A new study has found widespread presence of hazardous chemicals in fish in China's longest and most important river, raising questions about the effectiveness and enforcement of environmental regulations.

The study, conducted by Greenpeace, tested chemical levels in fish in four cities along the Yangtze river, which flows through the heart of China and sustains the lives of more than 400 million people. The study found high levels of hazardous chemicals used widely in the textile and leather industries. All the tested samples of catfish and carp — fish widely consumed in China — were found to contain alkylphenols, which are chemicals used in detergents and in textile and leather manufacturing, and perfluorinated compounds, which are used in food packaging and manufacturing plastics.

These chemicals have either been banned or are under restricted use in the European Union but have not been regulated in China. Wu Yixiu, toxics campaigner for Greenpeace, told The Hindu there was increasing scientific evidence to prove the chemicals posed serious health hazards, having caused altered sexual development in some species of fish and impacting hormonal functions in humans. The manufacture of both compounds, she said, had fallen across the world in the last decade but had doubled in China between 1995 and 2003.

“China needs to get a full understanding of the existence and production of these chemicals, which is the first step for legislation,” said Ms. Wu. “This problem must, of course, be seen in the context of the stage of China's industrialisation. Work related to registering and regulating hazardous chemicals is still at a starting point.”

The 6,300-km-long Yangtze river flows from Qinghai province in the Tibetan plateau, right through the heart of China to Shanghai on the east cost. It flows through 186 cities, and is in many ways the lifeblood of central China.

In the past three decades of China's rapid industrialisation, the Yangtze basin has also become home to a range of industries. In 2006, an estimated 10,000 chemical enterprises — half the total number in China — were located in the Yangtze basin. According to a recent report from the Ministry of Environmental Protection, the discharge into the river in 2008 exceeded 21 billion tonnes — 30 per cent of the national waste water discharge. Seventy per cent of this came from industrial sources. Increasing pollution has seen the river lose a number of species of fish and, most famously, the freshwater Baiji dolphin, which was found only in the Yangtze but declared extinct in 2006.

The government has begun to tighten environmental laws, though enforcement at the local level is often arbitrary. The Ministry of Environmental Protection has a Pollution Prevention and Control unit, which recently set up a separate unit dedicated to management of hazardous chemicals. “This is a positive sign we have seen from the government,” said Ms. Wu. “Having said that, many local-level departments still do not have a designated official to deal with hazardous chemicals.”

Hu Jianying, a professor at Peking University's College of Environmental Sciences, said hazardous chemicals like alkylphenols still remained out of the government's radar. “The government is paying more attention to the water pollution problem, but has not paid much attention to such chemicals,” she told The Hindu. “Part of the problem is the data is limited, and it is difficult to understand their toxicology. But a number of scientific studies have shown that these chemicals can cause problems.”

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