Think small. One microgram. That’s one millionth of a gram. One millionth the weight of a single paper clip.
Now think even smaller: just one tenth of that single microgram. One tenth of one millionth of a gram.
This is the amount of methylmercury per kilogram of your body weight that the EPA says is the most you can be exposed to without “adverse effects.” For a 150 pound person, this works out to about 6.8 µg (micrograms). It ain’t much.
Now, considering that your typical amalgam filling weighs much more than this and is about 50% mercury, you can be sure that a person with such fillings is being exposed to far more than the EPA maximum, even before you account for other sources of exposure from the environment and diet. While the ADA contends that this mercury is inert and thus harmless, the truth is that mercury vapor is consistently released from these fillings, and at least some of it is in the form of methylmercury. The mercury then circulates throughout the body, being especially attracted to the kidneys and liver – major organs of excretion – as well as the brain, where it can do major neurological damage.
Pun not intended, but this is especially important to keep in mind with respect to children and fetuses, whose brains are yet developing. They are thus vulnerable to damage that can result in learning disabilities, ADD/ADHD, mental retardation, cerebral palsy and autism. The evidence for this is strong enough to have convinced the FDA to do an about-face and issue a warning about neurotoxic effects of amalgam fillings on fetuses and youth. It’s why pregnant women are advised to be cautious about the kinds and amount of fish they eat, to further minimize exposure to methylmercury.
Now a new analysis of the epidemiological evidence of harm from methylmercury exposure states that even greater caution is needed, suggesting that the actual level of “safe” exposure may actually be lower than previously thought.
Philippe Grandjean of the Department of Environmental Health at Harvard School of Public Health, in Boston, and the University of Southern Denmark in Odense, explains that the causes of suboptimal and abnormal mental development are mostly unknown. However, severe exposure to pollutants during the development of the growing fetus can cause problems that become apparent as brain functions develop – and ultimately decline – in later life. Critically, much smaller doses of chemicals, such as the neurotoxic compound methylmercury, can harm the developing brain to a much greater extent than the adult brain.
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The toxicity of methylmercury is well known, but the researchers believe that the medical world has underestimated the risk of brain damage associated with exposure to this compound as well as numerous others. Professor Grandjean emphasizes that little research has been carried out into the effects of other neurotoxic chemicals.
“Until there is enough evidence to rule out effects of certain chemicals on the developing nervous system, a cautious approach would involve strict regulation of suspected developmental neurotoxicants and prudent counseling of expectant mothers regarding exposures to untested substances,” the researchers conclude.
Other new research is helping us further understand the impact of low doses of mercury on cardiovascular health. Notably, it’s been found to change the way that arteries work.
The aim of the study was to evaluate whether really low concentrations of mercury, administered over a prolonged period of time, “could have a prejudicial effect on vascular response”, that is to say, on the way the arteries behave.
Data confirm that low doses of mercury have a harmful effect on vascular function. Mercedes Salaices, one of the other authors of the study, emphasises that the impact of mercury “could be compared to the impact produced by other more traditional cardiovascular risk factors such as hypertension, diabetes or hypercholesterolaemia”.
The researchers analysed whether chronic exposure to mercury causes an endothelial dysfunction in resistance and conductance arteries. Treatment with mercury induces an increase in oxidative stress, which is responsible – at least in part – for the deterioration in vascular responses. “Arteries contract more and relax less because there is less nitric oxide”, the vasodilator factor that is attacked by oxidative stress, underlines Briones.
Just two more reasons to stay away from amalgam fillings…