Wasted Food could be recycled into Cheap Cooking Oil.

Slop oil is “refined” from slop or swill, which is the leftover “food” that people and restaurants throw away. Usually, slop or swill is fed to pigs but some unscrupulous people will gather the slop and “recycle” the oil in the slop to sell as cooking oil. Of course, this cooking oil is known as “slop oil” and it is cheaper than fresh cooking oil. Many street vendors who cook snacks (especially fried foods) may use this “slop oil” to save money and keep their costs low.

Recently, I eat at one stall and i notice they been using some stinky cooking oil. But the food they cook out was delicious. Till recently i found out that they are using slop oil. I didn't want to say which shop in kl. But i post up some important information regarding "Slop Oil" 

The "illegal cooking oil" is usually made from discarded kitchen waste that has been refined, the report said, adding that the oil, which contains a highly toxic and carcinogenic substance called "aflatoxin", can cause cancer. If you really go to google and search for "Aflatoxin" you would know what alfatoxin is something that we store for animals to eat, If human eat too much will cause of liver cancer and H-B virus

Why is china / malaysia and thailand making slop oil ? 

"One ton of cooking oil made from kitchen waste costs only 300 yuan ($44). A barrel of oil makes a profit of 70 to 80 yuan. On average, one person collects four barrels. Even if the oil is sold at half the price of ordinary oil, you could make over 10,000 yuan a month. Even a chore man in the business gets a monthly wage of 2,500 yuan," He told the newspaper.