Which of the following substances is likely to promote dehydration in the skin?

Iodides can promote dehydration in the skin due to their osmotic properties. Iodides, while they have some antiseptic and anti-inflammatory uses, can also lead to the evaporation of moisture from the skin's surface, thus contributing to dryness. This can occur through an increase in the skin's permeability or by drawing moisture away from the skin barrier.

In contrast, water is essential for hydration and is commonly used in skin care to maintain moisture levels. Antioxidants play a role in combating free radicals and promoting overall skin health but do not inherently cause skin dehydration. SPF (sun protection factor) is used to protect the skin from UV rays and does not contribute to dehydration; in fact, many sunscreen formulations include moisturizing ingredients to help maintain skin hydration. Understanding the effects of various substances on skin health is crucial in cosmetology, as maintaining proper skin hydration is a key goal in cosmetic treatments.