Isotope dilution high-performance liquid chromatography/tandem mass spectrometry method for quantifying urinary metabolites of atrazine, malathion, and 2,4-dichlorophenoxyacetic acid

Urinary pyrethroid metabolite and hearing threshold shifts of adults in the United States: A cross-sectional study

Hearing loss (HL) is a global health problem with a high prevalence and profound socioeconomic impact. Pyrethroids are one of the most commonly used insecticides. Although previous studies have reported the relationship between pyrethroids and neurotoxicity, little is known about the effect of pyrethroid exposure on the auditory system among the general population. This study is aimed to investigate the association of pyrethroid exposure with hearing threshold shifts of adults in the United States. A total of 726 adults, aged from 20 to 69 years from the 2011-2012 National Health and Nutrition Examination Survey (NHANES) data were included in the study. Urinary 3-phenoxybenzoic acid (3-PBA), a general pyrethroid metabolite, was used as a biomarker for pyrethroid exposure. HL was defined as a pure-tone average (PTA) at 0.5, 1, 2, 4 kHz ≥ 20 dB in the better ear. Analyses by using multivariate linear regressions were conducted to explore the associations of urinary 3-PBA with PTA hearing threshold shifts. There were no statistically significant correlations between Ln-transformed 3-PBA and either low-frequency or high-frequency hearing thresholds after adjusting for age, gender, race/ethnicity, education level, firearm noise exposure, occupational noise exposure, recreational noise exposure, serum cotinine, BMI, hypertension, and diabetes. However, associations of 3-PBA with both low-frequency and high-frequency hearing thresholds depended on age (P interaction < 0.0396 and 0.0017, respectively). Positive associations between Ln-transformed 3-PBA and both low-frequency and high-frequency hearing thresholds were observed in participants aged 20-39 years after adjusting confounders (β = 1.53, 95% CI: 0.04-3.01, and β = 3.14, 95% CI: 0.99-5.29, respectively) with the highest tertile (≥ 0.884 μg/g creatinine) of 3-PBA compared with the lowest tertile (< 0.407 μg/g creatinine). The possibility of interaction between 3-PBA and age on the hearing threshold shifts indicated that pyrethroid insecticides were prone to be more toxic to auditory system in younger adults than in older ones. Further studies will be required to confirm these findings.

Synthesis of C-13-labeled atrazine

Atrazine is a long-lasting herbicide that has been shown to affect hormone levels in amphibians. Using the C-13 labeled atrazine to detect its residue is effective and essential. This study presents three steps for the synthesis of [(13) C3 ]atrazine, which starts from [(13) C]urea, and results in the incorporation of C-13 atoms at the 1, 3 and 5 positions of the S-triazine ring of atrazine. The method prepares the product in an overall yield of 57.6% and chemical purity of 98.6%, for use as an internal standard.

Dissipation and residue of 2,4-D isooctyl ester in wheat and soil

A simple analytical method was developed to determine the 2,4-D isooctyl ester residue in wheat and soil by gas chromatography coupled with electron capture detector. Using the method, the dissipation and residue of 2,4-D isooctyl ester in wheat field was investigated. The average recoveries of 2,4-D isooctyl ester ranged from 80.1% to 110.0% with relative standard deviations of 2.4% to 16.1%. The pesticide showed a rapid dissipation rate either in wheat seedling or soil, with the half-lives of 1.0 to 3.0 days. The terminal residue results in wheat grain were much lower than the codex MRL (2.0 mg/kg). It could be considered safe to food and environment when using this herbicide for controlling weeds in wheat field.

[Biomonitoring of human exposure to triazine herbicides]

Triazine herbicides are very common and only 0.1 % reach the target pests, while the rest moves into other environmental compartments. Their fate in the environment depends on their movement through the air, water, and soil and on the rate of their degradation or transformation. Triazine compounds may be transformed by water, microorganisms, and sunlight. Widespread use and persistence of triazine herbicides in soil has resulted in contamination of surface, drinking, and even rain water with parent compounds and degradation products, posing a risk to the general population.The metabolism and effects of triazine herbicides have been studied in experimental animals and in experiments in vitro. There are only a few studies of their metabolism and excretion in humans. Agricultural and manufacturing workers are exposed to triazines during application and production. Human exposure is monitored by determining parent compounds and their metabolites in urine. Due to the low concentrations of urinary metabolites in occupationally exposed persons, very sensitive analytical methods are required. This paper describes the structure and properties of symmetric triazine herbicides, their metabolism, and effects in humans and animals and the levels of these compounds in the urine of occupationally exposed persons.

Review of pesticide urinary biomarker measurements from selected US EPA children's observational exposure studies

Children are exposed to a wide variety of pesticides originating from both outdoor and indoor sources. Several studies were conducted or funded by the EPA over the past decade to investigate children’s exposure to organophosphate and pyrethroid pesticides and the factors that impact their exposures. Urinary metabolite concentration measurements from these studies are consolidated here to identify trends, spatial and temporal patterns, and areas where further research is required. Namely, concentrations of the metabolites of chlorpyrifos (3,5,6-trichloro-2-pyridinol or TCPy), diazinon (2-isopropyl-6-methyl-4-pyrimidinol or IMP), and permethrin (3-phenoxybenzoic acid or 3-PBA) are presented. Information on the kinetic parameters describing absorption and elimination in humans is also presented to aid in interpretation. Metabolite concentrations varied more dramatically across studies for 3-PBA and IMP than for TCPy, with TCPy concentrations about an order of magnitude higher than the 3-PBA concentrations. Temporal variability was high for all metabolites with urinary 3-PBA concentrations slightly more consistent over time than the TCPy concentrations. Urinary biomarker levels provided only limited evidence of applications. The observed relationships between urinary metabolite levels and estimates of pesticide intake may be affected by differences in the contribution of each exposure route to total intake, which may vary with exposure intensity and across individuals.

Chromatographic quantitation at losses of analyte during sample preparation

Known methods of quantitative chromatographic analysis (calibration, external standard, internal standard and standard addition) require the application of sample preparation techniques without significant losses of analytes. If this condition cannot be satisfied, the compensation of these losses should be provided. The modification of known method of quantitative chromatographic analysis (double internal standard), implying the addition of two homologues (previous and following) of target analytes as internal standards into initial samples is considered. This approach permits us to compensate significant losses both analytes and standards at all stages of sample preparation. The advantages of this method are demonstrated on the examples of liquid-liquid extraction, head space analysis (HSA), distillation of volatile compounds with volatile solvents (concentration in condensates) and evaporation of volatile solvents (concentrating in the residues of solvents). In all cases the application of two homologues as internal standards provides accurate results (the typical relative errors are within 1-6%) at the values of a factor of composition distortion of initial samples (K', the definition is suggested) from 0.2 up to 4. These results are in accordance with general relationships between variations in any physicochemical properties of organic compounds within homologous series. The single found exception was the evaporation of volatile solvents (the open phase transition process) when to get the results with relative errors not more then +10% requires the minimal changes in the composition of initial samples (K' values should not be more then approximately 1.5).

Analytical Methods of Biological Monitoring for Exposure to Pesticides: Recent Update

Extensive use of synthetic pesticides for agricultural and nonagricultural purposes began in the past 50 years. As a result of their wide and extensive application, exposure to hazardous pesticides is a concern to the general population and occupationally exposed persons. Robust methods are therefore needed for measuring markers of pesticide exposure. This article presents a review of the most recently published analytical methodologies and instrumentations developed for and applied to biological monitoring of exposure to pesticides of various classes. Most of the methods reviewed here are based on chromatography combined with mass spectrometry detection. This work clearly demonstrates that although gas chromatography still appears to be the most widely employed technique for pesticide analysis in various biological samples, recently a trend has been observed toward the use of liquid chromatography coupled with tandem mass spectrometry.

Matrix effects in quantitative pesticide analysis using liquid chromatography-mass spectrometry

Combined liquid chromatography-mass spectrometry using electrospray or atmospheric-pressure chemical ionization has become an important tool in the quantitative analysis of pesticide residues in various matrices in relation to environmental analysis, food safety, and biological exposure monitoring. One of the major problems in the quantitative analysis using LC-MS is that compound and matrix-dependent response suppression or enhancement may occur, the so-called matrix effect. This article reviews issues related to matrix effects, focusing on quantitative pesticide analysis, but also paying attention to expertise with respect to matrix effects acquired in other application areas of LC-MS, especially quantitative bioanalysis in the course of drug development.

Potential uses of biomonitoring data: a case study using the organophosphorus pesticides chlorpyrifos and malathion

BACKGROUND

Organophosphorus pesticides such as chlorpyrifos and malathion are widely used insecticides. They do not bioaccumulate appreciably in humans and are rapidly metabolized and excreted in the urine. In nonoccupational settings, exposures to these pesticides are typically sporadic and short-lived because the pesticides tend to degrade in the environment over time; however, dietary exposures may be more chronic. Biologic monitoring has been widely used to assess exposures, susceptibility, and effects of chlorpyrifos and malathion; thus, the information base on these compounds is data rich. For biomonitoring of exposure, chlorpyrifos and malathion have been measured in blood, but most typically their urinary metabolites have been measured. For assessing early effects and susceptibility, cholinesterase and microsomal esterase activities, respectively, have been measured.

OBJECTIVES

Although many biologic monitoring data have been generated and published on these chemicals, their interpretation is not straightforward. For example, exposure to environmental degradates of chlorpyrifos and malathion may potentially increase f urinary metabolite levels, thus leading to overestimation of exposure. Also, the temporal nature of the exposures makes the evaluation of both exposure and effects difficult. We present an overview of the current biomonitoring and other relevant data available on exposure to chlorpyrifos and malathion and the use of these data in various environmental public health applications.

Environmental pyrethroid and organophosphorus insecticide exposures and sperm concentration

BACKGROUND

There is growing concern that poisoning and other adverse health effects are increasing because organophosphorous (OP) insecticides are now being used in combination with pyrethroid (PYR) insecticides to enhance the toxic effects of PYR insecticides on target insects, especially those that have developed PYR resistance.

OBJECTIVES

We conducted a pilot biomonitoring study to determine whether men in our reproductive cohort study were being exposed to pesticides environmentally by virtue of frequenting an agricultural setting.

METHODS

We screened 18 randomly selected urine samples collected from male participants of reproductive age for 24 parent compounds and metabolites of pesticides and examined the results in relation to sperm concentration.

RESULTS

Results showed high prevalence of exposure to OP and PYR pesticides and our preliminary analyses provided some suggestion that the higher exposure group had lower sperm concentration.

CONCLUSIONS

The potential of OP/PYR mixtures to have enhanced human toxicity needs more research attention.

Nonpersistent pesticide exposure self-report versus biomonitoring in farm pesticide applicators

PURPOSE

Few studies using biologic markers to examine nonpersistent pesticide exposure among pesticide applicators were conducted in field settings. This study compares self-reported dermal, inhalation, and ingestion exposures with urinalysis results after one-time application of the commonly used herbicide atrazine to field crops. It was hypothesized that: i) applicator reports of exposure would be associated positively with detection of urinary atrazine metabolites, and ii) applicator reports of personal-protective-equipment (PPE) use would be associated negatively with detection of urinary atrazine metabolites.

METHODS

Wisconsin dairy farmers were randomly selected to participate in 1997 to 1998 and were instructed to collect a urine sample 8 hours after the first pesticide application of the season. Farmers then were interviewed within 1 week of their first application to report on application practices. Eighty-six urine samples were analyzed for deethylatrazine, a major atrazine metabolite.

RESULTS

Comparing urinalysis results with self-reported dermal, inhalation, and ingestion exposure showed poor agreement between self-reported exposure and urinary deethylatrazine detections (all kappa < 0.40). Multivariate linear regression modeling with deethylatrazine level as the outcome showed that self-reported practices did not significantly predict atrazine metabolite levels.

CONCLUSIONS

Possible explanations for the discrepancies between urinalysis results and self-reported data include: i) inaccuracies in self-reported data and ii) substantial interpersonal variation in atrazine metabolism, resulting in major differences in body burden for similar exposures. Either explanation poses challenges for epidemiologic studies of the health effects of pesticides, which rely solely on self-reported measures of exposure. Additional evaluation of determinants of accuracy in self-assessed occupational and environmental exposures is needed.

Semen quality in fertile US men in relation to geographical area and pesticide exposure

We conducted the first US study to compare semen quality among study centres using standardized methods and strict quality control. We present data on semen quality in partners of 493 pregnant women recruited through prenatal clinics in four US cities during 1999-2001. Sperm concentration, semen volume and motility were determined at the centres and morphology was assessed at a central laboratory. While between-centre differences in sperm morphology and sample volume were small, sperm concentration and motility were significantly reduced in Columbia, MO (MO) relative to men in New York, NY, Minneapolis, MN and Los Angeles, CA; total number of motile sperm was 113 x 10(6) in MO and 162, 201 and 196 x 10(6) in CA, MN and NY respectively. Differences among centres remained significant in multivariate models that controlled for abstinence time, semen analysis time, age, race, smoking, history of sexually transmitted disease and recent fever (all p-values <0.01). We hypothesized that poorer sperm concentration and motility in MO men relative to other centres might be related to agricultural pesticides that are commonly used in the mid-west. We investigated this hypothesis by conducting a nested case-control study within the MO cohort. We selected 25 men in this cohort for whom all semen parameters (concentration, % normal morphology and % motile) were low as cases and an equal number of men for whom all semen parameters were within normal limits as controls. We measured metabolites of eight non-persistent, current-use pesticides in urine samples the men had provided at the time of semen collection. Pesticide metabolite levels were elevated in cases compared with controls for the herbicides alachlor and atrazine, and for the insecticide diazinon (2-isopropoxy-4-methyl-pyrimidinol) (p-values for Wilcoxon rank test = 0.0007, 0.012, and 0.0004 for alachlor, atrazine and diazinon respectively). Men with higher levels of alachlor or diazinon were significantly more likely to be cases than men with low levels [odds ratios (OR) = 30.0, 16.7 for alachlor and diazinon respectively], as were men with atrazine over the limit of detection (OR = 11.3). These associations between current-use pesticides and reduced semen quality suggest that agricultural chemicals may have contributed to the reduced semen quality seen in fertile men from mid-Missouri.

Quantification of six herbicide metabolites in human urine

We developed a sensitive, selective and precise method for measuring herbicide metabolites in human urine. Our method uses automated liquid delivery of internal standards and acetate buffer and a mixed polarity polymeric phase solid phase extraction of a 2 mL urine sample. The concentrated eluate is analyzed using high-performance liquid chromatography-tandem mass spectrometry. Isotope dilution calibration is used for quantification of all analytes. The limits of detection of our method range from 0.036 to 0.075 ng/mL. The within- and between-day variation in pooled quality control samples range from 2.5 to 9.0% and from 3.2 to 16%, respectively, for all analytes at concentrations ranging from 0.6 to 12 ng/mL. Precision was similar with samples fortified with 0.1 and 0.25 ng/mL that were analyzed in each run. We validated our selective method against a less selective method used previously in our laboratory by analyzing human specimens using both methods. The methods produced results that were in agreement, with no significant bias observed.

Critical review of the application of liquid chromatography/mass spectrometry to the determination of pesticide residues in biological samples

A critical review is made on the use of hyphenated liquid chromatography/mass spectrometry (LC-MS) for the identification and quantification of pesticides and their metabolites in human biosamples (whole blood, plasma, serum and urine). The first applications of LC-MS in this field began in the early 1990s. Since then, increasing interest has been shown in applying this powerful technique, with most applications dealing with the determination of a variety of chemically diverse metabolites in urine. The use of different LC-MS interfaces and mass spectral detection modes are discussed. Special attention is given to tandem mass spectrometry (MS/MS) due to its inherent advantages of increased sensitivity and selectivity, as well as its advantages for identification and confirmation of analytes in samples. Quantification can be severely affected by matrix effects, the most common being inhibition of the ionisation of analytes in the mass spectrometer, which leads to unacceptable errors if no correction is made. Different approaches can be employed to minimise this undesirable matrix effect, the preferred being the use of labelled internal standards (when available) in isotope dilution methods or the application of an efficient clean-up, performed off-line or automated on-line. Adequate criteria for confirming the identities of residues detected are required in order to avoid false positives. The criterion most commonly used with a triple quadrupole instrument is the monitoring of two MS/MS transitions together with the ion abundance ratio. TOF mass analysers are seldom used in pesticide residue analysis despite their improved resolution and mass accuracy characteristics, which makes them very suitable for confirmation purposes. The main reasons for the relative unpopularity of TOF MS in residue analysis are its limited sensitivity and its high acquisition cost. In this paper, we present a critical assessment on current techniques, trends and future developments, and give illustrative examples to point out the main characteristics of LC-MS for pesticide residue analysis in biological fluids.

Environmental and food applications of LC-tandem mass spectrometry in pesticide-residue analysis: an overview

An overview is given on pesticide-residue determination in environmental and food samples by liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS). Pesticides comprise a large number of substances that belong to many completely different chemical groups, the only common characteristic is that they are effective against pests. They still constitute a challenge in MS because there is no collective pathway for fragmentation. A brief introduction to the theory of tandem MS permits a discussion of which parameters influence the ionization efficiency when the ions are subjected to different actions. Emphasis is placed on the different tandem MS instruments: triple and ion-trap quadrupoles, and hybrid quadrupole time-of-flight (Q-TOF), including advantages and drawbacks, typical detection limits, and ion signals at low concentrations. The instrumental setup, as well as LC and mass spectrometric experimental conditions, must be carefully selected to increase the performance of the analytical system. The capacity of each instrument to provide useful data for the identification of pesticides, and the possibility to obtain structural information for the identification of target and non-target compounds, are discussed. Finally, sample preparation techniques and examples of applications are debated to reveal the potential of the current state-of-the-art technology, and to further promote the usefulness of tandem MS.

Assessment of data quality for the NHEXAS--Part II: Minnesota children's pesticide exposure study (MNCPES)

The Minnesota Children's Pesticide Exposure Study (MNCPES) of the National Human Exposure Assessment Survey (NHEXAS) was conducted in Minnesota to evaluate children's pesticide exposure. This study complements and extends the populations and chemicals included in the NHEXAS Region V study. One of the goals of the study was to test protocols for acquiring exposure measurements and developing databases for use in exposure models and assessments. Analysis of the data quality is one element in assessing the performance of the collection and analysis protocols used in this study. Data quality information must also be available to investigators to guide analysis of the study data. During the planning phase of MNCPES, quality assurance (QA) goals were established for precision, accuracy, and quantification limits. The data quality was assessed against these goals. The assessment is complex. First, data are not available for all analytes and media sampled. In addition, several laboratories were responsible for the analysis of the collected samples. Each laboratory provided data according to their standard operating procedures (SOPs) and protocols. Detection limits were authenticated for each analyte in each sample type. The approach used to calculate detection limits varied across the different analytical methods. The analytical methods for pesticides in air, food, hand rinses, dust wipe and urine were sufficiently sensitive and met the QA goals, with very few exceptions. This was also true for polynuclear aromatic hydrocarbons (PAHs) in air and food. The analytical methods for drinking water and beverages had very low detection limits; however, there were very little measurable data for these samples. The collection and analysis methods for pesticides in surface press samples and soil, and for PAHs in dust wipes were not sufficiently sensitive. Accuracy was assessed primarily as recovery from field controls. The results were good for pesticides and PAHs in air (75-125% recovery). Recovery was lower (<75%) for pesticides in drinking water and beverages. The recovery of pesticides from hand rinses met QA goals (75-100%), but surface press samples showed lower recovery (50-70%). Analysis by gas chromatography-mass spectrometry (GC-MS) did not confirm the presence of atrazine and other pesticides in hand rinse and surface press samples that had been detected by GC-ECD, but instead GC-MS confirmed background interferences. Assessment of the precision of sample collection and analysis is based on the percent relative standard deviation (%RSD) between the results for duplicate samples. Data are available only for pesticides and PAHs in air. Precision was good (<20% RSD) for analytes with measurable data. There were a few analytes with %RSD >20%, but the number of data pairs was very small in these cases. Precision for instrumental analysis of food sample extracts was excellent, with the median %RSD < 20 for all measurable pesticides. The median %RSD for the analysis of replicate aliquots of food from the same sample composite was considerably higher, indicating the potential for inhomogeneity of food homogenates.

Semen quality in relation to biomarkers of pesticide exposure

We previously reported reduced sperm concentration and motility in fertile men in a U.S. agrarian area (Columbia, MO) relative to men from U.S. urban centers (Minneapolis, MN; Los Angeles, CA; New York, NY). In the present study we address the hypothesis that pesticides currently used in agriculture in the Midwest contributed to these differences in semen quality. We selected men in whom all semen parameters (concentration, percentage sperm with normal morphology, and percentage motile sperm) were low (cases) and men in whom all semen parameters were within normal limits (controls) within Missouri and Minnesota (sample sizes of 50 and 36, respectively) and measured metabolites of eight current-use pesticides in urine samples provided at the time of semen collection. All pesticide analyses were conducted blind with respect to center and case-control status. Pesticide metabolite levels were elevated in Missouri cases, compared with controls, for the herbicides alachlor and atrazine and for the insecticide diazinon [2-isopropoxy-4-methyl-pyrimidinol (IMPY)]; for Wilcoxon rank test, p = 0.0007, 0.012, and 0.0004 for alachlor, atrazine, and IMPY, respectively. Men from Missouri with high levels of alachlor or IMPY were significantly more likely to be cases than were men with low levels [odds ratios (ORs) = 30.0 and 16.7 for alachlor and IMPY, respectively], as were men with atrazine levels higher than the limit of detection (OR = 11.3). The herbicides 2,4-D (2,4-dichlorophenoxyacetic acid) and metolachlor were also associated with poor semen quality in some analyses, whereas acetochlor levels were lower in cases than in controls (p = 0.04). No significant associations were seen for any pesticides within Minnesota, where levels of agricultural pesticides were low, or for the insect repellent DEET (N,N-diethyl-m-toluamide) or the malathion metabolite malathion dicarboxylic acid. These associations between current-use pesticides and reduced semen quality suggest that agricultural chemicals may have contributed to the reduction in semen quality in fertile men from mid-Missouri we reported previously.

Rapid multiresidue determination of organochlorine and organophosphorus compounds in human serum by solid-phase extraction and gas chromatography coupled to tandem mass spectrometry

A rapid analytical method for the multiresidue determination of several organochlorine and organophosphorus pesticides and polychlorinated biphenyls in human serum samples has been developed. Analytes were isolated by solid-phase extraction using C18 cartridges with subsequent analysis by GC-MS/MS using a glass liner packed with CarboFrit in the GC injection port. Labelled surrogate internal standards (fenitrothion D6, HCB (13)C6, p, p'-DDE D8 and PCB 138 (13)C12) were added to the samples before the extraction and were used for quantitation and for quality control in the analysis of real-world samples. Accuracy and precision were evaluated by using serum samples fortified at two concentration levels for the three families of compounds, with satisfactory results in the majority of cases. The high selectivity and sensitivity of GC-MS/MS allowed low detection limits of 0.05-0.5 ng mL(-1) for most of the analytes investigated. The developed procedure improves other current methodologies for the analysis of pesticides and PCBs in biological fluids, especially as regards to analysis time and simplicity of sample treatment. The method was applied to several serum samples obtained from farmers devoted to citrus crop production. Chlorpyrifos, HCB, p, p'-DDE and the higher chlorinated PCBs (153, 138 and 180) were the most frequently detected compounds.

Application of new high-performance liquid chromatography and solid-phase extraction materials to the analysis of pesticides in human urine

A method for the simultaneous determination of diuron and linuron pesticides in human urine was developed, using both solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) phases made in our own laboratory. These materials were prepared by sorption of polysiloxanes onto a silica surface, followed by immobilization. The HPLC columns were prepared from poly(methyloctylsiloxane), PMOS, immobilized onto silica with microwave radiation while the SPE cartridges where made with poly(methyloctadecylsiloxane), immobilized thermally. Method validation was performed for diuron and linuron for three fortification levels. The recoveries obtained were 85-103%, the inter- and intra-assay precisions were less than 1.6 and 1.8%, respectively. The limits of quantitation and detection for diuron were 2.4 and 8.0 microg/l and for linuron were 5.0 and 12 microg/l, respectively.

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.

Headspace solid-phase microextraction in combination with gas chromatography and tandem mass spectrometry for the determination of organochlorine and organophosphorus pesticides in whole numan blood

A method for the determination of several organochlorine and organophosphorus pesticides in human whole blood samples was developed. The combination of solid-phase microextraction in headspace mode with gas chromatography with tandem mass spectrometry allowed the determination of 11 selected pesticides at ppb levels, minimizing the sample treatment. Quantitation was carried out by means of calibration curves prepared in blood using labelled surrogate/internal standards. The method showed good linearity between 1 and 50 ng ml(-1) (0.5-25 ng ml(-1) for HCB) using second-order calibration curves. Precision was found to be better than 20% at the three concentration levels assayed in the range of ng ml(-1). The detection limits obtained were in the range 0.02-0.7 ng ml(-1), except for p,p'-DDT (3 ng ml(-1)). The developed procedure was applied to blood and serum samples obtained from agricultural workers. HCB. beta-HCH and p,p'-DDE were most frequently detected in the samples analyzed.

Microwave assisted solvent extraction and coupled-column reversed-phase liquid chromatography with UV detection use of an analytical restricted-access-medium column for the efficient multi-residue analysis of acidic pesticides in soils

A screening method has been developed for the determination of acidic pesticides in various types of soils. Methodology is based on the use of microwave assisted solvent extraction (MASE) for fast and efficient extraction of the analytes from the soils and coupled-column reversed-phase liquid chromatography (LC-LC) with UV detection at 228 nm for the instrumental analysis of uncleaned extracts. Four types of soils, including sand, clay and peat, with a range in organic matter content of 0.3-13% and ten acidic pesticides of different chemical families (bentazone, bromoxynil, metsulfuron-methyl, 2,4-D, MCPA, MCPP, 2,4-DP, 2,4,5-T, 2,4-DB and MCPB) were selected as matrices and analytes, respectively. The method developed included the selection of suitable MASE and LC-LC conditions. The latter consisted of the selection of a 5-microm GFF-II internal surface reversed-phase (ISRP, Pinkerton) analytical column (50 x 4.6 mm, I.D.) as the first column in the RAM-C18 configuration in combination with an optimised linear gradient elution including on-line cleanup of sample extracts and reconditioning of the columns. The method was validated with the analysis of freshly spiked samples and samples with aged residues (120 days). The four types of soils were spiked with the ten acidic pesticides at levels between 20 and 200 microg/kg. Weighted regression of the recovery data showed for most analyte-matrix combinations, including freshly spiked samples and aged residues, that the method provides overall recoveries between 60 and 90% with relative standard deviations of the intra-laboratory reproducibility's between 5 and 25%; LODs were obtained between 5 and 50 microg/kg. Evaluation of the data set with principal component analysis revealed that the parameters (i) increase of organic matter content of the soil samples and (ii) aged residues negatively effect the recovery of the analytes.

Determination of 2,4-dichlorophenoxyacetic acid (2,4-D) in human urine with mass selective detection

Method development and validation studies have been completed on an assay that will allow the determination of 2,4-dichlorophenoxyacetic acid (2,4-D) in human urine. The accurate determination of 2,4-D in urine is an important factor in monitoring worker and population exposure. These studies successfully validated a method for the detection of 2,4-D in urine at a limit of quantitation (LOQ) of 5.00 ppb (parts per billion) using gas chromatography with mass selective detection (GC/MSD). The first study involved the determination of 2,4-D in control human urine and urine samples fortified with 2,4-D. Due to chromatographic interference, a second study was conducted using 14C-2,4-D to verify the recoverability of 2,4-D from human urine at low levels using the GC/MSD method. The second study supports the results of the original data. The 2,4-D was extracted from human urine using a procedure involving hydrolysis using potassium hydroxide, followed by a liquid-liquid extraction into methylene chloride. The extracted samples were derivatized with diazomethane. The methylated fraction was analyzed by GC/MSD. Quantitation was made by comparison to methylated reference standards of 2,4-D. Aliquots fortified at 5-, 50-, and 500-ppb levels were analyzed. The overall mean recovery for all fortified samples was 90.3% with a relative standard deviation of 14.31%.

Simultaneous determination of malathion, permethrin, DEET (N,N-diethyl-m-toluamide), and their metabolites in rat plasma and urine using high performance liquid chromatography

A method was developed for the separation and quantification of the insecticide malathion (O,O-dimethyl-S-(1,2-carbethoxyethyl) phosphorodithioate), its metabolite malaoxon (O,O-dimethyl-S-(1,2-carbethoxyethyl) phosphorothioate), the insecticide permethrin (3-(2,2-dichloro-ethenyl)-2,2-dimethylcyclopropanecarboxylic acid(3-phenoxyphenyl)methylester), two of its metabolites m-phenoxybenzyl alcohol and m-phenoxybenzoic acid, the insect repellent N,N-diethyl-m-toluamide (DEET), and its metabolites m-toluamide and m-toluic acid in rat plasma and urine. The method used high performance liquid chromatography (HPLC) with reversed phase C(18) column, and UV detection at 210 nm. The compounds were separated using gradient of 45--99% acetonitrile in water (pH 3.5) at a flow rate ranging between 0.5 and 2 ml/min in a period of 15 min. The retention times ranged from 7.4 to 12.3 min. The limits of detection ranged between 20 and 100 ng/ml, while limits of quantitation were 50-150 ng/ml. Average percentage recovery of five spiked plasma samples were 80.1+/-4.2, 75.2+/-4.6, 84.5+/-4.0, 84.3+/-3.4, 82.8+/-3.9, 83.9+/-5.5, 82.2+/-6.0, 83.1+/-4.3, and from urine 78.8+/-3.9, 76.4+/-4.9, 82.3+/-4.5, 82.5+/-3.9, 81.4+/-4.0, 83.9+/-4.3, 81.5+/-5.0, and 84.5+/-3.8 for, malathion, malaoxon, DEET, m-toluamide, m-toluic acid, permethrin, m-phenoxybenzyl alcohol, and m-phenoxybenzoic acid, respectively. The method was reproducible and linear over range between 100 and 1000 ng/ml. This method was applied to analyze the above chemicals and metabolites following combined dermal administration in rats.

Investigation of atrazine metabolism in river sediment by high-performance liquid chromatography/mass spectrometry

Microbial degradation processes play an important role in chemical water clearance taking place in river sediments. Bacteria remove not only easily degradable organic species, but various xenobiotics as well, producing clear and xenobiotic free water for bank-filtered wells. Atrazine is a widely used herbicide, and it is one of the most common xenobiotics present in Danube water. In this study the pathway and kinetics of atrazine metabolism of sedimental microbiota were studied. Samples were collected from river sediment and from pure microbial growth cultures. An analytical scheme including sample preparation, chromatography and mass spectrometry was developed and optimised. Solid-phase extraction (SPE) was found to be satisfactory for sample preparation. For qualitative analysis of samples both reversed-phase and normal-phase high-performance liquid chromatography/mass spectrometry (HPLC/MS) methods were developed and used. Selectivity, detection limits and accuracy of the two methods were compared. Using this analytical scheme, the full atrazine metabolism of the organism Comamonas acidovorans was explored. Altogether, 12 metabolites were identified from the original compound to the urea end product. Detection limits in the range of 50 ng L(-1)-1 microg L(-1) were obtained for different metabolites.

Urinalysis of atrazine exposure in farm pesticide applicators

This study compared three relatively common laboratory methods for the detection of atrazine (a triazine herbicide commonly used in US agriculture), and related metabolites in urine. Ninety-nine samples collected from atrazine applicators within 8 h post application were analyzed. Thirty-seven percent of applicators showed detectable levels (minimum = 1.0 ng/ml) of deethylatrazine (an atrazine metabolite typically found in environmental samples) in their urine, based on gas chromatography-mass spectrometry (GC-MS) analysis (mean = 14.2 ng/ml). Fifty applicator samples were tested using an enzyme-linked immunosorbent assay (ELISA) designed for the mercapturate metabolic product. Most of these samples (80%) had detectable levels of the mercapturate product. A triazine in water ELISA was also used to test several diluted urine samples from atrazine applicators, and all samples were positive for triazines. Mediocre agreements between the three methods indicated that each detected distinct atrazine exposure products. The results indicate that single field applications of atrazine result in measurable pesticide doses to applicators and that the choice of field assay should depend on the exposure product to be evaluated.