High levels of mercury in fish such as tuna have been linked to heart and immune system damage, as well as fetal dangers. A new analysis by the Defenders of Wildlife (DW) cites canned tuna imported from Mexico and Ecuador as containing the highest mercury levels-- much higher than the federal limit.

The tuna caught by companies in these southern countries are generally larger, older fish. They have higher levels of mercury because they have had more time to absorb the metal into their bodies, largely due to being at the top of the food chain. DW advises avoidance of eating canned tuna from these countries. However, DW did note that canned tuna imported from Asia contain the lowest mercury levels.

Doctors at the Heart Hospital in London are urging awareness of the dangerous effects of chewing khat, an amphetamine-type African herb. Alarm rose when a 33-year-old man with no previous history suffered a full-scale heart attack with irreversible damages. He had been chewing khat consistently for two days. Research conducted in Yemen, where the drug is also widely-used, found a 39 percent increased heart attack risk in heavy khat users.

Six tons of khat are imported by air into the UK weekly. The Home Office decided not to put a ban on the drug, popular in the Somali community. Instead they encourage doctors and the public to be educated on khats effects. A survey last year of the Somali community showed half of the interviewees supported a ban. Currently khat is banned in the U.S., Canada, Norway and Sweden.

"Unless there is a public awareness campaign, khat will continue to cause serious harm to the health and prospects of people from these disadvantaged communities. The difficulty is that khat is seen as an integral part of cultural life for these communities, and any campaign will have to be culturally sensitive," said Dr. Kamran Abbasi, editor of the Journal of the Royal Society of Medicine.