Some of my essential oils are organic and some aren't, and there doesn't seem to be much difference in terms of sensitivity. There are some essential oils that I don't like to use at all, like cinnamon and peppermint, because they are very irritating even in small quantities. Even when I have used peppermint in body scrubs, I have only used about 1 drop for each 4 ounce container and it's plenty. I have found orange and anise to be the most gentle on lips. I have also put in an order for natural cosmetic flavours, which are made specifically for lip balm and formulated with totally natural and organic ingredients. You can get them in oil-soluble flavours that you can't usually get from essential oils (like strawberry) and they seem very gentle and safe. I think these are a good way to go and I'm looking forward to using them. I have actually found some synthetic flavour oils in the past to be somewhat irritating, so I think I will have more luck with these. Of course, customers are also more trusting of "natural flavours" than "flavours", which is a very good thing.