FOUR people who illegally processed metals and discharged waste water into a river have been sentenced to prison, according to the Shanghai Railway Transportation Court.

The actions of the four first emerged at the end of last year when a river in the Jiading District turned yellow and smelly. Investigation soon traced down an underground metal processing workshop, opened by a man surnamed Ren and his wife.

The couple didn’t open their workshop for long, and they recruited two of their relatives, also a couple. To save costs, they directly discharged heavy-metal-laden water into a nearby river, the court said.

Tests of water samples found excessive levels of chromium, which can cause irritation, poisoning and even cancer.

The four were convicted of environmental pollution.

The two husbands were sentenced to six months behind bars while their wives received a suspended sentence of five months’ detention.

Each was fined from 6,000 (US$899) to 8,000 yuan.