Skip to Main Content

Latest News

Advertisement
Advertise Here
March 31, 2011
DOI:10.1021/CEN031511173801

Harm From Mercury Passes Down Through Generations

Ecotoxicology: Maternal and dietary exposures in American toads have lethal effects when combined

Charlie Schmidt

  • Print this article
  • Email the editor

Latest News



October 28, 2011

Speedy Homemade-Explosive Detector

Forensic Chemistry: A new method could increase the number of explosives detected by airport screeners.

Solar Panel Makers Cry Foul

Trade: U.S. companies complain of market dumping by China.

Novartis To Cut 2,000 Jobs

Layoffs follow similar moves by Amgen, AstraZeneca.

Nations Break Impasse On Waste

Environment: Ban to halt export of hazardous waste to developing world.

New Leader For Lawrence Livermore

Penrose (Parney) Albright will direct DOE national lab.

Hair Reveals Source Of People's Exposure To Mercury

Toxic Exposure: Mercury isotopes in human hair illuminate dietary and industrial sources.

Why The Long Fat?

Cancer Biochemistry: Mass spectrometry follows the metabolism of very long fatty acids in cancer cells.

Text Size A A

American toads struggle to survive a double whammy of mercury exposure Shutterstock
American toads struggle to survive a double whammy of mercury exposure.

Traditional ecotoxicology studies that probe one toxic exposure at a time may consistently underestimate real-world hazards. That's the conclusion of researchers who studied the effects on tadpoles of mercury passed from a mother's tissues to her eggs and of mercury in the tadpoles' diet. The effects were synergistic and deadly: Only tadpoles exposed to both sources of mercury died off in large numbers (Environ. Sci. Technol., DOI: 10.1021/es104210a).

Scientists who study how contaminants affect juvenile development in birds, fish, and amphibians typically look at just one of two exposure routes: contaminant transfer from mother to eggs or environmental exposure from water or diet.  "Both routes are usually tested in isolation even though they often coincide in nature," says William Hopkins, an associate professor of fish and wildlife conservation at Virginia Polytechnic Institute and State University.

Scientists had found that juvenile American toads exposed to mercury by either route can suffer sublethal consequences. To combine exposures, Hopkins, Christine Bergeron, and their colleagues collected toads from a mercury-contaminated river near Waynesboro, Va. In the laboratory, they divided eggs harvested from breeding pairs into two groups: a non-contaminated reference group and a contaminated group. Hatchlings from each group then ate clean control diets or diets treated with mercury at one of two concentrations, each no higher than what's ordinarily measured in Waynesboro, Hopkins says.

The researchers then looked at the two exposure routes individually. Tadpoles hatched from contaminated eggs suffered more toxicity than did tadpoles that hatched from clean eggs but ate mercury-spiked food. The maternally exposed tadpoles swam more slowly and took a longer time to develop into adult toads.

But the combined effect was lethal at the higher dietary concentration to tadpoles from contaminated eggs. These animals experienced 50% greater mortality compared to tadpoles hatched from clean eggs that ate clean food. Hopkins says he doesn't know how the two routes interact to produce synergistic effects. The two routes of exposure cause different sublethal effects, he says. "That suggests they act on different physiological processes, or that the timing of exposure is influential with respect to outcome," he says. "But the net result of these multiple disruptions is mortality." 

Jason Rohr, an assistant professor of integrative biology at the University of South Florida, in Tampa, says that this could be the first study to combine these routes of exposure in amphibians. But Rohr cautions that in the real world, the results apply only to situations where the dual exposures occur.  And that varies, he adds, according to species mobility: In some species, offspring may move away from where their mother laid eggs, and toward or away from contaminants.

"This is a great foundational study but it's just a beginning," Rohr says. "We need to see if the results hold up with other species and other chemicals."

Chemical & Engineering News
ISSN 0009-2347
Copyright © 2011 American Chemical Society
  • Print this article
  • Email the editor

Services & Tools

ACS Resources

ACS is the leading employment source for recruiting scientific professionals. ACS Careers and C&EN Classifieds provide employers direct access to scientific talent both in print and online. Jobseekers | Employers

» Join ACS

Join more than 161,000 professionals in the chemical sciences world-wide, as a member of the American Chemical Society.
» Join Now!