Fragrant oil (Latin name Santalum album) that can cause skin irritation or allergic reactions. One animal study showed it to have antitumor properties.  Sandalwood oil is a must to avoid if you have extra-sensitive skin or normally react to fragrance.
- Dwivedi C, Zhang Y. Sandalwood oil prevent skin tumour development in CD1 mice. Eur J Cancer Prev. 1999;8(5):449-55.