According to a recent study at the University of Winnipeg, using sunscreens and DEET-based insect repellents may increase the skin absorption of chemical ingredients and endanger health – particularly in seniors and children. People may wish to apply these products separately, or purchase DEET-free repellents and more “natural” sun care products in health and nutrition stores.

Lead researcher Dr Xiaochen Gu, of the Faculty of Pharmacy at the University of Manitoba, notes: “In our lab we have found that when these products are combined, there is increased absorption through the skin and that can do more harm than good.” Gu explains that sunscreens and repellents are designed to stay on the surface of the skin. DEET (N, N-diethyl- m-toluamide) is the active ingredient in most popular repellants, but if it is absorbed, it can cause skin allergy, hypotension, headaches, disorientation and encephalopathy, especially in children.

Gu studied DEET and oxybenzone, a sunscreen agent, separately and then combined the two, measuring their penetrative value. In his tests, the combined products showed a marked increase in absorption rates. This could mean that the side effects of the chemicals may be heightened when they are used together.

“Children have a large body surface area and tender skin making them more prone to cross-skin absorption. People over 65 tend to have thinner skin and have had years of exposure to the sun which also makes their skin absorb more of these chemicals,” he said.

Most health and nutrition stores offer DEET-free insect repellents which utilize essential oils that naturally repel insects. Chemical-free sun care products are also available, many of which use zinc oxide as a physical block to UV rays.

University of Manitoba, July 22, 2003