Why is there mercury in fish?

[barf]

I've always heard that one shouldn't eat fish more than once a week because it contains mercury. Why fish and not poultry, beef, or fruits & vegetables?

Also, is it mostly a natural thing, or is it from man made pollution?

 

[ramonesfan05]

It is due to pollution from coal burning plants getting into the atmosphere and raining down into bodies of water (they are swimming/drinking it!). There are higher mercury levels in filter feeders (oysters) and longer living fish. Shrimp have negligible amounts of mercury because they are short lived. Mercury levels don't get high enough in terrestrial plants (grass, frit, vegetables) to pose a significant danger.

 

[critterman51]

Mercury COMPOUNDS are in everything, because humans have released them into the environment. Most mercury Compounds have been released by burning fossil fuels. How much fish you can eat depends on the species of fish and that fish's diet. Mercury compounds accumulate in a fish's tissues so that fish higher up on the food chain and fish that are older have more contamination. A little fish eats a little mercury then a bigger fish eats many little fish and get all of their mercury and then a BIGGER fish eats the bigger fish and keeps more mercury. Small fish and vegetarian fish will have less contamination. Poultry, pork, and beef have less contamination because they are not eating food that is as contaminated as Tuna, Swordfish, and Sharks eat.