Photo: DTU Civil Engineering/Lulu Weschler

Phthalates enter our skin directly from the air

Tuesday 20 Oct 15


Gabriel Bekö
Associate Professor
DTU Civil Engineering
+45 45 25 40 18

How weas the experiment conducted?

Six healthy males, aged 27-66, were isolated in a room where they were exposed to a slightly elevated dose of phthalates in six hour periods while breathing clean air through a breathing hood. Subsequently the urine from the subjects was collected for analysis of phthalate metabolites. The experiment showed that the body absorbs a considerable amount of phthalates just by being exposed to the substances from the air in the room.
We are far more susceptible to dermal absorptions of phthalates from air than previously presumed. This is the conclusion of new research from DTU Civil Engineering which is the first of its kind. Researchers behind the studies recommend that dermal absorption from air should therefore be included in future exposure assessments of phthalates.

Phthalates are synthetic substances that mainly enter our body through inhalation, ingestion and direct contact with the skin. This has been the prevailing presumption so far. New studies from DTU Civil Engineering show that the skin can absorb considerable doses of phthalate from the air, just by being in a room with phthalate-containing products without direct contact with or inhalation of the substances.

Everyday substances are absorbed by the skin from the air

“Phthalates are found indoors in different materials ranging from building materials, to plastic bottles to personal hygiene products such as shampoo. Phthalates are substances that are quickly processed which means that they disappear from our bodies quickly again. Nevertheless, measurements show that our bodies at all times contain a certain amount of phthalates; this suggests that we have a continuous intake of these substances. So it makes sense to study how phthalates are transferred to the human body through dermal absorption from air in order to examine all exposure channels,” says Gabriel Bekö, Assistant Professor at Section for Indoor Climate and Building Physics at DTU Civil Engineering and co-author of the new study.

The two substances which have been investigated in the study by DTU Civil Engineering are the phthalates DEP (diethyl phtalate) and DnBP (di-n-butyl phtalate). Common for both are that they are semi-volatile organic compounds, and that we often encounter them in our everyday lives. Both types of phthalates are found in cosmetic products. DEP is also found in perfume and personal hygiene products, whereas DnBP is used as plasticizer in building materials .

Exposure assessments should be updated

" it makes sense to study how phthalates are transferred to the human body through dermal absorption from air in order to examine all exposure channels"
Gabriel Bekö

Phthalates are suspected of being endocrine disruptors; particularly unborn babies and young children can be harmed by exposure to phthalates. Phthalates behave like hormones when they enter the body, which can harm a body still in the process of developing, while exposure to phthalates among adults has no immediate impact, explains Gabriel Bekö.

There is a lot of research into the effects of phthalates when used as plasticizer in plastic toys that come into direct contact with young children. The research from DTU Civil Engineering does not say anything about the health related risks of absorbing phthalates – the engineers leave this research field to medical science.  Gabriel Bekö nevertheless considers that it is worth taking this previously largely overlooked channel for recording into consideration with the exposure assessment of phthalates.

“Dermal absorption of phthalates, directly derived from the air has so far not been included as a risk factor in line with direct exposure. Our research shows that the dermal absorption of phthalates from air is in line with exposure occurring through inhalation. After six hours of exposure, the direct dermal exposure of DEP was on the same level as through inhalation. For DnBP, the dermal exposure from air was slightly lower than through inhalation. We therefore urge that dermal absorption of phthalates from air in future be included in the exposure assessment of phthalates.” concludes Gabriel Bekö.

The studies are published in the journal Environmental Health Perspectives in the October 2015 issue.