Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Seafood substitutions can expose consumers to unexpectedly high mercury

20.08.2014

New measurements from fish purchased at retail seafood counters in 10 different states show the extent to which mislabeling can expose consumers to unexpectedly high levels of mercury, a harmful pollutant.

Fishery stock "substitutions"—which falsely present a fish of the same species, but from a different geographic origin—are the most dangerous mislabeling offense, according to new research by University of Hawai‘i at Mānoa scientists.


Fish market in Oahu's Chinatown. Photo courtesy Flickr user Michelle Lee.

“Accurate labeling of seafood is essential to allow consumers to choose sustainable fisheries,” said UH Mānoa biologist Peter B. Marko, lead author of the new study published in the scientific journal PLOS One. “But consumers also rely on labels to protect themselves from unhealthy mercury exposure. Seafood mislabeling distorts the true abundance of fish in the sea, defrauds consumers, and can cause unwanted exposure to harmful pollutants such as mercury.”

The study included two kinds of fish: those labeled as Marine Stewardship Council- (MSC-) certified Chilean sea bass, and those labeled simply as Chilean sea bass (uncertified). The MSC-certified version is supposed to be sourced from the Southern Ocean waters of South Georgia, near Antarctica, far away from man-made sources of pollution.  MSC-certified fish is often favored by consumers seeking sustainably harvested seafood but is also potentially attractive given its consistently low levels of mercury.

In a previous study, the scientists had determined that fully 20 percent of fish purchased as Chilean sea bass were not genetically identifiable as such. Further, of those Chilean sea bass positively identified using DNA techniques, 15 percent had genetic markers that indicated that they were not sourced from the South Georgia fishery.

In the new study, the scientists used the same fish samples to collect detailed mercury measurements.  When they compared the mercury in verified, MSC-certified sea bass with the mercury levels of verified, non-certified sea bass, they found no significant difference in the levels. That’s not the story you would have expected based on what is known about geographic patterns of mercury accumulation in Chilean sea bass.

“What’s happening is that the species are being substituted,” Marko explained. “The ones that are substituted for MSC-certified Chilean sea bass tend to have very low mercury, whereas those substituted for uncertified fish tend to have very high mercury.  These substitutions skew the pool of fish used for MSC comparison purposes, making certified and uncertified fish appear to be much more different than they actually are.”

But there’s another confounding factor. Even within the verified, MSC-certified Chilean sea bass samples, certain fish had very high mercury levels—up to 2 or 3 times higher than expected, and sometimes even greater than import limits to some countries.

Marko and his team again turned to genetics to learn more about these fishes’ true nature.  “It turns out that the fish with unexpectedly high mercury originated from some fishery other than the certified fishery in South Georgia,” said Marko. “Most of these fish had mitochondrial DNA that indicated they were from Chile.  Thus, fishery stock substitutions are also contributing to the pattern by making MSC-certified fish appear to have more mercury than they really should have.”

The bottom line:  Most consumers already know that mercury levels vary between species, and many public outreach campaigns have helped educate the public about which fish species to minimize or avoid.  Less appreciated is the fact that mercury varies considerably within a species.

“Because mercury accumulation varies within a species’ geographic range, according to a variety of environmental factors, the location where the fish is harvested matters a great deal,” Marko said.

“Although on average MSC-certified fish is a healthier option than uncertified fish, with respect to mercury contamination, our study shows that fishery-stock substitutions can result in a larger proportional increase in mercury,” Marko said. “We recommend that consumer advocates take a closer look at the variation in mercury contamination depending on the geographic source of the fishery stock when they consider future seafood consumption guidelines.”

CITATION:

Marko PB, Nance HA, van den Hurk P (2014) Seafood Substitutions Obscure Patterns of Mercury Contamination in Patagonian Toothfish (Dissostichus eleginoides) or “Chilean Sea Bass”. PLoS ONE 9(8): e104140. doi: 10.1371/journal.pone.0104140

University of Hawaiʻi at Mānoa

Contact:
Peter Marko, (808) 956-6146
Associate Professor, Biology
Talia Ogliore, (808) 956-4531
Public Information Officer, Vice Chancellor for Research

Talia S Ogliore | Eurek Alert!
Further information:
http://manoa.hawaii.edu/news/article.php?aId=6675

Further reports about: DNA contamination exposure fishery seafood species techniques

More articles from Health and Medicine:

nachricht Second cause of hidden hearing loss identified
20.02.2017 | Michigan Medicine - University of Michigan

nachricht Prospect for more effective treatment of nerve pain
20.02.2017 | Universität Zürich

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Impacts of mass coral die-off on Indian Ocean reefs revealed

21.02.2017 | Earth Sciences

Novel breast tomosynthesis technique reduces screening recall rate

21.02.2017 | Medical Engineering

Use your Voice – and Smart Homes will “LISTEN”

21.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>