed following exposure. Those changes in the neonatal rats included significant increases in markers of cytotoxicity (cellular toxicity), as well as changes in gene and protein expression.

The study also shows the need for defined exposure conditions that can be replicated in future studies. Kennedy and colleagues are perfecting a system for generating such conditions. PM in the air is mixed with metals and allergens, making it more difficult to study the health effects of PM itself. In this study, the researchers used an experimental PM they developed that is free of metals and allergens and that can be used to study health effects specific to PM in animal models. In addition, the researchers are able to generate PM that contains either high or low concentrations of polycyclic aromatic hydrocarbons (PAHs), which are potent combustion byproducts.

For More Information Contact:

Ian M Kennedy
University of California-Davis
Department of Mechanical & Aeronautical Engineering
2094 Bainer Hall
Davis, California 95616
Phone: 530-752-2796

To learn more about this research, please refer to the following sources:

  • Chan JK, Fanucchi MV, Anderson DS, Abid AD, Wallis C, Dickinson DA, Kumfer BM, Kennedy IM, Wexler AS, Van Winkle LS. 2011. Susceptibility to inhaled flame-generated ultrafine soot in neonatal and adult rat lungs. Toxicol Sci 124(2):472-486. doi:10.1093/toxsci/kfr233 PMID:21914721 PMCID:PMC3216412

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