Environmentally relevant pesticides induce biochemical changes in Nile tilapia (Oreochromis niloticus)

Toxic mechanisms of imazalil, azoxystrobin and their mixture to hook snout carp (Opsariichthys bidens)

While combinations of pesticides better represent actual conditions within aquatic ecosystems, the specific toxic effects of these combinations have not been determined yet. The objective of this research was to assess the combined impact of imazalil and azoxystrobin on the hook snout carp (Opsariichthys bidens) and delve into the underlying causes. Our findings indicated that the 4-day LC50 value for imazalil (1.85 mg L-1) was greater than that for azoxystrobin (0.90 mg L-1). When imazalil and azoxystrobin were combined, they presented a heightened effect on the species. Enzyme activities like SOD, CAT, GST, and CarE, along with androgen and estrogen levels, displayed marked differences in most single and combined treatments in comparison to the baseline group. Moreover, four genes (mn-sod, cu-sod, il-1, and esr) related to oxidative stress, immunity, and the endocrine system exhibited more pronounced expression changes when exposed to combined pesticides rather than individual ones. Our tests revealed that the combined use of imazalil and azoxystrobin had more detrimental effect on aquatic vertebrates than when evaluated individually. This finding suggested that future ecological hazard analyses based only on individual tests might not sufficiently safeguard our aquatic ecosystems.

Embryonic Development Effects of Basagran® Herbicide in Danio Rerio: A Preliminary Study

Bentazon (Basagran®) belongs to the chemical group of benzothiadiazinones. Thus, this study aimed to estimate the influence of herbicide bentazon (3 µg.L-1, 6 µg.L-1, 12 µg.L-1, 300 µg.L-1) in Danio rerio embryos development. The study tested environmental relevant concentrations of bentazon as well as the limit established for drinking water (300 µg.L-1) in Brazil. We performed behavioral and developmental analyzes during 96 h of exposure. The bentazon measurements after experimental period showed reduction ranging from 5.0 to 18.93% between exposed groups. Our results showed significant differences in the heart rate, which was significantly higher in groups exposed to all bentazon concentrations compared to control groups. The absence of alterations in the behavioral parameters showing that the herbicide bentazon at the concentrations tested had few adverse effects on the development and behavior of the Danio rerio embryos. Considering the toxic point of view, there is a chance that bentazon acts together with other environmental contaminants as an additive or synergistic way.

Comparison of the drinking water standard for pesticides of the Brazil with other countries

The objective was to compare the types and concentrations of pesticides allowed in the water potability standard for human supply in Brazil with other countries considered to be the largest consumers of pesticides in dollars invested in purchase/trade. This is a descriptive and documentary study, with data collection in regulations available in official government websites in Brazil, USA, China, Japan, France, Germany, Canada, Argentina, India, Italy, and World Health Organization (WHO). Since Germany, France and Italy are part of the European Union (EU), the legislative resolution of the European Parliament was adopted. Pesticides number and maximum permitted values (MPV) differ between the countries and WHO. In the Brazilian ordinance there are forty pesticides, a number like the USA, Canada, China, and WHO, but that represents only 8% of the total pesticides registered for agricultural use in Brazil. When comparing the ordinance of Brazil with EU the values are only the same for Aldrin + Dieldrin. For other, amounts between 2 and 5000 times more are allowed in Brazil. Brazilian regulations do not establish a total value for the mixture of pesticides in water, only individual limits, which together can reach 1677.13 μg/L, while in EU standards it is only 0.5 μg/L. The study showed discrepancies of the pesticides allowed in water potability standard of the Brazil with other countries, but features 12 pesticides with the same concentrations as WHO guidelines, thus, a worldwide standardization in water potability regulations is necessary to promote health and reducing risk of exposure.

The Effect of Neonicotinoids Exposure on Oreochromis niloticus Histopathological Alterations and Genotoxicity

This study aimed to examine the side effects of selected neonicotinoids (Acetamiprid, Aceta, and Imidacloprid, Imid) on Oreochromis niloticus juveniles. The acute toxicity, Probit method, revealed an LC₅₀ of 195.81 and 150.76 ppm for Aceta/96 h and Imid/72 h respectively. The fish were divided into three groups that were exposed, for 21 days (n = 5/replicate), to 1/10 of the LC₅₀ of either neonicotinoids, however, the third was an unexposed control group. Results of erythrocytic micronucleus (MN), and nuclear abnormalities (NA) showed that Aceta and Imid exposure caused a significant (p < 0.05) increase in MN by ~ 2.2 and ~ 10 folds, respectively relative to control. NAs occurred at the order of kidney-shaped > budding > binucleated in Aceta, however, budding > binucleated > kidney-shaped was noticed in the Imid group. Histopathological changes in gills, liver, and muscles were observed significantly in both exposed groups with more severity in the Imid group. Collectively, Aceta and Imid have potential genotoxicity and histopathological alterations in O. niloticus.