title: Hospital or population controls? An unanswered question.
mesh_terms: D000328:Adult; D000368:Aged; D002273:Carcinogens; D003276:Contraceptives, Oral; D004651:Employment; D004812:Epidemiologic Methods; D005260:Female; D006202:Hair Dyes / Q000009:adverse effects*; D006203:Hair Preparations / Q000009:adverse effects*; D006760:Hospitalization; D006801:Humans; D008875:Middle Aged; D009369:Neoplasms / Q000453:epidemiology*; D009864:Ontario; D012907:Smoking; D011795:Surveys and Questionnaires
chemical_list: D002273:Carcinogens; D003276:Contraceptives, Oral; D006202:Hair Dyes; D006203:Hair Preparations