Organochlorine Pesticides in Sediment-Dwelling Animals from Mangrove Areas of the Calabar River, SE Nigeria

Abstract

Sediment-dwelling biota such as mollusks (clam) and crabs collected from mangrove areas of the Calabar River are important routes of exposure to organochlorine pesticides (OCPs) contamination. Residual levels of OCPs including HCHs, DDTs, heptachlor, heptachlor epoxide, aldrin, endrin ketone, entrin aldehyde, dieldrin, endosulfan, endosulfan sulphate, methoxychlor, were determined in these organisms. The results revealed the OCP loads to be predominated by DDTs and HCHs (much of which was derived from illegal usage of GAMMALIN 20 for fishing) with the overall means of 49.6 and 35.1 ng/g wet weight (ww), respectively, at 100% frequencies of occurrence. Concentrations of other OCP components were generally low and were not detected in all biota samples. This probably reflects low utilization of these OCPs in the region and/or low bioaccumulation potential in the biota species. In general, the OCP concentrations were higher in freshwater mollusks and crabs than in brackish water, indicating that freshwater biota were more easily influenced by OCPs than their brackish water counterparts. One way analysis of variance (ANOVA) indicated no significant relationship between lipid content (LC) or body size of organisms and contaminant load, probably because of the non-equilibrium situation: smaller animals accumulated more OCPs than their larger counterparts, suggesting different uptake and elimination rates for these compounds. Biota-sediment accumulation factors (BSAFs) for DDTs and HCHs varied among the organisms and were in the ranges 1.02-9.78 and 0.74-8.72, respectively, indicating probably that HCHs were less bio-available in the river than DDTs. They were generally lower for highly polluted site (UMA; freshwater area) and higher for areas of low anthropogenic pressure (MR-brackish water area). Risk assessment matched against various standards clearly showed that the biota were highly contaminated with HCHs and DDTs, and may pose serious health threats to local inhabitants of the catchments. Furthermore, other selected OCPs such as heptachlor and dieldrin may in addition pose lifetime cancer risk, especially to residents of the riverine/coastal communities who often consume more of these organisms than those living inland.

Organochlorine Pesticide Residue Levels and Potential Human Health Risks in Kolanuts from Selected Markets in Osun State, Southwestern Nigeria

“…γ-HCH, the major component of lindane was detected at a mean level of 0.044 mg kg -1. The HCH isomers (α, β, γ-HCH) detected have also been reported in animal products [34,46]. The higher concentration of α-HCH isomer recorded in this study compared to other isomers may be attributed to the relatively high volatility of this isomer whose uptake increases via deposition from the atmosphere or by direct treatment with pesticides [47].…”

“…. The cyclodienes group which include dieldrin, aldrin, endrin and endosulfan have been reported in some food products in Nigeria [30,31,34]. The mean concentration of aldrin was 0.156 mg kg -1 , while the mean concentration of endosulfan metabolite gave 0.076 mg kg -1 αendosulfan, 0.243 mg kg -1 β-endosulfan and 0.218 mg kg -1 endosulfan sulphate with total endosulfan concentration of 0.537 mg kg -1 .…”

“…In West Africa, many studies have reported contamination levels of pesticide residues in fruits and vegetables [19,20,21,22,23,24] and in maize and cowpea [25]. In Nigeria, several studies have also reported high levels of pesticide residues in fruits, vegetables and other food crops produce [26,27,28,29,30,31], on cocoa [32] and on kolanut [33] as well as seafood products [34].…”

Comparative Assessment of the Bioremediation Potential of Polychaetes (Lug worm-Arenicola marina sp and Syllidae Worm-Syllis prolifera sp) in Aquaculture Pond Sediment

“…The percentage total organic carbon (TOC), available sulfur (S), iron (Fe) and pH contents of sediments in each microcosm were analyzed following standard methods [15] before the start (initial) and after 30 days (final) of the experiment. Following the initial decarbonation protocol, TOC was determined as previously reported by Oyo-Ita et al [16] using flash combustion at 1024 o C and thermal conductivity detection in triplicate with a CHNS Elemental Analyser (Carlo Erba 1108).…”

“…Many studies showed that young animals usually lack resistance against pollutants because of their underdeveloped organs and weaker immunity [11]. In some pollution studies, for instance, it was also observed that small mollusks and crabs accumulated more α-HCH [16] and PAHs in shrimps [32] than their larger counterparts. This observation was supported by the fact that smaller individuals have faster rates of uptake but slower rates of elimination of hydrophobic contaminants than their larger counterparts [33].…”