Private investigators have been hired to find the workers to take part in a $500,000 testing program. The workers may have been exposed to the chemical chlordimeform (CDF), which is being investigated for links to bladder cancer.
The New South Wales WorkCover department is conducting a separate monitoring program of about 90 people involved in field applications of CDF. It is believed up to 400 people, including pilots, itinerant workers and farmers, could have been exposed to aerial spraying of CDF.
CDF was used extensively in aerial spraying in the 1970s and 1980s in the Moree region in northern NSW and the Emerald district in south- west Queensland. CDF was used to control insects in cotton crops, orchards and cattle dips.
Ciba and the other distributor of CDF in Australia, Schering Pty Ltd, conducted preliminary urine testing of about 90 workers in 1990. Two former Ciba employees were found to have already developed bladder cancer and had been treated.
CDF was imported to Australia and mixed to form products for marketing between 1968 and 1976, when it was initially withdrawn from the market after a study found that mice, fed high doses of the chemical, developed blood-vessel tumors.
It was reintroduced in 1978 with stricter permit conditions and warnings on its use. In 1986, Australia became the first country to withdraw CDF after a study of workers at a Hoechst plant in West Germany found a higher than usual incidence of bladder cancer among workers exposed to CDF.
Ciba has undertaken to pay any medical costs to former employees who have developed bladder cancer. Any compensation claims would be assessed individually. Because bladder cancer is also linked to smoking, alcohol and some medicines, CDF’s contribution could be inconclusive.
The managing director of Ciba, Mr Hermann Mani, said: “The screening program is being conducted because the possibility that formulation workers exposed to CDF alone may face an increased risk of bladder cancer warrants further investigation.
“It is important to understand that workers in Australia, unlike those at plants in Europe, did not handle 4-Cot as no CDF was manufactured here.” Mr Mani said the program was aimed at the “earliest possible detection of bladder cancer and employs the latest medical monitoring techniques”.