New sensitive LC-MS/MS method for the simultaneous determination of 13 phenolic and carboxylic acid pesticide biomarkers in human urine, including dicamba

The commercialization in 2016 of genetically engineered seeds tolerant to dicamba and/or 2,4-dichlorophenoxyacetic acid (2,4-D) has caused a rapid increase in the use of these herbicides. New questions about the reproductive and chronic health effects of long-term exposure to these herbicides have been raised. To assess exposure to dicamba and other pesticides of interest in the Heartland Study, a birth cohort study based in the United States, a new analytical method was needed. The present study describes the development and validation of this new solid phase extraction and liquid chromatography-tandem mass spectrometry method that detects simultaneously 13 pesticides or their metabolites in 250 μL of urine. More specifically, the method allows the analysis of dicamba, 2,4-D and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), which are herbicides, of malathion dicarboxylic acid (MDA), para-nitrophenol (PNP), 3,5,6-trichloro-2-pyridinol (TCPy), 2-diethylamino-6-methylpyrimidin-4-ol (DEAMPY) and 2-isopropyl-6-methyl-4-pyrimidinol (IMPY), which are metabolites of organophosphate insecticides, and finally of cis-3-(2,2-Dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (cis-DCCA), trans-3-(2,2-Dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (trans-DCCA), 3-Phenoxybenzoic acid (3-PBA), 4-Fluoro-3-phenoxybenzoic acid (4-F-3-PBA) and cis-3-(2,2-Dibromovinyl)-2,2-dimethylcyclopropane carboxylic acid (cis-DBCA), which are metabolites of synthetic pyrethroids insecticides. The method was validated under ISO/IEC 17025 guidance. The limit of detection (LOD) in urine samples was 0.10 μg/L for dicamba, while the LOD for other analytes ranged between 0.0038 μg/L and 0.091 μg/L. Accuracy was evaluated by analyzing samples from two External Quality Assessment Schemes, namely G-EQUAS and OSEQAS. Preliminary results obtained following the analysis of 91 urine samples taken from pregnant women enrolled in the Heartland Study are presented here. This method is suitable for human biomonitoring studies.

Residual characteristics and potential integrated risk assessment of synthetic pyrethroids in leafy vegetables from Zhejiang in China - Based on a 3-year investigation

Leafy vegetables have high nutritional value and are very popular in China. However, the long-term variation in residues and integrated risks of synthetic pyrethroids (SPs) in these vegetables have not been well examined. In this study, a total of 1005 samples were collected from 55 markets during 2017-2019. The cumulative exposure to nine kinds of SPs in Zhejiang, China, through the consumption of nine leafy vegetables was analyzed, and the potential integrated risk was assessed by the relative potency factor. A total of 191 samples were detected with SPs residues. The most frequently detected SPs were λ-cyhalothrin and cypermethrin. The integrated risk assessment results revealed that the dietary risk for these SPs via leafy vegetable exposure is acceptable for children, adults and elderly individuals. The data provided here will be helpful for the government to formulate food policies in China.

Exposure to pyrethroid pesticides and ovarian reserve

INTRODUCTION

Synthetic pyretroids are among the most common pesticides currently used worldwide. Animal studies suggest that exposure to pyrethroids could dysregulated the function of the ovary, mainly follicular development and/or synthesis of the reproductive hormone. Nevertheless data regarding the effect of exposure on female ovarian function is limited. So the aim of the present study is to assess the effect of exposure to synthetic pyrethroids on ovarian reserve.

MATERIALS AND METHODS

The study population consists of 511 females aged 25-39 years attending infertility clinics for diagnostic purposes, because of couples' infertility. Validated gas chromatography ion-tap mass spectrometry method was used to assess the urinary concentrations of pyrethroid metabolites (CDDCA (cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid), TDDCA (trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid), 3PBA (3-phenoxybenzoic acid) and DBCA (cis-2,2-dibromovinyl-2,2-dimethylcyclopropane-1-carboxylic acid)). Ovarian reserve was assessed using parameters of ovarian reserve (antral follicle count and concentrations of hormones: AMH (anti-Mullerian hormone), FSH (follicle stimulating hormone) and E₂ (estradiol)).

RESULTS

In the present analysis the association was found between urinary concentrations of 3-PBA and levels of AMH (p = 0.03), FSH (p = 0.04) and antral follicle count (p = 0.02). Urinary level of CDCCA, TDCCA and DBCA was not associated with any examined parameters of ovarian reserve.

CONCLUSIONS

Synthetic pyrethroids may affect female ovarian reserve. As this is the first, preliminary study the results need confirmation in a further detailed investigations.

Chronic exposure to environmental levels of cis-bifenthrin: Enantioselectivity and reproductive effects on zebrafish (Danio rerio)

Synthetic pyrethroids (SPs) are broadly used to control pests and have been widely detected in aquatic environments, prompting concern over its risk to the health of non-target organisms. The present study evaluated whether long-term (60 d) exposure to low doses (0, 20, 100, and 500 ng/L) of cis-BF enantiomers (1S-cis-BF and 1R-cis-BF) could cause reproductive endocrine disturbance to zebrafish. Exposure to 1S-cis-BF has stronger reproductive impairment effect than 1R-enantiomer, indicating that the enantioselectivity of cis-BF on fish reproduction. Significant decrease of cumulative spawning of zebrafish was observed as a result of cis-BF exposure. And the retardations of testis and ovaries development found in histopathological section were suggested to be important cause for the decreased fecundity. Cis-BF decreased the total motility of sperm but did not affect sperm density. Relatively high levels of cis-BF detected in the gonads of males and females may directly impair gametogenesis. In addition, alterations in the expression of key genes (cyp17, cyp19a and 17β-hsd) associated with reproductive endocrine pathways were correlated well with the significant changes in sex hormone contents (E2 and T) and these results may relate to gonadal development and maturation of germ cells in females or/and males which were suspected to be a likely underlying mechanism. Furthermore, the reduction of quality of F1 embryo derived from the unexposed females and exposed males (UE♀ × E♂) demonstrated that male exposure had greater adverse effects on offspring. Our results indicate that long term, low dose exposure to cis-BF can enantioselectively impair the reproduction system of fish, and induce toxicity related abnormalities in non-exposed offspring. This study has important implications for environmental risk assessment of chiral pesticides that are concurrently present in aquatic systems.

Temporal-spatial distribution of synthetic pyrethroids in overlying water and surface sediments in Guangzhou waterways: potential input mechanisms and ecological risk to aquatic systems

Temporal-spatial distribution of synthetic pyrethroids (SPs) in overlying water and surface sediments and ecological risk to aquatic systems were investigated, where paired water and surface sediments were collected during dry and wet periods in Guangzhou urban waterways. Eight target SPs (i.e., tefluthrin, bifenthrin, cyhalothrin, permethrin, cyfluthrin, cypermethrin, esfenvalerate, and deltamethrin), with cypermethrin and permethrin as major components, were ubiquitously detected in both water (dissolved and particle phases, separately) and sediments. Significant increases of ΣSP (sum of eight SPs) concentrations were observed in both water and sediment from the dry period to the wet period. The spatial distribution of SPs was mostly impacted by land-use type, with the highest ΣSP concentrations in the residential areas, which indicates the massive application of pyrethroids in household mosquito control. It is demonstrated that SPs preferred to be adsorbed to the particles, and rainfall-induced runoff was suggested as an important mechanism that moved SPs to the receiving waterways. A rising trend on sediment concentrations of SPs in the Guangzhou area in the last decade implied increasing application of pyrethroid insecticides, with cypermethrin and permethrin as the dominant components, where the contamination of SPs was positively related with urbanization rate (e.g., resident population and green coverage area). A special emphasis was placed on the potential effects of both individual SPs and their mixtures in three trophic levels (i.e., algae, daphnia, and fish) using toxic units (TUs) and risk quotients (RQs) for water and sediments. In spite of no acute effects due to SPs in the sediments, the toxic units showed daphnia as the most sensitive species in water, with acute risks to daphnia exhibited in several sampling sites. The risk assessment points out that a chronic toxicity (RQ index) caused by SPs in three trophic levels (algae, daphnia, and fish) exists, especially in Daphnia magna. Graphical abstract.

Synthetic pyrethroid resistance in Rhipicephalus (Boophilus) microplus ticks from north-western Himalayas, India

In the present study, adult immersion test (AIT) was used for evaluation of resistance against synthetic pyrethroids (deltamethrin and cypermethrin) in Rhipicephalus (Boophilus) microplus ticks collected from nine districts of three agro-climatic zones of north-western Himalayan region of India. Resistance factors (RFs) were calculated between 0.94 to 50.71 for deltamethrin and 0.32 to 13.18 for cypermethrin. Resistance to deltamethrin was detected at level I in two, level II in four, level III and level IV in one isolate each while one isolate was susceptible. Against cypermethrin, resistance at levels I and II was detected in three isolates each while three isolates were found susceptible. The low altitude sub-tropical zone revealed higher density of resistant ticks where intensive animal husbandry practices were followed and the synthetic pyrethroid usage was common. Data generated on pyrethroid resistance status of ticks in north-western Himalayan region will provide new insights in acaricidal resistance particularly from remote areas of this region and will help in formulating suitable control measures.

Discriminating lethal concentrations for pyrethroid compounds used in susceptibility monitoring of Anopheles epiroticus, a malaria vector in Thailand

Anopheles epiroticus is a malaria vector in Thailand found primarily along coastal areas with brackish water habitats. Insecticides, particularly pyrethroid class compounds, are commonly used to control malaria vectors in Thailand. The lack of specific discriminating lethal concentrations for An. epiroticus has possibly compromised a more accurate assessment of physiological susceptibility to various chemicals. The routine assessment of vector response to insecticides is a key program management component to prevent or mitigate the development of resistance. The purpose of this study was to determine the discriminating (diagnostic) lethal concentrations of five common synthetic pyrethroids (deltamethrin, permethrin, bifenthrin, lambda(λ)-cyhalothrin, and alpha(α)-cypermethrin) used in Thailand for malaria control, against a susceptible colonized population of An. epiroticus. Final discriminating concentrations were 0.006% deltamethrin, 0.349% permethrin, 0.033% bifenthrin, 0.012% λ-cyhalothrin, and 0.0009% α-cypermethrin. Using concentrations established for each chemical, a field population of An. epiroticus from southern Thailand was found completely susceptible to each concentration. Periodic monitoring of insecticide susceptibility of An. epiroticus and other malaria vector species is needed to assess the efficacy of chemicals and guide insecticide policy and control programs.

Distribution and risk assessment of banned and other current-use pesticides in surface and groundwaters consumed in an agricultural catchment dominated by cocoa crops in the Ankobra Basin, Ghana

The existence of pesticides, such as organochlorine pesticides, parathion-ethyl, methamidophos which is banned globally and some current-use non-banned pesticides of organophosphorus and synthetic pyrethroids in freshwater sources is an ecological and public health concern in many countries, including Ghana. Prompted by this concern, the exposure levels and risk assessment of these pesticides to humans and non-target organisms via groundwater and surface water sources in an agricultural catchment dominated by cocoa crops in the Ankobra Basin, Ghana, were investigated. The individual concentrations of the banned pesticides in the surface water and groundwater samples varied from < LOD to 0.110 μg/L and < LOD to 0.055 μg/L, respectively, while the concentrations of the non-banned pesticides ranged from < LOD to 0.925 μg/L and < LOD to 2 μg/L, respectively. The mean concentrations of chlorpyrifos, cypermethrin, p,p'-DDT and pirimiphos-methyl in some water sources exceeded the EU limit of 0.1 μg/L. Some surface water sources were more contaminated with DDTs, endrin, dieldrin, methoxychlor, chlorpyrifos, and HCH isomers than were freshwater sources in river basins in some countries of the world. Chlorpyrifos, p,p'-DDT and methoxychlor were ubiquitous in both water sources. The hydrochemical and compositional profiles of the pesticides indicate that water-exchange and secondary porosities in the bedrock likely contributed to the occurrence of the pesticides in the water sources. The pesticides were of low risk to humans that consume the water, but considering the US EPA safe limit for carcinogenic effects of 10^-6, the high levels of DDTs, β-HCH, and dieldrin in some of the surface water and groundwater sources may cause cancer in children or infants. The toxicity of pesticide mixtures to surface water non-target organisms decreased in the order of fish > Daphnia magna > algae. The pesticides in the water sources were anthropogenic in origin and recently used. DDT and HCH in the water were of technical-grade origin.

Fate, uptake, and distribution of nanoencapsulated pesticides in soil-earthworm systems and implications for environmental risk assessment

Nanopesticides are novel plant protection products offering numerous benefits. Because nanoparticles behave differently from dissolved chemicals, the environmental risks of these materials could differ from conventional pesticides. We used soil-earthworm systems to compare the fate and uptake of analytical-grade bifenthrin to that of bifenthrin in traditional and nanoencapsulated formulations. Apparent sorption coefficients for bifenthrin were up to 3.8 times lower in the nano treatments than in the non-nano treatments, whereas dissipation half-lives of the nano treatments were up to 2 times longer. Earthworms in the nano treatments accumulated approximately 50% more bifenthrin than those in the non-nano treatments. In the non-nano treatments, most of the accumulated material was found in the earthworm tissue, whereas in the nano treatments, the majority resided in the gut. Evaluation of toxicokinetic modeling approaches showed that models incorporating the release rate of bifenthrin from the nanocapsule and distribution within the earthworm provided the best estimations of uptake from the nano-formulations. Overall, our findings indicate that the risks of nanopesticides may be different from those of conventional formulations. The modeling presented provides a starting point for assessing risks of these materials but needs to be further developed to better consider the behavior of the nanoencapsulated pesticide within the gut system. Environ Toxicol Chem 2018;37:1420-1429. © 2018 SETAC.

Validation of QuEChERS analytical technique for organochlorines and synthetic pyrethroids in fruits and vegetables using GC-ECD

In the present day scenario of increasing awareness and concern about the pesticides, it is very important to ensure the quality of data being generated in pesticide residue analysis. To impart confidence in the products, terms like quality assurance and quality control are used as an integral part of quality management. In order to ensure better quality of results in pesticide residue analysis, validation of analytical methods to be used is extremely important. Keeping in view the importance of validation of method, the validation of QuEChERS (quick, easy, cheap, effective, rugged, and safe) a multiresidue method for extraction of 13 organochlorines and seven synthetic pyrethroids in fruits and vegetables followed by GC ECD for quantification was done so as to use this method for analysis of samples received in the laboratory. The method has been validated as per the Guidelines issued by SANCO (French words Sante for Health and Consommateurs for Consumers) in accordance with their document SANCO/XXXX/2013. Various parameters analyzed, viz., linearity, specificity, repeatability, reproducibility, and ruggedness were found to have acceptable values with a per cent RSD of less than 10%. Limit of quantification (LOQ) for the organochlorines was established to be 0.01 and 0.05 mg kg^-1 for the synthetic pyrethroids. The uncertainty of the measurement (MU) for all these compounds ranged between 1 and 10%. The matrix-match calibration was used to compensate the matrix effect on the quantification of the compounds. The overall recovery of the method ranged between 80 and 120%. These results demonstrate the applicability and acceptability of this method in routine estimation of pesticide residues of these 20 pesticides in the fruits and vegetables by the laboratory.

Exposure to widespread environmental endocrine disrupting chemicals and human sperm sex ratio

In recent years, a trend toward a declining proportion of male births has been noted in several, but not all, industrialized countries. The underlying reason for the drop in the sex ratio is unclear, but one theory states that widespread environmental endocrine disrupting chemicals affecting the male reproductive system in a negative manner could be part of the explanation. The present study was designed to investigate whether the urinary phthalate, pyrethroids and polycyclic aromatic hydrocarbons metabolites concentrations were associated with sperm Y:X ratio. The study population consisted of 194 men aged under 45 years of age who attended infertility clinic in Lodz, Poland for diagnostic purposes with normal semen concentration of 20-300 mln/ml or with slight oligozoospermia (semen concentration of 15-20 mln/ml) (WHO, 1999). The Y:X ratio was assessed by fluorescent in situ hybridization. Urinary concentrations of 1-hydroxypyrene were measured by high performance liquid chromatography, phthalate metabolites were analyzed using a procedure based on the LC-MS/MS methods and metabolites of synthetic pyrethroids were assessed by gas chromatography ion-tap mass spectrometry method. After adjustment for potential confounders (past diseases, age, abstinence, smoking, alcohol consumption, sperm concentration, motility, morphology) 5OH MEHP, CDCCA to TDCCA and 1-OHP was negatively related to Y:X sperm chromosome ratio (p = 0.033, p < 0.001, p = 0.047 respectively). As this is the first study to elucidate the association between the level of metabolites of widespread environmental endocrine disrupting chemicals (phthalates, synthetic pyrethroids, polycyclic aromatic hydrocarbons) on sex chromosome ratio in sperm therefore, these findings require further replication in other populations.

Survey of acaricides resistance status of Rhipiciphalus (Boophilus) microplus collected from selected places of Bihar, an eastern state of India

Monitoring acaricide resistance in field ticks and use of suitable managemental practices are essential for controlling tick populations infesting animals. In the present study, the acaricide resistance status in Rhipicephalus (Boophilus) microplus ticks infesting cattle and buffaloes of five districts located in the eastern Indian state, Bihar were characterized using three data sets (AIT, Biochemical assays and gene sequences). Adult immersion test (AIT) was adopted using seven field isolates and their resistance factor (RF) was determined. Six isolates (DNP, MUZ, BEG, VSH, DRB and SUL) were found resistant to both deltamethrin and diazinon and except VSH all were resistant to cypermethrin. One isolate (PTN) was susceptible with a RF below 1.5. To understand the possible mode of resistance development, targeted enzymes and gene sequences of the para sodium channel and achetylcholinesterase 2 (AChE2) were analyzed. The esterase, monooxygenase and glutathione-S-transferase (GST) activity of reference susceptible IVRI-I line was determined as 2.47 ± 0.007 nmol/min/mg protein, 0.089 ± 0.0016 nmol/mg of protein and 0.0439 ± 0.0003 nmol/mg/min respectively, which increased significantly in the resistant field isolates. However, except esterases, the fold increase of monooxygenase (1.14-2.27 times) and GST (0.82-1.53 times) activities were not very high. A cytosine (C) to adenine (A) nucleotide substitution (CTC to ATC) at position 190 in domain II S4-5 linker region was detected only in one isolate (SUL) having RF of 34.9 and in the reference deltamethrin resistant line (IVRI-IV). However, the T2134A mutation was not detected in domain IIIS6 transmembrane segment of resistant isolates and also in reference IVRI-IV line despite of varying degree of resistance. The flumethrin specific G215T and the recently identified T170C mutations were also absent in domain II sequences under study. Four novel amino acid substitutions in AChE2 gene of field isolates and in organophosphate (OP) resistant reference IVRI-III line were identified which can possibly have a role in resistance development.

Long-term toxic effects of deltamethrin and fenvalerante in soil

In this study, the long-term toxic effects of pyrethroids on the earthworm Eisenia fetida were evaluated. Earthworms were exposed to moist filter paper and soil for 14 days to evaluate the survival, exposed to soil for 56 days to assess the reproductive success and for 28 days to identify the cytotoxicity. Results showed that the earthworm survival rate decreased with increasing the concentration of either deltamethrin or fenvalerate in both filter paper test and soil test. No worms survived at 602.15 μg cm(-2) of deltamethrin and 0.86 μg cm(-2) of fenvalerate in the filter paper test, however 100-125 mg kg(-1) of both chemicals resulted in the maximum mortality of 90% in the soil test. The CYP3A4 enzyme activity responded significantly to deltamethrin and fenvalerante in soil at low concentration levels, however, the toxicity response of worms under the long-term exposure conflicted with the degradation of deltamethrin and fenvalerate in soil, indicating the possible formation of more toxic pyrethroid metabolites. This study gave an insight into the toxicological effects profile of pyrethroids for a better risk assessment of pyrethroids deltamethrin and fenvalerante in soil.

Biomonitoring of pyrethroid exposure among rural and urban populations in northern Poland

The aim of this study was to determine for the first time in Poland, levels of exposure to synthetic pyrethroids in preschool and school age children and their parents living in urban and rural areas. For this purpose concentrations of pyrethroid metabolites: 3-phenoxybenzoic acid (3-PBA), 2,2-dibromovinyl-2,2-dimethylcyclopropanecarboxylic acid (Br2CA), cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (cis-Cl2CA) and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (trans-Cl2CA) were determined in 374 urine samples using a validated GC-MS method. All measured metabolites were detected more frequently and in higher concentrations in rural areas. 3-PBA was detected in 77.4% and 93.8% of samples from urban and rural areas, respectively. Its geometric mean (GM) concentration in rural population was higher than in urban (0.364 vs. 0.223 ng mL(-1) and 0.272 vs. 0.155 μg g(-1) creatinine, p<0.0001). Among remaining metabolites, only cis- and trans-Cl2CA were detected in more than 50.0% of samples in rural population. Average concentrations of 3-PBA in children were higher than in adults, both in urban and rural areas. Moderate to very strong positive correlations were noticed between concentrations of pairs of pyrethroid metabolites in urine samples. Significant, moderate correlations between the concentrations of particular metabolites in parents and their children were observed in the urban population (range: r=0.2911-0.3919 for non-adjusted and 0.3827-0.4693 for creatinine adjusted concentrations), while in rural areas there were no such relationship. Application of pesticide formulations on pets in the past 6 months was associated with increased 3-PBA urinary concentration. Further studies on pesticide exposure among children in rural areas are needed to identify and possibly reduce or eliminate the sources of exposure.

Molecular interaction of fenvalarate with actin

The structure of α-Cyano-3-phenoxybenzyl-2-(4-chlorophenyl)-3-methylbutyrate (Fenvalarate) has been established by X-ray crystallography to understand the structure-activity relationship, which is of paramount importance in the toxicological studies of the compound. Fenvalarate is stabilized by intermolecular C-H…O, C-H…Cl, C-H…π and C-H…N interactions which are responsible for the stability of the compound and its interaction with the Actin. The crystallographic coordinates of the compound was extrapolated to docking studies to elucidate the action of fenvalarate against neural cytoskeletal protein of insect and mammalian β-actin. A strong affinity was observed in binding of fenvalarate with insect β-actin (-7.71kcal/mol, Ki = 2.23µM) indicating it as a potent insecticide and moderate toxicity towards mammalian β-actin (-7.07kcal/mol, Ki=6.54µM).

DELTAMETHRIN IMPREGNATED MOSQUITO NETS : AN EXPERIMENTAL STUDY IN AN AIR FORCE STATION IN CENTRAL INDIA (DELTAMETHRIN TRIAL)

An experimental study was carried out to determine the efficacy of deltamethrin impregnated mosquito nets in reducing malaria incidence under field conditions in an Air Force Station. Out of the total study population of 748 airmen and DSC personnel, 320 got their mosquito nets impregnated with deltamethrin, while 428 used unimpregnated mosquito nets. During the three months observation period, there was no significant difference in malaria incidence among the two groups (Yates Chi Sq=0.05, p=0.829405, Relative risk = 0.96 with 95% CI between 031 and 2.98). In view of study findings, it was concluded that in the station, use of deltamethrin impregnated mosquito nets will not reduce incidence of malaria appreciably, the stress has to be on outdoor personal protective measures.