Modern tattoo inks are causing increased complications like allergic reactions, serious infections and reactions that can mimic skin cancer, a dermatologist has claimed.

Tattoo ink`s composition has changed dramatically over the years. In the past, metal salts, lead, cobalt and carbon were used in inks but today, many modern tattoo inks (especially intense reds and yellows) contain organic azo dyes with plastic-based pigments, which also have industrial uses in printing, textiles and car paint.

As a result, Michi Shinohara, MD, FAAD, a board-certified dermatologist and clinical assistant professor of dermatology at the University of Washington in Seattle, explained that there are many unknowns about how these inks interact with the skin and within the body and if they are responsible for an increasing number of complications.

One of the most common problems associated with tattooing is allergic reactions to the tattoo pigments. Itching, bumps or rashes can occur days, months or even years after the initial tattoo.

In people suffering with psoriasis and eczema, tattoos may cause the chronic skin conditions to flare.

Sarcoidosis is an autoimmune disorder that is characterized by swelling and itching, which can occur in a tattoo decades after the procedure and can involve other organs, like lungs or eyes.

This type of reaction is not directly caused by the original tattoo, but can show up within the tattoo.

According to Shinohara, Skin cancer can occur within a tattoo, and for that reason tattoo artists need to be careful not to place a tattoo over an existing mole.

However, one reaction that can result is a bump that mimics skin cancer, which can ruin the tattoo.

This type of bump or lesion, which can occur within a tattoo looks like a type of skin cancer known as squamous cell carcinoma.

Since the bump is so hard to distinguish from this skin cancer, it requires a biopsy and, in some cases, may need to be treated as a skin cancer, with additional surgery.

Common infections linked to tattooing include localized bacterial infections.
In addition, there are reports that syphilis and hepatitis B and C are being transmitted due to non-sterile tattooing practices.

However, Shinohara noted that outbreaks can also stem from the tattoo ink rather than the tools used in the procedure.

A recent outbreak of atypical mycobacterial infections has been traced to contaminated tattoo ink, which cause itchy, painful pustules and red bumps within a tattoo during the first month of the procedure.

This type of bacteria is harder to treat than regular staph bacteria and can require a several-month course of oral antibiotics to clear the infection.

Lack of household work for modern women might be contributing to obesity, a new study has claimed.

According to researchers, since the 1960s, more women have taken desk jobs and cut back on physical activity like household chores.

In 1965, the average women spent nearly 26 hours per week on chores like cooking, cleaning and doing the dishes. Women today allot about half that time for chores, the study revealed.

"What we were trying to find is what has changed in our environment that has led to obesity," study leader Edward Archer, a researcher at the University of South Carolina, told the New York Daily News.

What changed, he said, is that more women went to work at sedentary jobs and fewer engaged in physical activity - like housework.

Obesity rates have been increasing steadily in past decades. In 2004, 32 percent of Americans were obese, compared to 13 percent in the 1960s, according to research from the Johns Hopkins Bloomberg School of Public Health.

For Archer`s study, researchers looked at the time and amount of energy women expended on "household management" over a 45-year span.

Non-working women spent 33.1 hours per week on housework in the 1960s, compared to 16.5 hours in 2010. Working women spent 17.1 hours on housework in the 1960s, compared to 10.4 in 2010.

By 2010, women were devoting 25 percent more time to "screen-based media use" - watching TV or on the computer.

The study is published in the science journal PLOS One.