Bedding
Woodshavings should never be used, as rabbits have very sensitive eyes, hence sadly, so
many are used in the testing of cosmetics. Cedar, pine and other softwoods produce toxins known as phenols which have been linked to liver problems in humans if exposed to them for a long amount of time. Aspen is another commonly used wood and it is in fact, a hardwood and is a much better alternative to cedar or pine, however some animals are allergic to aspen and it is better avoided in the case of rabbits. NEVER use the scented woodshavings or sawdust.
Clumping cat litter is not suitable as it dries out the skin and can cause serious problems if eaten as it swells up and is not digestible. The non-clumping, paper based cat litter is often eaten, and this can cause impaction, so best avoided.
Newspaper often contains toxic inks and cannot be easily digested, so again, best avoided, especially as rabbits chew everything! It can be used as a lining of litter trays and covered up with with a safe and more absorbant bedding on top, like carefresh.
Carefresh works well in my opinion as it is very absorbant and keeps smell down, although sometimes it can be a bit dusty. It is widely available in the USA and UK. If you live near to a walmart you can buy 'Crittercare', which is a cheaper version of carefresh available only in the USA, although I have heard it tends to be very dusty, so use your own judgement. Also, you may want to cover the carefresh with a layer of hay if your bunnies start munching on it... like mine have a habit of doing, despite the lovely fresh hay I haul from the farm shop!
Carefresh does tend to be more expensive than shavings, so I only use it in the pee corners and litter trays where I need absorbant material, and use a thick layer of hay for the other areas to cut down costs!
Other beddings like Megazorb, similar to carefresh can also be used and can be bought in large bags at most good horse feed suppliers.