Why mercury and PCBs?

A while back I reviewed the many seafood guides and the various ways they rank seafood choices.  They do share one thing in common, however, and that’s the special denotation of certain species as hazardous to human health because of toxin load. Specifically, high levels of mercury and PCBs as found by an Environmental Defense study.

First, kudos to EDF for making their data have immediate impact. Other studies of toxins in fish have sat around for literally decades before becoming part of the mainstream discourse about fisheries. But it does beg the question, what makes mercury and PCBs so important among the myriad toxins  in our oceans and our seafood?

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Oil Spill vs. Hypoxic Zone

There’s an elephant in the room as summer arrives on the Gulf Coast: hypoxia season.

This year, it’s a different Gulf, one covered in the largest oil slick in our country’s history.  No one is quite sure what the interaction between the oil and hypoxia will be.  Best guess is that both stresses will mean the end for most organisms living in the area and that hypoxia will exacerbate problems associated with the spill and hinder recovery by limiting oxygen availability for detoxifying bacteria.  However, step back for a minute and speculate on other possibilities: could the oil spill actually be helpful if it prevents or slows the eutrophication process? Could the damages associated with the oil spill be less than those associated with a large hypoxic zone?

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The Cove, Dolphins, and Mercury

thanks to www.savebay.info

The Cove has recently collected a long list of awards including most notably an Oscar for best documentary.  These well-deserved accolades reward the filmmakers for risky and groundbreaking filming in a highly protected cove in Japan where a dolphin fishery thrives, both to feed the aquarium trade and citizens wishing to enjoy a dolphin dinner.  However, I caution viewers, as with most works of art that rely heavily on scientific information, that you should use the movie as inspiration but turn to the scientific literature for accurate information, especially in terms of mercury concerns within the dolphins. Mercury poisoning is scary, but it is only one amongst a long and growing list of toxicological concern.  Its effects are relatively well-understood and known to be primarily of concern for pregnant women and small children.

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Roundup, Parasites, and Fish, oh my!

parasitic trematode

Telogaster: ubiquitous parasitic trematode helped out by a little Roundup, thanks indiana.edu

It takes a team from New Zealand to figure out that the US has its pesticide regulation wrong: toxins don’t act in the wild as they do in the carefully controlled and designed lab dosings.  Sounds reasonable, right?  Well, a recent article in the Journal of Applied Ecology by Kelly et al. was the first to describe Roundup’s ability to act synergistically with a parasitic worm.  Commercial formulations of Roundup, the most commonly used herbicide in the world, were found to increase the production of a parasitic worm’s (Telogaster opisthorchis) while at the same time decreasing a fish’s (Galaxias anomalus) immune system’s ability to fend off the parasite.

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