New Concept for Evaluating Toxicity of Herbicide for Ecological Risk Assessment

Mohammad, Munir J.; Itoh, Kazuhito

doi:10.5772/12977

Cited by 2 publications

(2 citation statements)

References 38 publications

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“…This concentration meets with OECD 308 guidelines and ensures that the biodegradation kinetics reflect those expected in the environment (i.e. First-Order kinetics) ( OECD, 2004 ) and is relevant to a worst-case exposure concentration following hypothetical direct overspray of a waterbody ( Mohammad and Itoh, 2011 ). Microcosms were subsequently incubated for up to 36 days.…”

Section: Methodsmentioning

confidence: 86%

Inclusion of seasonal variation in river system microbial communities and phototroph activity increases environmental relevance of laboratory chemical persistence tests

Southwell

Hilton

Pearson

et al. 2020

Science of The Total Environment

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Regulatory tests assess crop protection product environmental fate and toxicity before approval for commercial use. Although globally applied laboratory tests can assess biodegradation, they lack environmental complexity. Microbial communities are subject to temporal and spatial variation, but there is little consideration of these microbial dynamics in the laboratory. Here, we investigated seasonal variation in the microbial composition of water and sediment from a UK river across a two-year time course and determined its effect on the outcome of water-sediment (OECD 308) and water-only (OECD 309) biodegradation tests, using the fungicide isopyrazam. These OECD tests are performed under dark conditions, so test systems incubated under non-UV light:dark cycles were also included to determine the impact on both inoculum characteristics and biodegradation. Isopyrazam degradation was faster when incubated under non-UV light at all collection times in water-sediment microcosms, suggesting that phototrophic communities can metabolise isopyrazam throughout the year. Degradation rate varied seasonally between inoculum collection times only in microcosms incubated in the light, but isopyrazam mineralisation to 14 CO 2 varied seasonally under both light and dark conditions, suggesting that heterotrophic communities may also play a role in degradation. Bacterial and phototroph communities varied across time, but there was no clear link between water or sediment microbial composition and variation in degradation rate. During the test period, inoculum microbial community composition changed, particularly in non-UV light incubated microcosms. Overall, we show that regulatory test outcome is not influenced by temporal variation in microbial community structure; however, biodegradation rates from higher tier studies with improved environmental realism, e.g. through addition of non-UV light, may be more variable. These data suggest that standardised OECD tests can provide a conservative estimate of pesticide persistence end points and that additional tests including non-UV light could help bridge the gap between standard tests and field studies.

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Section: Methodsmentioning

confidence: 86%

Inclusion of seasonal variation in river system microbial communities and phototroph activity increases environmental relevance of laboratory chemical persistence tests

Southwell

Hilton

Pearson

et al. 2020

Science of The Total Environment

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show abstract

“…The lack of data about the effects of ATZ metabolites has prompted the U.S. Environmental Protection Agency (U.S. EPA) to state that the toxicity of atrazine's metabolites is equivalent to that of its parent compound and that exposure to these metabolites should be taken into account for risk assessment purposes (Ralston-Hooper et al, 2009). Mohammad & Itoh (2011) presented the relative risk of various scenarios of exposure and recovery with an aquatic test organism submitted a long-term exposure to herbicides and demonstrated the toxicity of isolated or mix t u r e s o f A T Z a t d i f f e r e n t c o n c e n t r a t i o n s . However, the patterns of accumulation of xenobiotics vary depending on the organism, characteristics of the chemical compound, quantity of this substance present in the environment, and the balance between assimilation and metabolic rates (Nwani et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Effects of Herbicide Atrazine in Experimental Animal Models

Severi-Aguiar¹,

Silva-Zacarín²

2012

Herbicides - Properties, Synthesis and Control of Weeds

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New Concept for Evaluating Toxicity of Herbicide for Ecological Risk Assessment

Cited by 2 publications

References 38 publications

Inclusion of seasonal variation in river system microbial communities and phototroph activity increases environmental relevance of laboratory chemical persistence tests

Inclusion of seasonal variation in river system microbial communities and phototroph activity increases environmental relevance of laboratory chemical persistence tests

Effects of Herbicide Atrazine in Experimental Animal Models

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