Bleaching powders, bleaching creams and other hair lightening preparations as sources for (airborne) allergic contact dermatitis and other health effects in hairdressers: Results of an empirical study.

BACKGROUND: Various products are available for lightening hair. There are no data on which applications are actually used in hairdressing, impeding proper estimation of actual exposure and necessary preventive measures. OBJECTIVES: To assess information about availability, usage and formulation of lightening preparations in the German hairdressing trade. METHODS: A market survey was conducted and hairdressers were surveyed by online questionnaires. RESULTS: Of 783 hairdressers clicking the link, 565 hairdressers (91.2% female, mean age of 40.2 ± 11.7 years) from all German states responded (response rate: 72.2%). The questionnaire survey has shown that available hair-lightening preparations in the German hairdressing trade are (multiple selection possible): dust-free (88.5%) and non-dust-free bleaching powders (22.1%), bleaching creams (41.9%), high-lifting hair colour creams (88.8%) and normal hair colour creams (58.4%). Five hundred eighteen (91.7%) hairdressers favour lightening hair with powder. The market survey revealed that bleaching powders and creams contain potassium persulfate, ammonium persulfate and sodium persulfate or combinations of these persulfate salts. CONCLUSIONS: Hairdressers are exposed to various hair-lightening applications containing different chemicals. Preventive measures need to address adverse skin and respiratory effects. Implementation of targeted health education already in early career stages (i.e., apprenticeship) seems advisable and can be maintained by refresher trainings.

Model-assisted Design of Experiments as a concept for knowledge-based bioprocess development.

Design of Experiments methods offer systematic tools for bioprocess development in Quality by Design, but their major drawback is the user-defined choice of factor boundary values. This can lead to several iterative rounds of time-consuming and costly experiments. In this study, a model-assisted Design of Experiments concept is introduced for the knowledge-based reduction of boundary values. First, the parameters of a mathematical process model are estimated. Second, the investigated factor combinations are simulated instead of experimentally derived and a constraint-based evaluation and optimization of the experimental space can be performed. The concept is discussed for the optimization of an antibody-producing Chinese hamster ovary batch and bolus fed-batch process. The same optimal process strategies were found if comparing the model-assisted Design of Experiments (4 experiments each) and traditional Design of Experiments (16 experiments for batch and 29 experiments for fed-batch). This approach significantly reduces the number of experiments needed for knowledge-based bioprocess development.