Analytical method for the determination of urinary 3-phenoxybenzoic acid in subjects occupationally exposed to pyrethroid insecticides

Association between pyrethroids and prostate endpoints; stratified according to renal function

BACKGROUND

Pyrethroids, one of the most commonly used pesticide classes, are considered to be selectively toxic toward insects rather than toward humans. However, there are accumulating data about pyrethroids toxicity in humans, especially sex organs. Thus, we investigated whether pyrethroids affected reproductive organs, especially the prostate gland.

METHODS

With 1305 subjects who participated in the National Health and Nutrition Examination Survey, several measurements were performed: 3-phenoxybenzoic acid (3-PBA), a common metabolite of pyrethroids; prostate-specific antigen (PSA); and other covariates. Both logistic and linear regression analyses were performed after stratifying according to kidney function, which was evaluated based on the estimated glomerular filtration rate (eGFR).

RESULTS

By logistic regression, the ORs (95% CIs) of the highest quantile to the reference group for higher total PSA were 2.039 (1.018 - 4.084) in the total study population and 2.219 (1.083-4.548) in the high eGFR group. The ORs (95% CIs) of the highest quantile to the reference group for a lower PSA ratio were 1.979 (1.057 - 3.707) in the total study population and 2.101 (1.086 - 4.064) in the high eGFR group. By linear regression, a marginally significant positive correlation between urinary 3-PBA and total PSA (β ± Standard Error = 0.049 ± 0.026, p = 0.0712) and a significant positive correlation between urinary 3-PBA and PSA ratio (β ± Standard Error = 0.018 ± 0.007, p = 0.0191) among the low eGFR group were observed.

CONCLUSION

This study showed that exposure to pyrethroids was associated with either increased levels of total PSA or alterations in the PSA ratio.

Detection of 3-phenoxybenzoic acid in river water with a colloidal gold-based lateral flow immunoassay

3-Phenoxybenzoic acid (3-PBA) is a general metabolite of synthetic pyrethroids. It could be used as a generic biomarker for multiple pyrethroids exposure for human or pyrethroid residues in the environment. In this study, monoclonal antibodies (mAbs) against 3-PBA were developed by using PBA-bovine serum albumin (BSA) as an immunogen. In the competitive enzyme-linked immunosorbent assay (ELISA) format, the I50 and I10 values of purified mAbs were 0.63 and 0.13 μg/ml, respectively, with a dynamic range between 0.19 and 2.04 μg/ml. Then, the colloidal gold (CG)-based lateral flow immunoassay was established based on the mAbs. The working concentration of coating antigen and CG-labeled antibodies and the blocking effects were investigated to get optimal assay performance. The cutoff value for the assay was 1 μg/ml 3-PBA, and the detection time was within 10 min. A total of 40 river water samples were spiked with 3-PBA at different levels and determined by the lateral flow immunoassay without any sample pretreatments. The negative false rate was 2.5%, and no positive false results were observed at these levels. This lateral flow immunoassay has the potential to be an on-site screening method for monitoring 3-PBA or pyrethroid residues in environmental samples.

Hippocampal ER stress and learning deficits following repeated pyrethroid exposure

Endoplasmic reticulum (ER) stress is implicated as a significant contributor to neurodegeneration and cognitive dysfunction. Previously, we reported that the widely used pyrethroid pesticide deltamethrin causes ER stress-mediated apoptosis in SK-N-AS neuroblastoma cells. Whether or not this occurs in vivo remains unknown. Here, we demonstrate that repeated deltamethrin exposure (3 mg/kg every 3 days for 60 days) causes hippocampal ER stress and learning deficits in adult mice. Repeated exposure to deltamethrin caused ER stress in the hippocampus as indicated by increased levels of C/EBP-homologous protein (131%) and glucose-regulated protein 78 (96%). This was accompanied by increased levels of caspase-12 (110%) and activated caspase-3 (50%). To determine whether these effects resulted in learning deficits, hippocampal-dependent learning was evaluated using the Morris water maze. Deltamethrin-treated animals exhibited profound deficits in the acquisition of learning. We also found that deltamethrin exposure resulted in decreased BrdU-positive cells (37%) in the dentate gyrus of the hippocampus, suggesting potential impairment of hippocampal neurogenesis. Collectively, these results demonstrate that repeated deltamethrin exposure leads to ER stress, apoptotic cell death in the hippocampus, and deficits in hippocampal precursor proliferation, which is associated with learning deficits.

Amelioration of prallethrin-induced oxidative stress and hepatotoxicity in rat by the administration of Origanum majorana essential oil

This study was carried out to evaluate the adverse effects of exposure to prallethrin on oxidant/antioxidant status and liver dysfunction biomarkers and the protective role of Origanum majorana essential oil (EO) in rat. Male rats were divided into 4 groups: (i) received only olive oil (ii) treated with 64.0 mg/kg body weight prallethrin (1/10 LD₅₀) in olive oil via oral route daily for 28 days, (iii) treated with 64.0 mg/kg body weight prallethrin (1/10 LD₅₀) and EO (160 μL/kg b.wt.) in olive oil and (iv) received EO (160 μL/kg b.wt.) in olive oil via oral route twice daily for 28 days. Prallethrin treatment caused decrease in body weight gain and increase in relative liver weight. There was a significant increase in the activity of serum marker enzymes, aspartate transaminase, alanine transaminase, and alkaline phosphatase. It caused increase in thiobarbituric acid reactive substances and reduction in the activities of superoxide dismutase, catalase, and glutathione-S-transferase in liver. Consistent histological changes were found in the liver of prallethrin treatment. EO showed significant protection with the depletion of serum marker enzymes and replenishment of antioxidant status and brought all the values to near normal, indicating the protective effect of EO. We can conclude that prallethrin caused oxidative damage and liver injury in male rat and co-administration of EO attenuated the toxic effect of prallethrin. These results demonstrate that administration of EO may be useful, easy, and economical to protect human against pyrethroids toxic effects.

The relation between dietary habits and urinary levels of 3-phenoxybenzoic acid, a pyrethroid metabolite

Concerns about pesticide exposure through food consumption have increased during the past several years. Pyrethroids are applied as insecticides throughout the world. Human metabolism of pyrethroids results in urinary metabolites that are suitable for biological monitoring. The objective of our study was to investigate the relation between food consumption and urinary levels of 3-phenoxybenzoic acid (3-PBA), a general metabolite of pyrethroids, in a non-occupational exposed adult population from the IDI-IRCCS, Rome, Italy. Information on socio-demographic characteristics, smoking, diet and self-reported household pesticide exposure was collected. Urinary 3-PBA level of each subject was measured and adjusted by urinary creatinine. We found that people consuming both raw and cooked vegetables five times weekly or more had higher mean levels of 3-PBA in urine (1.03 μg/g creatinine versus 0.52 μg/g creatinine; p=0.009 and 0.99 μg/g creatinine versus 0.58 μg/g creatinine; p=0.01, respectively) than subjects consuming less than five times weekly. In a multivariate model, after adjusting for age, sex, BMI, smoking and household insecticide exposure, high intake of raw vegetables (OR: 5.31; 95%CI: 1.32-21.3) and high intake of cooked vegetables, in particular cruciferous (OR: 4.67; 95%CI: 1.07-20.5) and leafy vegetables (OR: 6.88; 95%CI: 1.50-31.7), were associated with high urine 3-PBA levels (≥0.70 μg/g creatinine). The results of this study suggest that part of the variation in pyrethrois intake is explained by vegetable intake.

Residential pesticide usage in older adults residing in Central California

Information on residential pesticide usage and behaviors that may influence pesticide exposure was collected in three population-based studies of older adults residing in the three Central California counties of Fresno, Kern, and Tulare. We present data from participants in the Study of Use of Products and Exposure Related Behaviors (SUPERB) study (N = 153) and from community controls ascertained in two Parkinson’s disease studies, the Parkinson’s Environment and Gene (PEG) study (N = 359) and The Center for Gene-Environment Studies in Parkinson’s Disease (CGEP; N = 297). All participants were interviewed by telephone to obtain information on recent and lifetime indoor and outdoor residential pesticide use. Interviews ascertained type of product used, frequency of use, and behaviors that may influence exposure to pesticides during and after application. Well over half of all participants reported ever using indoor and outdoor pesticides; yet frequency of pesticide use was relatively low, and appeared to increase slightly with age. Few participants engaged in behaviors to protect themselves or family members and limit exposure to pesticides during and after treatment, such as ventilating and cleaning treated areas, or using protective equipment during application. Our findings on frequency of use over lifetime and exposure related behaviors will inform future efforts to develop population pesticide exposure models and risk assessment.

Urinary concentrations of metabolites of pyrethroid insecticides in the general U.S. population: National Health and Nutrition Examination Survey 1999-2002

BACKGROUND

Pyrethroid insecticides are the most commonly used residential insecticides in the United States.

OBJECTIVES

Our objective was to assess human exposure via biomonitoring to pyrethroid insecticides in a representative sample of the general U.S. population >or= 6 years of age.

METHODS

By using isotope-dilution high-performance liquid chromatography/electrospray chemical ionization/tandem mass spectrometry, we measured five urinary metabolites of pyrethroid insecticides in 5,046 samples collected as a part of the 1999-2002 National Health and Nutrition Examination Survey (NHANES). Univariate, multivariate, and Pearson correlation analyses were performed using SUDAAN and SAS software, incorporating the appropriate sample weights into the analyses. Multivariate analyses included age, sex, race/ethnicity, creatinine, fasting status, and urine collection time as covariates.

RESULTS

We detected 3-phenoxybenzoic acid (3PBA), a metabolite common to many pyrethroid insecticides, in more than 70% of the samples. The least-squares geometric mean (LSGM) concentration (corrected for covariates) of 3PBA and the frequency of detection increased from 1999-2000 (0.292 ng/mL) to 2001-2002 (0.318 ng/mL) but not significantly. Non-Hispanic blacks had significantly higher LSGM 3PBA concentrations than did non-Hispanic whites and Mexican Americans in the 2001-2002 survey period and in the combined 4-year survey periods but not in the 1999-2000 survey period. Children had significantly higher LSGM concentrations of 3PBA than did adolescents in both NHANES periods and than adults in NHANES 1999-2000. Cis- and trans-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid were highly correlated with each other and with 3PBA, suggesting that urinary 3PBA was derived primarily from exposure to permethrin, cypermethrin, or their degradates.

CONCLUSIONS

Pyrethroid insecticide exposure in the U.S. population is widespread, and the presence of its metabolites in the urine of U.S. residents indicates that children may have higher exposures than adolescents and adults.

Urinary excretion of 3-phenoxybenzoic acid in middle-aged and elderly general population of Japan

Limited data are available on the background levels of exposure to synthetic pyrethroid (PYR) in Japan, despite their frequent application for agriculture and indoor extermination and possible effects of chronic and/or low-dose PYR exposure on human health. This study was conducted to describe the level and distribution of one of the major PYR metabolites, 3-phenoxybenzoic acid (3-PBA), in urine samples collected from a general population in Japan. The subjects were 535 individuals (184 men and 351 women; 61.5+/-9.8 years of age, mean+/-S.D.) residing in a town in Hokkaido, a dairy and agricultural area. Urinary 3-PBA was found detectable in 98% of samples above the limit of detection of 0.02 microg/l. The geometric mean values of urinary 3-PBA in occupationally exposed farmers (n=87) and the remaining general group without occupational exposure (n=448) were 0.38 and 0.29 microg/l, respectively, ranging from <LOD to 17.09 microg/l. No significant differences in urinary 3-PBA concentrations were shown between these two groups. Moreover, 3-PBA concentrations were found comparable to those reported in some countries. The present study is, to our knowledge, the first report of a biological monitoring study of urinary 3-PBA, which elucidated the background environmental exposure level of PYR in the Japanese general population without occupational exposure. Further nationwide studies covering different seasons and age distribution are needed to monitor the urinary 3-PBA levels in Japan.

Cross validation of multiple methods for measuring pyrethroid and pyrethrum insecticide metabolites in human urine

The objective of our study was to compare three vastly different analytical methods for measuring urinary metabolites of pyrethroid and pyrethrum insecticides to determine whether they could produce comparable data and to determine if similar analytical characteristics of the methods could be obtained by a secondary laboratory. This study was conducted as a part of a series of validation studies undertaken by the German Research Foundation's Committee on the Standardization of Analytical Methods for Occupational and Environmental Medicine. We compared methods using different sample preparation methods (liquid-liquid extraction and solid-phase extraction with and without chemical derivatization) and different analytical detection methods (gas chromatography-mass spectrometry (single quadrupole), gas chromatography-high resolution mass spectrometry (magnetic sector) in both electron impact ionization and negative chemical ionization modes, and high-performance liquid chromatography-tandem mass spectrometry (triple quadrupole) with electrospray ionization). Our cross validation proved that similar analytical characteristics could be obtained with any combination of sample preparation/analytical detection method and that all methods produced comparable analytical results on unknown urine samples.

A liquid chromatography--tandem mass spectrometry multiresidue method for quantification of specific metabolites of organophosphorus pesticides, synthetic pyrethroids, selected herbicides, and deet in human urine

The ability to estimate low-dose human exposure to commonly used pesticides often is requested in epidemiologic studies. Therefore, fast and robust methods are necessary that can measure many analytes in the same sample. We have developed a method for high-throughput analysis of 19 markers of commonly used pesticides in human urine. The analytes were seven specific metabolites of organophosphorus pesticides, five metabolites of synthetic pyrethroids, six herbicides or their metabolites, and one insect repellant. Human urine (2 mL) was spiked with stable isotopically labeled analogues of the analytes, enzymatically hydrolyzed, extracted using solid-phase extraction, concentrated, and analyzed using high-performance liquid chromatography-tandem mass spectrometry. The sample was divided into two portions and analyzed on two different mass spectrometers, one using atmospheric pressure chemical ionization (APCI) and the other using turbo ion spray atmospheric pressure ionization (TIS). All analytes except the pyrethroid metabolites were analyzed using APCI. The detection limits for all analytes ranged from 0.1 to 1.5 ng/mL of urine, with the majority (17) below 0.5 ng/mL. The analytical precision for the different analytes, estimated as both the within-day and between-day variation, was 3-14 and 4-19%, respectively. The extraction recoveries of the analytes ranged from 68 to 114%. The throughput, including calibration standards and quality control samples, is approximately 50 samples a day. However, the analysis time with the TIS application is much shorter, and if only pyrethroid metabolite data are of interest, the throughput can be increased to 100-150 samples/day.

Twenty-four-hour urinary excretion of ten pesticide metabolites in healthy adults in two different areas of Italy (Florence and Ragusa)

The determination of pesticide metabolites in human biological fluids represents an important biomarker of exposure in the general population and exposed workers. In the frame of a prospective study, we measured the 24-h urinary excretion of 10 pesticide metabolites to evaluate non-occupational exposure to pesticides in the general population in two different areas in Italy. We collected 24-h urine samples from 69 healthy adults residing in Florence (Central Italy, n = 51) and Ragusa (Southern Italy, n = 18). The volunteers (25 males, 44 females; mean age 56 years) did not report any occupational exposure. We measured: six alkylphosphates, aspecific metabolites of organophosphorus pesticides [dimethylphosfate (DMP), dimethylthiophosfate (DMTP), dimethyldithiophosfate (DMDTP), diethylphosfate (DEP), diethylthiophosfate (DEDP), and diethyldithiophosfate (DEDTP)]; 3,5,6-trichloro-2-pyridinol (TCP), the main metabolite of chlorpyrifos; 3-phenoxybenzoic acid (3-PBA), a metabolite of pyrethroid insecticides; ethylenethiourea (ETU) a metabolite of ethylenebisdithiocarbamates; methamidophos (METH), an organophosphorus insecticide. We also measured PABA excretion as compliance marker (mean recovery 95%). Dimethylphosphates were found in detectable concentrations in the majority of samples (89.9%, 82.6% and 60.9% for DMP, DMTP and DMDTP, respectively). Urinary diethylphosphates (DEP, DETP, DEDTP) concentrations were above the detection limit in 80.9%, 61.8% and 27.5% of samples, respectively. TCP, 3-PBA and ETU were detected in 78.3%, 53.6% and 21.7% of samples, respectively. Methamidophos was detected in two samples (2.8%). The median number of metabolites detected in the same urine sample was 6 (range 0-9). Excretion levels were highest for alkylphosphates, particularly for DMTP (median: 142.6 nmol/day). Multivariate analysis showed statistically significant differences between these two groups of adults, with higher mean values of urinary excretion of alkylphosphates, TCP and ETU in Florence in comparison to Ragusa. Overall, a very high percentage of 24-h urine samples positive for several pesticide metabolites emerged, with higher levels of urinary daily excretion in subjects residing in the more urbanised area. Our results suggest that food monitoring programs should be supported by general campaigns aimed to reduce the use of pesticides in agriculture.

Analytical methods for biological monitoring of exposure to pesticides: a review

Synthetic pesticides have been used since in the early to mid twentieth century. In the US alone, over 800 pesticide active ingredients are formulated in about 21,000 different commercial products. Although many public health benefits have been realized by the use of pesticides, their potential impact on the environment and public health is substantial. For risk assessment studies, exposure assessment is an integral component, which has unfortunately, often been weak or missing. In the past several decades, researchers have proposed to fill these missing data gaps using biological monitoring of specific markers related to exposures. In this paper, we present a review of existing analytical methodology for the biological monitoring of exposure to pesticides. We also present a critical assessment of the existing methodology and explore areas in which more research is needed.

Evaluation of respiratory and cutaneous doses of chlorothalonil during re-entry in greenhouses

Five female workers were monitored for 5 consecutive days during re-entry into a greenhouse containing ornamental plants. Skin contamination (excluding hands) was evaluated with nine pads of filter paper placed on the skin. Hand contamination was assessed by washing with 95% ethanol. Respiratory exposure was evaluated by personal air sampling. The respiratory dose was based on a lung ventilation of 15 l/min. The doses absorbed were estimated assuming 10% skin absorption and 100% lung retention. Dislodgeable foliar residue was determined on days of re-entry to evaluate the decay of chlorothalonil. Chlorothalonil was analysed in the different matrices by GC-MS. Respiratory exposure was less than skin contamination, being 11.4+/-5.1% (mean+/-SD) of total exposure. The estimated total absorbed dose did not exceed the acceptable daily intake of 0.03 mg/kg body mass. The hands and unexposed skin of all workers were always found to be contaminated. Greater precautions are therefore needed to reduce skin exposure (clean gloves and suitable clean clothing every day).

New gas chromatographic-mass spectrometric method for the determination of urinary pyrethroid metabolites in environmental medicine

We have developed and validated a new, reliable and very sensitive method for the determination of the urinary metabolites of the most common pyrethroids in one analytical run. After acidic hydrolysis for the cleavage of conjugates, the analytes cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (cis-Cl(2)CA), trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (trans-Cl(2)CA), cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (Br(2)CA), 4-fluoro-3-phenoxybenzoic acid (F-PBA) and 3-phenoxybenzoic acid (3-PBA) were extracted from the matrix with a liquid-liquid extraction procedure using n-hexane under acidic conditions. For further clean-up, NaOH was added to the organic phase and the carboxylic acids were re-extracted into the aqueous phase. After acidification and extraction into n-hexane again, the metabolites were then derivatised to volatile esters using N-tert.-butyldimethylsilyl-N-methyltrifluoroacetamid (MTBSTFA). Separation and detection were carried out using capillary gas chromatography with mass-selective detection (GC-MS). 2-Phenoxybenzoic acid (2-PBA) served as internal standard for the quantification of the pyrethroid metabolites. The limit of detection for all analytes was 0.05 microg/l urine. The RSD of the within-series imprecision was between 2.0 and 5.4% at a spiked concentration of 0.4 microg/l and the relative recovery was between 79.3 and 93.4%, depending on the analyte. This method was used for the analysis of urine samples of 46 persons from the general population without known exposure to pyrethroids. The metabolites cis-Cl(2)CA, trans-Cl(2)CA and 3-PBA could be found in 52, 72 and 70% of all samples with median values of 0.06, 0.11 and 0.16 microg/l, respectively. Br(2)CA and F-PBA could also be detected in 13 and 4% of the urine samples.

Biological monitoring of pesticide exposure: a review of analytical methods

A wide range of studies concerned with analytical methods for biological monitoring of exposure to pesticides is reviewed. All phases of analytical procedures are assessed, including sampling and storage, sample preparation and analysis, and validation of methods. Most of the studies aimed at measuring metabolites or unchanged compounds in urine and/or blood as biological indicators of exposure or dose. Biological indicators of effect, such as cholinesterase, are also evaluated. The principal groups of pesticides are considered: organophosphorus pesticides, carbamate pesticides, organochlorine pesticides, pyrethroid pesticides, herbicides, fungicides and other compounds. Choice of the method for biological monitoring of exposure depends on the study population: a detection limit of 1 microg/l or less is required for the general population; higher values are adequate for occupationally exposed subjects. Interpretation of results is also discussed. Since biological indices of exposure are only available for a few compounds, biological reference values, established for the general population, may be used for comparison with levels of professionally exposed subjects.

A solid phase extraction method for the screening and determination of pyrethroid metabolites and organochlorine pesticides in human urine

A screening method has been developed for the determination of 23 organochlorine pesticides (OCPs) and 3-pyrethroid metabolities [cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-(1-cyclopropane) carboxylic acid, cis-3-(2,2-dibromovinyl)-2,2-dimethyl-(1-cyclopropane) carboxylic acid and 3-phenoxybenzoic acid] from human urine. OCPs were directly detected in urine samples while pyrethroid metabolites required acid-induced hydrolysis to convert their conjugates into free acids; all compounds were then cleaned-up/preconcentrated using solid phase extraction. Determination and quantitation was achieved by gas chromatography with a mass spectrometer detector operating in selected ion monitoring mode. Limits of detection varied between 0.1 and 0.3 ng/mL with linear ranges from 0.3 to 700 ng/mL; the precision of the method was high (4.3-7.2%). Recoveries of all analytes from urine samples fortified at levels of 30 ng/mL for each OCP and 15 ng/mL for each pyrethroid metabolite ranged from 88 to 101% (captan gave the lowest recovery). The results obtained from the analysis of real urine samples show the suitability of the proposed method for monitoring people exposed to organochlorine and pyrethroid pesticides.