Weighing the risk of ink

As Americans increasingly ink up, experts are questioning tattoos’ health risks. Tattoo ink particles contain carcinogenic chemicals and metals and can spread to the lymph nodes. A recent study from researchers at Lund University in Sweden determined such particles could be linked to lymphatic cancer.

The researchers used Swedish national population registers to compare tattoo prevalence among approximately 1,400 people diagnosed with malignant lymphoma and a control group of over 4,000 people without lymphoma. Twenty-one percent of the participants with lymphoma had at least one tattoo, while just 18 percent in the control group did. After adjusting for factors known to affect cancer, like smoking, age, and sex, the scientists found that the tattooed individuals had a 21 percent higher risk of lymphoma than did the non-tattooed people. The risk was highest for those who had received a tattoo less than two years earlier or at least 11 years earlier.

Surprisingly, having a greater surface area of the body tattooed was not associated with an increased risk for lymphoma. “We do not yet know why this was the case. One can only speculate that a tattoo, regardless of size, triggers a low-grade inflammation in the body, which in turn can trigger cancer,” said lead author Christel Nielsen in a news release. Laser treatment to remove tattoos further increased the likelihood of lymphoma. The study was published in the June edition of eClinicalMedicine.

Some experts are unconvinced by the study’s findings. Dr. Timothy Rebbeck, an epidemiologist at the Dana-Farber Cancer Institute and a professor at the Harvard T.H. Chan School of Public Health, told CNN the data doesn’t suggest a strong association. He claimed the study’s finding of a 21 percent increased likelihood of lymphoma for people with tattoos was not statistically significant.

The study authors cautioned that their work shows an association between tattoos and lymphoma but doesn’t prove a causal relationship. They plan next to evaluate the association between tattoos and other types of ­cancer, as well as inflammatory diseases.

Peanut butter benefit

Peanut allergies threaten the peanut butter and jelly sandwich’s standing as a favorite lunchtime staple, but a recent study provides some hope: It indicated that infants exposed to peanuts while as young as 4 months old are much less likely to develop a peanut allergy in adolescence. Previous research found that 5-year-olds who ate peanut products between infancy and age 5 were 81 percent less likely to have developed allergies than children who avoided peanuts altogether. Following up on the same kids, the investigators found that young children who had eaten peanuts were 71 percent less likely to have developed a peanut allergy by age 12 or older. The results, which confirm the protective effect of early peanut consumption, were published May 28 in NEJM Evidence. —H.F.