Fig. 1

Penalized regression spline of log-transformed creatinine-adjusted urinary phthalate metabolite concentrations and handgrip strengths. Solid lines, spline curves; shaded areas, 95 % confidence intervals; MEOHP, mono-(2-ethyl-5-oxohexyl) phthalate; MEHHP, mono-(2-ethyl-5-hydroxyhexyl) phthalate; MnBP, mono-n-butyl-phthalate. The models were adjusted for age, sex, smoking status, alcohol consumption, physical activity, monthly income, education level, city of residence, body mass index, and comorbidity status