The council also advised that some tattoo inks had been found to contain cancer-causing substances.

Furthermore, it raised concerns about the possibility of toxic tattoo ink making its way inside the body.

The warnings come amid a big increase in the number of people getting tattoos and the amount of skin being covered.

Tattoos that cover entire arms – known as “sleeve tattoos” – have become popular among professional athletes and, subsequently, the general population.

This has coincided with a rise in health concerns about tattoos.

“If a tattoo covers or surrounds a mole, you might not see changes that could indicate skin cancer,” Cancer Council NSW Hunter regional manager Shayne Connell said.

“The tattoo pigments in your skin may make it difficult for a doctor to accurately detect cancer, delaying diagnosis of melanoma or skin cancer.

“If you are concerned, don’t get tattooed.”

Dr Adrian Lim, a member of the Australasian College of Dermatologists, agreed that tattoos made it difficult to detect skin cancers.

“Tattoo ink obscures interpretation of the melanoma pigment network,” Dr Lim said.

“Tattoos can make early detection of all skin cancers more challenging for both patient and doctor.”

He raised concerns that larger tattoos, in particular, “could result in later detection of skin cancers and therefore a less favourable outcome and prognosis”.

A European Commission report found that tattoos could “blur” the surveillance of skin cancers and “interfere with the diagnosis and treatment of several other pathologies”.

“Tattoos should be avoided in skin areas containing moles or pigmentary changes, as they could delay or complicate the diagnosis of potential malignant growth,” the report said.

Concerns are also being raised about toxic tattoo ink travelling inside the body.

A study by German and French scientists found that nanoparticles from tattoo ink can travel inside the body and end up in lymph nodes, which are part of the immune system.

The study found “several toxic elements, such as chromium and nickel, in the lymph nodes”.

It concluded that these contaminants came from tattoo ink.

Mr Connell said the cancer council was “not aware of a reported cancer case directly attributable to tattooing”.

“However, evidence does show that some tattoo inks contain carcinogens (cancer-causing substances),” he said.

He added that these substances were “chemicals that have been classified as known or possible carcinogens by the World Health Organisation’s International Agency for Research on Cancer”.

He also referred to a report from the federal government’s Department of Health into tattoo inks in Australia.

The report, from the department’s National Industrial Chemicals Notification and Assessment Scheme (NICNAS), found that inks had been used for tattooing, which were not intended for this purpose.

It also found that ingredients listed on the labels of some tattoo inks were incorrect.

“A number of the tattoo inks analysed are non-compliant with the Poisons Standard,” the report said.

The report also found that polycyclic aromatic hydrocarbons (PAHs) in tattoo inks were associated with black tattoo inks.

Mr Connell said PAHs were “a group of chemicals which are known carcinogens”.

He said these chemicals were found “in a fifth of the samples tested and in 83 per cent of the black inks tested”.

“Other hazardous components included barium, copper, mercury, amines and various colourants,” he said.

“To achieve the permanent effect, tattoo ink is injected into the dermis – the deeper layer of the skin – and stays there for a lifetime.

“Over time, macrophages [large white blood cells] take up pigment and may transport it into the lymphatic system and lymph nodes.

“This means other tissue in the body can be exposed to potentially carcinogenic materials in the tattoo ink.”

In October last year, doctors at Sydney’s Royal Prince Alfred Hospital examined a 30-year-old woman with numerous lumps under both arms.

They first thought she had lymphoma.

She’d had swollen lymph nodes for a fortnight, but was otherwise in good health.

She had a scan which showed several swollen nodes down her chest wall and between her lungs. 

A needle biopsy was unable to confirm cancer.

Doctors operated, removing one lymph node. It was black. No sign of cancer was found in the node, but it did contain black particles.

The woman had a large black tattoo covering her entire back.

Doctors determined that the particles came from the black ink.

“A large black-ink tattoo that had been present for 15 years covered her back,” the researchers stated.

“Another black-ink tattoo on her left shoulder was 2.5 years old.”

“It’s known that skin on the back drains into these lymph nodes,” Dr Jad Othman said at the time.

Doctors concluded that she was having a delayed hypersensitive reaction to the accumulation of particles.

In another case, researchers examined lymph nodes and skin from four corpses with tattoos. They found stained lymph nodes in two – one with blue ink and the other green ink. The nodes and skin had elevated levels of metals including aluminum, chromium, iron, nickel and copper.

Mr Connell said a number of carcinogens found in tattoo inks “have been associated” with cancers of the liver and bladder.

The European Commission report said many substances contained in tattoo inks were “classified as mutagenic, genotoxic and carcinogenic”.

The report added that cancer was a disease that involved a number of factors, especially genetic or environmental factors, “which may take decades to express”.

“A direct correlation between tattoo and tumour is challenging to establish and a straightforward causality between tattooing and cancer formation is far from being demonstrated,” it said.

“The risk of tattoo-induced tumours cannot be totally excluded, due to the carcinogenic properties of many ink impurities.”

However, epidemiological studies would be needed to establish direct cause-and-effect links, along with risk assessments of ink ingredients.