Evaluating the Presence of Pesticide Residues in Organic Rice Production in An Giang Province, Vietnam

The presence of pesticide residues was investigated in the organic rice production model in An Giang province, Vietnam. A total number of sixteen pesticide residues was been recorded during the investigation. Based on their contamination rate, they are classified as follows. The high-risk group includes tricyclazole (80%). The medium-risk group includes chlorpyrifos (47%), isoprothiolane (47%), difenoconazole (40%), propiconazole (40%), hexaconazole (40%), chlorfenapyr (33%), azoxystrobin (20%), and cypermethrin (20%). The low-risk group includes metalaxyl & metalaxyl-M, paclobutazol, niclosamide, chlorfenson, fipronil, fipronil-desulfinyl, and fenoxanil, which were detected with a contamination rate of 7%. There were seven insecticides, seven fungicides, one snail killer, and one growth regulator.

Handheld SERS coupled with QuEChERs for the sensitive analysis of multiple pesticides in basmati rice

Pesticides are a safety issue globally and cause serious concerns for the environment, wildlife and human health. The handheld detection of four pesticide residues widely used in Basmati rice production using surface-enhanced Raman spectroscopy (SERS) is reported. Different SERS substrates were synthesised and their plasmonic and Raman scattering properties evaluated. Using this approach, detection limits for pesticide residues were achieved within the range of 5 ppb-75 ppb, in solvent. Various extraction techniques were assessed to recover pesticide residues from spiked Basmati rice. Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERs) acetate extraction was applied and characteristic spectral data for each pesticide was obtained from the spiked matrix and analysed using handheld-SERS. This approach allowed detection limits within the matrix conditions to be markedly improved, due to the rapid aggregation of nanogold caused by the extraction medium. Thus, detection limits for three out of four pesticides were detectable below the Maximum Residue Limits (MRLs) of 10 ppb in Basmati rice. Furthermore, the multiplexing performance of handheld-SERS was assessed in solvent and matrix conditions. This study highlights the great potential of handheld-SERS for the rapid on-site detection of pesticide residues in rice and other commodities.

Biotransformation and oxidative stress responses in fish (Astyanax aeneus) inhabiting a Caribbean estuary contaminated with pesticide residues from agricultural runoff

The estuarine ecosystem of Laguna Madre de Dios (LMD), in the Caribbean coast of Costa Rica, is exposed to contamination with pesticide residues coming from the upstream agricultural areas. Biomarkers can provide a better indication of the fitness of biota in real mixture exposure scenarios than traditional lethal dose toxicity measurements. Here, we measured biomarkers of biotransformation, oxidative stress and neurotoxicity on Astyanax aeneus, an abundant fish species in LMD. Glutathione S-transferase activity (GST), catalase activity (CAT), lipid peroxidation (LPO), and cholinesterase activity (ChE) were measured in fish collected during seven sampling campaigns, carried out between 2016 and 2018. Pesticide residues were analysed in surface water samples collected every time fish were sampled. Residues of 25 pesticides, including fungicides, insecticides and herbicides, were detected. The biomarkers measured in A. aeneus varied along the sampling moments, however, biotransformation and oxidative stress signals showed coupled responses throughout the assessment. Furthermore, significant correlations were established between three biomarkers (GST, LPO and CAT) and individual pesticides, as well as between GST and LPO with groups of pesticides with shared biocide action. Among pesticides, insecticide residues had a major influence on the responses observed in fish. This work shows that the frequent exposure to environmentally relevant concentrations of pesticides can be related to physiological responses in fish that affect their health. This early warning information should be considered to improve the protection of estuarine ecosystems in the tropics.

Estimation and human health risk assessment of organochlorine and organophosphate pesticide residues in raw milk collected in Kenya

Background: This study determined the levels of organochlorine (OCPs) and organophosphate (OPPs) pesticide residues in cow milk from Kiambu and camel milk from Isiolo and Laikipia. The human dietary intake and the potential consumer health risks were also evaluated. Methods: In total, 90 cow and 82 camel milk samples were collected and analyzed using gas chromatography tandem mass spectroscopy to determine the levels of OCPs and OPPs. The levels were compared to the maximum residue limits (MRLs) established by the Codex Alimentarius (CA), EU Pesticides Database (EUPD), and the United States Department of Agriculture. The estimated daily intake and chronic hazard quotient (cHQ) of the milk were also calculated. Results: Cow milk from Kiambu was contaminated with 11/18 of the evaluated OCPs and 13/14 of the evaluated OPPs while camel milk from Isiolo was contaminated with 9/18 of the evaluated OCPs and 9/14 of the evaluated OPPs. Camel milk from Laikipia was contaminated with 11/18 of the evaluated OCPs and 11/14 of the evaluated OPPs. The mean heptachlor value in camel milk from Isiolo was above the EUPD MRLs. The mean value of heptachlor in Camel milk from Laikipia was above the CA and EUPD MRLs. The cHQs for Disulfoton, Fenamiphos, and Methacrifos in Cow milk were above 1 for adults and children. The cHQs for Fenchlorphous and Profenofos in Camel milk were above 1 for adults and children. The cHQs for α-endosulphan, β-endosulphan, dieldrin, and heptachlor in cow milk was above 1 for adults and children while the cHQs for heptachlor in camel milk was above 1 for adults and children. Conclusions: The potential health risks from chronic dietary intake of cow and camel milk in Kenya cannot be excluded. The routine monitoring of organophosphate and organochlorine pesticide levels in milk is recommended to minimize risks to human health.