Table 1. Responder characteristics, presented as means (SD) unless stated otherwise.

	Hair & questionnaire data (n = 183)	Saliva & questionnaire data (n = 92)
Age in years	15.6 (2.0)	15.3 (2.1)
European ethnicity, n (%)	163 (89.1)	87 (94.6)
Height in cm	170.1 (10.7)	169.4 (10.9)
Weight in kg	59.1 (13.1)	58.0 (14.4)
BMI in kg/m2	20.3 (3.2)	20.0 (3.2)
High SES n (%)	20 (10.9)	11 (12.0)
Smokers (ever) n (%)	41 (22.4)	19 (20.7)
Puberty stage	2.9 (0.7)	2.8 (0.7)

BMI = body mass index; SES = socioeconomic status.