Pesticide Residues in Fish - Pesticides: Evaluation of Environmental Pollution - page 380

Bangladesh), high levels of DDT powder (locally known as white powder) are used, though
Bangladesh banned the “dirty dozen” in 1997 (Barua 2007). Therefore, a study was carried
out for the detection and determination of the concentration levels of insecticides (DDT
and heptachlor) in dry fish under normal condition (without washing) and after various
traditional washing procedures to elucidate the actual concentration level of insecticides
taken in through dry fish.
Twenty samples of five different fish species analyzed were found to contain organo-
chlorine insecticides. The concentrations of DDT in the samples of Bombay duck at
normal, cold washing, hot washing, and boiling treatment were 97.0195, 76.604, 49.802,
and 38.195 ppb, respectively. In the samples of ribbon fish, the concentrations were
36.563, 29.966, 21.565, and 9.918 ppb, respectively. In the samples of shrimp at normal,
cold washing, hot washing, and boiling treatment these were 12.617, 7.673, 6.779, and
5.136 ppb, respectively.
In the samples of Chinese pomfret at normal, cold washing, hot washing, and boiling
treatment, concentrations were 712.155, 372.119, 256.847, and 197.740 ppb, respectively.
In the samples of Indian salmon at normal, cold washing, hot washing, and boiling
treatment concentrations were 737.238, 469.106, 142.188, and 135.516 ppb, respectively.
The concentrations of heptachlor in the samples of Bombay duck at normal, cold wash-
ing, hot washing, and boiling treatment were 1.237, 0.752, 0.456 ppb, and not detected
respectively.
In the samples of ribbon fish following different treatments, concentrations were 1.208,
1.991, 0.915, and 0.562 ppb respectively. In the samples of shrimp at normal, cold wash-
ing, hot washing, and boiling treatment, these were 44.806, 29.863, 26.665, and 16.868 ppb,
respectively. In the samples of Chinese pomfret at normal, cold washing, hot washing, and
boiling treatment, concentrations were 5.318, 4.186, 2.811, and 2.139 ppb, respectively. In the
samples of Indian salmon at normal, cold washing, hot washing, and boiling treatment,
concentrations were 4.834, 4.117, 2.208, and 1.272 ppb, respectively.
From the above results, it was found that all the samples of dry fish contained DDT and
heptachlor, and these insecticides were not removed 100% by any type of washing, even
after washing was followed by 10 min boiling, (except in Bombay duck boiling treatment
sample, in which heptachlor was not detected).
In the Republic of Bénin, aquatic ecosystems are subject to poisoning risks due to the
inappropriate use of pesticides, such as washing of empty bottles in rivers and using pes-
ticides to catch fish. In some areas, cotton fields are located near riverbanks, increasing the
probability of pesticide emission to the river. To assess contamination levels in the Ouémé
River catchment area, different fish species were collected from different geographical
areas along the river. DDT, its metabolites, and its isomers were the most frequently iden-
tified pesticides in fish flesh; α-endosulfan, β-endosulfan, dieldrin, telodrin, lindane, and
octachlorostyrene were also detected. Concentrations of pesticide residues in fish ranged
from 0 to 1364 ng/g lipid. A preliminary risk assessment indicated that the daily intake of
chlorinated pesticides by people consuming fish from the Ouémé River is still rather low
and does not present an immediate risk.
The OCP residues were measured in three species of fish: Tilapia zillii (redbelly tilapia),
Ethmalosa fimbriata (Bonga shad), and Chrysichthys nigrodigitatus (catfish). These fish spe-
cies are a significant part of the diet of residents of Lagos, Nigeria. The mean concentra-
tion of OCPs ranged from 0.01 to 8.92 ppm. The concentrations of the OCPs (except for
HCHs) in fish samples in this study were below the extraneous residue limit of 5 ppm,
set by the Codex Alimentarius Commission of FAO-WHO-1997. However, the concentra-
tions were higher than those detected during previous studies of fish samples from Lake