Effects of mixtures containing chlordecone and a dechlorinated by-product on hydra regeneration capacity: use of experimental design to evaluate the toxicity risk associated with remediation programs in long-lasting polluted areas

Chlordecone (CLD), an obsolete insecticide, used in the French West Indies between 1972 and 1993, is persistent in the environment but can be dechlorinated either chemically or under the action of microorganisms. Therefore, if soil remediation programs based on these processes are implemented in areas still contaminated today, those will see their concentrations of dechlorinated derivatives increase and these compounds will be also found in freshwater by streaming, leaching and erosion processes. The purpose of the present study was to evaluate, at environmental concentrations, the toxic effects of mixtures of chlordecone and a three-chlorine substituted byproduct. A hydra clone, which has been confirmed to be Hydra vulgaris Pallas, 1766 has been retained for bioassays where the toxicity has been evaluated by regeneration capacity during exposure. Exposure to mixtures is complex to investigate by classical methods, therefore, an experimental design associated to a mathematical model has been used to predict the effects of all the mixtures and to detect the toxic influence of each compound. The predictive model is discussed regarding the stochastic “endocrine disruptor effect” of CLD. At probable environmental concentrations of the compounds in the mixture, results show that impairment of regeneration capacity is explained mostly by the presence of CLD in the mixtures and support the implementation of remediation programs aimed at dechlorination of this persistent organochlorine pesticide.

Assessment of Persistent Organochlorine Pesticide Residues in Commercially Important Fin and Shell Fishes of River Majidun, Lagos, Nigeria

Aim: The pesticide pollution of aquatic ecosystems has developed serious environmental anxiety, provoking a necessity for continuous evaluation of harmful constituents. Study Design: A quantitative cum descriptive experimental design was used to evaluate the occurrence and concentration of Persistent Organochlorine Pesticides (POPs) in water, sediment, fish (Tilapia zilli and Chrysichthys nigrodigitatus) and shell fishes (Macrobrachium vollenhovenii, Littorina littorea and Callinectes pallidus) of River Majidun, Lagos, Nigeria. Place and Duration of Study: Nigerian Institute of Oceanography and Marine Research (NIOMR) between June and December, 2019. Methodology: Sediment samples were collected by the Rigosha grab sampler and fish samples were purchased from commercial fishermen. Sample preparation was done according to the Environmental Protection Agency (US EPA) 3570 method. POPs were evaluated using Hewlett Packard 5890 series II gas chromatography with electron capture detector. Results: Twenty-one organochlorine residues were identified including p’p’DDT, Lindane (γ-HCH), Dieldrin, Heptachlor, Aldrin, Chlordane, Endrin aldehyde, Endrin ketone, Methoxichlor and Endosulphan. Concentrations in water ranged between 0.03 µg l-1 (Endrin ketone) and 1.97 µg l-1 (Methoxychlor). In sediment, it is between 4.55 µg kg-1 (β-HCH) and 128.25 µg kg-1 (Methoxychlor). In Macrobrachium vollenhovenii, Methoxychlor was 123.83 µg kg-1 and Lindane ((γ)- HCH) was highest here (39.35 µg kg-1). Callinectes pallidus had a high concentration of Endrin ketone (133.13 µg kg-1). The Tilapia zilli highest concentration was 110.35 µg kg-1 (endrin ketone) and it had the highest pp’DDT which was 41.40 µg kg-1. Conclusion: Evidently, there was sequestration of POPs from water into sediment and bioaccumulation in the organisms, due to exposure. The level of POPs in all samples were below the limits of 200 µg kg-1 fresh weight in fish and sea food set by Codex Alimentarius Commission by FAO/WHO. The attendant environmental/human menace cum inherent danger of the raised levels of POPs, calls for continuous monitoring of River Majidun.

Preliminary Studies of Organochlorine Pesticides (OCPs) in Sediment, Water and Fish Samples from Ethiope River, Abraka Axis, Southern Nigeria

Selected persistent organochlorine pollutants, including DDT and its metabolites, hexachlorobenzene, dieldrin, Aldrin, heptachlor, HCH as well as some of their isomers were determined in water, sediment and fish samples from the Ethiope River in Southern Nigeria. Twenty organochlorine pesticides were detected in both seasons from October 2012 – September 2013. Results revealed ∑HCH to be 0.620µg/L (water), 33 ng/g (sediment) and 29.00 ng/g (fish) for the rainy season while concentrations of 0.170 µg/L (water), 14 ng/g (sediment) and 28.00 ng/g (fish) were obtained for the dry season. 0.05–0.15 ng/g for aldrin, 0.12–5.8 ng/g for dieldrin, 0.22–0.64 ng/g for endrin, 0.24–6.37 ng/g for endosulfan and 0.21–8.81 ng/g for ΣDDT (p, p` -DDD, p, p` -DDE, p, p` -DDT). Among the OCPs, ∑HCH, endosulfan and PDDT were the most dominant compounds in the river sediments. γ- HCH was the most frequent detected compound in all the samples from this river. Among the cyclodiene compounds, aldrin was in abundance in most of the sediments, water and fish samples. γ-HCH, γ-HCH and HCB contributed this highest value for the water, sediment and fish sample respectively in the rainy season while aldrin, endrin and HCB were the highest contributors to the ΣOCPs to the mean of water, sediment and fish respectively. Hazard quotient and bioaccumulation analysis carried out on the fish sample revealed that the fishes were heavily contaminated with values >1 for both seasons which possess a possibility for ecological concern.

Concentrations and sources of persistent organochlorine residues in the sediments and soils from an industrially impacted area in Anhui, China

In this study, a typical site that had been contaminated by the chemical industry in the past was selected for investigation. To reveal the pollution status, 18 organochlorine pesticides (OCPs) and seven polychlorinated biphenyls (PCBs) in the surface soil and sediment samples were analysed by gas chromatography-mass spectrometry (GC-MS). The levels of the persistent organochlorine residues in the sediment ranged from 44.59–143.29 ng/g, whereas they were 13.94–97.91 ng/g in the soil. A principal component analysis identified that PCBs and dichlorodiphenyltrichloroethanes (DDTs) were the primary sources of the organochlorine residues in the study area. The p,p'-DDT/(p,p'-DDE + p,p'-DDD) values were all below 1, which indicated that the historical inputs of the technical DDT and dicofol were the major sources of DDTs rather than recent inputs. The composition diversity of the hexachlorocyclohexane (HCH) isomers showed that the main sources in the soil were the past use of pesticides, whereas the sediment sources might be due to the historical use of technical HCHs and recent lindane inputs. The ecological risk assessment showed that γ-HCH could pose the highest risks for benthic organisms, followed by DDTs and heptachlor epoxide. These compounds are known to bio-accumulate in fatty tissues. Therefore, routine monitoring of the persistent organochlorine residues in the area is needed and the health risks to local residents should be assessed.