Exposure to pesticides has already been associated with an increased incidence of HL in many studies. Exposure to the insecticide chlorpyrifos was found to be significantly associated with increased risk of HL. In addition, a first-degree relative with cancer and diagnosis of acne or shingles also increased risk. A previous diagnosis of measles is associated with a decreased risk of developing HL. In this analysis, no associations were identified with exposure to herbicides, fumigants, or fungicides.