Unveiling the presence of endocrine disrupting chemicals in northern French soils: Land cover variability and implications

Endocrine disrupting chemicals (EDCs) are chemicals that can be found in the environment and have adverse effects on human health by mimicking, perturbing and blocking the function of hormones. They are commonly studied in water surfaces, rarely in soils, although it can be an important source of their presence in the environment. Their detection in soils is analytically challenging to quantify, hence the lack of known background concentrations found in the literature. This scientific research aimed to detect EDCs in soils by analyzing 240 soil samples using an optimized protocol of double extraction and analysis using liquid chromatography coupled to mass spectrometry. The optimized protocol allowed for very sensitive detection of the targeted compounds. The results showed a high concentration of 29.391 ng/g of 17β-estradiol in soils and 47.16 ng/g for 17α-ethinylestradiol. Testosterone and Progesterone were detected at a highest of 1.02 and 6.58 ng/g, respectively. The ∑EDCs which included estrogens, progesterone, testosterone and Bisphenol A was found at an average of 22.72 ± 35.46 ng/g in the study area. The results of this campaign showed a heterogeneous geographic distribution of the EDCs compounds in the different zones of study. Additionally, the study conducted a comparison of the concentration of EDCs in different land covers including urban areas, agricultural lands, grasslands and forests. We observed a significant difference between forests and other land covers (p < 0.0001) for 17α-ethinylestradiol, estriol, and progesterone. This presence of EDCs in forest lands is not yet understood and requires further studies concerning its origins, its fate and its effect on human health. This study is the first large-scale sampling campaign targeting EDCs in soils in Europe and the second in the world. It is also the first to assess the concentrations of these compounds based on different land covers.

Combined toxic effects and DNA damage to two plant species exposed to binary metal mixtures (Cd/Pb)

Acute and long-term (3-, 10- and 56-day exposure) laboratory toxicity tests were carried out to assess the individual and combined toxic effects of cadmium (Cd) and lead (Pb) in Brassica oleracea and Trifolium repens. In addition to morphological parameters, this work also used comet assay to address endpoints in relation to genotoxicity. Bioaccumulation was measured to demonstrate the influence of the mixture on the concentrations of each metal in the plant. The statistical method reported by Ince et al. (1999) was used to evaluate the types of interaction between Cd and Pb in each treatment and concerning their combined effect. This study concludes that the combined effects of binary metal combinations of Cd/Pb on morphological parameters are most often additive, sometimes antagonistic and more rarely synergistic, thus extending the findings of previous publications on this subject. DNA damage analysis revealed concentration- and time-dependent interactions. Synergistic effects of mixed metals (more breaks than individually applied metals) are observed in T. repens after a short exposure. Antagonistic effects are statistically significant after 10 days-exposure, suggesting competition between metals. At 56 days, the rate of DNA damage observed in plants exposed to the Cd/Pb mixture was similar to that measured in plants exposed to lead only and was significantly lower than the rate of DNA damage induced by Cd. This supports the idea that there may be competition between metals and also strengthens the hypothesis that long-term reparation mechanisms may be implemented. Cd/Pb co-exposure does not significantly influence the bioaccumulation of each metal. It is nevertheless important to note that a statistically significant 'interaction' is not necessarily biologically relevant and should therefore be considered with caution when assessing heavy metals combined effects.

Antioxidant defense gene analysis in Brassica oleracea and Trifolium repens exposed to Cd and/or Pb

This study focused on the expression analysis of antioxidant defense genes in Brassica oleracea and in Trifolium repens. Plants were exposed for 3, 10, and 56 days in microcosms to a field-collected suburban soil spiked by low concentrations of cadmium and/or lead. In both species, metal accumulations and expression levels of genes encoding proteins involved and/or related to antioxidant defense systems (glutathione transferases, peroxidases, catalases, metallothioneins) were quantified in leaves in order to better understand the detoxification processes involved following exposure to metals. It appeared that strongest gene expression variations in T. repens were observed when plants are exposed to Cd (metallothionein and ascorbate peroxidase upregulations) whereas strongest variations in B. oleracea were observed in case of Cd/Pb co-exposures (metallothionein, glutathione transferase, and peroxidase upregulations). Results also suggest that there is a benefit to use complementary species in order to better apprehend the biological effects in ecotoxicology.

Combined effect of Cd and Pb spiked field soils on bioaccumulation, DNA damage, and peroxidase activities in Trifolium repens

The present study was designed to investigate the combined effects of Cd and Pb on accumulation and genotoxic potential in white clover (Trifolium repens). For this purpose, T. repens was exposed to contaminated soils (2.5-20 mg kg(-1) cadmium (Cd), 250-2000 mg kg(-1) lead (Pb) and a mixture of these two heavy metals) for 3, 10 and 56 days. The resulting bioaccumulation of Cd and Pb, DNA damage (comet assay) and peroxidase activities (APOX and GPOX) were determined. The exposure time is a determinant factor in experiments designed to measure the influence of heavy metal contamination. The accumulation of Cd or Pb resulting from exposure to the two-metal mixture does not appear to depend significantly on whether the white clover is exposed to soil containing one heavy metal or both. However, when T. repens is exposed to a Cd/Pb mixture, the percentage of DNA damage is lower than when the plant is exposed to monometallic Cd. DNA damage is close to that observed in the case of monometallic Pb exposure. Peroxidase activity cannot be associated with DNA damage under these experimental conditions.

Antioxidant responses of Annelids, Brassicaceae and Fabaceae to pollutants: a review

Pollutants, such as Metal Trace Elements (MTEs) and organic compounds (polycyclic aromatic hydrocarbons, pesticides), can impact DNA structure of living organisms and thus generate damage. For instance, cadmium is a well-known genotoxic and mechanisms explaining its clastogenicity are mainly indirect: inhibition of DNA repair mechanisms and/or induction of Reactive Oxygen Species (ROS). Animal or vegetal cells use antioxidant defense systems to protect themselves against ROS produced during oxidative stress. Because tolerance of organisms depends, at least partially, on their ability to cope with ROS, the mechanisms of production and management of ROS were investigated a lot in Ecotoxicology as markers of biotic and abiotic stress. This was mainly done through the measurement of enzyme activities The present Review focuses on 3 test species living in close contact with soil that are often used in soil ecotoxicology: the worm Eisenia fetida, and two plant species, Trifolium repens (white clover) and Brassica oleracea (cabbage). E. fetida is a soil-dwelling organism commonly used for biomonitoring. T. repens is a symbiotic plant species which forms root nodule with soil bacteria, while B. oleracea is a non-symbiotic plant. In literature, some oxidative stress enzyme activities have already been measured in those species but such analyses do not allow distinction between individual enzyme involvements in oxidative stress. Gene expression studies would allow this distinction at the transcriptomic level. A literature review and a data search in molecular database were carried out on the basis of keywords in Scopus, in PubMed and in Genbank™ for each species. Molecular data regarding E. fetida were already available in databases, but a lack of data regarding oxidative stress related genes was observed for T. repens and B. oleracea. By exploiting the conservation observed between species and using molecular biology techniques, we partially cloned missing candidates involved in oxidative stress and in metal detoxification in E. fetida, T. repens and B. oleracea.

Biomarker measurements in Trifolium repens and Eisenia fetida to assess the toxicity of soil contaminated with landfill leachate: a microcosm study

To assess the toxicity of a soil contaminated with landfill leachate, biomarker measurements in two species living in close contact with the soil, i.e. a plant species Trifolium repens and an animal species Eisenia fetida, were conducted. Briefly, both species were studied after simultaneous exposure conducted in microcosms. The organisms were exposed to soil supplemented with pure leachate, leachate diluted to 50%; leachate diluted to 25% and without leachate. After a 10 weeks exposure period, we observed an increase in the Olive Trail Moment in T. repens, compared to the reference, for 50% and pure leachate. The response observed appears to be dose-dependent and linear in our experimental conditions. Addition of the leachate to the reference soil induced an increase in Cd-Metallothionein-coding mRNA quantity in E. fetida. In addition, expression level of another gene implied in detoxification and coding Phytochelatin synthase was significantly induced in worms exposed to the reference soil spiked with the leachate, regardless presence of T. repens. Thus, T. repens and E. fetida can be used in a complementary manner to assess soil quality. Sensitivities of the test species yield sensitive bioassays as both species responded at low doses despite the buffering effect of the soil.

Zinc and cadmium accumulation among and within populations of the pseudometalophytic species Arrhenatherum elatius: implications for phytoextraction

The purpose of this study was to investigate, under standard conditions, the bioaccumulation of zinc and cadmium in Arrhenatherum elatius, a perennial grass with a high biomass production. Nine populations of three different origins were tested: three metallicolous populations (mpop); three non-metallicolous populations (nmpop) and three populations developing on soils moderately metal polluted (medpop). We have found that bioaccumulation differs among these populations, with nmpop accumulating significantly more zinc (p<0.0001) and cadmium (p<0.0001) than mpop. Indeed, we have observed a concentration of 325 mg kg(-1) of zinc and 52 mg kg(-1) of cadmium in A. elatius shoots from mpop, whereas in nmpop, the concentration reached on average 524 mg kg(-1) zinc and 83 mg kg(-1) cadmium. In the same way, medpop accumulated as much zinc but more cadmium than nmpop. Moreover, the standard deviation of medpop was larger than the one for mpop and nmpop. Indeed, some A. elatius samples from medpop presented a high metal content whereas, others presented low concentrations in their shoots (ranging from 60 to 210 mg kg(-1) cadmium). Hence, these medpop exhibited a large variability among and within populations in accumulating zinc and cadmium in their shoots. Based on these results, the possibility of selecting A. elatius plants with the best accumulating capacity from medpop was proposed. We concluded that if the accumulation capacity is genetically controlled in A. elatius, this species fulfils this necessary condition for efficiently increasing species bioaccumulation by crossbreeding A. elatius plants with the higher accumulation capacity.