Does the use of stained maggots present a risk of bladder cancer to coarse fishermen?

A case-control study in West Yorkshire has been used to investigate possible risks of bladder cancer amongst those fishermen who used azo-based dyestuffs to stain maggots or who purchased ready coloured maggots. No risks have been found, although the confidence limits of the estimates are wide. These data refer to exposures over ten years ago and it is possible recent changes in fishing practice, if they have occurred, are not yet assessable due to the long mean latency seen in bladder cancer when exposure to carcinogens is not great. This paper does not suggest the general use of these substances is without hazard, merely that no risk is associated with the study group and that the chemicals under study are not a major cause of bladder cancer.