Sunscreen and insect repellent

Which goes on first, insect repellent or sunscreen?

The Centers for Disease Control and Prevention says "sunscreens should be applied to the skin before insect repellents." But the CDC also advises not to use combination products containing repellents and sunscreens: "DEET-containing insect repellents may decrease the effectiveness of sunscreens, and sunscreens may increase absorption of DEET through the skin."

We also discovered research demonstrating that DEET and the sunscreen ingredient oxybenzone (benzophenone-3) mutually increased skin absorption. Oxybenzone has estrogenic activity; increased absorption is not desirable. Sunscreens relying on zinc oxide or titanium dioxide should not be a concern.


I had heard that floating stools were no cause for concern. I read in your column that it could be an early symptom of pancreatic cancer.

Doctors have argued for years about why stool sometimes floats. Some attribute it to gas, some to high-fiber diets.

In most cases, floating stools are not worrisome. But some situations require medical investigation. People with celiac disease, cystic fibrosis or short bowel syndrome may produce stools that float.

Pancreatic cancer is a rare but deadly cancer. Most [people with floating stools] have nothing to worry about. If, however, the floaters are pale, bulky and greasy, and accompanied by abdominal pain, weight loss, jaundice or generalized itching, a person should seek medical care promptly.


Joe Graedon is a pharmacologist and Teresa Graedon is an expert in medical anthropology and nutrition.

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