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Environment International Jan 2022Pesticides are pollutants of high concern in drinking water. Several approaches aimed to promote pesticide risk management in drinking water have been brought forward by...
Pesticides are pollutants of high concern in drinking water. Several approaches aimed to promote pesticide risk management in drinking water have been brought forward by diverse ways, however, these methods usually take too many indicators into consideration, which are complex and non-universal. In this study, a more focused and data driven ranking model was proposed for the purpose of development of the priority control list in drinking water. By determining three parameters including the total health risks of dietary exposure pathways, drinking water contribution rates, and the drinking water health risks, pesticides could be divided into four categories including the priority control list, secondary control list, candidate control list, and non-regulatory list. As a case study, the proposed model was implemented for 23 pesticides detected in drinking water from 36 major cities across China during two major science and technology program for water pollution control and treatment. Totally 13 kinds of pesticides including carbofuran, dicofol, chlorpyrifos, 2,4-D, acetochlor, deltamethrin, dimethoate, heptachlor, parathion, hexachlorobenzene, DDT, hexachlorocyclohexane and atrazine are selected for priority control, methyl parathion, dichlorvos and chlorothalonil are recommended for secondary control, butachlor and malathion are classified into candidate control list, and fenobucarb is suggested to be removed from the pesticide control list.
Topics: Atrazine; China; Drinking Water; Environmental Monitoring; Pesticides; Water Pollutants, Chemical
PubMed: 34607044
DOI: 10.1016/j.envint.2021.106901 -
F1000Research 2020: Developmental delay among children under 5 years of age is a serious global public health problem and much research has been carried out to find potential causes....
: Developmental delay among children under 5 years of age is a serious global public health problem and much research has been carried out to find potential causes. Pesticides - especially organophosphates - are suspected to be one of the main causes of the problem. This study aimed to investigate the association between pesticide use by the mother during pregnancy and preschool children development using a case-control study. : Data on prenatal and postnatal pesticide exposure of 442 children with suspected developmental delay, and 413 controls with normal development were included for analysis. The children were matched for gender, age, and residency. Data on pesticide exposure were collected via interview with the mother, and data on pregnancy outcomes abstracted from hospital records. : Chlorpyrifos exposure significantly increased the risk of developmental delay with an odds ratio (OR) of 3.71 (95% CI 1.03-13.36) for ever use of the pesticide, and an OR of 5.92 (95% CI 1.01-34.68) for postnatal exposure (p <0.05). Some other pesticides also had a positive association with developmental delay but none were statistically significant (p <0.05). Those pesticides were insecticide, fungicide, herbicide, and molluscicide. Individual pesticides with a positive association were glyphosate, paraquat, butachlor, methyl parathion (pholidon), savin, methomyl, endosulfan, carbosulfan, methamidophos, monochrotofos, mancozeb, and bordeaumixture. : This case-control study found that chlorpyrifos and some other pesticides exposure during pregnancy were positively associated with developmental delay in children aged under 5 years. Further research should be conducted to better understand this potential effects of pesticides on child neurodevelopment, and the public - especially those who plan to have families - should be informed.
Topics: Case-Control Studies; Child, Preschool; Chlorpyrifos; Female; Humans; Pesticides; Pregnancy; Pregnancy Outcome; Thailand
PubMed: 34557296
DOI: 10.12688/f1000research.27874.5 -
Applied and Environmental Microbiology Oct 2021-Nitrophenol (PNP) is a hydrolytic product of organophosphate insecticides, such as parathion and methylparathion, in soil. Aerobic microbial degradation of PNP has been...
-Nitrophenol (PNP) is a hydrolytic product of organophosphate insecticides, such as parathion and methylparathion, in soil. Aerobic microbial degradation of PNP has been classically shown to proceed via the "hydroquinone (HQ) pathway" in Gram-negative degraders, whereas it proceeds via the "benzenetriol (BT) pathway" in Gram-positive ones. The "HQ pathway" is initiated by a single-component PNP 4-monooxygenase and the "BT pathway" by a two-component PNP 2-monooxygenase. Their regioselectivity intrigued us enough to investigate their catalytic difference through structural study. PnpA1 is the oxygenase component of the two-component PNP 2-monooxygenase from Gram-positive Rhodococcus imtechensis strain RKJ300. It also catalyzes the hydroxylation of 4-nitrocatechol (4NC) and 2-chloro-4-nitrophenol (2C4NP). However, the mechanisms are unknown. Here, PnpA1 was structurally determined to be a member of the group D flavin-dependent monooxygenases with an acyl coenzyme A (acyl-CoA) dehydrogenase fold. The crystal structure and site-directed mutagenesis underlined the direct involvement of Arg100 and His293 in catalysis. The bulky side chain of Val292 was proposed to push the substrate toward flavin adenine dinucleotide (FAD), hence positioning the substrate properly. An N450A variant was found with improved activity for 4NC and 2C4NP-probably because of the reduced steric hindrance. PnpA1 shows an obvious difference in substrate selectivity with its close homologues TcpA and TftD, which may be caused by the unique Thr296 and a different conformation in the loop from positions 449 to 454 (loop 449-454). Above all, our study allows structural comparison between the two types of PNP monooxygenases. An explanation that accounts for their regioselectivity was proposed: the different PNP binding manners determine their choice of - or -hydroxylation on PNP. Single-component PNP monoxygenases hydroxylate PNP at the 4 position, while two-component ones do so at the 2 position. However, their catalytic and structural differences remain elusive. The structure of single-component PNP 4-monooxygenase has previously been determined. In this study, to illustrate their catalytic difference, we resolved the crystal structure of PnpA1, a typical two-component PNP 2-monooxygenase. The roles of several key amino acid residues in substrate binding and catalysis were revealed, and a variant with improved activities toward 4NC and 2C4NP was obtained. Moreover, through comparison of the two types of PNP monooxygenases, a hypothesis was proposed to account for their catalytic difference, which gives us a better understanding of these two similar reactions at the molecular level. In addition, these results will also be of further aid in rational design of enzymes in bioremediation and biosynthesis.
Topics: Bacterial Proteins; Catalysis; Mixed Function Oxygenases; Nitrophenols; Rhodococcus
PubMed: 34469195
DOI: 10.1128/AEM.01171-21 -
Zhejiang Da Xue Xue Bao. Yi Xue Ban =... Jun 2021To investigate the effects of maternal exposure to 13 chemicals mixture (CM) during pregnancy on pregnancy outcome and health status of maternal/offspring mice. C57BL/6...
To investigate the effects of maternal exposure to 13 chemicals mixture (CM) during pregnancy on pregnancy outcome and health status of maternal/offspring mice. C57BL/6 pregnant mice were given drinking water containing carbaryl dimethoate glyphosate methomyl methyl parathion triadimefon aspartame sodium benzoate calcium disodium ethylene diamine tetra-acetate ethylparaben butylparaben bisphenol A and acacia gum The effects of CM exposure on pregnancy outcome, health status of dams/offspring, levels of circulating inflammatory cytokines in dams/offspring and emotional related behaviors of offspring were evaluated. CM exposure during pregnancy had no significant effect on pregnancy outcome, liver function, body weight of the dams in late pregnancy and uterine/ovarian weight after delivery, however, it led to an increase in maternal serum IFN-γ level (<0.05). CM exposure during pregnancy had no significant effect on the liver function of offspring, but increased the serum IFN-γ, prefrontal cortex IFN-γ, and TNF-α and hippocampus IFN-γ levels in the offspring(all <0.01). In addition, the offspring of CM group showed significant abnormal emotion-related (autism-like) behaviors in adulthood, especially in male offspring. Low dose CM exposure during pregnancy may induce inflammation status in dams/offspring, and lead to autism-like behaviors in offspring, indicating the potential effects of low dose CM exposure on human maternal and infant health.
Topics: Adult; Animals; Autistic Disorder; Female; Humans; Male; Maternal Exposure; Mice; Mice, Inbred C57BL; Phenotype; Pregnancy; Prenatal Exposure Delayed Effects
PubMed: 34402257
DOI: 10.3724/zdxbyxb-2021-0182 -
Frontiers in Chemistry 2021In this work, a facile one-pot hydrothermal route was employed to synthesize a series of fluorescent carbon dots (CDs) by using 20 natural amino acids, respectively, as...
In this work, a facile one-pot hydrothermal route was employed to synthesize a series of fluorescent carbon dots (CDs) by using 20 natural amino acids, respectively, as the starting materials. It was found that the CDs synthesized using phenylalanine could possess the intrinsic peroxidase-like activity that could effectively catalyze a traditional peroxidase substrate like 3, 3', 5, 5'- tetramethylbenzidine (TMB) in the presence of HO to produce a blue solution; thereby, a catalytic sensing system for HO has been developed. On the basis of this catalytic reaction, together with the fact that glucose oxidase (GOx) can catalyze the hydrolysis of glucose to generate HO, a sensitive catalytic sensing system for glucose could be further established. Furthermore, based on this catalytic reaction, taken together with the two enzymatic catalytic systems of acetylcholinesterase (AChE) and choline oxidase (CHO), a highly sensitive multi-catalytic sensing system could be successfully developed for organophosphorus (OPs) pesticides such as dimethoate, DDVP, and parathion-methyl. Limit of detections (LODs) of HO and glucose were estimated to be 6.5 and 0.84 μM, respectively. The limit of detection of the sub-nM level could be obtained for tested dimethoate, DDVP, and parathion-methyl OPs pesticides. The established sensing systems can exhibit good practical application performance in serum and several fruit samples.
PubMed: 34395382
DOI: 10.3389/fchem.2021.713104 -
Nature Communications Jun 2021Enzymes can evolve new catalytic activity when environmental changes present them with novel substrates. Despite this seemingly straightforward relationship, factors...
Enzymes can evolve new catalytic activity when environmental changes present them with novel substrates. Despite this seemingly straightforward relationship, factors other than the direct catalytic target can also impact adaptation. Here, we characterize the catalytic activity of a recently evolved bacterial methyl-parathion hydrolase for all possible combinations of the five functionally relevant mutations under eight different laboratory conditions (in which an alternative divalent metal is supplemented). The resultant adaptive landscapes across this historical evolutionary transition vary in terms of both the number of "fitness peaks" as well as the genotype(s) at which they are found as a result of genotype-by-environment interactions and environment-dependent epistasis. This suggests that adaptive landscapes may be fluid and molecular adaptation is highly contingent not only on obvious factors (such as catalytic targets), but also on less obvious secondary environmental factors that can direct it towards distinct outcomes.
Topics: Adaptation, Physiological; Amino Acid Sequence; Bacteria; Bacterial Proteins; Biocatalysis; Epistasis, Genetic; Evolution, Molecular; Gene-Environment Interaction; Genotype; Hydrolases; Kinetics; Metals; Methyl Parathion; Mutation; Protein Domains; Sequence Homology, Amino Acid
PubMed: 34162839
DOI: 10.1038/s41467-021-23943-x -
BMC Public Health Jun 2021Nepal recorded 5754 suicides in 2018-19 - a high number for a relatively small country. Over 24% of these suicides were by poisoning, most by ingestion of highly...
BACKGROUND
Nepal recorded 5754 suicides in 2018-19 - a high number for a relatively small country. Over 24% of these suicides were by poisoning, most by ingestion of highly concentrated agricultural pesticides. Nepal has actively regulated pesticides to reduce their health impacts since 2001. We aimed to analyse Nepal's history of pesticide regulation, pesticides responsible for poisonings, and relate them to national suicide rates.
METHODS
Information on pesticide regulation was collected from the Plant Quarantine and Pesticide Management Centre of the Ministry of Agriculture and Livestock Development. National data on suicides from 1980 to 2019 were obtained from the National Statistical Bureau and Nepal Police. Data on the pesticides responsible for self-poisoning and pesticide suicides over time were obtained from a systematic literature review.
RESULTS
As of June 2020, 171 pesticides were registered for use in Nepal, of which one was extremely hazardous (WHO Class Ia), one other highly hazardous (WHO Class Ib), and 71 moderately hazardous (WHO Class II). Twenty-four pesticides have been banned since 2001, with eight (including five WHO Class I compounds) banned in 2019. Although the suicide rate has increased more than twelve-fold since 1980, particularly for hanging (15-fold increase from 1980 to 2018), fatal pesticide self-poisoning has increased by 13-fold. Methyl-parathion is reported to be the key pesticide responsible for pesticide self-poisoning in Nepal, despite being banned in 2006.
CONCLUSION
The full effect of the recent pesticide policy reform in Nepal remains to be seen. Our analysis shows a continuing increase in suicide numbers, despite bans of the most important pesticide in 2006. This may indicate smuggling across the border and the use of the brand name (Metacid) for pesticides in general making it difficult to identify the responsible pesticide. More information is required from forensic toxicology labs that identify the individual compounds found. The effect of recent bans of common suicide pesticides needs to be monitored over the coming years. Evidence from other Asian countries suggests that HHPs bans will lead to a marked reduction in suicides, as well as fewer cases of occupational poisoning.
Topics: Asia; Eating; Humans; Nepal; Pesticides; Poisoning; Suicide
PubMed: 34120596
DOI: 10.1186/s12889-021-11155-3 -
Food Chemistry Nov 2021Organophosphate pesticides (OPs) are often used as insecticides and acaricides in agriculture, thus improving yields. OP residues may pose a serious threat,...
Organophosphate pesticides (OPs) are often used as insecticides and acaricides in agriculture, thus improving yields. OP residues may pose a serious threat, duetoinhibitionof the enzymeacetylcholinesterase(AChE). Therefore, a competitive bio-barcode immunoassay was designed for simultaneous quantification of organophosphate pesticide residues using AuNP signal amplification technology and Au@Pt catalysis. The AuNP probes were labelled with antibodies and corresponding bio-barcodes (ssDNAs), MNP probes coated with ovalbumin pesticide haptens and Au@Pt probes functionalized with the complementary ssDNAs were then prepared. Subsequently, pesticides competed with MNP probes to bind the AuNP probes. The recoveries of the developed assay were ranged from 71.26 to 117.47% with RSDs from 2.52 to 14.52%. The LODs were 9.88, 3.91, and 1.47 ng·kg, for parathion, triazophos, and chlorpyrifos, respectively. The assay was closely correlated with the data obtained from LC-MS/MS. Therefore, the developed method has the potential to be used as an alternative approach for detection of multiple pesticides.
Topics: Catalysis; Chlorpyrifos; Chromatography, Liquid; Food Analysis; Food Contamination; Gold; Immunoassay; Limit of Detection; Metal Nanoparticles; Organophosphorus Compounds; Organothiophosphates; Oxazines; Parathion; Pesticide Residues; Platinum; Tandem Mass Spectrometry; Triazoles
PubMed: 34082296
DOI: 10.1016/j.foodchem.2021.130118 -
Journal of Pharmaceutical Analysis Apr 2021A highly sensitive and selective method was developed for both UV-vis spectrophotometric and fluorimetric determination of organophosphorus pesticides (OPs). This method...
A highly sensitive and selective method was developed for both UV-vis spectrophotometric and fluorimetric determination of organophosphorus pesticides (OPs). This method used silver nanoparticles (AgNPs) modified with graphitic carbon nitride (g-CN). The AgNPs reduced the fluorescence intensity of g-CN. Acetylthiocholine (ATCh) could be catalytically hydrolyzed by acetylcholinesterase (AChE) to form thiocholine, which induces aggregation of the AgNPs. This aggregation led to the recovery of the blue fluorescence of g-CN, with excitation/emission peaks at 310/460 nm. This fluorescence intensity could be reduced again in the presence of OPs because of the inhibitory effect of OPs on the activity of AChE. The degree of reduction was found to be proportional to the concentration of OPs, and the limit of fluorometric detection was 0.0324 μg/L (S/N = 3). In addition, the absorption of the g-CN/AgNPs at 390 nm decreased because of the aggregation of the AgNPs, but was recovered in presence of OPs because of the inhibition of enzyme activity by OPs. This method was successfully applied to the analysis of parathion-methyl in real samples.
PubMed: 34012694
DOI: 10.1016/j.jpha.2020.04.007 -
Current Opinion in Structural Biology Aug 2021The evolution of novel enzymes has fueled the diversification of life on earth for billions of years. Insights into events that set the stage for the evolution of a new... (Review)
Review
The evolution of novel enzymes has fueled the diversification of life on earth for billions of years. Insights into events that set the stage for the evolution of a new enzyme can be obtained from ancestral reconstruction and laboratory evolution. Ancestral reconstruction can reveal the emergence of a promiscuous activity in a pre-existing protein and the impact of subsequent mutations that enhance a new activity. Laboratory evolution provides a more holistic view by revealing mutations elsewhere in the genome that indirectly enhance the level of a newly important enzymatic activity. This review will highlight recent studies that probe the early stages of the evolution of a new enzyme from these complementary points of view.
Topics: Evolution, Molecular; Mutation; Proteins
PubMed: 33865035
DOI: 10.1016/j.sbi.2021.03.001