Risk analysis of herbicide quinclorac residues in irrigated rice areas, Santa Catarina, Brazil

Abstract

Deterministic and probabilistic risk analyses were carried out for seven hydrographic basins in the State of Santa Catarina (Brazil), where irrigated rice is cultivated. Monitoring studies conducted in 1998/1999 and 1999/2000 had found that the herbicide quinclorac was the most frequently detected agrochemical residue, occurring in five of the seven hydrographic basins. In order to assess the ecological risk posed by quinclorac, median lethal concentration (LC(50)) and median effective concentration (EC(50)) data were obtained for quinclorac in toxicity tests with organisms routinely used in Brazil for this purpose. Experiments were carried out on microcosms associated with the irrigated rice crop to evaluate the effects of the herbicide on the natural plankton community. The deterministic analyses showed that the risk presented by the herbicide residues to the phytoplankton require mitigating action, while the probabilistic analysis revealed that the levels of risk for the aquatic community were acceptable. Field experiments showed that the recommended application concentration of the product directly affects phytoplankton and has an indirect, short-term effect on the zooplankton community.

AVALIAÇÃO DA TOXICIDADE AGUDA PARA O ORGANISMO-TESTE Vibrio Fischeri DOS PRINCIPAIS HERBICIDAS E INSETICIDAS APLICADOS NA LAVOURA DE ARROZ IRRIGADO DOS ESTADOS DE SANTA CATARINA E RIO GRANDE DO SUL

“…A avaliação de estudos sobre o comportamento dos agroquímicos no ambiente em conjunto com resultados obtidos em bioensaios, realizados com diferentes organismos-teste, assume extrema importância para a criteriosa análise do risco potencial de impacto desses compostos sobre o meio ambiente (RESGALLA JR. et al, 2007).…”

Rice transcriptome analysis to identify possible herbicide quinclorac detoxification genes

“…However, some grass weeds such as barnyard grass ( Echinochloa crusgalli ) significantly reduce the world's rice yield. Quinclorac (3,7-dichloro-8-quinolinecarboxylic acid) is a herbicide with specific selectivity between annual grass weeds and some graminaceous crops (Koo et al, 1996 ; Resgalla et al, 2007 ). Quinclorac is a compound of the chemical group of quinolines with toxicological class III (low toxicity), and in the recent years, it has been widely used on paddy rice fields to effectively control barnyard grass (Resgalla et al, 2007 ).…”

“…Quinclorac (3,7-dichloro-8-quinolinecarboxylic acid) is a herbicide with specific selectivity between annual grass weeds and some graminaceous crops (Koo et al, 1996 ; Resgalla et al, 2007 ). Quinclorac is a compound of the chemical group of quinolines with toxicological class III (low toxicity), and in the recent years, it has been widely used on paddy rice fields to effectively control barnyard grass (Resgalla et al, 2007 ). Quinclorac is a highly selective auxin-type herbicide, originally emerged from lead optimization with more than 3000 synthesized derivatives by BASF and was introduced into rice cultivation systems in 1988 (Haden et al, 1985 ; Grossmann, 2000b , 2003 ).…”

Aquatic risk assessment of pesticides in Latin America

“…Because local data are often lacking, risk assessments are also often based on data from other regions that, depending on the protection goals, can raise additional uncertainties and concerns as to whether this yields appropriate assessments. Few studies on risk assessment of pesticides for Latin America aquatic ecosystems are reported in the literature (Barra et al 2000;Waichman et al 2002;Resgalla et al 2007;Venturino et al 2007;Ronco et al 2008;Waichman 2008;Tosi et al 2009;Di Marzio et al 2010;Rico et al 2011;Chelinho et al 2012;Martini et al 2012;Schiesari et al 2013).…”