Tattoos don't increase the risk of skin cancer   Tattoos can
increase the risk of skin cancer.   As more Americans tattoo
their bodies, some have wondered whether there may be a hidden
risk (other than the risk of regretting the tattoo a few years
down the road).  Many inks are made with metals; blue, for
example, contains cobalt and aluminum, and red may contain
mercury sulfide. That, along with the fact that tattooing can be
traumatizing to the skin, prompted suspicion that tattoos might
lead to skin cancer. Studies in recent years have documented a
few cases of cancer at a tattoo site.  But Dr. Ariel Ostad, an
assistant clinical professor of dermatology at NYU Langone
Medical Center in Manhattan, says that does not mean the tattoo
caused the cancer. Indeed, he said, the ink is unlikely to do
any harm because it is confined to cells in the skin called
macrophages, whose job is to absorb foreign material.  More
likely, he said, the tattoo was placed on an existing mole,
making any changes in the mole hard to