Federal regulators will require sunscreen manufacturers to test
their products' effectiveness against sun rays that pose the
greatest risk of skin cancer. Under new rules being announced
Tuesday, they also will have to follow stricter guidelines when
describing how well their products work against ultraviolet B
rays. Currently, the Food and Drug Administration only requires
testing for ultraviolet B rays that cause sunburn. That's what
the familiar SPF measure is based on. Starting by next summer,
products must be tested for how well they deflect the more
dangerous ultraviolet A rays. UVA rays are most commonly linked
to skin cancer. The federal government first announced plans for
sunscreen standards in 1978. The process was delayed by
difficulties assessing UVA protection.