No abstract

Test systems to screen for estrogenicity and appropriate biomarkers of human exposure are required for epidemiological studies of endocrine disruption. We addressed these issues by developing and standardising a method to assess the total estrogenic xenobiotic burden in human adipose tissue. In this study, which is the continuation of a previous work, we have improved the protocol for extensive fractionation of a higher number of tissue samples in order to investigate bioaccumulated xenoestrogens that are candidates for estrogenicity and to assess their combined estrogenic effect. This was achieved by extensive HPLC separation of xenoestrogens from endogenous hormones followed by testing of individual fractions in the E-Screen test for estrogenicity. Organochlorine pesticides, PCBs and halogenated bisphenols and alkylphenols were collected in the most lipophilic fractions, followed by progestins, androgens and estradiol esters, and then by steroidal estrogens; phyto- and myco-estrogens were collected around the end of the run. These results were confirmed by exhaustive chemical analysis. In 458 human adipose tissue samples, the total effective xenoestrogen burden was positive in 75% of samples in the pooled fraction that contained organohalogenated xenoestrogens (mean 515.3 pM Eeq/g lipid; range 0-14.5 nM) and in 82% of samples in the pooled fraction where natural estrogens eluted (mean 696.6 pM Eeq/g lipid; range 0-12.9 nM). Organochlorine pesticides emerged as candidate chemicals for the estrogenicity of the first pooled fraction, because DDT and derivatives were present in 98.3% of the samples. However, no correlation was found between the concentration of any single chemical and the estrogenicity determined in the bioassay. There may be several reasons for this lack of concordance: (i) the estrogenic effects depicted in the E-Screen bioassay are a consequence of the combined effect of several organohalogens or (ii) the proliferative effect is due to other chemicals not measured. Because additive, synergistic or antagonistic mechanisms may account for the final effect observed in the pooled fractions, the approach proposed in this work is more appropriate for exposure assessment in epidemiological studies than the determination of individual chemicals in human samples.

No abstract

A new procedure has been proposed for the determination of biopesticides (nicotine, sabadine, veratridine, rotenone, azadirachtin, cevadine, deguelin, spynosad D, and pyrethrins) and piperonyl butoxide in agricultural soils. Several extraction procedures such as solid-liquid extraction using mechanical shaking, sonication, pressurized liquid extraction, and modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) have been tested, obtaining better results when QuEChERS procedure without further cleanup steps was applied. The determination of the compounds was carried out by ultra high pressure liquid chromatography coupled to tandem mass spectrometry, using methanol and aqueous solution of ammonium formate 5 mM as mobile phase. The method was validated for all compounds at concentrations ranging from 10 to 100 μg/kg and recoveries ranged from 68 to 116%, except for nicotine and sabadine, with recoveries lower than 50%. Precision was estimated through intra- and inter-day studies, obtaining intra-day precision lower than 20% for most of the compounds, and inter-day precision was lower than 25%. Limits of detection and quantification were also estimated, obtaining limits of quantification equal or lower than 10 μg/kg. Finally, the method was applied to the analysis of 20 real agricultural soil samples and no biopesticide residues were found over the limit of quantification.

No abstract