Emerging contaminants in Brazilian rivers: Occurrence and effects on gene expression in zebrafish (Danio rerio) embryos

Abstract

Emerging contaminants (ECs) are synthetic or naturally occurring chemicals that are not commonly monitored despite having the potential of entering the environment and causing adverse ecological and/or human health effects. This study aimed to determine whether ECs are present in the surface waters of two rivers in Mato Grosso do Sul State, Brazil, and evaluate the effects of ECs mixtures at environmentally relevant concentrations on zebrafish (Danio rerio) gene expression. ECs concentrations were determined using solid-phase extraction and liquid chromatography-mass spectrometry. The ECs most frequently detected were caffeine, imidacloprid, 2-hydroxy atrazine, tebuthiuron, atrazine, and bisphenol A. We used these data to reconstruct ECs mixtures reflecting environmental concentrations, codenamed T1, T2, and T3. No effects were observed, so the concentrations were increased. After a preliminary evaluation of the No Observed Effect Concentration for each mixture, we analyzed changes in the expression of zebrafish target genes (cyp1a, hsp70, cat, sod1, tsh, cyp19a1a, cyp19a1b, cyp26b1, casp8, sox2, cyb561d2, and thrb). cat was overrepresented in T1 and underrepresented in the other treatments. All of the mixtures induced the expression of cyp19a1b, which is a marker for (xeno-)estrogen exposure, and two of them increased the expression of cyp1a, which is used to indicate the presence of dioxin-like compounds. The rivers studied had low EC concentrations, and there was no indication of any harmful effects on the zebrafish. However, intensive agricultural activity may result in unsuspected peaks of EC pollution, and subsequent negative effects on living organisms.

Pesticide Determination in Water Samples from a Rural Area by Multi-Target Method Applying Liquid Chromatography-Tandem Mass Spectrometry

“…The presence of atrazine, carbendazim, imidacloprid, hexazinone and tebuthiuron in the Mato Grosso do Sul State was also evaluated by the researchers, with concentrations lower than 0.1 µg L -1 . 15 Effective concentrations (EC, 50%) of diuron were reported in the literature at the same range of those found in SP 5, 7 and 9 (1.03-12.59 µg L -1 ). 42 Researchers also have been studying imazethapyr and tebuconazole concentrations in surface water surrounded by rice crop areas, where the maximum concentrations reported for these compounds were 0.326 and 0.015 µg L -1 , .…”

“…9,41 A study performed with samples collected from two rivers from Mato Grosso do Sul State, an area with a strong agricultural activity obtained concentrations of diuron lower than 0.01 µg L -1 . 15 The lowest concentration of diuron in the present work was 0.16 µg L -1 . The presence of atrazine, carbendazim, imidacloprid, hexazinone and tebuthiuron in the Mato Grosso do Sul State was also evaluated by the researchers, with concentrations lower than 0.1 µg L -1 .…”

“…[10][11][12][13][14] Besides pesticides, the presence of other emerging contaminants in the environment, such as industrial compounds, pharmaceuticals, personal care products and disinfection by-products, results in negative effects in living organisms due to the non-target effect and contributes to increase surface and groundwater pollution. 15,16 Recent studies have shown that the exposure of parents before a child's birth increases the risk of infant leukemia and Parkinson's disease to 70%. 17,18 At the South of Brazil, the Paraná State is known for the intensive production and commercialization of pesticides, occupying the third position according to the report made by the Ministries of Health in 2016 and of Agriculture in 2018.…”

Emerging Contaminants in Trans-American Waters

“…In a study of 16 Brazilian rivers, cocaine was found above the quantification limit in 85% of the samples studied with concentrations between 6 to 62 ngL -1 ; its metabolite, benzoylecgonine, was also found in 94% of the samples and with concentrations between 10 and 1019 ngL -1 (Campestrini and Jardim, 2017). A study of the surface waters of the Dourados and Brilhante Rivers in the state of Mato Grosso do Sul, Brazil, found 9 of the 21 ECs studied, with caffeine the most-concentrated (Maximum: 1040 μgL -1 ) (Sposito et al, 2018). In another study done in Brazil, 8 ECs were found in the Ave River and 13 in the Sousa River among the 17 ECs studied (Sousa et al, 2019).…”

Occurrence of caffeine in wastewater and sewage and applied techniques for analysis: a review

“…Sposito et al (2018) detected caffeine in all analyzed samples of the Dourados and Brilhante rivers 31 . The highest concentration of caffeine determined was 1040 ng L -1 , measured at a point near the city of Dourados, a city with 218,000 inhabitants.…”