To my friends and to any woman who dream to become pregnant and cannot…..  you should read this. Mercury In Fish It is known that mercury is toxic to the nervous system of the foetus and young children. Older children and adults are more resistant to the adverse effects of mercury. Our largest exposure to mercury is from eating fish and several countries, including the USA and Australia, have recommended that pregnant women and young children restrict their intake of fish that contain high levels of mercury.

Studies have shown that adults and children in Hong Kong have relatively high levels of mercury, which seems to be due to a higher total intake of fish rather than due to the fish that are eaten having a higher mercury content. In one study the average mercury content of fish commonly eaten in Hong Kong was 120 (mcg/kg) for sea fish and 80 for freshwater fish (Ip, Paediatrics International 2004). This is relatively low, there are several large fish species that have mercury levels consistently above 500. As a result of high mercury intake by pregnant women, one study (Fok 2007 at the Prince of Wales Hospital in Shatin) found that more than 75% of newborns in HK had blood levels of mercury above the level that is considered safe.

 

We have gathered some data of mercury levels in fish to allow informed choices. These data come from more than one source and we have quoted all the results as mcg/kg for easy comparison. The results show the average mercury level, which will vary between different geographical locations and individual fish. The US and HK government data have been added in full and, at the end of this article, we have added a shorter list of the fish that are most commonly eaten by our patients

 

Australian Government:

Pregnant women or women intending to become pregnant within the next six months should be careful about which fish they eat.

They should:

Avoid fish with high levels of mercury (more than 500 mcg/kg) ie: shark, ray, swordfish, barramundi, gemfish, orange roughy, ling and southern bluefin tuna.

Limit other fish, such as tuna steaks, to one portion per week or two 140g cans of tuna per week (smaller tuna contain less mercury).

However, there is no restriction needed on the amount of salmon, including canned salmon, which is eaten.

 

US Government:

Women Who Might Become Pregnant, Women Who are Pregnant, Nursing Mothers, Young Children: Do not eat Shark, Swordfish, King Mackerel, or Tilefish because they contain high levels of mercury (more than 500mcg/kg). Eat up to 12 ounces (2 average meals) a week of a variety of fish and shellfish that are lower in mercury.