I've seen tea tree oil been advertized as powerful anti-fungal & anti-bacterial agent, which people seem to use for practically anything:

  • laundry (in particular cloth diapers)
  • room freshener
  • bathroom cleaner
  • insect deterrent

I can attest that tea tree oil really works wonders. Old T-shirts (5+ years) that have become smelly even after washing and sun-drying smell like new (2-3 drops in the washing); bathroom mold disappears; fleas (I live next to a cow pasture) leave never to return.

I recently bought a bottle of tea tree oil in Germany. On the bottle it says


Umweltgefährlich (pollutant) and Xn Gesundheitsschädlich (health hazard).

Xn basically means "don't ingest", but concerning the "pollutant" label, I seriously wonder what exactly the effects are and why it is being advertised by manufacturers as a natural alternative to chemical solutions.

(I don't customarily use chemical cleaners, so I don't know, but it might just say the same thing for other "conventional" products...?)

Is there any information on how detrimental using tea tree oil is to the environment?

As a bonus question, my waste water is "bio-digested" on-site. What would be the effects of 2-3 drops of tea tree oil per day (diluted in hundreds of litres of grey water) on the anaerobic tank and on the ground water?

2 Answers 2


I know that tea tree oil is poisonous when ingested, just like you said, but it is also toxic for animals upon contact. It must go into the blood stream by penetrating the skin. Because it exists in the composition of insect-repellents and plant fungicids, I presume that it is toxic to insects too.

There are discussions at the European Union parliament as to ban tea tree oil, or as to ban products that contain a high concentration of it. New studies think that over-using it may cause hormonal damage.

But everything I read concerning its toxicity or danger talked about dosage. Are you sure the bottle you bought contains 100% tea tree oil? What country is the oil from? Sometimes, the same plant but from another country actually has a different chemical composition.


I had a painful full-body hives reaction to Tea Tree Oil when applied topically. I suppose this was an allergic reaction or some kind of hyper-sensativity.

Also, there has been some research indicating tea tree oil is an endocrine disruptor, even when applied topically, which means it has unpredictable effects on the human hormone system. (http://www.nejm.org/doi/full/10.1056/NEJMoa064725) Definitely, don't use it in your house if you have kids.

An alternative might be borax, which is available in bulk as a laundry detergent in most grocery stores. Borax also has anti-fungal properties and can be used safely as a cleaning agent. Chemically, Borax is just a salt and has no known impact on humans (although it still shouldn't be taken internally). It is also an insecticide, sometimes used to treat wood to protect against both mold and termites.

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