The active chemical used in spray tans, dihydroxyacetone (DHA), can enter the lungs and is then absorbed into the bloodstream where it could damage DNA and cause tumours, according to a panel of medical experts who reviewed 10 scientific studies on DHA, according to American television broadcaster ABC News.

Scientists claim the chemical may make asthma worse, as well as other lung problems such as emphysema and chronic obstructive pulmonary disease (COPD).

"I have concerns," Dr. Rey Panettieri, a toxicologist and lung specialist at the University of Pennsylvania's Perelman School of Medicine, told ABC. "The reason I'm concerned is the deposition of the tanning agents into the lungs could really facilitate or aid systemic absorption -- that is, getting into the bloodstream."

He adds: "These compounds in some cells could actually promote the development of cancers or malignancies," he said, "and if that's the case then we need to be wary of them."

Are you at risk? "For the casual user - the person who goes [to the salon] once a month - frankly there's probably no problem at all," Panettieri adds. However, there could be problems for people who use salons frequently or employees who apply the spray tans to their customers, he warns.

Also, according to the report, while America's Food and Drug Administration (FDA) approved DHA's use in self-tanning products back in the 1970s, that was before spray tanning, which presents the possibility of inhaling or ingesting the chemical -- this holds true for both tanning salons and at-home aerosol spray tanning products.

According to the FDA's website: "The use of DHA in 'tanning' booths as an all-over spray has not been approved by the FDA, since safety data to support this use has not been submitted to the agency for review and evaluation."

The FDA also advises spray tanning consumers take protective measures, such as wearing protective eyewear, lip balm, nose filters, and protective undergarments to prevent the chemical from entering the body.