Table 2.

The hierarchical “STOP” principle of prevention with some examples pertaining to hairdressers’ exposure to haptens and allergens, respectively [26]

	Principle	Examples
S	Substitution	GMTG was banned and has been replaced by other waving agents. This reduced GMTG sensitization in hairdressers
		Dusting hair bleaching powders were mostly substituted by dust-free bleaching powders or bleaching creams, reducing respiratory exposure
T	Technical measures	Suitable room ventilation, e.g., at least 100 m3/employee
		For mixing and decanting work, specially designated workplaces are needed if hazardous gases, vapors, or suspended matter occur during handling
O	Organizational measures	Even/fair distribution of “wet work” tasks among all employees
P	Personal measures	Suitable protective glovesa must be made available to employees for the several activitiesb
		A skin protection plan must be displayed in a clearly visible place in every hairdressing salon

GMTG glyceryl thioglycolate

^a(i) impervious to hairdressing chemicals (low chemicals hazards protection required), (ii) extending above the wrist, (iii) low-sensitizing, (iv) single-use gloves must not be re-used

^b(i) head massage; (ii) coloring, tinting, and bleaching; (iii) perming/relaxing, including trial wrapping and fixation; (iv) preparation, mixing, and decanting of hazardous substances; (v) hair washing; and (vi) wet cleaning or disinfection of work equipment, devices, tools, and rooms