Farmers in Jiangsu province sprayed a man-made plant hormone called forchlorfenuron on watermelons this month and saw them burst one after another. The farmers blamed forchlorfenuron for their loss of income, skittish consumers complained about the health threats it caused, and state-owned media highlighted it as yet another loophole in the mainland's food safety regulations. But scientists said forchlorfenuron was innocent; probably misused and overdosed by farmers who had no experience of growing watermelons. The industrially synthesised plant-growth regulator has been used worldwide for decades. There is no scientific evidence that the plant hormone had any health effect -positive or negative - on people. Professor Wang Liangju, fruit expert at the Nanjing Agricultural University's College of Horticulture and lead scientist of an official investigation into the incident this week, said many factors might have caused the melons to burst, including the possible overuse of forchlorfenuron and its being used at the wrong time. Wang said that the exploding watermelons were of a commercially successful species whose skin was extremely thin. Local residents called them 'explosive melons', meaning one must handle them with care, or they would split. A months-long drought in Danyang ended on May 7, the day Liu said the melons began to burst. The watermelons must have been dry and took on more water than they should, Wang said. The misuse of forchlorfenuron might have been the last straw. Most affected farmers were growing watermelons for the first time. The chemical should also be applied when the watermelon is small, but the farmers had sprayed it on overripe melons, Wang said. The watermelons have become a big topic on mainland television, newspapers and internet forums this week, prompting concerns about forchlorfenuron's use in agriculture and its health implications. Wang said the public had overreacted. Agricultural authorities on the mainland conducted independent and long-term safety evaluations including animal trials, and approved Forchlorfenuron's use in 1992. 'The experiments are very sophisticated, but the baseline theory is very simple. Forchlorfenuron is a plant hormone, and plant hormones do not affect animals, including humans,' Wang said. Indian researcher Dr Dinesh Agrawal, of CSIR National Chemical Laboratory's plant tissue culture division, agreed. He said high concentrations of forchlorfenuron could have made the watermelons burst, but there was no scientific evidence that the chemical was harmful to people or the environment. 'Forchlorfenuron is not banned in India and is actually widely used to increase the size of grapes,' he said. The US Environmental Protection Agency also approved the use of forchlorfenuron in 2004.