Nail polish in and of itself does not cause toenail fungus. That's not to say the it doesn't contribute to the situation. Fungus is an opportunist that infects the toenails when they are damaged. Nail polish can cause damage to the toenails.
Most nail polishes contain damaging chemicals, such as formaldehyde and toluene. Nail polish remover contains acetone. All of these damage the toenails and cause the white streaking that many women experience when removing their polish. This damage weakens the toenails and make them more susceptible to developing a fungus infection.
The are alternatives to harmful nail polish. As a podiatrist in Houston, I realize that it is impractical to tell women to not wear nail polish. We carry Dr.'s Remedy Enriched Nail Polish products which do not contain the harmful chemicals and contain vitamins and natural antifungals to nourish the nails. Everyone who has used are happy with the healthier appearance of their nails. You can visit our Houston podiatry office to pick up your favorite color.