Breast absorption is the process where substances applied to the skin of the breast move through its layers and enter underlying tissues, with the potential to reach the bloodstream. The skin serves as a protective barrier, but it is not entirely impermeable. The ability of a substance to be absorbed through the skin is influenced by its chemical properties and the condition of the skin itself.
How Absorption Through Breast Skin Works
Absorption through the skin, or transdermal absorption, is regulated by the skin’s outermost layer, the stratum corneum. This layer acts as the main barrier, determining the rate at which a chemical can pass through. A substance must navigate this layer to reach the dermis, where blood vessels and lymphatic channels reside.
A molecule’s size and its solubility are determining characteristics for skin penetration. Smaller molecules and those that are lipid-soluble (fat-soluble) can more easily move through the stratum corneum. The condition of the skin also plays a part, as damaged, thinner, or irritated skin is more permeable.
The skin on the breast has specific features that can influence absorption. It contains a high density of hair follicles and glands, which provide additional pathways for substances to bypass the stratum corneum. Once past the outer skin layers, substances can enter the dense network of blood and lymphatic vessels within the breast tissue.
Common Substances Absorbed Through the Breasts
A variety of substances in everyday products can be absorbed through the skin of the breast. Personal care items like lotions, creams, and deodorants often contain chemicals like parabens and phthalates. Antiperspirants, commonly applied near the breast, contain aluminum compounds that can also penetrate the skin.
Certain medications are designed for transdermal absorption. Topical hormone creams containing estrogen or progesterone are formulated to pass through the skin. Pain-relieving gels applied to the chest for muscle soreness also work by having their active ingredients absorbed through the skin.
Environmental chemicals can also be absorbed through the skin. Per- and polyfluoroalkyl substances (PFAS), often called “forever chemicals,” are found in a wide range of consumer products, from cosmetics to waterproof clothing. A 2024 study confirmed many PFAS can be absorbed through the skin, finding that substances with shorter carbon chains were more readily absorbed.
Implications for Breastfeeding and Health
The absorption of substances through the breast has implications for those who are breastfeeding. Chemicals that enter the bloodstream after skin absorption can be transferred into breast milk. This has been a consideration in studies on PFAS in breast milk, linking it to personal care products. This potential for transfer makes selecting skin products a consideration for lactating individuals.
Beyond breastfeeding, there are broader health considerations related to dermal absorption. Some chemicals that can be absorbed through the skin are studied for their potential to act as endocrine disruptors, meaning they may interfere with the body’s hormonal systems. Research into the effects of low-dose exposure to such chemicals is ongoing to understand the full context of their impact on health.