Evaluation of the combined effect of carbofuran and temperature to Ceriodaphnia dubia

Submitted by Gilvan Almeida ([email protected]) on 2016-08-10T18:28:18Z No. of bitstreams: 2 372.pdf: 660614 bytes, checksum: 5ebfbc088dec5da87e5ea9f60756c503 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5)Approved for entry into archive by Maria Arruda ([email protected]) on 2018-01-31T16:47:31Z (GMT) No. of bitstreams: 2 372.pdf: 660614 bytes, checksum: 5ebfbc088dec5da87e5ea9f60756c503 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5)Made available in DSpace on 2018-01-31T16:47:31Z (GMT). No. of bitstreams: 2 372.pdf: 660614 bytes, checksum: 5ebfbc088dec5da87e5ea9f60756c503 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2014Fundação Oswaldo Cruz. Escola Nacional de Saúde Pública Sergio Arouca. Rio de Janeiro, RJ, Brasil.Desde 2008, o Brasil ocupa a posição de maior consumidor de agrotóxicos do mundo. Em 2001 o grupo dos agrotóxicos mais usados foi o grupo dos inseticidas. O Carbofurano é um inseticida carbamato sistêmico de amplo espectro, utilizado em todo o mundo. O Carbofurano possui meia vida no meio ambiente relativamente curta e sendo relativamente estável em condições neutras ou ácidas. Ele possui baixa tendência a volatilizar e é altamente móvel no solo, podendo lixiviar para águas subterrâneas e cursos d’água. O Carbofurano inibe a colinesterase, estimulando o sistema nervoso e causa efeitos cancerígenos, teratogênicos e genotóxicos. Estresses físicos como a mudança de temperatura podem afetar a susceptibilidade dos organismos à químicos, alterando a toxicodinâmica da interação química com o organismo, a toxicocinética, o metabolismo e estado fisiológico dos mesmos. As mudanças climáticas e o aquecimento global causados pela emissão de gases de efeito estufa, representam estressores que afetam a ocorrência de espécies levando à redução da biodiversidade. Acredita-se o aumento de 1,5-2,5oC nas temperaturas médias globais aumentam em 20-30% o risco de extinção de espécies e estudos indicam que um aumento na escala de 3oC é passível de ocorrer até o ano de 2100. Para a liberação e avaliação dos efeitos ambientais de agrotóxicos, são geralmente exigidos testes de toxicidade e o monitoramento através da avaliação ecotoxicológica é recomendado por diversos autores. Ceriodaphnia dubia é um microcrustáceos zooplanctônico muito utilizado como bioindicador, são filtradores, vivem em água doce e ocupam uma posição chave na cadeia alimentar. Dentre os fatores ambientais que influenciam as comunidades zooplanctônicas, a temperatura altera o ciclo de vida de muitos organismos, podendo modificar a taxa de reprodução e de filtração de várias espécies. Alterações nestes fatores podem influenciar a toxicidade de contaminantes para bioindicadores planctônicos. Diversos estudos encontraram relação entre o aumento da temperatura e o aumento da sensibilidade dos organismos e, consequentemente, da toxicidade dos contaminantes químicos. No entanto, esta toxicidade depende do contaminante testado. Não foram encontrados estudos sobre a avaliação do efeito combinado de Carbofurano e Temperatura sobre Ceriodaphnia dubia. O presente estudo visa avaliar este efeito combinado. Os resultados deste estudo, corroboraram com os de outros estudos, demostrando que temperaturas fora da faixa ótima influenciam a reprodução, desenvolvimento e alimentação de C. dubia, assim como influenciam negativamente na sensibilidade do organismo ao Carbofurano. Este efeito não pode ser observado apenas através de testes agudos, no entanto, os testes crônicos possibilitaram a observação do efeito combinado. Independente da temperatura, os resultados obtidos no presente estudo demonstram que as CL50 estão em concentrações inferiores às encontradas em ambientes naturais no Brasil e às estabelecidas pela OMS como padrão. Assim, conclui-se que os testes crônicos podem ser ferramentas interessantes para aplicação e uso rotineiro por agências ambientais. Esta avaliação deve ser realizada de acordo com as características ambientais locais e estes fatores devem ser levados em consideração durante a compilação de legislações, já que legislações nacionais podem não ser suficientes para evitar impactos a nível local.Since 2008, Brazil is the largest consumer of pesticides in the world. In 2011 insecticides were the most used group of pesticides. Carbofuran is a systemic, carbamate insecticide of broad spectrum useds worldwide. Carbofuran has a relatively short half-life in the environment and is relatively estable under neutral or acid conditions. It also has low tendency to volatilize, is highly mobile in soil and may reach groundwaters and aquatic environments. Carbofuran inhibits cholinesterase, stimulates the nervous system and causes carcinogenic, teratogenic and genotoxic effects. Physical stresses such as temperature change may affect the susceptibility of organisms to chemicals by changing the toxicodynamics, toxicokinetics, chemical interaction with the body, metabolism and physiological state of organisms. Climate change and global warming caused by the emission of greenhouse gases are stressors that affect the occurrence of species reducing biodiversity. It is believed that an increase of 1,5–2,5oC in the global average temperatures will increase the risk of extinction of species by 20–30% and studies indicate that an increase in the range of 3oC is likely to occur by the year 2100. Toxicity tests and monitoring through ecotoxicological evaluation are often required and recommended by several authors for agricultural use approval and evaluation of the environmental effects of pesticides. Ceriodaphnia dubia is a zooplanktonic microcrustacean widely used as bioindicator. They are filter feeders, live in fresh water and occupy a key position in the food chain. Temperature changes affect the life cycle of many organisms, may modify the reproductive and filtration rates of many species, being one of the environmental factors that have more influence on zooplankton communities. Changes in these factors can alter the toxicity of contaminants to planktonic bioindicators. Several studies have found a relationship between increased temperature and increased sensitivity of organisms to chemical contaminants. However, this change in toxicity depends on the tested contaminant. No studies assessing the combined effect of temperature and Carbofuran on C. dubia have beenfound and the present study aims to evaluate this combined effect. The results of this study corroborate those of other studies, showing that temperatures outside the optimum range influences reproduction, development and feeding of C. dubia as well as negatively influences the sensitivity to Carbofuran. This combined effects cannot be observed only by acute tests but can be clearly observed on chronic testes. The results obtained in this study demonstrate that, independent of temperature, acute toxicity of Carbofuran to C. dubia is observed at concentrations below those found in natural environments in Brazil and established by WHO as standard. Thereby, it is concluded that chronic tests are interesting tools for application and routine use by environmental agencies. This evaluation shall be conducted in accordance with local environmental characteristics and these factors must be taken into account during the compilation of laws, since national legislation may not be sufficient to avoid local impacts

Acute toxicity of single and combined rare earth element exposures towards Daphnia similis

The increasing use of Rare Earth Elements (REE) in emerging technologies, medicine and agriculture has led to chronic aquatic compartment contamination. In this context, this aimed to evaluate the acute toxic effects of lanthanum (La), neodymium (Nd) and samarium (Sm), as both single and binary and ternary mixtures on the survival of the microcrustacean Daphnia similis. A metal solution medium with (MS) and without EDTA and cyanocobalamin (MSq) as chelators was employed as the assay dilution water to assess REE bioavailability effects. In the single exposure experiments, toxicity in the MS medium decreased following the order La > Sm > Nd, while the opposite was noted for the MSq medium, which was also more toxic than the MS medium. The highest MS toxicity was observed for the binary Nd + La (1:1) mixture (EC50 48 h of 11.57 ± 1.22 mg.L−1) and the lowest, in the ternary Sm + La + Nd (2:2:1) mixture (EC50 48 h 41.48 ± 1.40 mg.L−1). The highest toxicity in the MSq medium was observed in the single assays and in the binary Sm + Nd (1:1) mixture (EC50 48 h 10.60 ± 1.57 mg.L−1), and the lowest, in the ternary Sm + La + Nd (1:2:2) mixture (EC50 48 h 36.76 ± 1.54 mg.L−1). Concerning the MS medium, 75 % of interactions were additive, 19 % antagonistic, and 6 % synergistic. In the MSq medium, 56 % of interactions were synergistic and 44 % additive. The higher toxicity observed in the MSq medium indicates that the absence of chelators can increase the concentrations of more toxic free ions, suggesting that the MS medium should be avoided in REE assays. Additive interactions were observed in greater or equivalent amounts in both media and were independent of elemental mixture ratios. These findings improve the understanding of environmental REE effects, contributing to the establishment of future guidelines and ecological risk calculations