Climate change could drive heavy metal toxicity

New research from the Coorporative Research Centre for Contamination Assessment and Remediation of the Environment (CARE) has found that climate change could lead to increased human exposure to heavy metals and metalloids such as mercrury, arsenic and lead.

“People’s exposure to chemical contaminants could increase due to climate change,” says Dr Bhabananda Biswas, a researcher with CARE and the University of South Australia’s Future Industries Institute.

Dr Biswas says the toxic properties of pollutants, and their movement, transport, storage and release from the soil, are controlled by properties and processes vulnerable to climate change, including temperature, moisture, and microbial activities.

"Warmer soil, more extreme rainfall, extended drought, and soil erosion could increase our exposure to soil contaminants," says Dr Biswas.

"For example, warmer soil and stronger winds enhance the release and dispersion of contaminants from soils to the air. We could see 70 to 300 tonnes of surface soil lost per hectare each year due to extreme climate conditions, compared with typical losses of 60 to 80 tonnes annually per hectare now. This could lead to the movement of pollutants bound to soil, adding to health concerns through, for example, inhalation of contaminated soil dust.

"As frozen arctic soils thaw, they expose previously frozen compounds. Flooding causes the movement of toxic pesticides stored in the soil and of chemicals such as lead, mercury, arsenic and cadmium."

Worse, the rise in temperatures we are seeing now can increase the toxicity of contaminants by increasing bioavailability – a measure of how easily chemicals are taken up into our bodies. In other words, climate change could convert pollutants into a form that poses greater risk.

Warmer conditions enable an increase in the availability to plants of contaminants such as lead, mercury and arsenic, so heavy metals can be more readily taken up by plants and enter the food chain. ‘We could face greater exposure by breathing dust-based pollutants, or through the food chain,’ he says.

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