“…For example, hair color, which overlaps with ethnicity, has been shown to be associated with hair cortisol concentration (Binz et al, 2018;Rippe et al, 2016). Because sweat on the scalp affects hair cortisol concentrations, frequency of hair washes should be considered (Greff et al, 2018). However, the effect of chemical treatment of hairs (e.g., dyes, shampoos) on hair cortisol has been inconclusive and thus should be documented (Hoffman, Karban, Benitez, Goodteacher, & Laudenslager, 2014;Kristensen, Larsen, Olsen, Fahrenkrug, & Heitmann, 2017).…”