In May 2018 researchers from Italy published their study to assess the level of oxidative stress in hairdressers and consumers exposed to hair dyes. Saliva samples were collected from hairdressers, consumers who had used hair dyes for at least 10 years, and from a control group. Results showed that the level of malondialdehyde (an indicator of oxidative stress) in the saliva was significantly higher in the hairdressers than the control group. A further analysis revealed that the level was higher for those working in a small workplace which was probably due to a more direct exposure to the gas produced by the dye. Consumers who had used hair dyes for at least 10 years also had an increased level of malondialdehyde in their saliva. Age was also a factor in the level of malondialdehyde in both the hairdresser and consumer group.
Menicagli R et al. The Question on the Potential Cancerous Effects of Hair Dyes: The Monitoring of the Oxidative Stress Induced by the Hair Dyes with the Dosage of the Salivary Free Radicals. Indian J Occup Environ Med. 2018 May-Aug;22(2):109-112