Measuring DNA damage and repair as possible biological markers for long-term, low-dose chemical exposure in hairdressers

Abstract

Hairdressers are exposed to combinations of chemicals, some of which are known or suspected allergens, carcinogens or organic solvents. The objective of this study was firstly to compare DNA damage and repair capacity between individuals with short-term exposure (STE) to those with long-term exposure (LTE) and secondly to that of control subjects (CTR). In addition, the study also wanted to show that the Comet Assay can be used in biological monitoring to measure occupational exposure in hairdressing. From information gathered in questionnaires, 20 test subjects and 11 controls were chosen, matched in gender, age and smoking habits. A heparinised blood sample was taken and lymphocytes isolated. One set of Comet Assays were performed with lesion-specific enzymes FPG and Endo III to test oxidative DNA damage. In another version of the Comet Assay, hydrogen peroxide was used to test individual DNA repair capacity. Serum from each sample was frozen immediately and later used for testing antioxidant capacity (ORAC). Levels of VOCs were measured inside salons using a photo-ionization detector. DNA damage test showed significantly increased inherent DNA damage among the LTE group compared to the controls (p=0.033), while the DNA repair capacity test showed significant inherent DNA damage among the STE group (p=0.0028) compared to the control group. The controls had least damage after T60 (p=0.05 compared to STE), least DNA damage after treatment with H202 and had greater DNA repair capacity than the test groups. Additionally, the controls show an increased antioxidant capacity, especially compared to the LTE group (p=0.042). Levels of VOCs, measured well below occupational exposure standards. It is concluded that hairdressers are exposed to a combination of low levels of harmful chemicals over the prolonged period of their working careers and that this could impact negatively on their health. This study also finds that the Comet Assay is in fact an effective tool for biological monitoring to measure the effects of chemical exposure in the hairdressing industry. This study recommends effective ventilation for every occupation that involves the use of chemicals, as well as proper training regarding the use and handling of chemicals and the importance of using personal protective equipment.