Researchers identify two traits responsible for the accumulation of toxic chemicals in aquatic food chains

Monday, May 02, 2016 by: S. Johnson
Tags: toxic chemicals, aquatic food chains, biomagnification

---

(NaturalNews) Researchers have discovered two traits responsible for the accumulation of toxic chemicals in aquatic food webs. As a result, scientists have created a screening method that can help determine which chemicals are most damaging to the environment.

According to a study conducted by the U.S. Geological Survey published in the journal Environmental Science & Technology, there are two traits responsible for the buildup of toxic chemicals at high concentrations. These include how easy it is for an organism to break down, or metabolize, a certain chemical and how the chemical is dissolved in water.

Magnifying the problem

In particular, the researchers discovered that a pattern known as biomagnification, the increasing concentration of a substance in organisms, is associated with a chemical's ability to be broken down by an organism and dissolved in water. The researchers noted chemicals that are insufficiently metabolized remain in the tissue of organisms, which are consumed by predators and passed up the food chain. Chemicals that don't dissolve in water have a proclivity to concentrate in fat.

"Chemical manufacturers and regulators can use this information to reduce the risks of harmful chemical exposures to ecosystems and the fish, wildlife and people who live in them," noted lead author of the study, David Walters, an USGS research ecologist, in a press release. "By screening for these two characteristics, we can identify chemicals that pose the greatest risk of the thousands that are on the market and for new ones being developed."

The researchers also discovered that some ecosystems and food webs are more susceptible to biomagnification than others. Significant biomagnification took place in aquatic food webs comprising both birds and mammals. The scientists speculate this may be due to the fact that aquatic food webs tend to have longer food chains, and because warm-blooded animals consume more food than cold-blooded animals.

Learning from past mistakes

The buildup of toxic pollutants originally alarmed scientists with the development of DDT more than 50 years ago. It was widely used by farmers across the globe as an effective pest control, being both easy to manufacture and having a long lifespan. DDT was eventually canceled, because it persisted in the environment, accumulated in fatty tissue and caused adverse health reactions in wildlife.

Based upon the results of the study, the researchers devised a model of biomagnification founded on how chemicals are broken down and dissolved in water. The probability that a chemical would biomagnify was almost 100 percent for compounds that were poorly metabolized, including chlorinated flame retardants, independent of their water solubility.

"We need to learn from our previous mistakes and have more informed and responsible design and use of chemicals in the environment," said co-author of the study, Karen Kidd, a Canada Research Chair at University of New Brunswick Saint John, in a press statement. "Our global review provides a straightforward approach for reducing the use of chemicals with the properties to concentrate through food webs. This is a critical step for decreasing risks for humans and wildlife from potentially harmful chemical exposures in foods."

In wake of the DDT incident tracing back to the 1950s and 1960s, researchers have been trying to keep tabs on environmental pollutants that accumulate in the food supply. Many of the pollutants are virulent to both human and non-humans animals and can persist in the environment for decades. Although biomagnification can be detected in a laboratory, Walters noted that it is best to gauge how much a chemical accumulates in the food supply by reviewing each kink in the food chain.

Sources include:

Pubs.ACS.org

USGS.gov

Chem.info

NPIC.OrSt.edu