May 31, 2011
E-waste recycling in China is dangerous to human health
Researchers in China are calling for the Chinese government to improve the way electronic waste (e-waste) is dismantled because their research has shown pollutants released by a Chinese e-waste recycling park could be dangerous to human health.
The researchers exposed human lung epithelial cells to pollutants extracted from air samples taken from the vicinity of an e-waste dismantling industrial park in Taizhou, Zhejiang province, which employs 60,000 people. They found that the cells showed signs of inflammation and oxidative stress – which can be precursors to cardiovascular disease, DNA damage and possibly cancer.
"Our results show that it is imperative that the primitive techniques for dismantlement of e-waste in China must be improved," Fangxing Yang from the Zhejiang University told environmentalresearchweb. "The 'open' dismantlement of e-waste must be forbidden and the workers must be given proper protection during dismantling."
Inhalation of contaminated air is believed to be one of the most important pathways for pollutants to enter the human body. The pollutants are absorbed onto the surface of particulate matter emitted by e-waste dismantling plants, with particles under 2.5 microns (PM2.5) being the most dangerous to human health.
Yang and his colleagues took air samples from sites near the dismantling park and used organic solvents and water to extract the pollutants from the PM2.5. They then exposed human lung cells to these pollutants and tested for the level of interleukin-8 (IL-8) – a key mediator of inflammatory response – and reactive oxygen species (ROS) – chemically reactive molecules that can cause extensive damage in excess.
The samples were also tested for the expression of the p53 gene – a tumour suppressor gene that produces a protein to help counteract cell damage. If there is evidence of this gene being expressed it can be seen as a marker that cell damage is taking place.
"We found that both the organic-soluble and the water-soluble extracts induced increases of IL-8 release, ROS production and p53 protein expression," said Yang. The researchers did not perform chemical analysis on the air samples, so they do not know which pollutants were present in the air samples they took. "However, we did find that the organic-soluble pollutants have more potential to induce adverse effects on human health than water-soluble pollutants," said Yang.
Organic-soluble pollutants include compounds such as polychlorinated biphenyls (PCBs), which are used in the manufacture of electrical transformers.
While IL-8 release and ROS production can result in p53 expression, Yang and his colleagues did not find a correlation between these events and suggest that IL-8 release and ROS production were not the only causes of p53 protein expression. "There are a variety of factors that can cause DNA damage and therefore p53 expression and we believe that p53 protein expression in the cells also originates from other factors that we did not examine in our study," said Yang, who now plans to characterise the components present in the polluted air and identify the key contributors to these adverse effects.
A large proportion of the world's e-waste is exported to China and Yang believes this practice has to stop. "The countries that export their waste should set up their own recycling plants to deal with their e-waste," said Yang. "We would also urge manufacturers of electronic goods to use more environmentally friendly materials and components in their products."
The researchers published their work in Environmental Research Letters (ERL).
About the author
Nadya Anscombe is a freelance science journalist based in Bristol, UK.