New reports find mercury contaminating the food chain even in areas that most would consider to have a pristine environment.
This week, new reports on the extent to which mercury is contaminating our food supply came out of both the US and Canada.
Mercury is a highly toxic heavy metal that causes neurological damage, especially in the developing brains of children. The metal has been linked with autism over many years now and some studies have found increased levels of both the metal, and antibodies against it, in the blood of autistic children.
Mercury is produced as a byproduct by many heavy industries, particularly coal-fired power stations. It ends up in the air after being expelled from smoke stacks and then begins to settle back down to the earth. The toxic metal then enters water systems and eventually accumulates in the flesh of large predatory fish such as tuna, which make up a sizeable portion of human food intake.
Elemental mercury is also converted to an even more toxic compound, methylmercury, in the environment, mainly by certain bacteria.
That such a potent neurotoxin as mercury is contaminating our food is bad enough but the fact that fish, whose omega-3 containing oils are now known to be vital for brain developmental and mental health, are most affected, is adding insult to injury. It's a catch-22 situation in which fish are recommended by some authorities trying to promote the importance of omega-3 fatty acids for health, whilst other authorities are saying we should strictly limit our consumption of fish to avoid exposure to mercury.
The fact is that mercury exposure needs to be limited as much as possible, especially by children and women of child-bearing age, but an untainted source of omega-3 fatty acids is also vital for good health.
This week dailypress.com reported that officials in the state of Virginia have vowed to thoroughly investigate mercury contamination of food. This comes after testing of fish for mercury over the past few years has revealed that even fish from remote rivers in Southeastern Virginia, including the supposedly "pristine" Dragon Run, are contaminated with the toxic metal.
Previous testing has apparently shown that 11 of the 13 rivers and lakes in Virginia east of Richmond are contaminated with mercury, and most are in Hampton Roads or on the Middle Peninsula, including Dragon Run and the Pamunkey, Mattaponi and Piankatank rivers. Even Lake Drummond which is isolated from urban and industrial areas by over 100,000 acres of wilderness has high levels of mercury.
This week Virginia Governer, Timothy M. Kaine, announced plans for a new study with the aim of learning more about mercury sources in Virginia and whether the state's regulations on mercury emissions need to be reviewed.
Talking to dailypress.com about the study, Gov. Kaine said "Our understanding of mercury's effect on the environment is incomplete," adding that "We need more information on the steps we should take to reduce mercury contamination."
An important aim of the planned study in Virginia is to determine how mercury is entering the lakes and rivers and where it is coming from. The problem of mercury contamination is a national and international one, rather than being a regional problem.
In Canada authorities have been prompted to issue guidelines on the amount of tuna that is safe to eat after a CBC News investigation revealed that levels of mercury in many cans on supermarket shelves exceeded their own guidelines. Health Canada has established a guideline level of 0.5 parts per million (ppm) for mercury in commercial fish.
The Canadian Food Inspection Agency (CFIA) routinely tests canned tuna before it reaches the supermarkets to make sure it meets the 0.5 ppm guideline for mercury content. The agency says that around six per cent of the albacore tuna tested fails and is not allowed to go on sale. A spokesman for the CFIA told CBC News that the agency was confident in its testing methods and that it was providing assurance to the public that canned tuna on the shelves was safe to eat.
CBC decided to test these assertions and carried out the first independent testing to determine the mercury content of canned tuna that reaches store shelves in Canada.
According to the CBC web site the investigation focused on "white" (Albacore) tuna as it typically contains higher amounts of mercury due to it generally being a larger, older fish that "light" tuna, and therefore accumulates more mercury.
The station purchased 60 cans of "white" tuna from nine different grocery stores in Vancouver, Winnipeg and Toronto. The tuna was then sent to the University of Ottawa's Centre for Advanced Research in Environmental Genomics, where it underwent testing for mercury content. The centre is internationally recognized for its work with mercury.
What the testing found was that mercury levels in 13% of the tuna tested exceeded the Health Canada guideline level of 0.5ppm, and some tuna contained as much as 0.9ppm, almost double the maximum allowed amount.
Even the man who supervised the testing was shocked by the results. Dr. David Lean told CBC "I was surprised. They were a good deal higher than I'd thought." He added that "Clearly these tuna should not be eaten on a regular basis."
Prior to CBC reporting on the results from their testing there had been no official guidelines for consumption of canned tuna in Canada. Following the disclosure of the testing results Health Canada has now issued guidelines on the issue.
They now say that "as a precaution":
- Pregnant or breastfeeding women can eat up to four servings of canned albacore tuna per week.
- Children between the ages of one and four years can eat up to one serving per week.
- Children between the ages of five and 11 years can eat up to two servings per week.
One serving of tuna is 75 gm, 2½ oz, 125 mL, or ½ cup.
So here we have further evidence that not only are rivers and lakes in remote wilderness areas contaminated with mercury, but the mercury actually makes it onto our plates in significantly large amounts. The sad truth seems to be that no place on Earth is safe from mercury contamination, and fish which would otherwise be a highly nutritious and healthful food choice, are often unsafe to consume in any meaningful amount.
With mercury, and methylmercury in particularly, being linked to a whole range of environmental illnesses from autism, to chronic fatigue syndrome and fibromyalgia, which are causing disability to an ever increasing number of people, something must be done to address the problem at its cause. Mercury emissions from industry must be much more tightly controlled and safer alternatives sought. A vast amount of mercury is emitted by fast growing economies such as China, where a new coal-fired power plant comes online every week. This mercury inevitably spreads around the world on atmospheric currents. The international community must work together to help these nations limit their mercury emissions.