On a recent trip to Taizhou, a city in Zhejiang Province south of Shanghai that was another center of e-waste processing, I saw evidence of both the crackdown and its limits. Until a few years ago, the hill country outside Taizhou was the center of a huge but informal electronics disassembly industry that rivaled Guiyu's. But these days, customs officials at the nearby Haimen and Ningbo ports—clearinghouses for massive volumes of metal scrap—are sniffing around incoming shipments for illegal hazardous waste.

High-tech scrap "imports here started in the 1990s and reached a peak in 2003," says a high school teacher whose students tested the environment around Taizhou for toxics from e-waste. He requested anonymity from fear of local recyclers angry about the drop in business. "It has been falling since 2005 and now is hard to find."

Today the salvagers operate in the shadows. Inside the open door of a house in a hillside village, a homeowner uses pliers to rip microchips and metal parts off a computer motherboard. A buyer will burn these pieces to recover copper. The man won't reveal his name. "This business is illegal," he admits, offering a cigarette. In the same village, several men huddle inside a shed, heating circuit boards over a flame to extract metal. Outside the door lies a pile of scorched boards. In another village a few miles away, a woman stacks up bags of circuit boards in her house. She shoos my translator and me away. Continuing through the hills, I see people tearing apart car batteries, alternators, and high-voltage cable for recycling, and others hauling aluminum scrap to an aging smelter. But I find no one else working with electronics. In Taizhou, at least, the e-waste business seems to be waning.

Yet for some people it is likely too late; a cycle of disease or disability is already in motion. In a spate of studies released last year, Chinese scientists documented the environmental plight of Guiyu, the site of the original BAN film. The air near some electronics salvage operations that remain open contains the highest amounts of dioxin measured anywhere in the world. Soils are saturated with the chemical, a probable carcinogen that may disrupt endocrine and immune function. High levels of flame retardants called PBDEs—common in electronics, and potentially damaging to fetal development even at very low levels—turned up in the blood of the electronics workers. The high school teacher in Taizhou says his students found high levels of PBDEs in plants and animals. Humans were also tested, but he was not at liberty to discuss the results.