Your hair greying or turning white with age is a natural process, but history proves that improving on nature is an ever-evolving goal for most humans. And so, the ancients used everything from henna and amla to turmeric, red ochre and leeks to dye their hair and hide the greys, and this trend has carried into modern times. Synthetic hair colours and dyes were created in the 1860s, with the credit for the first synthetic dye going to Eugene Schueller (also the founder of a world-renowned brand of hair care products).
Now, people tend to use both plant-derived and synthetic dyes to hide greys or to simply look fashionable. Hair dye use and application has been made so easy now that most people can, and do, use it in the comfort of their homes. A study published in Frontiers in Bioscience in 2012 indicates that over 50 percent of the global adult population will use hair dyes at some point during their lifetime.
The use of hair dyes and cancer risks
The 2012 study - and many others over the last two decades - also indicates that synthetic dyes, especially the permanent kind, contain a number of chemicals that act as carcinogens or possible mutagens. A study published in the International Journal of Cancer in July 2020 says that most hair dyes and hair products contain endocrine-disrupting compounds and carcinogens that increase the risks of breast cancer.
Another study in Critical Reviews in Toxicology in 2007 explains that exposure to carcinogens in permanent hair dyes - also known as oxidative hair dyes - can increase the risk of bladder cancer in hairdressers. A 2019 study in Medical Principles and Practice found that use of permanent hair dyes is linked to an increased risk of non-Hodgkin's lymphoma (NHL), a type of malignant tumour that originates in the lymph nodes. These studies clearly show that chemicals present in permanent hair dyes are potential carcinogens, and they increase the risk of certain types of cancers in not just consumers but also hairdressers.
New study on ever users of permanent hair dye
A recent observational study published in the British Medical Journal (BMJ) throws further light on permanent hair dye use and cancer incidence. The study included 117,200 women enrolled in the ongoing Nurses' Health Study in the US. All participants were cancer-free at the beginning of the study, and their personal use of permanent hair dye was monitored for 36 years. The duration and frequency of use of these dyes were taken into account during analysis.
The study found that frequent users of permanent hair dyes had no significant increase in the risk of overall solid or hematopoietic cancers compared to non-users. They did not have an increased risk of specific cancers like cutaneous squamous cell carcinoma, bladder cancer, melanoma, brain cancer, colorectal cancer, kidney cancer, lung cancer, or cancer-related deaths. However, before you start rejoicing at these findings, here's the flipside.
Basal cell carcinoma risk was slightly increased for frequent users of permanent hair dyes, and the cumulative dose of these dyes over the years was associated with an increased risk of estrogen receptor-negative breast cancer, progesterone receptor-negative breast cancer, hormone receptor-negative breast cancer and ovarian cancer. A higher risk of developing Hodgkin's lymphoma was also observed in women with naturally dark hair. The greatest limitation of this study was that it lacked racial diversity, and so its findings cannot be automatically picked up for global resonance.
Taking the findings of this recent study and previous studies into account, the specifics of which cancers have an increased incidence due to permanent dye use is still foggy in the absence of better global studies. Yet, it is clear that prolonged or excessive use of permanent hair dyes does increase carcinogen exposure and thereby the risk of cancer. The takeaway here is to limit hair dye use (especially if you already have a family history of cancer or greater exposure to carcinogens) or look for natural or organic hair dyes with less harmful chemicals.
For more information, read our article on Cancer.
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