Exposure to low doses of mercury changes the way the arteries work

Oct 23 2008

An international team of researchers has shown that mercury is another important factor in cardiovascular disease as it changes the way arteries work. One of the possible sources of exposure of humans to mercury is by eating contaminated fish.

The main effects of mercury affect the central nervous system and renal function. Over recent years the scientific community has reported an increase in cardiovascular risk following exposure to mercury, "although the mechanisms responsible for this increase are not completely known", state the authors of the new study that has been published recently in the American Journal of Physiology-Heart and Circulatory Physiology explain.

Ana María Briones is a researcher at the Universidad Autónoma of Madrid (UAM) and is one of the authors of the study. Briones explains the aim of the investigation to SINC: "Because the relationship between mercury and cardiovascular risk has been explained recently, and that cardiovascular risk is known to be related to changes in vascular function, we intended to see whether a relationship existed between mercury and changes in vascular responses".

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.

The risk of exposure to mercury today

Humans have been exposed to different metal pollutants such as mercury, although the possible consequences to health are not known in depth. At the present time, exposure to mercury is due, mainly, to the consumption of polluted fish, to the administration of anti-fungal agents and Thimerosal antiseptics in vaccines and to the inhalation of mercury vapour from some dental re-constructions

The European Environment Agency (EEA) recommended a reference blood mercury concentration of 5.8 nanograms per milliliter (ng/ml). It is considered that there are no adverse effects below this level. Data reveal that the concentration of mercury in the general population is less than 1 ng/ml, whereas in workers who suffer exposure in polluted zones, the levels are between 7 and 10. The percentage reaches up to 5.6 ng/ml amongst people who eat fish on a regular basis.