While it is an off-label usage of moth balls, they are definitely toxic to mammals, and can often be useful in discouraging larger mammals in your area. Keep in mind the standard precautions about not letting children eat them. Pets and other animals will probably have enough sense not to touch them. Racoons, of course, are also not likely to eat them, but the fumes are intended to encourage them to find other places to cause damage. Since moth balls sublime (turn directly from solid to vapor), there is a constant release of vapors into the impacted area. If they get wet, they will decompose, and you may need to repply them. My look at the various data sheets does not lead me to believe that any of the products put into the soil as a result of rain disolving them would be much of an issue.

I've seen several State Extention sites now recommending moth balls for uses like this which they would at one time have not done. On its own, this confirms my hunch that they have been tried by various folks, and actually found effective. Many of the old objections you used to see from people hesitant to put any synthetic chemical in their yard are being balanced by the challenges posed by some critters. Moth balls are also a very cheap and easy material to try before going on to more complex schemes. My only use of them, to discourage another pest many years ago, was quite successful. I also found that the garden area was not offensive to humans with the moth balls in place. In fact, I could not smell them unless I got very close to the ground where they were. I would suspect that racoons with their proverbial particular habits would object to the smell and move on.

In a former home, there were lots of racoons in the neighborhood. They were fairly easy to trap. I also remember people using long sticks with ropes on them to pull them out of trees. It seemed to make them consider a move.

Renais

Mothballs are not registered for use as an animal deterrent and are harmful to the environment. I wouldn't use them. Also, in my experience, they simply don't work. Usually the only way to get rid of a female raccoon in at attic is:

1)Find and remove the baby raccoons from the attic by hand.

2)Use the young as "live bait" in a large cage trap to catch the mom.

3)Remove and relocate them, if legal, and patch up the hole they used to enter.

It is work usually best left to a pro.

Here is a link that might be useful: How to Get Rid of Raccoons

"While it is an off-label usage of moth balls, they are definitely toxic to mammals, and can often be useful in discouraging larger mammals in your area. Keep in mind the standard precautions about not letting children eat them."

Note: Humans are large mammals.

note: don't eat the moth balls.

Moth balls gas off Napthalene a known human carcinogen and has been linked to causing cataracts and other eye related problems. Inhalation is the most common source of human exposure, not ingestion, although that has happened.
A comment such as "note: don't eat the moth balls." indicates either gross ignorance of the product or a serious "I don't care about human lives" attitude.