> Participants were adults in the National Institutes of Health–AARP Diet and Health Study (NIH-AARP) cohort; the PLCO Cancer Screening Trial cohort; and the Ag

> Participants were adults in the National Institutes of Health–AARP Diet and Health Study (NIH-AARP) cohort; the PLCO Cancer Screening Trial cohort; and the Agricultural Health Study (AHS) cohort (eFigure 1 in Supplement 1). The NIH-AARP Diet and Health Study began in 1995 to 1996, when questionnaires were mailed to current AARP members who were aged 50 to 71 years and resided in 1 of 2 US metropolitan areas or 6 states. > The PLCO study was a randomized cancer-screening trial that enrolled 154 887 participants at 10 US centers between 1993 and 2001.23 Participants were aged 55 to 74 years at baseline. > The AHS enrolled 52 394 licensed pesticide applicators, 4916 commercial pesticide applicators, and 32 345 spouses of private applicators who were aged 18 years or older from Iowa and North Carolina from 1993 to 1997. That sounds like more a broader approach then just "middle class and above types".