Despite their drawbacks – skin irritation – they are effective as a low-cost way to solubilize iodine. A 1% iodine teat dip product would typically contain 7%-10% NPE.
A concern raised by China is that NPEs may be endocrine disruptors. This relates to the chemical structure of nonylphenol, mimicking certain hormones similar to estrogen. The potential effects are greatest to infants and young children who consume the highest amounts of fluid milk.