Natural materials, including organic cotton, wool and latex, will not keep dust mites away. (Don’t believe the hype that wool and latex protect against dust mites.) Dust mites are widely believed to be the single greatest source of allergens. Furthermore, it is common for dust mites to live in mattresses.
Any non-waterproof mattress (including the Quilted Organic Baby Crib Mattress) would require an external dust mite barrier encasing to prevent dust mites from penetrating the mattress. However, an organic waterproof pad will provide protection for the top of the mattress which mostly solves the problem.
The Classic Organic Baby Crib Mattress, Ultra Organic Baby Crib Mattress, Lightweight Organic Baby Crib Mattress, and 2 in 1 Organic Baby Crib Mattress all feature a waterproof surface that cannot be penetrated by dust-mites. There is no need for any additional dust mite barriers for these models.