heavy metals in fish..

[JiminyCricket]

..how much do I need to worry about them? dd (15 m) is a fishaholic. I quite often give her tinned fish (usually sardines) for convenience i.e. probably not every week, but if she has it then she might finish the tin off the next night, and she will easily eat half a tin. Then we sometimes have salmon fillets etc I guess its not that often, I just wondered about the portion in relation to her size?

I'm sure I remember reading something recently about the heavy metals and pcb content in fish being a worry more in the larger oilly fish, such as tuna, shark and marlin – and the reason given is that they live much longer than the smaller fish and are higher up the food chain, so have more time to accumulate pollutants. Sardines are quite small – and a good source of calcium, I think, too if you eat the bones. Farmed salmon have been in the news recently, too, in connection with pollutants, so if you can, I'd try and buy wild salmon.
There'll be info about guidelines for eating tuna etc on the FSA website, but I think it's largely aimed at pregnant women. Once a week or every other week doesn't sound that much to me, and she's probably eating fairly small quantities. I'm sure other people may know more about this, but personally, I wouldn't worry too much.