hair spray

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NEW BRUNSWICK, N.J. — The next time you spray a disinfectant, you might want to consider how much you’re contributing to the air pollution in your own home. A new study finds common household products release nanoparticles — grains of engineered material so small they’re invisible to the human eye. Moreover, just walking through that same room stirs up these potentially harmful particles, which people breathe in.

Nanoparticles range between one and 100 nanometers. To put it into context, a nanometer is one billionth of a meter. The human eye can only see particles greater than approximately 50,000 nanometers. A single sheet of office paper is 100,000 nanometers thick.

When household sprays such as disinfectants, cleaners, sunscreens, hair sprays, cosmetic mists, and powders are used, study authors say residual nanoparticles stick to carpet fibers and floors. They are also suspended three to five feet in the air. That means children would be more likely to inhale nanoparticles since they are closer to the floor.

“If an adult is walking in a room and steps on some of these deposited particles, we found that the particles will be re-suspended in the air and rise as high as that person’s breathing zone,” says Gediminas Mainelis, a professor in the department of environmental science at Rutgers School of Environmental and Biological Sciences in New Jersey, in a media release.

Rutgers researchers collected this resuspended silver nanoparticle during a study on indoor exposure to the microscopic particles.
Rutgers researchers collected this resuspended silver nanoparticle during a study on indoor exposure to the microscopic particles. (CREDIT: Mainelis Lab/Rutgers University)

Nanoparticles often contain silver, copper, or zinc. In recent decades, more industries have used nanoparticles in household products because they exhibit unusual properties when manipulated at a microscopic level. For example, some nanoparticles have strong magnetic properties compared to other forms or sizes of the same materials. Additionally, some nanoparticles conduct heat or electricity more efficiently, while others reflect light or change color.

Limited research exists on the long-term health effects of nanoparticle exposure. Prior work found that pollutant particles sticking to floors could become airborne again as people start walking around. However, before this study, it was unknown whether this also applied to nanotechnology-enabled consumer sprays.

The researchers created a closed, air-controlled laboratory chamber containing carpeting and vinyl flooring. Using protective suits and respirators, the team walked along the surface after spraying seven products containing silver, zinc, and copper nanoparticles into the air. A small robot simulated the actions of a child moving along the floor surfaces.

When the products were sprayed in the air, children were found to have a higher exposure to particle concentrations than adults. They were also more at risk of exposure to particles stuck on carpets than vinyl surfaces. The authors concluded that the concentration of particles resuspended in the air depended on the product.

“We can use this knowledge to minimize our exposures, in this case to various nanomaterials,” Mainelis concludes. “Overall, this work could help us understand the resulting exposures and support future studies on human exposure reduction,” adds Mainelis.

The study is published in the journal Science of The Total Environment.

About Jocelyn Solis-Moreira

Jocelyn is a New York-based science journalist whose work has appeared in Discover Magazine, Health, and Live Science, among other publications. She holds a Master's of Science in Psychology with a concentration in behavioral neuroscience and a Bachelor's of Science in integrative neuroscience from Binghamton University. Jocelyn has reported on several medical and science topics ranging from coronavirus news to the latest findings in women's health.

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