This Article Full Text (PDF) References Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via Google Scholar Citing Articles via Scopus Google Scholar Articles by Brand, R. M Articles by Charron, A. R Search for Related Content PubMed PubMed Citation Articles by Brand, R. M Articles by Charron, A. R Social Bookmarking                         What's this?

Sunscreens containing physical UV blockers can increase transdermal absorption of pesticides

Department of Internal Medicine, Evanston Northwestern Healthcare and Feinberg School of Medicine at Northwestern University, Evanston, IL, USA, rhbrand{at}enh.org

James Pike

Department of Internal Medicine, Evanston Northwestern Healthcare and Feinberg School of Medicine at Northwestern University, Evanston, IL, USA

Roselyn M Wilson

Department of Internal Medicine, Evanston Northwestern Healthcare and Feinberg School of Medicine at Northwestern University, Evanston, IL, USA

Anna R Charron

Department of Internal Medicine, Evanston Northwestern Healthcare and Feinberg School of Medicine at Northwestern University, Evanston, IL, USA

People are encouraged to wear sunscreens because of their effectiveness at reducing the risk of skin cancer. The dermal penetration of the herbicide 2,4-D can be enhanced by commercial formulations containing chemical ultraviolet (UV) absorbers, the absorbers themselves and the insect repellent DEET. This work has been extended to determine whether commercially available sunscreens containing the physical UV absorbers titanium dioxide (TiO₂) or zinc oxide (ZnO) enhance the transdermal absorption of pesticides. Hairless mouse skin was pretreated with either commercially available sunscreens or the UV absorbers themselves, dissolved in phenyl trimethicone. In vitro permeability studies were performed with the pesticides 2,4-D, paraquat, parathion or malathion. The data demonstrate that pretreatment with five of the nine sunscreens tested increased the transdermal absorption of 2,4-D (P <0.05). Transdermal studies using paraquat, parathion and malathion pretreated with a representative sunscreen all demonstrated significant penetration enhancement when compared to controls (P <0.05). Repeated 2,4-D and sunscreen applications resulted in either no change between pulses or an increase in absorption after the second pulse depending on the washing regimen. Examining penetration of individual UV absorbers formulated in phenyl trimethicone showed that that ZnO can impede 2,4-D penetration and TiO₂ had no effect. Combining UV absorbers in the presence of trimethicone resulted in ‘sunscreens’ that could actually inhibit 2,4-D penetration. Inert ingredients therefore control the increased absorption seen in commercial sunscreen products and this enhancement can be eliminated by substituting phenyl trimethicone as the solvent. Sunscreen use must still be encouraged even with the undesirable side effect of increased penetration through the skin.

Key Words: multiple applications • pesticides • sunscreens • transdermal • UV absorbers

Toxicology and Industrial Health, Vol. 19, No. 1, 9-16 (2003)
DOI: 10.1191/0748233703th169oa


CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?