We further compared Pm with interaction P-values from exposure-specific (smoking and physical activity) genome-wide interaction tests for BMI (Pint); this was only done for BMI owing to the requirement for an adequately powered external dataset (such a dataset was accessible through the GIANT consortium) (Table 2). Marginal effects GWAS were performed by strata of smokers vs. non-smokers and physically active vs. inactive participants (n = 210,316 European-ancestry adults ) respectively, and a heterogeneity test  was used to generate exposure specific Pint distributions. Spearman ρ for the pruned set of SNPs in the SNP × physical activity and the SNP × smoking analyses were low and not statistically significant (Table 2). We also compared Pint values and Pv values for BMI. Spearman’s ρ for the pruned set of SNPs were low and not statistically significant.