Earlier efforts to determine the health and environmental effects of the nanoparticles that are finding use in hundreds of consumer products may have produced misleading results by embracing traditional toxicology tests that do not take into account the unique properties of bits of material so small that 100,000 could fit in the period at the end of this sentence.
- It focuses on monitoring how exposure to nanoparticles affects a cell’s ability to function normally, rather than just its ability to survive the exposure.
That was among the observations presented here at the 245th National Meeting & Exposition of the American Chemical Society (ACS), the world’s largest scientific society, by one of the emerging leaders in nanoscience research. The talk by Christy Haynes, Ph.D., was among almost 12,000 presentations at the gathering, which organizers expect to attract more than 14,000 scientists and others.
Haynes delivered the inaugural Kavli Foundation Emerging Leader in Chemistry Lecture at the meeting, being held in the Ernest N. Morial Convention Center and downtown hotels.
Haynes, who is with the University of Minnesota, explained that as manufacturers began using or considering use of nanoparticles in consumer and other products, concerns emerged about the possible health and environmental effects. More than 800 consumer products based on nanotechnology are on the market, according to some estimates. A new field sometimes termed “nanotoxicology” emerged in the last 10 years to investigate those concerns.
“Initial work focused on using the toxicology tests that had been used for years to evaluate bulk materials,” Haynes said. “Nanoparticles, however, are inherently different. A nanoparticle of material used in food or a cosmetic lotion may contain just a few atoms, or a few thousand atoms. Regular-sized pieces of that same material might contain billions of atoms. That difference makes nanoparticles behave differently than their bulk counterparts.”
Haynes said that some of the earlier nanotoxicology tests did not fully take those and other factors into account when evaluating the effects of nanoparticles. In some cases, for instance, the bottom line in those tests was whether cells growing in laboratory cultures lived or died after exposure to a nanoparticle.
“While these results can be useful, there are two important limitations,” Haynes explained. “A cell can be alive but unable to function properly, and it would not be apparent in those tests. In addition, the nature of nanoparticles — they’re more highly reactive — can cause ‘false positives’ in these assays.”
Haynes described a new approach used in her team’s work in evaluating the toxicity of nanoparticles. It focuses on monitoring how exposure to nanoparticles affects a cell’s ability to function normally, rather than just its ability to survive the exposure. In addition, they have implemented measures to reduce “false-positive” test results, which overestimate nanoparticle toxicity. One of the team’s safety tests, for instance, determines whether key cells in the immune system can still work normally after exposure to nanoparticles. In another, the scientists determine whether bacteria exposed to nanoparticles can still communicate with each other, engaging in the critical biochemical chatter that enables bacteria to form biofilms, communities essential for them to multiply in ways that lead to infections.