Evaluating Improvements to Exposure Estimates from Fate and Transport Models by Incorporating Environmental Sampling Effort and Landscape-level Contaminant Use

Rumschlag, Samantha L.; Rohr, Jason R.; Bessler, Scott

doi:10.1101/472969

Cited by 3 publications

References 30 publications

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Risk assessment of glyphosate and malathion pollution and their potential impact on Oreochromis niloticus: role of organic selenium supplementation

Hassan

Hozien²,

Wahab³

et al. 2022

Sci Rep

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A field survey was conducted on five fish farms to trace glyphosate and malathion pollution with some physicochemical parameters. A precise half-life time, LC50-96h, of these agrochemicals on Oreochromis niloticus, as well as chronic exposure with organic selenium (OS) supplementation, were experimentally investigated. Oreochromis niloticus was subjected to the following: (negative control); (2 mg L−1 glyphosate); (0.5 mg L−1 malathion); (glyphosate 1.6 mg L−1 and 0.3 mg L−1 malathion); (glyphosate 2 mg L−1 and OS 0.8 g kg−1 diet); (malathion 0.5 mg L−1 and OS 0.8 g kg−1 diet) and (glyphosate 1.6 mg L−1; malathion 0.3 mg L−1 and OS 0.8 g kg−1 diet). Furthermore, data from the analyzed pond revealed a medium risk quotient (RQ) for both agrochemicals. The detected agrochemicals were related to their application, and vegetation type surrounding the farms, also their biodegradation was correlated to water pH, temperature, and salinity. Glyphosate and malathion had half-lives of 2.8 and 2.3 days and LC50-96h of 2.331 and 0.738 mg L−1, respectively. The severest nervous symptoms; increased oxidative stress markers, as well as high bacterial count in the livers and kidneys of fish challenged with Aeromonas hydrophila, were observed in the combined exposure, followed by a single exposure to malathion and then glyphosate. Organic selenium mitigated these impacts.

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Risk assessment of glyphosate and malathion pollution and their potential impact on Oreochromis niloticus: role of organic selenium supplementation

Hassan

Hozien²,

Wahab³

et al. 2022

Sci Rep

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Identifying low risk insecticides that can enhance food production without increasing mortality of biocontrol agents for human schistosomiasis

Haggerty

Delius

Jouanard

et al. 2021

Preprint

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Synthetic chemicals, such as pesticides, have increased faster than other agents of global change have, yet their ecological impacts remain understudied. Additionally, agricultural expansion to address human population growth and food shortages is predicted to increase the use of pesticides, some of which have been linked to increases in infectious diseases of humans, such as schistosomiasis, which infects >250 million people worldwide. Previous work revealed that ecologically relevant concentrations of organophosphate and pyrethroid insecticides are highly toxic to crayfish. Whether these same insecticides are also highly toxic to Macrobrachium rosenbergii and M. vollenhovenii prawns, which are closely related to crayfish and are important predators on snails that transmit schistosomiasis in Asia and Africa, respectively, is unknown. We performed laboratory dose-response studies for M. rosenbergii using three pyrethroid (esfenvalerate, λ-cyhalothrin, and permethrin) and three organophosphate (chlorpyrifos, malathion, and terbufos) insecticides. Pyrethroid LC50 values were consistently several orders of magnitude lower than for organophosphate insecticides. Pyrethroids also had a greater likelihood of field runoff at levels lethal to prawns. To corroborate these findings in natural settings, we experimentally tracked survival of individually caged M. vollenhovenii at 31 waterways in West Africa that varied widely in their insecticide use. Consistent with laboratory results, pyrethroid insecticide use in these villages was positively associated with Macrobrachium mortality when controlling for village-level and prawn-level attributes, including levels of organophosphate applications. Villages with the most pyrethroid use had lower prawn survival, despite using on average 20% less total insecticides than villages with high prawn survival. Our findings suggest that pyrethroid insecticides widely used in sub-Saharan Africa have strong non-target effects on Macrobrachium spp. prawns, with possible implications for human schistosomiasis. Thus, regulations or incentives to avoid high-risk insecticides, especially near waterways, could have important human health implications in countries undergoing agricultural expansion in schistosomiasis-endemic regions.

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Effect of agrochemical exposure onSchistosoma mansonicercariae survival and activity

Jones

Davila

Nguyen

et al. 2019

Preprint

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AbstractLand conversion and agrochemical use has altered freshwater systems worldwide, introducing chemicals and pathogens (e.g., helminths) that threaten human health. In developing countries where stringent pesticide use and water treatment is limited, understanding how contaminants and pathogens interact is of particular importance. Schistosomiasis, a neglected tropical disease, is caused by the free-swimming cercariae of Schistosoma mansoni, a flatworm (trematode) that is transmitted from snails to humans. Schistosomiasis afflicts over 200 million people, reinforces poverty, and has an enormous impact on children. To investigate the effects of pesticide exposure on S. mansoni, we exposed cercariae to four insecticides (cypermethrin, deltamethrin, dimethoate, and methamidophos) at five concentrations above estimated environmental concentrations, and recorded survival and activity during a 24-hr time-to-death assay. To identify live, but paralyzed, cercariae from dead cercariae, we used Trypan blue dye, which is only expelled from live cells. We found no effect of cypermethrin, deltamethrin, or dimethoate exposure on the survival and activity of S. mansoni cercariae. Surprisingly, methamidophos exposure decreased activity and increased survival of cercariae compared to those in control treatments. This result is likely due to methamidophos causing paralysis of cercariae, which reduced energy consumption lengthening lifespan. Although methamidophos exposure increased survival time, the pesticide-induced paralysis left cercariae functionally dead, which could influence overall disease prevalence and thus human health. Future studies that examine the influence of agrochemicals on waterborne disease prevalence and transmission need to consider both the lethal and sublethal effects of exposure to fully understand the complexity of host-parasite interactions.Author SummaryPrevious methods used to investigate the effects of pesticide exposure on free-swimming life stages of trematode pathogens include 1) normal activity, 2) movement following stimuli, or 3) staining dyes. As pesticides commonly target motor function, the use of an individual metric to assign trematode survival might misidentify pesticide-induced paralysis as mortality, therefore underestimating trematode tolerance. In this study, we used activity assays in tandem with Trypan blue staining dye to assess the effects of four pesticides on Schistosoma mansoni cercariae. We found that cercariae are highly tolerant to pesticide levels far beyond environmentally relevant concentrations. Surprisingly, exposure to methamidophos increased the survival and decreased the activity of cercariae compared to those in control treatments. Reduced activity was presumably caused by methamidophos-induced paralysis of cercariae. Although we observed increased survival following methamidophos exposure, the pesticide-induced paralysis rendered cercariae functionally dead. Our results highlight the need for future assays examining trematode tolerance to contaminants to employ both activity assays and staining dye to discern cercarial paralysis from mortality. Understanding the effects of pesticide exposure on disease transmission is of vital importance as pesticide use and agricultural activities intensify in developing nations endemic to waterborne pathogens.

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Evaluating Improvements to Exposure Estimates from Fate and Transport Models by Incorporating Environmental Sampling Effort and Landscape-level Contaminant Use

Cited by 3 publications

References 30 publications

Risk assessment of glyphosate and malathion pollution and their potential impact on Oreochromis niloticus: role of organic selenium supplementation

Risk assessment of glyphosate and malathion pollution and their potential impact on Oreochromis niloticus: role of organic selenium supplementation

Identifying low risk insecticides that can enhance food production without increasing mortality of biocontrol agents for human schistosomiasis

Effect of agrochemical exposure onSchistosoma mansonicercariae survival and activity

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