A prohibitive is any material that, if it exceeds allowed limits, would make recycled paper unusable as the grade specified. Example- If the quantity of prohibitives in Grade #12, Double-sorted Corrugated, exceeds 1/2 of 1%, the bale might be downgraded to Grade #11, Corrugated Containers.

tending to discourage (especially of prices); "the price was prohibitive"

That prohibits; prohibitory; as, a tax whose effect is prohibitive.