Search

Nanopesticides (Npes) offer improved efficacy compared to their conventional forms while reducing the usage/application rates, hence being more sustainable options. However, there is still a knowledge gap on the Npes environmental impacts. To support the safety of nano-enabled pesticides, the present study aimed at assessing the toxicity of the commercial Npe NUCOP-M and the active substance copper oxychloride, using the ecotoxicological soil model Enchytraeus crypticus and LUFA 2.2 soil. Bioassays were performed to assess various endpoints within short-to longer-term exposures: avoidance behaviour (2 d), hatching (13 d), survival, reproduction and organisms' size (based on the standard OECD test (28 d), the OECD extension (56 d), and the Full Life Cycle test – FLCt (46 d)). Based on the standard OECD test and its extension, NUCOP-M had a similar level of toxicity as copper oxychloride without indications of increase in toxicity over time (28 versus 56 d). The shorter-term exposures (2 and 13 d) showed higher toxicity for copper oxychloride. The exposure from cocoon stage (FLCt) seemed to provide an adaptative advantage (reduced toxicity) to NUCOP-M. The differences might be related to a slower release of Cu2+ ions from NUCOP-M, which seems to account for the toxicity at longer-term. Based on the recommended application doses (ca. 1.72 mg NUCOP-M kg−1, i.e. 0.62 mg Cu kg−1 in the topsoil) there is no unacceptable risk of NUCOP-M on the enchytraeid population. [Display omitted] • Environmental impacts of nanopesticides (Npes) should be studied. • Ecotoxicity of commercial Npe NUCOP-M was assessed in E. crypticus. • High screening level (endpoints and exposure time) are relevant. • NUCOP-M presented lower risks to enchytraeids than Cu-oxychloride. • Differences might be related to a slower release of Cu2+ ions from NUCOP-M. [ABSTRACT FROM AUTHOR]

This work focuses on the analysis of the deleterious effects in case of spills in aqueous and soil environments of palm kernel oil methyl esters (PKOME) and castor oil methyl esters (COME) prototyped to substitute mineral oils in power transformers. Two main properties were investigated according to the Organization for Economic Cooperation and Development (OECD) standards. Biodegradability based on the OECD-301B guideline for CO2 release in biological media; and acute toxicity, analysed according to the OECD-203 guidelines for fish and OECD-207 guidelines on earthworms. At the end of 28 days of incubation, the PKOME samples showed a biodegradation rate of 92.6% in Wouri water and 74.93% in Douala soil. COME samples showed a biodegradation rate of 67.4% in aqueous medium and 57.64% in soil medium. Whatever the biological medium, the degradation rates of the PKOME prototypes were better than that of COME, and both were higher than those of mineral oils. The acute toxicity test was carried out on Arius africanus fish in an aqueous medium and earthworms type Eisenia foetida in soil medium at different doses of the substances. In both bioindicators, spills from the COME prototypes showed a moderate toxic effect. In aqueous medium, they caused 50% mortality at an LC50 concentration of 1.35 gl−1 and LC100 of 2.66 gl−1. In soil, the LC50 obtained were 1958.4 ppm (PKOME) and 541.73 ppm (COME).

In order to predict the fate of chemicals in the environment, a range of regulatory tests are performed with microbial inocula collected from environmental compartments to investigate the potential for biodegradation. The abundance and distribution of microbes in the environment is affected by a range of variables, hence diversity and biomass of inocula used in biodegradation tests can be highly variable in space and time. The use of artificial or natural biofilms in regulatory tests could enable more consistent microbial communities be used as inocula, in order to increase test consistency. We investigated spatial and temporal variation in composition, biomass and chemical biodegradation potential of bacterial biofilms formed in river water. Sampling time and sampling location impacted the capacity of biofilms to degrade p -nitrophenol (PNP). Biofilm bacterial community structure varied across sampling times, but was not affected by sampling location. Degradation of PNP was associated with increased relative abundance of Pseudomonas syringae. Partitioning of the bacterial metacommunity into core and satellite taxa revealed that the P. syringae could be either a satellite or core member of the community across sampling times, but this had no impact on PNP degradation. Quantitative PCR analysis of the pnpA gene showed that it was present in all samples irrespective of their ability to degrade PNP. River biofilms showed seasonal variation in biomass, microbial community composition and PNP biodegradation potential, which resulted in inconsistent biodegradation test results. We discuss the results in the context of the mechanisms underlying variation in regulatory chemical degradation tests. [ABSTRACT FROM AUTHOR]

Society׳s reliance upon chemicals over the last few decades has led to their increased production, application and release into the environment. Determination of chemical persistence is crucial for risk assessment and management of chemicals. Current established OECD biodegradation guidelines enable testing of chemicals under laboratory conditions but with an incomplete consideration of factors that can impact on chemical persistence in the environment. The suite of OECD biodegradation tests do not characterise microbial inoculum and often provide little insight into pathways of degradation. The present review considers limitations with the current OECD biodegradation tests and highlights novel scientific approaches to chemical fate studies. We demonstrate how the incorporation of molecular microbial ecology methods (i.e., ‘omics’) may improve the underlying mechanistic understanding of biodegradation processes, and enable better extrapolation of data from laboratory based test systems to the relevant environment, which would potentially improve chemical risk assessment and decision making. We outline future challenges for relevant stakeholders to modernise OECD biodegradation tests and put the ‘bio’ back into biodegradation. [ABSTRACT FROM AUTHOR]

Abstract: Nineteen compounds listed in the category of priority substances (PS) were selected for a biodegradation study using standardized tests. The compounds consist of pesticides, chlorinated solvents and volatile organic compounds (VOCs). In this paper, the choice of the most suitable method is discussed in relation to the physico-chemical properties of each substance. Zahn–Wellens, manometric respirometry and closed-bottle tests are alternatively used. Experimental results are presented and interpreted. Toxicity (Microtox™) and bacterial viability (Bac-light™) are also used as tools to investigate the influence of each substance on the microbial population (activated sludge). In addition, experimental values are compared with predictive data calculated according to quantitative structure activity relationships (QSARs) models. Biodeg Models were permitted to correctly estimate 17 substances; Survey Models and screening tests also revealed the same behavior for 16 target compounds. [Copyright &y& Elsevier]

Organosilicon compounds have numerous applications in consumer products. After entering the environment most of them are resistant against microbial degradation and they persist in the environment. Accordingly, they are ubiquitously present in the environment. Therefore, better environmentally degradable organosilicon compounds are urgently needed. A systematic investigation of environmental degradability of organosilicon compounds allows to derive some general design principles, which in turn would enable chemists to reduce or better avoid environmental persistence of organosilicon compounds in the environment. Therefore, in this study, all organosilicon substances registered in the European Chemicals Agency (ECHA) database were evaluated for their environmental biodegradability. Results of own experiments with different organosilicon substances were added to extend the data basis. A dataset was generated. An assessment of all data was done and invalid data were excluded. The remaining 182 substances were grouped regarding their structure to derive general rules for the environmental biodegradability of organosilicon compounds. Non-biodegradable at all were for example cyclic, linear and branched siloxanes. Groups like ethers, esters, oximes, amines, and amides were prone to hydrolysis, which can result in readily biodegradable intermediates if they do not contain silicon functional groups anymore. This knowledge could be used for the design of better degradable organosilicon compounds as non-degradable substances should be avoided if they enter the environment after their usage. [Display omitted] • Collection of biodegradation data of the ECHA database and own experiments. • Grouping of the substances to derive general findings. • 12 out of 182 organosilicon substances were readily biodegradable. • Hydrolysis was a mandatory step prior to biodegradation. • Groups like ethers, esters, oximes, amines, and amides can improve biodegradability. [ABSTRACT FROM AUTHOR]

Lubricating oils used in machines with an open cutting system, such as a saw or harvester, are applied in forest areas, gardening, in the household, and in urban greenery. During the operation of the device with an open cutting system, the lubricating oil is emitted into the environment. Therefore, the use of an oil base and refining additives of petroleum origin in the content of lubricants is associated with a negative impact on health and the environment. The current legal regulations concerning lubricants applicable in the European Union (EU) assess the degree of biodegradability. Legislation permits the use of biodegradable oils at 60% for a period of 28 days. This means that, in practice, lubricating oil considered to be biodegradable can contain up to 50% of the so-called petroleum oil base. The paper aims to draw public attention to the need to reduce the toxicity and harmful effects, due to their composition, of lubricating oils emitted into the environment on health. The authors discuss the impact of petroleum oil lubricants on soils, groundwater, vegetation, and animals, and the impact of petroleum-origin oil mist on health. An overview of test methods for the biodegradability of lubricating oils is presented, including the Organization for Economic Cooperation and Development (OECD) 301 A-F, 310, and 302 A-D tests, as well as their standard equivalents. The current legal regulations regarding the use and control of lubricating oils emitted into the environment are discussed. Legal provisions are divided according to their area of application. Key issues regarding the biodegradability and toxicity of petroleum fractions in lubricating oils are also addressed. It is concluded that lubricating oils, emitted or potentially emitted into the environment, should contain only biodegradable ingredients in order to eliminate the negative impact on both the environment and health. Total biodegradability should be confirmed by widely applied tests. Therefore, a need to develop and implement low-cost and simple control procedures for each type of lubricating oil, ensuring the possibility of an indisputable conclusion about the presence and total absence of petroleum-derived components in oil, as well as the content of natural ingredients, occurs.