Toxicity and risk assessment of six widely used pesticides on embryo-larval development of the Pacific oyster, Crassostrea gigas.

This study aims to assess the toxic effects and the potential risk of widely used agricultural pesticides on the development (malformations and developmental arrest), growth and swimming activity of oyster D-larvae (Crassostrea gigas). Freshly fertilized oyster embryos were exposed for 24 h at 24 °C to different concentrations (0, 0.01, 0.1, 1 and 10 µg.L-1) of six different pesticides: Glyphosate and its commercial solution (Roundup), Isoproturon, Nicosulfuron, Chlortoluron and Boscalid. The six pesticides tested induced a significant increase in larval malformations and developmental arrests. All pesticides except Glyphosate and Isoproturon affected larval growth. Roundup, Nicosulfuron, Chlortoluron and Boscalid also affected the swimming behaviour of the D-larvae, with a significant decrease recorded in their maximum swimming speed. Comparison of the LOEC (Lowest-Observed-Effect Concentration) of each compound led to the following toxicity classification: Boscalid > Chlortoluron = Nicosulfuron > Glyphosate > Roundup > Isoproturon, with respectively LOEC of 0.0028; 0.015; 0.017; 0.11; 0.3 and 0.78 µg.L-1. By comparison of the maximum concentrations in the Pertuis Charentais (South West, France) and LOEC of each pesticide, the following risk scale was obtained: Chlortoluron > Boscalid > Glyphosate > Roundup > Nicosulfuron > Isoproturon. Our results revealed that Chlortoluron, Boscalid and to a lesser extent Glyphosate represent a potential threat to early life stages of oyster living in the Pertuis Charentais marine area.

Toxicity assessment of pollutants sorbed on environmental microplastics collected on beaches: Part II-adverse effects on Japanese medaka early life stages.

While microplastics are present in great abundance across all seas and oceans, little is known about their effects on marine life. In the aquatic environment, they can accumulate a variety of chemicals and can be ingested by many marine organisms including fish, with chronic physical and chemical effects. The purpose of this paper is to evaluate the toxic effects of pollutants sorbed at the surface of environmental microplastics (MPs), collected on various beaches from three islands of the Pacific Ocean. Developmental toxicity of virgin MPs or artificially coated with B[a]P and environmental MPs from Easter Island, Guam and Hawaii was evaluated on embryos and prolarvae of Japanese medaka. Mortality, hatching success, biometry, malformations, EROD activity and DNA damage were analyzed after exposure to DMSO extracts. No toxicity was observed for extracts of virgin MPs whatever the endpoint considered. Extracts of virgin MPs coated with 250 µg.g-1 of B(a)P induced lethal effects with high embryo mortality (+81%) and low hatching rate (-28%) and sublethal effects including biometry and swimming behavior changes, increase of EROD activity (+94%) and DNA damage (+60%). Environmental MPs collected on the three selected islands exhibited different polymer, pollutant and toxicity patterns. The highest toxicity was detected for MPs extract from Hawaï with head/body length and swimming speed decreases and induction of EROD activity and DNA stand breaks. This study reports the possible sublethal toxicity of organic pollutants sorbed on MPs to fish early life stages.

Toxicity assessment of pollutants sorbed on environmental sample microplastics collected on beaches: Part I-adverse effects on fish cell line.

Microplastics (MPs), are tiny plastic fragments from 1 µm to 5 mm generally found in the aquatic environment which can be easily ingested by organisms and may cause chronic physical but also toxicological effects. Toxicological assays on fish cell lines are commonly used as an alternative tool to provide fast and reliable assessment of the toxic and ecotoxic properties of chemicals or mixtures. Rainbow trout liver cell line (RTLW-1) was used to evaluate the toxicity of pollutants sorbed to MPs sampled in sandy beaches from different islands around the world during the first Race for Water Odyssey in 2015. The collected MPs were analyzed for polymer composition and associated persistent organic pollutants: polycyclic aromatic hydrocarbons (PAHs), polychlorobiphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT). In addition, DMSO-extracts from virgin MPs, MPs artificially coated with B[a]P and environmental MPs were analyzed with different bioassays: MTT reduction assay (MTT), ethoxyresorufin-O-deethylase (EROD) assay and comet assay. Microplastics from sand beaches were dominated by polyethylene, followed by polypropylene fragments with variable proportions. Organic pollutants found on plastic from beach sampling was PAHs (2-71 ng g-1). Samples from Bermuda (Somerset Long Bay) and Hawaii (Makapu'u) showed the highest concentration of PAHs and DDT respectively. No toxicity was observed for virgin microplastics. No cytotoxicity was observed on cells exposed to MP extract. However, EROD activity was induced and differently modulated depending on the MPs locations suggesting presence of different pollutants or additives in extract. DNA damage was observed after exposure to four microplastics samples on the six tested. Modification of EROD activity level and DNA damage rate highlight MPs extract toxicity on fish cell line.

Assessment of pollution in the Bizerte lagoon (Tunisia) by the combined use of chemical and biochemical markers in mussels, Mytilus galloprovincialis.

In order to assess the environmental quality of the Bizerte lagoon (Tunisia), biomarker and contaminant levels were measured in Mediterranean mussels (Mytilus galloprovincialis) from five selected sites. Persistent organic pollutants (POPs) were quantified in whole body and enzyme activities such as acetylcholinesterase (AChE), catalase (CAT) and glutathione S-transferase (GST) in gills. Despite the relatively low levels of organic contaminants, the selected biomarkers responded differently according to the pollution level at the different sites. GST and AChE activities were correlated with the amount of DDTs in mussel tissues. These two enzymatic activities were also correlated to temperature and pH. No significant difference was observed for CAT activity. Principal component analysis showed a clear separation of sampling sites in three different assemblages which is consistent with POP body burden in mussels. Our results confirmed the usefulness of combining biomarker and chemical analyses in mussels to assess chemical pollution in the Bizerte lagoon.