When the EPA warned that some spot-on flea treatments are toxic, they only listed seven products.  

Not all essential oils used to treat pet pests are safe for pets or people. Herbal or natural products that
contain cedarwood, lemongrass, peppermint, rosemary and thyme are likely safer. Use herbal or natural products
containing citrus, cinnamon, clove, d-limonene, geranium, tea tree, lavender, linalool, bay, eucalyptus,
and rue oils sparingly because they can cause allergic reactions in people—and severe reactions in cats and dogs have been reported.

Avoid the use of any flea or tick product containing pennyroyal oil. It can cause seizures, comas,
and even death in animals.