Scientists are increasingly interested in what happens when the shampoos, soaps, gels, conditioners, and shampoos we use wash down the drain. Many ingredients in these personal care products are considered emerging contaminants because standard water-treatment plants aren't able to filter out the tens of thousands of chemicals found in popular, everyday products.
The latest culprit? A powerful anti-fungal chemical used in many popular dandruff shampoos. The new study, published in the journal Environmental Toxicology and Chemistry, found that—even in very tiny doses—dandruff-fighting shampoos containing the active ingredient climbazole are throwing off waterway health.
The fungicides killed off algae and impacted the germination rate, stem size, seed production, and leaf color of certain water plants. Scientists classified it as very toxic to important water plants like algae and Lemna, part of the duckweed family, toxic to fish, and harmful to daphnia, small crustaceans that serve as food for many other water creatures.
Scientists are concerned about dandruff-fighting fungicides that remain in water after it's treated and released back into rivers and other waterways, but also its impact on land. The nasty chemicals can stay behind in the solids left behind at water-treatment plants—sewage sludge that's often then sold back to farmers to apply to crop fields.
In soils containing climbazole-laced sewage sludge, crops like turnips and oats suffered damaged growth patterns, even when the anti-fungal chemical was present in only tiny doses.
Read More: Is Your Shampoo Loaded with This Cancer Causer?
But we get it. Nobody wants to deal with those embarrassing flakey hitchikers. So we reached for our trusty copy of The Green Pharmacy Guide to Healing Foods to pinpoint some natural dandruff remedies that will keep your scalp in check without messing with the streams and rivers we love:
Get sugar smart. In The Green Pharmacy Guide to Healing Foods, author and medicinal plant expert James A. Duke suggests cutting added sugars from your diet. In the 1960s, British researchers noticed that people living with seborrheic dermatitis, one cause of dandruff, ate significantly more sugar than people who didn't have it. (There are plenty of other reasons to cut back on hidden, added sugars. Read 11 Weird Things Sugar's Doing to Your Body for more info.)
Try this sweet treatment. A United Arab Emirates study found that honey can halt the itching and scaling of dandruff. Participants diluted raw honey slightly with warm water (9 parts honey to 1 part water) and applied the mixture to their scalps every other day for four weeks. They gently rubbed the honey into the scalp for two to three minutes, leaving the mixture on for three hours, and then rinsed with warm water. The patients' itching and scaling eased up, and—get this additional benefit—they experienced less hair loss, too.
Aim for a proper pH. Your scalp is naturally acidic, but sometimes hair care products and the natural oils in your scalp make it too alkaline. To remedy this, try massaging a few tablespoons of fresh lemon juice into your scalp, and rinse with water. Repeat this once a day until your dandruff is gone. If you're not a citrus fan, apple cider vinegar can have the same acidic effect. Warm the vinegar in the microwave or in a saucepan on the stove, then soak a small towel in it and lay it on your hair for one hour. After that, wash it out well with a mild shampoo.
Get your zinc on. Researchers have discovered that a zinc deficiency can lead to dandruff, so try adding barley, oysters, kidney beans, and other zinc-rich foods to your diet. A side benefit? These will also bolster your immune system heading into flu season.
Try this yogurt trick. An old folk remedy calls for coating your scalp with plain yogurt, then covering it with a towel for 20 minutes before rinsing the yogurt away with warm water. This home remedy is said to ease the itching and flakiness associated with dandruff. We recommend using organic yogurt—you'll bypass pesticides and other nasty ingredients.