Hong Kong-listed companies in Guangdong province are depositing dangerous chemicals into the Pearl River, according to a study by Greenpeace China. The group spent seven months investigating five factories, three of which are owned by circuit-board maker Kingboard Chemical Group, the Wall Street Journal reported. While Greenpeace acknowledges that it focused on just a small fraction of the thousands of factories in the Pearl River Delta, which is the source of many of China’s exports, the findings add weight to long-held concerns about pollution in Guangdong. Edward Chan, the Greenpeace project coordinator, said that the emissions from one factory run by printing company Cheong Ming Investments contained high concentrations of chromium, copper, zinc and nickel. The Pearl River supplies drinking water to about 47 million people.