They were desperate to have their voices heard when lead poisoning destroyed their health and families, but now they have fallen prey to another source of suffering - a government crackdown. At least seven people from Shaanxi's Fengxiang county are in jail more than four months after protests against lead pollution which left hundreds of children sick. The demonstrations erupted in early August as the scale of the public health emergency caused by the Dongling Lead and Zinc Smelting Plant became clear. One of those who remains behind bars for the August 17 unrest is Ma Weibo, a 26-year-old worker at a nearby power plant. 'In the evening, exactly a week after the demonstration, five policemen from different levels of public security bureaus including Baoji city, Fengxiang county and Changqing township came over and detained my eldest son,' said his father, Ma Changxiong, a peasant in Madaokou village. 'The police told me that they had identified him as one of the leading figures of the riot, with the help of closed-circuit television.' Ma said eight people, including his son, were held in the aftermath of the protest. 'As far as I know, five of the eight detainees come from Madaokou village and another three from Gaozuitou village,' the 54-year-old said. 'Now, 100 days have gone, and all remain in detention, except one guy who was released as a result of ... Madaokou's party secretary.' Another villager from Madaokou said more than 100 people were initially detained over the protests. The villager, who would not give his name, said he took part without hesitation when he learned his three-year-old daughter's blood contained 300 milligrams of lead per litre, three times the acceptable standard. 'I was taken away and questioned for the part I played in the demonstration,' said the man, who was released the next day. The biggest protest took place on August 17, after a 17-year-old girl attempted suicide after learning she had four times the acceptable amount of lead in her blood. Because she was over 14, she was not entitled to compensation or medical aid. Hundreds of people from Madaokou, Gaozuitou and Sunjianantou villages surrounded the factory and smashed a 300-metre length of its outside wall. Armed police were needed to break up the riot and a dozen vehicles were damaged. An environmental assessment concluded that nobody should have been living within a kilometre of the plant, and more than 600 children were confirmed to have lead poisoning. However, tests were denied to many people over the age of 14, which suggests the total number poisoned could be higher. Residents had demanded the smelter be shut, but despite a promise from the local government it remained open. 'In a stark contrast to our expectations, what we peasants saw was the factory carrying on the following day,' Ma said. 'I've got no way to air my grievances and bitterness,' He says his son is a well-behaved and restrained person who protested because of his outrage at the impact of the lead poisoning. 'I was told that my son could face a jail term ranging from six months to three years, once he was convicted of disturbing social order. 'So far, hardly anyone over 14 has been allowed to be tested for lead poisoning. All of the confirmed victims are children. My son has not married and, of course, he does not have a child. Everything he did was for his fellow villagers.' A neighbouring woman described Ma Weibo as a 'kind, disciplined and obedient young man' who was fighting for people from Madaokou village. She said he was forced to give up school at a young age when his mother died, and he supported his family financially. Ma insisted his son was innocent, saying: 'I'm 100 per cent sure my son has nothing to do with either smashing or looting the factory or its office. All he did was protest strongly.' Under detention, Ma Weibo reportedly has been beaten and was constantly hungry. 'I have spent more than 1,000 yuan (HK$1,135) to have the warders bring him some food and clothes. Instead of seeing him face-to-face, I was only allowed to see him on a surveillance camera twice since his detention. The only thing he asked me to do was spend some money and get him out,' his father said. However, Ma has no money to do this. His second son is in the army and does not remit money, while his daughter makes 1,000 yuan a month in a Guangzhou factory. 'Weibo makes around 2,300 yuan per month. He is the economic pillar of the family,' he said. 'All I've been able to do is go to the Communist Party's village committee for help, but officials there said they could not do anything. 'It's like the old saying 'Killing the chicken to frighten the monkeys' - my son is being sacrificed for over-actively committing himself in the anti-pollution protest.' A peasant in Gaozuitou village, who is in his 50s, said keeping people behind bars was a trick to silence the public. He said he could not risk speaking out publicly even though he knew all about the lead poisoning.