Environmental Health Criteria, No 199
World Health Organization
ISBN-13    9789241571999 ISBN-10    9241571993
Order Number    11600199 Format    E-book collection (PDF)
Price    CHF    36.00 / US$    43.20 Developing countries:    CHF    25.20
English     1998        178   pages
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Evaluates the risks to human health and the environment posed by chlordimeform, a broad-spectrum acaricide active against motile forms of mites and ticks and against the eggs and early instars of some Lepidoptera insects. Introduced in the late 1960s, the compound was initially used in numerous countries to protect a wide variety of food crops. Application was later restricted to cotton and, in one country, to rice. Although worldwide production and use ceased a decade ago, concern continues to centre on evidence that exposure is linked to an increased risk of urinary bladder cancer in humans.
Concerning risks for the general population, the main sources of previous exposure are identified as the consumption of residues in food. Of greater importance is the large number of workers exposed to higher levels during the compound's manufacturing or application, particularly in view of the long latency period of urinary bladder cancer.
The most extensive section evaluates the results of toxicity studies in laboratory mammals and in vitro test systems. Following short- and long-term exposure, treatment-related changes observed include haematological abnormalities and, at high doses, hyperplasia of the epithelium of the bile duct and urinary bladder. Studies in mice, but not in rats, produced evidence of a dose-related increase in haemorrhagic malignant tumours of vascular origin. The report found no evidence of teratogenic potential or adverse effects on reproduction.
The evaluation of effects on human health draws on epidemiological studies of exposed workers as well as close to 1,000 case reports of accidental or intentional poisoning. These studies support the conclusion that chlordimeform has significant potential to cause both immediate and long-term toxicity in exposed humans. Current evidence also supports the conclusion that exposure to the metabolite, 4-chloro-o-toluidine and, to a lesser extent, chlordimeform is associated with an increased risk of urinary bladder cancer in humans. In view of the long latency period for this cancer, the report calls for the continued screening of previously exposed workers in programmes that include urinary cytology and tests for haematuria.