It’s clear from our analysis that there’s a possible link between exposure to heavy metals or metalloids and risk of conditions such as heart disease, even at low doses – and the greater the exposure, the greater the risk
- Rajiv Chowdhury
The researchers have also challenged the omission of environmental risk factors such as toxic metal contaminants in water and foods from the recent World Health Organization report on non-communicable diseases (NCDs).
In recent decades, exposures to environmental toxic metals such as arsenic, copper, lead, cadmium and mercury, have become a global public health concern. Although often naturally occurring, these contaminants have made their way into water supplies and, via irrigation, into the food chain. For example, in Bangladesh, deep wells were introduced in the Ganges Delta to draw water clear of bacterial and viral pathogens, but this inadvertently led to exposure to toxic metals.
Concern has often focused on the toxicity or carcinogenic properties of the metals, particularly at high doses. However, there is increasing evidence to suggest that heavy metals may have other adverse effects on health – including cardiovascular disease such as heart disease and stroke – even at lower levels of exposure, which might be prevalent in many parts of the world, including the UK and the US.
To interpret the available evidence, a team led by researchers at Cambridge’s Department of Public Health and Primary Care carried out a systematic review and meta-analysis of published studies covering 350,000 unique participants from 37 countries.
The results of the study showed that exposure to arsenic, lead, cadmium and copper – but not mercury – was associated with an increased risk of coronary heart disease and cardiovascular disease.
“It’s clear from our analysis that there’s a possible link between exposure to heavy metals or metalloids and risk of conditions such as heart disease, even at low doses – and the greater the exposure, the greater the risk,” says Dr Rajiv Chowdhury, the study’s first author. “While people shouldn’t be overly worried about any immediate health risk, it should send a message to policymakers that we need to take action to reduce people’s exposure.”
Worldwide, those at greatest exposure of arsenic, lead, cadmium and copper were around 30% to 80% more likely to develop cardiovascular disease than those at lowest exposure.
Image: Filter bed beside Afon Rheidol Water draining from an adjacent disused silver-lead mine is passed through these filter beds so as to allow the toxic heavy metals to settle out, thereby reducing pollution of the river.
Credit: geograph.org.uk
Reproduced courtesy of the University of Cambridge