Two-year-old Xu Yilin, whose blood, according to her family, has been shown to have almost three times the national limit for lead exposure in children, stands in a neighbour's house in Dapu town, Hunan province, June 25, 2014. REUTERS/Alexandra Harney

Drinking milk can flush out lead in blood, according to Chinese officials.

Residents of Dapu, a rural town in Hunan province of China, said they were offered milk, in addition to medicines, for their children diagnosed with lead exposure. In return, the officials asked them to hand over the blood test results.

This is one of the towns abounding in smelters and chemical plants.

"I still give my grandsons milk, but it's useless," Mao Baozhu, 61, a local resident was quoted by Reuters as saying. She says her three grandchildren have all been diagnosed with high lead levels. "Isn't the resident's committee just trying to deceive us by distributing milk and saying all the kids have to do is drink it and they'll be cured?"

Residents submitted a petition to local officials regarding their concerns about lead pollution in late 2012. Only residents who turned in their blood test results received milk and only those that provided the originals – rather than a copy – would be reimbursed for cost of the tests, said Mao Baozhu. She said subsequent tests showed one of her grandson's levels are down from three times the national limit for lead exposure in children to twice that level; another is often dizzy and complains of stomach pains.

Zhao Heping says he was offered medicines and milk for his toddler grandson and in return asked that he hand over his grandson's blood test results.

However, the officials denied any attempts to distribute milk and collect test results.

The country's National Health and Family Planning Commission recommends "nutritional intervention" for children exposed to lead. However, it added that its guidelines went well beyond nutrition, and it was neither "complete nor correct" to say that milk flushed lead out of the body. It also recommended removing the source of lead pollution and medical treatment in severe cases.

China's rapid economic development has paid scant attention to environment imperatives. Pollution from local factories has led to the mushrooming of "cancer villages" with high incidence of cancer.

Hunan province has significant deposits of lead, zinc, mercury, antimony and tungsten but is also the country's largest producer of rice. In 2003, Dapu officials set up an industrial zone which, by 2013, had expanded to include at least 12 smelting factories producing tungsten, copper, lead and zinc.

A study by Greenpeace found high levels of cadmium and lead in local rice samples, some as high as 22 times the national standard.

Exposure to lead is particularly dangerous for children as it inhibits intellectual and physical development, and can cause poor concentration, disruptive behaviour, even death at high levels. Its effects are irreversible.

There are no national data on lead levels in China. The Capital Institute of Pediatrics in Beijing, which conducted a survey in 15 cities between 2004 and 2008, found 7.6% of those surveyed had lead levels above 100 micrograms per litre (ug/L), China's threshold for safe lead exposure.

Dapu's lead problem made national headlines during a state broadcast by CCTV, in which the mayor was shown saying children might have raised their own blood levels by chewing on pencils.

Following the broadcast, which claimed that more than 300 children had high lead levels, there was an investigation and a local chemical plant and smelter were shut down.