Blood samples from the Norwegian Women and Cancer (NOWAC) study will be used in the current project. NOWAC is a large, population based prospective study with more than 170000 Norwegian female participants. All participants have answered at least one 8-pa ge questionnaire regarding their current health status, diet and lifestyle. The NOWAC study is unique in terms of the design as it contains questionnaire data from several different time periods in addition to plasma samples and blood samples for RNA anal ysis. This exceptional study design allows us to study gene expressions in relation to environmental PFC exposure among the general population and at the same time adjust for confounding variables (information available from questionnaires). This further enables a nested case-control study on diabetes and PFC exposure adjusted for other risk factors. The fact that PFC exposure was found to affect genes in the citric acid cycle in our pilot study supports this design.
Samples from 29778 participants are a vailable. The participants answered questionnaires in 1997/1998 and 2002-2005 and a 2-page questionnaire in relation to donating blood 3-9 months after the second questionnaire. First, 200 randomly selected control samples will be used in a cross-sectiona l analysis, in the second and third part of the study 200 cases and 200 controls will be assessed. Cases will be selected from the 688 women that answered that they had diabetes in 2002-2005 and also reported use of anti-diabetic medicine or insulin at t he time of blood sampling.
The recently improved quality of microarray platforms implicate increased sensitivity and improved techniques for studying low-dose exposure of environmental pollutants in a nested case-control design kept through all phases of the laboratory work and statistical analysis. This is the first time blood gene profiles are evaluated as effect measures of environmental contaminants and linked to actual diseases among the general population.