In e-waste recycling centers in China, discarded products are dipped into open pits of acid and heated over grills fueled with coal blocks to extract precious metals, such as gold. These processes often release toxic metals, such as lead, and organic compounds, such as dioxins. The emissions are not regulated, and occupational exposure is high because of the poor working conditions for e-waste recycling laborers.

In March 2007, researchers at Hong Kong Baptist University showed that soil at e-waste recycling sites in China has high levels of dioxins and polybrominated diphenyl ether (PBDE) flame retardants. (Read the paper at ES&T's ASAP website.) More recently, another study published in ES&T showed that the workers at these sites have blood levels of the heavy PBDE, BDE–209, 50–200 times higher than those previously reported. Whereas dioxins are potentially carcinogenic for humans, PBDEs affect thyroid metabolism and brain development.

In the current study, Ping'an Peng of the Guangzhou Institute of Geochemistry (China) and his colleagues sampled the air from Guiyu for a week in both the summer and the winter and analyzed the samples for 2,3,7,8-PCDD/Fs. The levels varied between 64.9 and 2765 picogram per cubic meter (pg/m3). The toxic equivalents (TEQ)—a value used to account for the different levels of toxicity of the individual dioxins—was 0.909–48.9 pg TEQ/m3. Given that Guiyu has no municipal or medical solid-waste incinerators, which are known to be major sources of dioxins, the authors attributed the elevated dioxin levels to e-waste recycling.

The team also found that the dioxin concentrations in the air around Guiyu were 12–18 times higher than those in Chendian, a town 9 kilometers (km) from Guiyu, and 37–133 times higher than those in Guangzhou, which is 450 km from the e-waste site. The results suggest that dioxin pollution from e-waste recycling is spreading to nearby areas.

When they calculated the exposure of adults to dioxins through inhalation, the researchers found that it (68.9 and 126 pg TEQ per kilogram per day in the summer and winter, respectively) was a whopping 15–56 times higher than the World Health Organization recommended maximum of 1–4 pg TEQ/kg/day.

Combustion of various goods, including electronics, is known to produce dioxins, and "it is not surprising" that researchers are finding high levels of these chemicals in these parts of the world, says Oladele Ogunseitan of the University of California Irvine. "The significance of the paper is to provide us with the first estimate of what [levels] to expect," he adds. "As a next step, what needs to be done is as an epidemiological study looking for actual symptoms, but I imagine that this is not a trivial thing to do."

The results emphasize the need to "implement the kind of restrictions we have" in the developed world, says Gareth Thomas of Lancaster University (U.K.) who has monitored blood levels of PBDEs in workers in the area. M. H. Wong of Hong Kong Baptist University agrees. We need to "switch to proper recycling facilities" with cleaner technologies, he says, as well as limit the use of toxic metals and flame retardants in the manufacturing process.

"As long as there is unemployment and labor is cheap, this kind of work will be done in less-than-adequate conditions," says Ogunseitan. And countries like the U.S. that export their e-waste to developing countries must also bear the responsibility, he says. "I've always advocated that the U.S. must now take very seriously the Basel Convention that prohibits the shipment of hazardous wastes to other countries. We are, in principle, a country that will do this kind of thing on purpose. But by our inaction on international laws that protect vulnerable populations all over the world, we are essentially saying that it's OK." Although individual states have laws that seek to prevent shipping e-waste to developing countries, the Basel Action Network calculates that 50–80% of U.S. e-waste is sent to China."