August 13, 2022

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The 36-year Harvard study tells you if dyeing hair causes cancers

The 36-year Harvard study tells you if dyeing hair causes cancers

The 36-year Harvard study tells you if dyeing hair causes cancers

Is it true that dyeing hair causes cancer? Harvard University spent 36 years investigating 120,000 people and finally came to a conclusion
Tumor today

Young people pursue fashion, love trends, and like to dye their hair brightly. There are also more and more elderly people falling in love with hair dyeing, mostly to cover up the traces of time.

But is dyed hair really healthy?

1. Hair dyeing causes cancer? Harvard large-scale research is here

In order to explore the impact of hair dyeing on cancer, Harvard Medical School’s Brigham and Women’s Hospital and the Dana-Farber Cancer Institute jointly analyzed and discussed the data of American nurse health research and published the results in the well-known journal “British Medical Journal.” superior.

The 36-year Harvard study tells you if dyeing hair causes cancers

This data covers approximately 120,000 female subjects between the ages of 30 and 55.

The researchers analyzed the subjects’ height and weight, race, smoking and drinking status, natural hair color, family history of cancer, menopausal status, etc., and collected information on their use of permanent hair dye and cancer incidence and death.

Researchers follow up the subjects every two or four years to update relevant information in a timely manner. After 36 years of follow-up investigation, the researchers came to the following conclusions:

Conclusion 1:

After adjusting for other factors, they found that compared with women who have never used permanent hair dyes, women who have used permanent hair dyes did not have an increased risk of most cancers (including kidney cancer, brain cancer, some breast cancers, etc.) Solid cancers, blood cancers, skin cancers), and no significant associations were found in cancer-related deaths.

Conclusion 2:

However, in a small number of cancers, the use of permanent hair dye is related to the increased risk of some breast and ovarian cancers, and the more times it is used, the higher the risk.

Conclusion 3:

Of the 120,000 subjects, 38,000 had used permanent hair dye, and they were more likely to smoke and drink.

However, the researchers also emphasized that although this study has found some findings, it is ultimately an observational study, and its causality cannot be determined. The study also has limitations. For example, the subjects are mostly white women, lack of ethnic diversity, and there are unpredictable factors that may cause bias in the results.

2. “Hair dyeing causes cancer” or a misunderstanding

“Whether hair dye is carcinogenic” has always been controversial. In the last century, literature pointed out the correlation between hair dye and hematological tumors, and carcinogens were also found in some hair dyes.

However, since the 1980s, people have re-researched hair dyes and found that bacteria do mutate when they come into contact with hair dyes. When they are applied to animal fur, they are not carcinogenic. In addition, the researchers did statistics on the incidence of tumors and population exposure after using hair dyes, and there was no increase in tumor incidence.

The World Health Organization classifies hair dye as a “third-level carcinogen”, which means that the carcinogenicity of humans cannot be classified, and it is the same level as coffee.

In general, there is still a lack of large-scale studies to confirm that “hair dyes are carcinogenic.” People’s views on hair dyes may be a misunderstanding.

3. Health risks still exist

Although there is no strong association between hair dye and cancer, the four major problems that hair dye may cause are still worthy of our attention.

1) Allergies

The use of hair dyes is prone to allergic problems, especially inferior hair dyes, which manifest as redness, itching, scaling, etc., and even scalp and facial edema. In addition, hair dyes may also cause allergic reactions in the bath.

If allergies are severe or persistent, go to a dermatologist.

2) Liver damage

Certain chemical components in hair dyes have been proven to cause drug-induced liver damage. The frequency of use of hair dyes and product quality are also factors that cause liver damage. In particular, long-term use of low-quality hair dyes may cause greater liver damage.


3) Kidney damage

Common anti-inflammatory analgesics, some Chinese herbal medicines, and folk prescriptions all have nephrotoxicity, and long-term or large amounts of them can damage kidney health. In addition, whitening products commonly used by women and low-quality hair dyes commonly used by young people may affect kidney health.

4) Heavy metals

The hair dyes produced by regular channels and manufacturers are allowed to contain a certain amount of lead, mercury and arsenic, but the content is minimal and has no effect on human health. Inferior hair dyes mostly have the problem of excessive lead. If used for a long time, it may cause chronic lead poisoning.

4. Safe hair dyeing, remember four suggestions

1) Purchase qualified hair dye

Regular and qualified hair dyes are less irritating and no harmful substances exceed the standard. Therefore, before dyeing your hair, you must confirm that the hair dye used is produced by a regular manufacturer, has been audited, and has an exclusive production batch number and approval number.

2) Perform an allergy test

It is best to perform an allergy test before dyeing your hair. Apply a small amount of hair dye behind your ears or inside your wrists and observe for 2 to 4 days to see if there are skin redness, itching, rashes and other problems. If not, you can use hair dye.

3) Twice a year, wash more

Try to dye your hair as little as possible. If you really want to dye your hair, you should also control the frequency of dyeing your hair. It is recommended not to exceed twice a year. In addition, you should avoid the hair dye remaining on the scalp for a long time, and you should wash your hair frequently after dyeing your hair.

4) Don’t get infected with these people

People with allergic diseases, pregnancy, breastfeeding and children should try not to dye their hair.

In general, although “hair dyeing causes cancer” is inconclusive, long-term and frequent hair dyeing does affect health. However, health experts remind everyone who loves beauty not to dye hair frequently. When dyeing hair, choose qualified hair dyes and be responsible for your health.

The 36-year Harvard study tells you if dyeing hair causes cancers

(source:internet, reference only)

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