The active ingredient in this product, 2% salicylic acid ( also known as Beta hydroxy acid, BHA), is a multifunctional acne-fighting ingredient. Salicylic acid is an effective exfoliant and also an anti-irritant. In concentrations of 0.5% to 2%, it gently exfoliates the surface of skin and penetrates into the pore, and thus can exfoliate inside the pore as well as on the surface of the skin, which makes it effective for reducing blemishes, including blackheads and whiteheads. It also treats acnes due to its anti-inflammatory and antimicrobial properties. So indeed this scrub is effective towards blackheads and acnes.
In fact another ingredient willow bark extract is the precursor of salicylic acid when eaten. But the chance of the transformation on skin is next to none. However it still has some anti-inflammatory benefits for skin.
Another acne control ingredient is chamomilla recutita (matricaria) flower oil. It has anti-inflammatory properties and can be added to acne treatment products.
Besides BHA the other main exfoliator is crushed walnut shell. The finely crushed powder is multifaceted and an effective yet gentle abrasive.
Now for the BAD ingredients...I am most worried about two, propylene glycol (PG) and triethanolamine (TEA). PG is derived from petroleum and used in cosmetics as solvents mostly. It is the fourth abundant ingredient in this product. The problem with PG is that it is easily absorbed through skin and is a potent skin irritant. PG could provoke skin irritation and sensitization at concentration as low as 2%. PG being the fourth abundant ingredient makes me worry about how likely it will cause problem. In fact U.S. Environmental Protection Agency (EPA) has issued a warning to avoid PG skin contact to prevent brain, liver, and kidney abnormalities.
TEA appeared at the middle of the ingredient list. The problem with TEA is that like all amines, it has the potential for creating nitrosamines. It may or may not. There is no way of knowing, at least without a well-equipped chemistry lab. But it will be really bad if it does. Nitrosamines are readily absorbed through skin and they have been proved to be strong carcinogen. Whether or not the concentrations used in cosmetics should be of concern is still a matter of debate. Better avoid if possible. If you have to use this product, rinse off completely and use cold water to reduce absorption.
Safety alert: Cautious
review based on scientific information of the product ingredients.