HLA-DRB1 and non-Hodgkin lymphoma: For NHL, statistically significant interactions (p = 0.02) were observed between HLA-DRB1*01:01 and termite treatment before 1988 and blood-based exposures to PCB180 whereby previously reported 1.5-fold elevation in NHL risk for these environmental exposures were limited and statistically significantly only among individuals who did not have the HLA-DRB1*01:01 allele.