Chicago Recycling Coalition
Compost piles have the same ability to transfer harmful or disease-causing microorganisms as soil does. When working with compost, you should use the same precautions you do when gardening--for example, wear gloves.
What Can't You Compost?
Some composters become overexcited about the incredible ability of the compost pile to transform waste into a useful soil amendment, and try to compost everything. There are things you can compost, but shouldn't, such as pet wastes, especially cat litter.
Manure from horses, cows, and even chickens is a great compost addition, but these animals are herbivores, and their manure is different from that of omnivores or carnivores. Some composters say it's okay to compost these materials if you don't use the compost in areas where you are growing food, but keeping stocks separate requires careful attention.
Leaves collected from curbs and getters may be saturated with automotive products, or even heavy metals that don't break down in compost. Other people's lawn trimmings may be treated with pesticides. If you are composting only your own organic wastes, you know what the source is, and these issues needn't concern you. If you are collecting materials from other sources, become informed about their origins.
While you can add kitchen scraps such as vegetable trimmings to your compost pile, don't add actual leftovers of prepared food, especially if they contain fats, such as butter or oil. One reason is that fats are difficult for microorganisms in the compost pile to digest, and don't contribute anything healthy to the end product. Another is that rats will be attracted to these rich, delicious smells. However, any leftovers can be added to a vermicomposting bin.