Studies indicating that prolonged or recurring inhalation and topical contact with phthalates can be a health risk are increasingly common.
In the October issue of EHP, researchers expanded the field by documenting that dermal uptake of airborne DEP and DnBP was greater than the amount absorbed via inhalation.
The team of scientists from Rutgers University in the US as well as institutions in Denmark and Germany published their work under the title, Transdermal Uptake of Diethyl Phthalate and Di(n-butyl) Phthalate Directly from Air: Experimental Verification.
Facts and findings
In a nutshell, “this study shows that dermal uptake directly from air can be a meaningful exposure pathway for DEP and DnBP,” conclude the researchers.
The experiment was inspired by a gap in the research on phthalate absorption: “[Inhalation as a] pathway has not been experimentally evaluated and has been largely overlooked when assessing uptake of phthalate esters,” explains the team in their abstract.
They found that the dermal uptake of airborne DEP was 4.0 μg/(μg/m3 in air) and that figure for DnBP was 3.1 μg/(μg/m3 in air).
“The impact of age is surprisingly strong,” write the researchers in the EHP article. Older subjects absorbed far larger amounts of airborne phthalates through their skin. The team documented that “the uptake of DEP by the 66-year-old is five times greater than that of the 27-year-old, while the uptake of DnBP is seven times greater.”
This contrasts to the effect age has on how much of the phthalates a person absorbs by breathing. “[Spearman’s correlation coefficients] indicate that the trend for increased dermal uptake with increasing age is significant for DEP and DnBP, whereas the trend for increased inhalation uptake is significant for DnBP, but not DEP.”
The findings also seem to provide clues to the skin’s diminishing efficacy as a protective barrier—though that’s not something the researchers were considering deeply. They do however cite several articles that explore how the skin metabolises phthalates.
More to learn
A small sample of subjects—six healthy men—participated in the testing. The team ran the subjects through a series of two distinct experiments: one with the subjects able to both inhale and absorb the chemical through their skin and another with only their skin exposed to the airborne phthalates.
Similar results from further studies would add credence to the team’s findings. Even so, the research team holds that “dermal absorption directly from indoor air should be included as a contributory exposure pathway in risk assessments of low-molecular-weight phthalates.”