Effects of environmentally relevant sub-chronic atrazine concentrations on African clawed frog (Xenopus laevis) survival, growth and male gonad development

Abstract

Sub-chronic toxicity of environmentally relevant atrazine concentrations on exposed tadpoles and adult male African clawed frogs (Xenopus laevis) was evaluated in a quality controlled laboratory for 90 days. The aim of this study was to determine the effects of atrazine on the survival, growth and gonad development of African clawed frogs. After exposure of tadpoles to atrazine concentrations of 0 (control), 0.01, 200 and 500 μg L in water, mortality rates of 0, 0, 3.3 and 70% respectively were recorded for the 90 day exposure period. Morphometry showed significantly reduced tadpole mass in the 500 μg L atrazine exposed tadpoles (p < 0.05). Light microscopy on testes of adult frogs exposed to the same atrazine concentrations using hematoxylin and eosin (H&E) and Van Gieson staining techniques revealed gonadal atrophy, disruption of germ cell lines, seminiferous tubule structure damage and formation of extensive connective tissue around seminiferous tubules of frogs exposed to 200 μg L and 500 μg L atrazine concentrations. Ultrastructural analysis of the cellular organelles using transmission electron microscopy (TEM) revealed significant amounts of damaged mitochondria in testosterone producing Leydig cells as well as Sertoli cells. Biochemical analysis revealed reduced serum testosterone levels in adult frogs at all exposure levels as well as presence of six atrazine metabolites in frog serum and liver. The results indicate that atrazine concentrations greater than the calculated LC50 of 343.7 μg L cause significant mortality in tadpoles, while concentrations ≥200 μg L adversely affect reproductive health of adult frogs and development of tadpoles sub-chronically exposed to atrazine.

Effects of atrazine on fish, amphibians, and reptiles: update of the analysis based on quantitative weight of evidence

“…As mortality was only were observed at )100 lg/L, the score for relevance was reduced to 0 (see SI). Rimayi et al (2018) exposed adult male and tadpoles of African clawed frog (Xenopus laevis) to atrazine for 90 d under laboratory conditions at concentrations of 0.01, 200, and 500 mg/L (score for quality of methods was 1.6). Mortality of adult males was not reported at any tested concentration.…”

“…There were several new studies on the effects of atrazine on the size and/or weight of test organisms (Figure 8). Most of these showed no effects, highly inconsistent effects, or effects were observed only above the relevance threshold of 100 mg atrazine/L (Chen et al 2015;Syngenta 2015Syngenta , 2017aSyngenta , 2017bEhrsam et al 2016;Liu et al 2016;Wirbisky et al 2016b; Du Gas et al 2017;Ali et al 2018b;Rimayi et al 2018;Saka et al 2018). The studies ranged in quality from a score of 1 to 3.4.…”

Polymer sequestrants for biological and environmental applications

“…Atrazine (Fig. ), the most widely used pesticide in the USA and other parts of the world, was banned by the European Union due to its proven toxicity to animals and humans; however, it is still used in the USA . Atrazine is a monochlorotriazine and an endocrine disruptor – a compound that interferes with the functions of hormones…”

Degradación De La Mezcla Comercial De Los Herbicidas Atrazina Y Ametrina, Utilizando Cultivos Con Células en Suspensión E Inmovilizadas

“…El control químico de las malezas requiere conocer las especies presentes y su nivel de infestación; en el caso de las especies anuales, una estrategia elemental es aplicar herbicidas residuales que cubran todo el espectro de malezas presentes, como es el caso de la atrazina (Olea et al 2009). La atrazina es el herbicida triazínico más utilizado a nivel mundial para controlar una variedad de malezas de hoja ancha, principalmente en cultivos de maíz, sorgo, caña de azúcar y suelos no cultivados (Pussemier et al 1997, Jacobsen et al 2001, Ralebitso et al 2002, Strong et al 2002, Hansen et al 2013, Domínguez-Garay et al 2016, Sun et al 2017, Rimayi et al 2018, Singh et al 2018, Yu et al 2018. Para un control más efectivo de algunas gramíneas difíciles, es usual la aplicación de la mezcla con ametrina en pre emergencia y en post emergencia temprana (IRET 2018).…”

“…El uso excesivo de estos agroquímicos ha provocado, por filtración o escorrentías, la progresiva contaminación de los cuerpos de agua, se ha detectado contaminación por atrazina en agua de lluvia, aguas subterráneas, superficiales y aguas para consumo humano (Kontchou y Gschwind 1999, Jacobsen et al 2001, Sun et al 2017, Rimayi et al 2018. En el caso de la ametrina se encontraron altas concentraciones en muestras de sedimentos, indicando su persistencia en ríos (Jacomini et al 2011).…”