*2.3.2 Dosing of formaldehyde*

The methodology used to identify and quantify the formaldehyde content in progressive brush products was applied according to the standard method


**Table 1.**

*Qualitative compositions described on the labels of the capillary straighteners (A1–A4).*


**Table 2.**

*Qualitative compositions described on the labels of the capillary straighteners (A5–A8).*

recommended by the National Institute of Occupational Safety and Health [11], followed by the modifications described by Gasparini et al. [12].
