We are constantly exposed to the environmental pollutant lead. What are the health effects of this exposure?
There have been studies that linked concentrations of lead in the blood to cardiovascular disease but supporting evidence has been weak. Researchers at the Harvard School of Public Health (HSPH) and the University of Michigan School of Public Health believe they may have found a better indicator of cumulative lead exposure, an indicator that can be linked to number of diseases including cardiovascular disease. The researchers look at levels of lead in the bone.
Where does the lead come from?
Lead is everywhere. In the food we eat, in the things we use daily. In the air we breathe. Air pollution has been the main source of lead exposure, mainly from emissions from cars using leaded fuel. Since the introduction of lead-free gasoline and the banning of leaded fuel in many countries (including the US in the 1990s), the lead levels in the air have significantly decreased. However, lead accumulates in the body especially in the bone and remains there for years. Thus, health problems due to lead exposure are not brought about by acute but rather by chronic toxicity. People in US who were born before the 1990s have been exposed more to lead than the younger generation and are still carrying the pollution burden in their body.
The researchers looked at the levels of lead in the blood and bone of 868 male study participants. The results showed that
- High levels of lead accumulated in the bone are associated with high risk of mortality from all causes, especially cardiovascular disease.
- Men with the highest lead levels are 2.5 more likely to die from any disease than those with the lowest levels.
- Men with the highest lead levels are 6 times more likely to die from cardiovascular disease than their peers with the lowest levels.
This increased risk for death is not dependent on socioeconomic factors such as age, smoking, education, race, alcohol, physical activity, or underlying conditions such as obesity, high density lipoprotein or total cholesterol levels, hypertension or diabetes.
According to lead author Dr. Marc Weisskopf,
“The findings with bone lead are dramatic. It is the first time we have had a biomarker of cumulative exposure to lead and the strong findings suggest that, even in an era when current exposures are low, past exposures to lead represent an important predictor of cardiovascular death, with important public health implications worldwide.”
So what does lead do? Lead might badly affect our health due to oxidative stress, a mechanism closely linked to cardiovascular disease. Lead exposure has also been linked to stiffening of the arteries and hypertension.
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