Guinea pigs have one habit that can annoy some people, and that is they will chew anything. This includes the area where they live, and if they are allowed to roam freely, furniture, wires, and anything else they can get their jaws around is fair game. Obviously chewing wires is not good for them, nor the electronic item that uses them, but this can easily be stopped by preventing access to wiring.
One thing that they can often get their teeth into easily though is newspaper. Printed paper is a very cheap way to use in guinea pig habitats. It can make cleaning out a cage easier, and it does a very good job of soaking up pee. The only problem with newspaper is that guinea pigs can get a taste for it.
So, is newspaper safe for guinea pigs to eat? Years ago, the answer to this question was no. This was because some of the chemicals used in the ink and paper where toxic. Even so, they would have done little harm to a guinea pig, as they only eat small quantities. I have yet to meet a guinea pig that eats a whole newspaper!
These days things have changed, the majority of newspaper is now made with non-toxic materials, so when eaten, they do not cause any harm. This means that you can use as much of it as is required for lining guinea pig homes with. If your guinea pig starts eating it, then it will only provide it with a supply of fiber, which is good for its digestive system. Some guinea pigs will just enjoy ripping the paper apart, and will then spit it out.
As newspaper is now 100% safe for guinea pigs to eat, it is no surprise that wood pulp has become an excellent bedding material. Wood pulp is the leftover from the newspaper industry. It is very absorbent, soft to lie on, and safe to eat. In the UK, wood pulp can be bought in large bags under the name of Megazorb. It is available in the US under different names.
A lot of people tend to use wood shavings for guinea pig bedding, but please read my article on this subject: Are Guinea Pig Wood Shavings Safe To Use As Bedding? Wood pulp costs about the same as wood shavings, and so it is best to use the former one.