The use of metals has expanded substantially in the last century and gives rise to widespread exposure of humans. It has long been recognized that metals are important toxic agents that may cause acute and chronic poisoning in metal workers and population groups with high exposures. In recent years evidence has been presented indicating that low level exposures to metallic compounds contribute to the occurrence of several common diseases. The World Health Organization (WHO, 2009) has estimated that on a Global basis, 143,000 deaths and nearly 9 million disability-adjusted life years (DALYs; i.e. years of healthy life lost) were caused by lead exposure in 2004. Although lead exposure in the general population of many countries has decreased since 2004 because of the continued phase-out of lead in gasoline, several recent epidemiological studies support the notion that low-exposure effects of lead occur in addition to those considered by the WHO (2009). It is therefore quite possible that the present global burden of disease caused by lead exposure is the same or greater than the one estimated in 2004.
In addition to the estimates of lead-related disease and mortality, there are other well documented effects that were not included in the WHO estimates of the global burden of disease. This organization further summarized data indicating 9100 deaths and 125,000 DALYs per year in Bangladesh from arsenic in drinking water and that mercury exposure (mainly methylmercury) through fish consumption causes cognitive deficits and mild retardation in a considerable number of children. An increased incidence of myocardial infarction has been reported in populations with a high intake of methylmercury from fish and a low intake of polyunsaturated fatty acids. The public health impact of this observation of interaction between a nutritional factor and a toxic metal compound may be considerable. There is evidence for a role for relatively low occupational exposure to manganese as well as exposure in the general environment as a contributory factor to the increasing prevalence of Parkinson disease and there is a potentially great importance of metal exposure in early life as a risk factor for neurodegenerative disorders later in life. Recent epidemiological evidence indicates a role for cadmium in the general environment in increasing the occurrence of renal effects and osteoporosis, as well as cardiovascular diseases. There is no doubt thus that exposure to toxic metals and their compounds represents important causal factors contributing to the global burden of disease. Deficient dietary intake of essential metals in food in a global perspective was estimated by the WHO (2009) to cause 433,000 deaths and 15,580,000 DALYs from zinc deficiency and 273,000 deaths and 19,734,000 DALYs per year from iron deficiency.
In view of the considerable global burden of disease caused by metals there is an obvious need for preventive action.
2015. Vol. 13, no 1, 12-14 p.