Investigating the Estrogenic Risk Along the River Po and Its Intermediate Section

Abstract

Different endpoints have been used to investigate the occurrence of estrogenic risk along the Po River, particularly its middle section. An in vitro assay based on recombinant yeast could not detect estrogenic activity in bed sediments of the Italian river or in bile samples of five Cyprinid species, with the only exception being one carp (Cyprinus carpio) captured downstream of the River Lambro, a polluted tributary of the middle River Po. Chemical analyses of fish bile and water samples from the same middle section showed diffuse contamination by moderately low levels of estrogenic chemicals (estrone [E1], 17beta-estradiol, estriol [E3], 17alpha-ethinylestradiol, 4-nonylphenol [NP], 4-tert-octylphenol [tOP], 4-n-octylphenol, and bisphenol A) but they were of limited help in understanding the risk present in the downstream area where intersex barbel were previously found. In contrast, the analyses of River Lambro waters showed that this tributary is a source to the middle River Po of all eight estrogens investigated. Analyses of bed sediments and macroinvertebrates from the same area consistently showed at least two levels of contamination, with the downstream stretch showing higher concentrations of natural steroids (E1 and E3) and xenoestrogens (NP and tOP). Accordingly, new histologic examinations undertaken on young barbel (Barbus sp.) showed intersex gonads only in the individuals captured in the downstream stretch, thereby confirming previous results. Present findings confirm the occurrence of disrupting conditions in the middle River Po and provide the first suggestions of cause-effect relationships.

Derivation of an Aquatic Predicted No-Effect Concentration for the Synthetic Hormone, 17α-Ethinyl Estradiol

“…NOECs range between 0.3 (or a calculated value of 0.16) and 1 ng/L, yet 100% feminization occurs at 3 ng/L and above. A SSD derived from the reproduction NOECs allows for a statistical derivation of the HC 5,50 and, therefore, a PNEC by considering all existing, relevant data for the 26 species that have been studied for reproductive effects. This approach further reduces the uncertainty associated with the fish data by considering data from other chordata demonstrating similar sensitivity to EE2 (e.g., frogs).…”

“…The bootstrap simulation consisted of taking 2000 sets of n () 52) samples from the fitted distribution (with n ) 52 ) the number of data points used for the determination of the Best Fit distribution), and each time, the fifth percentile is calculated. The resulting distribution of HC5's is used to calculate the 50% confidence interval and the median value determined (HC 5,50).…”

“…A species sensitivity distribution was constructed using no observed effect concentrations (NOECs) for reproductive effects from 39 papers in 26 species, resulting in a median hazardous concentration at which 5% of the species tested are affected (HC 5,50 ) of 0.35 ng/L. After comparing this HC 5,50 to all of the laboratory and field-derived toxicity information available for EE2, we recommend using 0.35 ng/L as the PNEC for EE2 in surface water. This PNEC is below 95% of the existing NOECs for effects on reproduction and is also below virtually all of the NOECs for vitellogenin induction in the key fish reproduction studies.…”

Aryl hydrocarbon receptor (AhR) inducers and estrogen receptor (ER) activities in surface sediments of Three Gorges Reservoir, China evaluated with in vitro cell bioassays

“…It is hypothesized that this distribution may relate with a sedimentation effect in the reservoir. Surface sediments are frequently a sink for persistent organic pollutants and EDCs in riverine environments (Ahlf et al 2002;Forstner and Westrich 2005;Labadie et al 2007;Vigano et al 2006;Peck et al 2004;Wang et al 2011). The sediment load in the Yangtze River is 500 Mt (1 Mt=1,000,000 t) year −1 (Zhang 1995).…”

“…In addition to sediments, periphyton and invertebrate can also accumulate organic pollutants and estrogenic mimics (Maenpaa and Kukkonen 2006;Maenpaa et al 2008;Peck et al 2007;Vigano et al 2006). These organisms can variably contribute to the diet and, thus, the exposure of fish and other species (Pedersen et al 2003;Pickford et al 2003).…”