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Bat Guano and Mascara Myth Debunked

Have you ever heard the rumor that mascara is made from bat poop? If so, you might be wondering if there is any truth to it, or if it is just another urban legend. In this blog post, we will explore the origin and validity of this claim, and reveal what mascara is really made of.

What is bat guano?

Bat guano is the term used for bat feces, which are rich in nitrogen and phosphorus, and can be used as a natural fertilizer. Bat guano can also harbor various pathogens, such as fungi, bacteria, and viruses, that can cause diseases in humans and animals. Therefore, bat guano is not something you would want to put near your eyes, or anywhere else on your body.

What is guanine?

Guanine is a crystalline substance that is derived from the Spanish word guano, meaning dung. Guanine is one of the four nucleobases that make up DNA and RNA, and it is also found in fish scales, bird feathers, and reptile skin. Guanine has a shiny, iridescent quality, and it is used as a colorant and an opacifying agent in cosmetics, such as mascara, lipstick, nail polish, and shampoo.

How did the bat guano and mascara myth start?

The bat guano and mascara myth started because of the similarity between the words guano and guanine, which caused some people to confuse them for each other. However, guanine and guano are not the same thing, and they have different sources and uses. Guanine is not derived from bat poop, or any other animal poop, but from fish scales, which are processed and purified before being added to cosmetics. Guanine is also approved by the FDA as a safe and effective ingredient for cosmetic products.

What is mascara made of?

Mascara is a cosmetic product that is used to enhance the appearance of the eyelashes, by darkening, lengthening, curling, or volumizing them. Mascara is typically made of a combination of ingredients, such as:

  • Waxes, such as beeswax, carnauba wax, or paraffin wax, that provide structure and hold to the mascara.
  • Oils, such as lanolin, mineral oil, or castor oil, that moisturize and condition the eyelashes.
  • Pigments, such as carbon black or iron oxide, that give color and intensity to the mascara.
  • Polymers, such as nylon or acrylic, that form a film that coats the eyelashes and prevents smudging or flaking.
  • Preservatives, such as parabens or phenoxyethanol, that prevent the growth of bacteria and fungi in the mascara.
  • Guanine, that adds a shimmering or light-diffusing effect to the mascara.


Here are some frequently asked questions and answers about bat guano and mascara:

  • Q: Is there bat poop in mascara?
  • A: No, there is no bat poop in mascara. Mascara contains guanine, which is a crystalline substance derived from fish scales, not bat poop.
  • Q: Is guanine vegan or cruelty-free?
  • A: No, guanine is not vegan or cruelty-free, as it is an animal-derived ingredient. However, there are some vegan and cruelty-free alternatives to guanine, such as synthetic mica or mineral pigments, that can also create a shimmery or opalescent effect in cosmetics.
  • Q: Is mascara harmful to the eyes or the environment?
  • A: Mascara is generally safe to use, as long as it is applied properly and removed gently. However, some people may have allergic reactions or sensitivities to some of the ingredients in mascara, such as preservatives, pigments, or guanine. Therefore, it is advisable to do a patch test before using a new mascara, and to stop using it if any irritation, redness, or swelling occurs. Mascara can also be harmful to the environment, as it can contribute to plastic waste and microplastic pollution. Therefore, it is advisable to choose eco-friendly mascaras that are made of natural or organic ingredients, and that come in recyclable or biodegradable packaging.


In conclusion, the bat guano and mascara myth is debunked, as there is no evidence or logic to support it. Mascara is not made from bat poop, but from a variety of ingredients, including guanine, which is a crystalline substance derived from fish scales. Guanine is used to add a shimmery or light-diffusing effect to mascara, and it is approved by the FDA as a safe and effective ingredient for cosmetic products. However, guanine is not vegan or cruelty-free, and mascara can also have some negative impacts on the eyes and the environment. Therefore, it is important to be aware of the ingredients and the effects of mascara, and to choose the best option for your personal preferences and values.

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