The estrogenic activity of phthalate esters in vitro.

Abstract

A large number of phthalate esters were screened for estrogenic activity using a recombinant yeast screen. a selection of these was also tested for mitogenic effect on estrogen-responsive human breast cancer cells. A small number of the commercially available phthalates tested showed extremely weak estrogenic activity. The relative potencies of these descended in the order butyl benzyl phthalate (BBP) > dibutyl phthalate (DBP) > diisobutyl phthalate (DIBP) > diethyl phthalate (DEP) > diisiononyl phthalate (DINP). Potencies ranged from approximately 1 x 10(6) to 5 x 10(7) times less than 17beta-estradiol. The phthalates that were estrogenic in the yeast screen were also mitogenic on the human breast cancer cells. Di(2-ethylhexyl) phthalate (DEHP) showed no estrogenic activity in these in vitro assays. A number of metabolites were tested, including mono-butyl phthalate, mono-benzyl phthalate, mono-ethylhexyl phthalate, mon-n-octyl phthalate; all were wound to be inactive. One of the phthalates, ditridecyl phthalate (DTDP), produced inconsistent results; one sample was weakly estrogenic, whereas another, obtained from a different source, was inactive. analysis by gel chromatography-mass spectometry showed that the preparation exhibiting estrogenic activity contained 0.5% of the ortho-isomer of bisphenol A. It is likely that the presence of this antioxidant in the phthalate standard was responsible for the generation of a dose-response curve--which was not observed with an alternative sample that had not been supplemented with o,p'-bisphenol A--in the yeast screen; hence, DTDP is probably not weakly estrogenic. The activities of simple mixtures of BBP, DBP, and 17beta-estradiol were assessed in the yeast screen. No synergism was observed, although the activities of the mixtures were approximately additive. In summary, a small number of phthalates are weakly estrogenic in vitro. No data has yet been published on whether these are also estrogenic in vitro. No data has yet been published on whether these are also estrogenic in vivo; this will require tests using different classes of vertebrates and different routes of exposure.Imagesp802-aFigure 1.Figure 2. AFigure 2. BFigure 2. CFigure 3.Figure 4.Figure 5. AFigure 5. BFigure 5. CFigure 6.Figure 7.

Miniaturized solid-phase extraction as a sample preparation technique for the determination of phthalates in water

“…Furthermore, a wide variety of polymer coatings, that is, liquid phases of GC columns, are available to extract particular classes of compounds. Particular attention has recently been focused on the analytical method for the determination of low-level phthalates in aqueous sample matrices, because of their estrogenic activities [21,22,23]. Although the quantification and the activities of phthalates as endocrine disruptors have been investigated, an effective and rapid preconcentration technique is still needed for the routine analysis of real environmental water samples, such as wastewater.…”

Determination of Estrogen Activity in River Waters and Wastewater in Luxembourg by Chemical Analysis and the Yeast Estrogen Screen Assay

“…The screen has been validated and shows high specificity for estrogen-like compounds. Androgens, progesterone, and corticosteroids are completely inactive, unless high concentrations are present which show weak activity (Routledge and Sumpter 1996;Harris et al, 1997). The DNA sequence of the human estrogen receptor (hER) is integrated into the yeast genome, also containing expression plasmids carrying estrogen-responsive sequences (ERE) controlling the expression of the reporter gene lac-Z.…”

Epigenetic Manifestation of Environmental Exposures

“…They are often classified as endocrine active compounds because of their antiandrogenic and pro-estrogenic abilities (Harris et al, 1997). Kang and Lee introduced several phthalates like the ones described above to MCF-7 and MCF10A human breast cells and examined their effects on DNA methylation and endocrine receptor gene expression (Kang and Lee, 2005).…”