Links found between soil pollution and heart disease

Pesticides and heavy metals in soil may have detrimental effects on the cardiovascular system, according to a review paper published in the journal Cardiovascular Research. As noted by study author Professor Thomas Münzel, of the University Medical Center Mainz, “evidence is mounting that pollutants in soil may damage cardiovascular health through a number of mechanisms including inflammation and disrupting the body’s natural clock”.

Pollution of air, water and soil is responsible for at least nine million deaths each year, more than 60% of which are due to cardiovascular disease such as chronic ischaemic heart disease, heart attack, stroke and heart rhythm disorders (arrhythmias). The authors say that soil contaminated with pollutants such as heavy metals, pesticides and plastics may lead to cardiovascular disease by increasing oxidative stress in the blood vessels, causing inflammation and disturbing the body clock (circadian rhythm).

Dirty soil may enter the body by inhaling desert dust, fertiliser crystals or plastic particles. Heavy metals such as cadmium and lead, plastics and organic toxicants (eg, in pesticides) can also be consumed orally. Soil pollutants wash into rivers and create dirty water, which may be consumed. Pesticides have also been linked with an elevated risk of cardiovascular disease and, while employees in the agricultural and chemical industries face the greatest exposure, the general public may ingest pesticides from contaminated food, soil and water.

Cadmium is a heavy metal that occurs naturally in small amounts in air, water, soil and food, and also comes from industrial and agricultural sources. Food is the main source of cadmium in non-smokers. The paper cites a Korean study showing that middle-aged Koreans with high blood cadmium had elevated risks of stroke and hypertension.

Lead is a naturally occurring toxic metal with environmental contamination through mining, smelting, manufacturing and recycling. Studies have found associations between high blood lead levels and cardiovascular disease, including coronary heart disease, heart attack and stroke, in women and in people with diabetes. Further studies have indicated a higher risk of death from cardiovascular disease associated with exposure to arsenic, a naturally occurring metalloid whose levels can increase due to industrial processes and using contaminated water to irrigate crops.

“Although soil pollution with heavy metals and its association with cardiovascular diseases is especially a problem for low- and middle-income countries since their populations are disproportionately exposed to these environmental pollutants, it becomes a problem for any country in the world due to the increasing globalisation of food supply chains and uptake of these heavy metals with fruits, vegetables and meat,” the study authors wrote.

The potential hazards of contaminated airborne dust are also noted. Desert dust can travel long distances, and research has shown that particles from soil in China and Mongolia were related to increased odds of heart attacks in Japan. The number of cardiovascular emergency department visits in Japan was 21% higher on days with heavy exposure to Asian dust.

“More studies are needed on the combined effect of multiple soil pollutants on cardiovascular disease, since we are rarely exposed to one toxic agent alone,” Münzel said. “Research is urgently required on how nano- and microplastic might initiate and exacerbate cardiovascular disease. Until we know more, it seems sensible to wear a face mask to limit exposure to windblown dust, filter water to remove contaminants and buy food grown in healthy soil.”

Image credit: ©stock.adobe.com/au/pingpao

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