High levels of tungsten in the body could double the risk of suffering a stroke, a new study published in the open access journal PLOS ONE has found.
Using data from a large US health survey, the study has shown that high concentrations of tungsten -- as measured in urine samples -- is strongly linked with an increase in the occurrence of stroke, roughly equal to a doubling of the odds of experiencing the condition.
Conducted by a team from the University of Exeter, the study represents the most comprehensive analysis to date of the potential health effects of the metal.
According to figures from the World Health Organization, stroke is currently the second leading cause of death in the Western world, ranking only second to heart disease. It is also the leading cause of disability in adults, often resulting in loss of motor control, urinary incontinence, depression and memory loss.
The research used data from the US based National Health and Nutrition Examination Survey (NHANES), analyzing information for 8614 participants aged between 18 and 74 over a 12 year period.
Higher tungsten levels were found to be strongly associated with an increase in the prevalence of stroke, independent of typical risk factors. Importantly, the findings show that tungsten could be a significant risk factor for stroke in people under the age of 50.
Whilst our current exposure to tungsten is thought to be very low, recent years have seen a significant increase in the demand and supply of the material -- which is commonly used in consumer products such as mobile phones and computers, as well as a number of industrial and military products.
During its production, small amounts of the metal can be deposited in the environment, eventually making their way into water systems and onto agricultural land. With largely unknown health consequences, tungsten has been identified as a toxicant of emerging concern.
Lead author of the research, Dr Jessica Tyrrell, of the University of Exeter Medical School's European Centre for Environment and Human Health, said "Whilst currently very low, human exposure to tungsten is set to increase. We're not yet sure why some members of the population have higher levels of the metal in their make-up, and an important step in understanding and preventing the risks it may pose to health will be to get to the bottom of how it's ending up in our bodies."
The tungsten-stroke relationship observed in this research highlights another example of the potentially negative impact new materials can have on health. Recent years have seen an exponential increase in the production of chemicals for commercial exploitation, including the introduction of nanotechnology. In many cases the health effects of these chemicals are largely unknown and there are few controls to prevent their discharge into the environment.
Another of the paper's authors, Dr Nicholas Osborne, added "The relationship we're seeing between tungsten and stroke may only be the tip of the iceberg. As numerous new substances make their way into the environment, we're accumulating a complex 'chemical cocktail' in our bodies. Currently we have incredibly limited information on the health effects of individual chemicals and no research has explored how these compounds might interact together to impact human health."
- Jessica Tyrrell, Tamara S. Galloway, Ghada Abo-Zaid, David Melzer, Michael H. Depledge, Nicholas J. Osborne. High Urinary Tungsten Concentration Is Associated with Stroke in the National Health and Nutrition Examination Survey 1999–2010. PLoS ONE, 2013; 8 (11): e77546 DOI: 10.1371/journal.pone.0077546
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