Have a green dilemma or question for Planet Green? Please send questions to askplanetgreen [at] gmail [dot] com. (Questions may be edited for publication.)

Dear Planet Green,

Why do cosmetic manufacturers use mercury in mascara?

—Seriously Confused in Santa Barbara

Dear Seriously Confused in Santa Barbara,

Mercury is used as a germ killer and preservative in mascara. It makes the product last longer than it normally would and it's used to prevent bacteria. Federal law currently allows cosmetic eye products to contain up to 65 parts per million of mercury. It has however been removed from a good majority of mascara products because of the toxicity that mercury can cause when it builds up in the body but the Environmental Working Group found mercury in Paula Dorf mascara, listed as the mercury preservative thimerosal.

Mercury poison can cause neurological symptoms in adults and it can slow brain development in children and fetuses. Minnesota recently banned the use of mercury in cosmetics and Connecticut, Rhode Island, and Louisiana banned products that contain more than low levels of mercury.

Dear Planet Green,

What are parabens and are they harmful?

—Health Skeptic in Illinois

Dear Health Skeptic in Illinois,

Parabens are sythetic preservatives found in a huge majority of cosmetics, beauty, and grooming products. While it's still up in the air, according to the FDA, a study published in 2004 (Darbre, in the Journal of Applied Toxicology) detected parabens in breast tumors. The study also discussed this information in the context of the weak estrogen-like properties of parabens and the influence of estrogen on breast cancer. However, the study left several questions unanswered. For example, the study did not show that parabens cause cancer. According to the Environmental Working Group, parabens can disrupt the hormone (endocrine) system, and were found in the breast cancer tumors of 19 of 20 women studied.