The paper addresses the problems of researching the subject because of the serious limitations of many cancer mortality information systems, the varied and small workplaces, the problems of tracking the exposed populations, and the fact that most occupational cancers are clinically indistinguishable from non-occupational ones. It notes: “Most workplaces in developing countries are ‘informal’, i.e. they are not regularly surveyed/inspected and laws for workers’ protection are not implemented. Research on occupational risks in informal workplaces and the related cancer burden is needed. The results of studies addressing exposures among informal workers are difficult to generalize because of the specificities of social contexts, and study populations are small. The estimation of the burden of cancers attributable to occupational exposures is also made difficult by the fact that occupational cancers are usually clinically indistinguishable from those unrelated to occupation.”

Vilma Santana and Fatima Ribeiro. Occupational cancer burden in developing countries and the problem of informal workers, Environmental Health, volume 10 (Supplement 1): S10, 2011.