“…Although, adjustment by urinary creatinine is traditionally used, Weaver et al (Weaver et al, 2016) have shown that this could potentially lead to inconsistences because of a misleading statistical effect, by which the associations between urine creatinine-adjusted toxicants and kidney outcomes may be statistical rather than biological. Other approaches to account for urine dilution include timed urine collections, usually over a 24 h period (Waikar et al, 2010), overnight spot urine sample (first morning) (Akerstrom et al, 2014), adjustments using urine specific gravity (Suwazono et al, 2005), using urine creatinine as a covariant in the regression model (Barr et al, 2005) or not adjusting at all Moriguchi et al, 2003). In the present study, we used three different methods to deal with this issue: Model 1 was an unadjusted model, whereas Model 2 and 3 used urinary specific gravity or creatinine, respectively as separate covariates.…”