You may never eat street food in China again after watching this video

This still from the below video shows a Chinese restaurant using cooking oil. (YouTube)

China's food safety problems have no better symbol than the illegal and utterly disgusting problem of gutter oil. Cooking oil is used heavily in Chinese food, so some street vendors and hole-in-the-wall restaurants buy cheap, black market oil that's been recycled from garbage. You read that correctly. Enterprising men and women will go through dumpsters, trash bins, gutters and even sewers, scooping out liquid or solid refuse that contains used oil or animal parts. Then they process that into cooking oil, which they sell at below-market rates to food vendors who use it to cook food that can make you extremely sick.

This video, produced by Radio Free Asia, shows in excruciating detail how a couple of gutter oil vendors go about their work. It starts with the couple scooping sewage out of the ground, and it ends with unwitting Chinese consumers chowing down on the end product:

To reiterate, this is illegal, something that Chinese authorities are trying to stop and not used by all street vendors. But it's also thought to be widespread. Being reprocessed garbage and sewage, gutter oil contains all sorts of untold carcinogens. Many of the operations, like the one shown in the video, are small-time. But there's enough money to be made that some producers go much bigger.

In April, Chinese authorities uncovered a gutter oil production ring that spanned 13 cities and over 100 people, who somehow acquired rotten animal parts and boiled down the fat into oil. The sting, which came after a five-month investigation, yielded 3,200 tons of the stuff; authorities estimated the black-market producers had already sold a stunning $1.6 million worth of their product.

Don't cancel any vacation plans to China over this. Food in China is delicious, and gutter oil typically is used just in some street food stalls or cheap, hole-in-the-wall dives. But it is a reminder why authorities there are deeply concerned about food safety issues.