On June 14, 2014, it was disclosed by many media accounts including CCTV that “more than 300 children in Dapu Town, Hengdong County of Hunan Province have excessive blood lead level” which seriouly affected their physical and mental health.  The blood lead test revealed that among the 315 children around Hengdong County Melody Chemical plant, 82 were in the excessive blood lead level, 8 were in mild poisoning blood lead level and 2 were in moderate poisoning blood lead level, which can be identified as a major environmental pollution incident.  In children, high lead exposure leads to cognitive delays and behavioral problems and can be fatal at extremely high levels. Its effects are permanent and irreversible. Studies have shown that childhood lead exposure is associated with higher adult violent crime rates. 
The environmental indicators of the Melody Chemical plant also revealed that the emissions are up to standard. However, regarding the reasons for children’s excessive blood lead, Fenglan Xiao, director of the Environmental Protection Bureau of Hengdong County, said that they could not confirm that Melody Chemical was the only source of lead. In response to CCTV’s doubts, Hengdong County Government and the Environmental Protection Bureau indicated that the relevant chemical enterprises have achieved environmental protection standards. Dapu’s lead problem made national headlines in 2014 in an exposé by state broadcaster CCTV, in which the head of the township was shown saying children might have raised their own lead levels by chewing on pencils. This also triggered heating discussions and blames on the social media platform - Weibo. 
On June 15, the Hengdong County Party Committee and the county government set up an incident investigation team to initiate investigation procedures in accordance with the law. The county environmental protection department quickly shut down the polluting enterprises, and the county public security departments initiated investigations on the suspected enterprises. At the same time, the government set up a special organization to go to Dapu Town to inspect other polluting enterprises, check the number of children with excessive blood lead, distribute milk and related drugs, and deal with complains from the affected families. On June 16, according to the Hengdong County Party Committee, Zhang Zhengguo, deputy director of the Hengdong County Environmental Protection Bureau, was investigated. The person in charge of the pollution-related enterprise Melody Pigment Chemical Co., Ltd. was detained by the police. 
The Hunan Hengyang Blood Lead Collective Environmental Lawsuit was filed on March 13, 2015 in the Hengdong County People's Court. While more than fifty families agreed to participate in the lawsuit at the outset, many were later forced to withdraw due to pressure from local government authorities. After the case was filed, the government staff came to the affected families every day to request for the withdrawal of the lawsuit. Sometimes, they stayed until in the early hours of the morning, which obviously disturbed the daily life of the affected families. Some of them were told that the minimum living allowance would be cancelled if they would not withdraw the lawsuit. Some affected families who have relatives and friends working in the government were threatened to ‘be dismissed from their jobs’. If the affected families promised to withdraw the lawsuit, they could get compensation ranging from CNY 1,000 to 10,000. As a result, there were 42 plaintiffs’ families submitting a written application to withdraw the case after one month.  On June 12, 2015, a court in Hunan Province began hearing this landmark pollution lawsuit filed by a group of 13 families in and around nearby Dapu town, who have accused Melody Chemical, a chemical plant and metal smelter, of pollution that caused elevated levels of lead in the blood of their children and grandchildren. They are seeking compensation, although the precise amount varies by child.  Four days before the court time, litigation representative signed his name on the extension of the trial agreement.  According to the first-instance judgment of the Hengdong County People's Court, only 2 of the 13 plaintiffs were affirmed to get compensation for moderate lead poisoning. The remaining 11 children with excessive blood lead levels would not get any compensations. 
In 2016, the final trial of the ‘Children's Excessive Blood Lead’ lawsuit maintained the first-instance judgment: only two of the 13 plaintiffs received compensation of 26,372 yuan.  Seven victims refused to accept the judgment of the first and second instance and applied for retrial in the Higher People's Court of Hunan Province.
On December 28, 2016, the Hunan Provincial Higher People's Court ruled that the basic facts ascertained in the original judgment were lack of evidence and the law was improperly applied. Therefore, the Intermediate People's Court of Hengyang City was instructed to retry the case.
During this time, the factory had been shut down permanently. By May 2017, the local waste water disposal met standards of health, putting an end to the improper processes of polluted water disposal. Within three years, a total of 117 heavy metal enterprises were shut down or transformed, and 71 pollution control projects were implemented in Hengdong, the water quality of the Hengyang section of the Xiangjiang River has been improved significantly. 
On September 12, 2018, the lawsuit of "Children's Blood Lead Violation" in Hengdong County, Hengyang City, Hunan Province was reconfirmed. After 4 years, 7 plaintiffs and parents of children with excessive blood lead have signed a mediation book in the Intermediate People's Court of Hengyang City. Each of them finally received compensation ranging from 40,000 ($5,818) to 90,000 yuan to put an end to the case. It is clear therefore the compensation is far from enough to recover from the health and environmental damages. The Environmental Protection Law stipulates that a plaintiff is obliged to collect evidence and shoulder the burden of persuasion to hold the polluting enterprise accountable for the damage he or she has incurred. This is beyond the capacity of the farming families. The law also stipulates that a lawsuit to claim environmental damages should be filed within three years of incurring a damage of suffering an illness. But, as in the Hunan case, if the complainants are farmers, they might take a much longer time to realize that their children are suffering from lead poisoning. Therefore, the legislature should consider revising the law, which in effect has shielded the polluters in many cases, and raise the compensation for environmental pollution victims. 
Dai Renhui, a lawyer from Beijing Huanzhu Law Firm who represented the families, said that one of the major difficulties in such cases is how to judge the severity of the health problems. Legal documents from the Hengyang Intermediate People’s Court also noted a shortage of professional institutes for assessing the health effects of industrial contamination. The cases have been further complicated by China’s standard for measuring blood lead concentration in children, which differs from the standard set by the World Health Organization. According to the global health authority, there is no safe blood lead level where children are concerned. Even a concentration as low as 50 micrograms per liter may result in decreased intelligence, behavioral difficulties, and learning problems, according to WHO. But “this case will be a useful reference for other families affected by pollution, particularly heavy metals pollution, and give them the confidence and courage to use the law to defend their environmental rights.” 
Pan Qing’an, an environmentalist who concerns heavy metal pollution in China, recorded the case as a documentary.