Organochlorine concentrations in aquatic organisms from different trophic levels of the Sundarbans mangrove ecosystem and their implications for human consumption

Abstract

The Sundarbans, a highly biodiverse tropical ecosystem stretching across India and Bangladesh, is also the largest mangrove forest in the world. Organochlorine compounds (OCs) have been extensively used for agriculture and sanitary purposes in the region. OCs can accumulate in biological tissues and biomagnify in organisms through food webs, for which reason they reach high concentrations in top predators. Because marine food webs are long and marine predators are extensively used in the region as human food, assessment of potential health-related risks caused by OC pollution is in order. This study is the first to determine the concentration of PCBs in fish and crustaceans from the Sundarbans mangroves, their accumulation trends through the food web, and the potential toxicological risk that their consumption poses to humans. DDT concentrations, which had already been assessed in the region, were also determined. The median concentrations ranged from below detection limits to 176.3 ng g -1 lipid weight for tDDT and 30,982 ng g -1 for PCBs. Overall, these concentrations were lower than those usually observed in other regions of the world, apparently as a result of the interplay of several factors: low environmental organochlorine inputs, the physical and climatic characteristics of an ecosystem dominated by high temperatures in a highly flushed ecosystem that dilutes and rapidly disperses pollutants, and the comparatively short food chain lengths that, similarly to other mangrove ecosystems, characterize the Sundarbans. Organochlorine concentrations were 2-3 orders of magnitude lower than commonly accepted tolerance levels, so their consumption do not pose a sensible risk to the population. However, concentrations of DDT in dry fish from retail markets were higher because this compound is used for pest control during fish processing. Potential risks involved in this practice likely outweigh potential benefits, so it is recommended that this compound is substituted by less hazardous alternatives.

Quantification of insecticides in commercial seafood sold in East Asian markets: risk assessment for consumers

“…This indicates that DDT is still detected in commercial samples, reflecting the need for active monitoring programs in market samples. DDT levels quantified here were also higher than from crustaceans collected in other Asian countries (20-fold higher than in Bangladesh or Singapore (Bayen et al 2005;Borrell et al 2019), or even 40-fold higher than in Taiwan (Das et al 2020).…”

The role of chemical exposures in reducing the effectiveness of water–sanitation–hygiene interventions in Bangladesh, Kenya, and Zimbabwe

“…The use of the organochlorine DDT^( 135) was banned in the early 1980s in Bangladesh, but its production in the country continued until 1991, mainly for malaria control (Bergkvist et al, 2012). However, the use of DDT^( 135) in agriculture has increased since 2000 (Bergkvist et al, 2012;Borrell, Tornero, Bhattacharjee, & Aguilar, 2019). The World Bank reported that, of 161 pesticide formulations used in the country, 19% were extremely hazardous (WHO class I), 51% very hazardous (WHO class II), 10% moderately hazardous (WHO class III), and 20% were low risk (class U) (Dasgupta et al, 2005).…”

“…Consequently, residues of pesticides are found "in an alarming proportion on vegetable crops" (Miah et al, 2014). For example, several studies have found pesticide residues in different vegetable samples such as tomatoes, okra, eggplant, long yard bean, cauliflower, as well as meat, milk, and fish (Bergkvist et al, 2012;Borrell et al, 2019;Hasan et al, 2019;Islam et al, 2018;Miah et al, 2014).…”

“…Other studies have shown high levels of DDT^( 135) and heptachlor^in fish (Islam et al, 2018). DDT^( 135) contamination of dried fish was due to fishermen and vendors spraying the product to prevent spoilage (Bergkvist et al, 2012;Borrell et al, 2019;Islam et al, 2018).…”

High-Throughput Mega-Method for the Analysis of Pesticides, Veterinary Drugs, and Environmental Contaminants by Ultra-High-Performance Liquid Chromatography–Tandem Mass Spectrometry and Robotic Mini-Solid-Phase Extraction Cleanup + Low-Pressure Gas Chromatography–Tandem Mass Spectrometry, Part 2: Catfish

“…However, consumers are often concerned about hazardous chemical contaminants potentially present in fish and seafood. Indeed, the occurrence of lipophilic contaminants, such as nonpolar pesticides and polychlorinated biphenyls (PCBs), has been previously documented in various fish and seafood samples. , Additionally, various drugs are used in aquaculture production to control diseases and prevent mortality that can also accumulate in fish tissues to potentially cause harm to consumers.…”