PLUMBERS, construction workers and carpenters are at high risk from cancer of the larynx because of regular exposure to certain substances, American researchers write in the British Journal of Occupational Medicine. Others at risk include farmers, bartenders and textile- machine operators.

While heavy smoking and drinking are known to increase the risk, the study, from Washington State, confirmed that occupational exposure to asbestos, chromium, nickel, cutting oils, diesel fumes and formaldehyde is another important factor.