Human Exposures to Neonicotinoids in Kumasi, Ghana

Abstract

Neonicotinoid insecticides (NNIs) are now popular in many agricultural systems across Africa; however, the extent of human exposures to NNIs in African countries is scarcely reported. The present study evaluates neonicotinoid exposures in the consumer population of Kumasi, a cosmopolitan city in Ghana. A total of 75 human urine samples were collected from healthy volunteers (nonfarmers, aged 13-80 yr) and analyzed with a liquid chromatography electrospray ionization tandem mass spectrometry system. Seven NNIs and 3 NNI metabolites were detected in the following pattern (frequency, median concentration, maximum concentration): N-dm-acetamiprid (94.7%, 0.41 µg/L, 8.79 µg/L) > imidacloprid (70.7%, 0.15 µg/L, 211.62 µg/L) > N-(6-chloro-3-pyridylmethyl)-N-ethyl-N′-methylformamidine (62.2%, 0.43 µg/L, 53.85 µg/L) > 2-[N-(6-chloro-3pyridylmethyl)-N-ethylamino]-2-(methylimino)acetic acid (56.8%, 0.10 µg/L, 3.53 µg/L) > clothianidin (40%, >limit of quantification [LOQ], 0.45 µg/L) > nitenpyram (18.7%, >LOQ, 0.14 µg/L) ≈ thiamethoxam (18.7%, >LOQ, 0.21 µg/L) > dinotefuran (12.0%, >LOQ, 1.01 µg/L) > acetamiprid (2.7%, >LOQ, 0.08 µg/L) ≈ thiacloprid (2.7%, >LOQ, 0.14 µg/L). Approximately 92% of the subjects were found to be exposed to multiple neonicotinoids simultaneously. The mean, median, and maximum imidacloprid equivalent of the relative potency factor of NNIs were found to be 1.6, 0.5, and 22.52, respectively. The median estimated daily intakes of acetamiprid, imidacloprid, and nitenpyram were 0.47, 1.27, and 0.02 µg/kg/d for females and 0.91, 0.66, and 0.08 µg/kg/d for males, respectively. The maximum daily intakes of all the NNIs were <1% of their chronic reference doses (cRfDs), except for imidacloprid and thiacloprid which recorded maximum daily intakes corresponding to 17.97 and 8.28% of cRfDs, respectively. To the best of our knowledge, the present study is the first biomonitoring report on neonicotinoid insecticides in Africa.

Neonicotinoid residues in commercial Japanese tea leaves produced by organic and conventional farming methods

“…This strongly confirms that dinotefuran dominates in the domestic applications of NEOs in Japan. The median concentration of all the target NEOs recorded in the green tea leaves were higher than the urinary NEO concentrations reported in Japanese [ [24] , [25] , [26] ] and other populations in Ghana [ 27 ], China [ 28 , 29 ] and USA [ 30 ]. Apart from imidacloprid and nitenpyram, the maximum concentrations of all the NEO parent compounds (acetamiprid, clothianidin, dinotefuran, thiacloprid and thiamethoxam) detected in the current green tea samples were higher than their respective urinary concentrations reported in urine of Japanese, Ghanaians, Chinese and Americans [ [24] , [25] , [26] , [27] , [28] , [29] , [30] ], as shown in Supplementary Data, Table S6.…”

“…The median concentration of all the target NEOs recorded in the green tea leaves were higher than the urinary NEO concentrations reported in Japanese [ [24] , [25] , [26] ] and other populations in Ghana [ 27 ], China [ 28 , 29 ] and USA [ 30 ]. Apart from imidacloprid and nitenpyram, the maximum concentrations of all the NEO parent compounds (acetamiprid, clothianidin, dinotefuran, thiacloprid and thiamethoxam) detected in the current green tea samples were higher than their respective urinary concentrations reported in urine of Japanese, Ghanaians, Chinese and Americans [ [24] , [25] , [26] , [27] , [28] , [29] , [30] ], as shown in Supplementary Data, Table S6. Moreover, the total concentrations of NEOs recorded in the green tea leaves were far higher than the cumulative urinary levels of NEOs reported in the various human populations (Supplementary Data, Table S6, [ [24] , [25] , [26] , [27] , [28] , [29] , [30] ]).…”

“…Apart from imidacloprid and nitenpyram, the maximum concentrations of all the NEO parent compounds (acetamiprid, clothianidin, dinotefuran, thiacloprid and thiamethoxam) detected in the current green tea samples were higher than their respective urinary concentrations reported in urine of Japanese, Ghanaians, Chinese and Americans [ [24] , [25] , [26] , [27] , [28] , [29] , [30] ], as shown in Supplementary Data, Table S6. Moreover, the total concentrations of NEOs recorded in the green tea leaves were far higher than the cumulative urinary levels of NEOs reported in the various human populations (Supplementary Data, Table S6, [ [24] , [25] , [26] , [27] , [28] , [29] , [30] ]). Urinary levels of NEOs were lower in human urine compared to NEO residues in tea leaves probably because of enzyme-mediated metabolism and subsequent excretions of NEOs in humans.…”

“…Spot urinary contaminant data alone are of uncertain value because of highly variable dilutions that may be instigated by wide fluctuations of fluid intakes [ 31 ]. Hence, the reported urinary concentrations observed in the human subjects [ [24] , [25] , [26] , [27] , [28] , [29] , [30] ] may not entirely reflect the total urinary contents of NEOs in the various human populations. Meanwhile, the maximum urinary concentration of dm-acetamiprid reported in Japanese (53.3 ng/mL [ 25 ]), Ghanaians (8.79 ng/mL [ 27 ]) and Chinese (18.3 ng/mL [ 29 ]), were found to be far higher than the maximum dm-acetamiprid concentration recorded in the green tea leaves (1.27 ng/g) used for the current study (Supplementary Data, Table S6 ).…”

“…Hence, the reported urinary concentrations observed in the human subjects [ [24] , [25] , [26] , [27] , [28] , [29] , [30] ] may not entirely reflect the total urinary contents of NEOs in the various human populations. Meanwhile, the maximum urinary concentration of dm-acetamiprid reported in Japanese (53.3 ng/mL [ 25 ]), Ghanaians (8.79 ng/mL [ 27 ]) and Chinese (18.3 ng/mL [ 29 ]), were found to be far higher than the maximum dm-acetamiprid concentration recorded in the green tea leaves (1.27 ng/g) used for the current study (Supplementary Data, Table S6 ). This tendency was probably because of the prolific metabolic formation of dm-acetamiprid from acetamiprid in humans by CYP450 enzymes [ 32 ].…”