Samples were stored from collection at −196°C in liquid nitrogen at the coordinating centre at the International Agency for Research into Cancer (IARC) in Lyon, France, or in liquid nitrogen in local biorepositories with the exception of Umeå where −80°C freezers were used. Follow-up data on mortality and disease status has been ascertained via registries, clinical records, and other sources of clinical information [15;16]. At least one follow-up was conducted in each centre 3-5 years after baseline and questionnaires and telephone-based interviews were administered to repeat exposure measurement and collect self-reported health status data.
