Air Pollutants Get Into the Body via the Skin


While lungs remain the main way by which air pollutants get into the body, and, if in sufficient quantities, cause ill-health effects, a new study shows that certain pollutants (‘semi-volatiles’ like phthalates) can be drawn in by the skin. This effect is known as ‘dermal uptake’ and the levels absorbed can be equivalent to those drawn in through breathing via the lungs.

Phthalates are esters of phthalic acid. They are used as plasticizers (substances added to plastics to increase their flexibility). Some reports indicate that these substances can, in sufficient concentrations and over a prolonged period of exposure, cause asthma and cancer.

The new finding is based on a formal study. Researchers examined six participants, who were exposed to elevated air concentrations of the chemicals diethyl phthalate (DEP) and di(n-butyl) phthalate (DnBP). DEP is used as a solvent in personal care products, like moisturizers, DnBP is used as a plasticizer, such as in nail polish.

Assessing the participants in special chambers, the levels of exposure through the skin were measured, and found to be unexpectedly high. Assessment was made via urine samples.

The finding challenges earlier research which points to the skin either being a relative intact barrier to air pollution (unlike a liquid spilling onto the skin) or the mechanism for skin absorption being relatively slow, which reduces the potential harm that air pollutants can cause.

The finding has led researcher John Kissel of the University of Washington in Seattle to tell Science News that “we’re big sponges for these chemicals.”

The risk from both pollution breathed in, and now via the skin, is where a noxious chemical enters the blood stream in sufficiently high concentrations as to cause a toxic reaction.

The risk of skin absorption of toxins is the main conclusion of the research, which is published in the journal Environmental Health Perspective, titled: “Transdermal uptake of diethyl phthalate and di(n-butyl) phthalate directly from air: experimental verification.”