Overview: During the 1980s, we established a series of longer-term occupational cohort studies to investigate known or suspected cancer hazards. By definition, such cohorts are difficult to incept and very long-term follow-up is required. As a result of careful maintenance, we have analysed data on workers exposed to: formaldehyde, phenoxy herbicides and styrene between 11 and 22 years in total, thereby publishing information vital to regulatory policy and practice not only in the UK but elsewhere.