Feel strongly about these letters, or any other aspects of the news? Share your views by emailing us your Letter to the Editor at letters@scmp.com or filling in this Google form . Submissions should not exceed 400 words, and must include your full name and address, plus a phone number for verification. The decision by China’s General Administration of Sport to significantly restrict tattoos among football players is medically prescient. A 2013 study found that tattooing is associated with hepatitis C infection, even among those without traditional hepatitis C risk factors such as intravenous drug use and blood transfusion before 1992. Hepatitis B and HIV can also be spread through tattooing. The ink used in tattooing is also of concern. A paper published in the New England Journal of Medicine in 2012 confirmed an outbreak of tattoo-associated Mycobacterium chelonae skin and soft-tissue infections in Rochester, New York. In 2019, the Food and Drug Administration in the United States issued a warning to consumers, tattoo artists and retailers “of the potential for serious injury from use of tattoo inks that are contaminated with bacteria” after microbiological analysis of tattoo inks identified six inks contaminated with bacteria harmful to human health. As a surgeon I have also seen many infected tattoos, which required surgical drainage, not to mention numerous allergic reactions and skin-destroying hypertrophic scars. Tattoo ink typically comprises a mixture of many chemicals, including preservatives, viscosity regulators , solvents and several pigments. One of the preservatives found in some inks is formaldehyde, which the International Agency for Research on Cancer classifies as a carcinogen. A 2021 study found that 73 per cent of the 127 US tattoo inks examined tested positive for formaldehyde release. A European Commission study looking at the safety of tattooing noted that “more than 60 per cent of [the colourants in use] are azo-pigments, some of which can release carcinogenic aromatic amines”. A 2016 Australian government report on tattoo inks in the country found that red and yellow tattoo inks in particular contained azo-colourants. These inks also contain polycyclic aromatic hydrocarbons (PAHs), which are carcinogenic chemicals. PAHs were found in more than one-fifth of the ink samples tested, and in 83 per cent of the black inks in the Australian study. The impact to the skin when these chemicals are exposed to ultraviolet radiation is of concern in relation to the development of cancer. Also, over time, these pigments can be transported to the lymph system and the lymph nodes. Barium, copper and titanium oxide have been found in tattoo ink. The question is how much or how little of these chemicals could be implicated in future cancers. A Danish study in 2016 found tattoo inks contain barium, cadmium and lead which have effects on the cardiovascular system, the developing nervous system, and bones and the kidney respectively. The step taken by the Chinese authorities is therefore to be commended, underlining that tattoos have both short and long-term medical risks. This recognition will hopefully initiate a much-needed counter to the current unchallenged “coolness” of tattoos on social media as well as stimulate the need for more definitive medical research on the cancer-related risks of tattoos. Dr Paul Anderson, North Island, New Zealand