Levels of heavy metals in blood and urine and increased mortality

October 1, 2021

Levels of heavy metals in blood and urine and increased mortality

People are exposed to heavy metals in many ways during the course of their daily life. However, the effect of mixtures of heavy metals on mortality in the U.S. general population is unclear.

Study published in Environmental pollution journal aimed to investigate the association between heavy metal concentrations in blood (lead, cadmium and mercury) and urine (barium, cadmium, cobalt, cesium, molybdenum, lead, antimony, titanium, tungsten and uranium) and all-cause, cardiovascular disease (CVD) and cancer mortality. Study used data from the National Health and Nutrition Examination Survey (NHANES) 1999–2014. Data from total of 26,056 subjects was used to estimate relative risk of all cause, cancer and cardio vascular mortality.

The blood metal mixture was associated with all-cause mortality(RR 1.38, 95% CI 1.25, 1.51), CVD mortality (RR 1.43, 95% CI 1.06, 1.94) and cancer mortality (RR 1.41,95% CI 1.12, 1.76) and cadmium had the highest weight among all the metals for both blood and urine. This numbers simply mean that all of the heavy metals increase health risks, and cadmium is the major contributor. Another striking understanding is that risk grows 40% for all cause and CVD mortality for every unit of Cd or Pb in blood, and distribution of concentrations in population is quite wide.

In accordance with Longevica screening study in mice, most of the compounds extending average lifespan up to 20% might be involved in direct or indirect Cadmium (and other heavy metals) detoxification process. Presented paper provides epidemiological insight into mechanisms of ageing, important fact is that Cadmium and other heavy metals influence health risks in the whole range of concentration, and therefore it makes sense to work continuously on lowering concentration on both environmental and physiological levels. Screening in mice confirms epidemiological observations in human population, removing cadmium from the body using chelating agents and via activating innate detoxification mechanisms allows to create the effect of very low cellular cadmium concentration which becomes the hallmark of healthy ageing.

Another study [2] published in 2017 was discussing improvement in cadmium and lead exposure have improved since 1988, less toxic compounds in combustion engines, improvement in paints composition and markedly decrease in smoking population have lead to 42.0% decrease in blood lead and a 31.0% decrease in urine cadmium concentrations. Authors associate the decline in exposure with reduction in cardiovascular mortality from 1988 to 2004. However, authors note that the population remains exposed to both lead and cadmium, mainly via food and water and both metals remain associated with cardiovascular disease even at relatively low levels of exposure.

1 - Duan, Weiwei, Cheng Xu, Qian Liu, Jin Xu, Zhenkun Weng, Xin Zhang, Til Bahadur Basnet, Maginsh Dahal, and Aihua Gu. "Levels of a mixture of heavy metals in blood and urine and all-cause, cardiovascular disease and cancer mortality: A population-based cohort study." Environmental Pollution 263 (2020): 114630. https://pubmed.ncbi.nlm.nih.gov/33618481/

2 - Adrian Ruiz-Hernandez et al, Declining exposures to lead and cadmium contribute to explaining the reduction of cardiovascular mortality in the US population, 1988–2004, International Journal of Epidemiology, Volume 46, Issue 6, December 2017, Pages 1903–1912, https://doi.org/10.1093/ije/dyx176

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