Analytical Methods - HH-RA.org

Bibliography Tag: analytical methods

Larsson et al., 2017

Larsson, M. O., Nielsen, V. S., Brandt, C. O., Bjerre, N., Laporte, F., & Cedergreen, N.; “Quantifying dietary exposure to pesticide residues using spraying journal data;” Food and Chemical Toxicology, 2017, 105, 407-428; DOI: 10.1016/j.fct.2017.05.014.

ABSTRACT:

Relatively few studies are available on the combined risk of realistic dietary pesticide exposure. Despite available studies showing low risk, public concern remains. Recent methods used to estimate realistic exposure levels have a number of drawbacks, and better methods are needed. Using a novel approach, we estimated the combined exposure in the Danish population, resulting from pesticide usage in Danish agriculture. The complete Danish spraying journal data from 2014, and supervised trial residue levels reported by EFSA, were used in combination, generating residue estimates in 25 crops. Cumulative risk assessments were made for six typical Danish consumer diets. In terms of intake of cereals, sugar, fruits and vegetables, the 25 crops included accounted 70% of the diets of Danish consumers. The Hazard Index (HI) method was used to assess the consumer risk. Despite the conservative (cautious) approach, low HI values where obtained. Highest HI was 14% of the Acceptable Daily Intake (ADI) for Children. The main advantages of the new exposure estimation method are 1) comprehensive use data not relying on random samples, 2) coverage of all pesticides used, and 3) more precise estimates of residues that are below the standard reporting limits in the national monitoring program. FULL TEXT

Sieke et al., 2018

Sieke, C., Michalski, B., & Kuhl, T.; “Probabilistic dietary risk assessment of pesticide residues in foods for the German population based on food monitoring data from 2009 to 2014;” Journal of Exposure Analysis and Environmental Epidemiology, 2018, 28(1), 46-54; DOI: 10.1038/jes.2017.7.

ABSTRACT:

Dietary risks for the German population owing to pesticide residues in foods were assessed based on food monitoring data, consumption surveys for children and adults and compound specific toxicological reference values or general thresholds of toxicological concern. A tiered probabilistic modelling was conducted to screen 700 pesticides for significant long- and short-term dietary exposures. Especially for the short-term dietary exposure, the probabilistic methodology used allows simultaneous consideration of the complete daily consumption, whereas most regulatory bodies still rely on single commodity approaches. After screening, refined exposure assessments were conducted for 19 compounds under consideration of conversion factors for toxicologically relevant metabolites, processing information, experimentally derived variability factors and the edible portion for each food item. In total, for 693 compounds the dietary exposure was unlikely to present a chronic or acute public health concern for the German population. In contrast, the refined assessments indicate that the short-term dietary exposure for chlorpyrifos and the cumulative short-term dietary exposure for dimethoate and omethoate may present a public health concern. For copper, owing to exposure assessment limitations, as well as for dimethylvinphos, halfenprox and tricyclazole, which exceeded the thresholds of toxicological concern, the dietary risk assessment remained inconclusive. FULL TEXT

Thomas et al., 2010b

Thomas, K. W., Dosemeci, M., Coble, J. B., Hoppin, J. A., Sheldon, L. S., Chapa, G., Croghan, C. W., Jones, P. A., Knott, C. E., Lynch, C. F., Sandler, D. P., Blair, A. E., & Alavanja, M. C.; “Assessment of a pesticide exposure intensity algorithm in the agricultural health study;” Journal of Exposure Analysis and Environmental Epidemiology, 2010, 20(6), 559-569; DOI: 10.1038/jes.2009.54.

ABSTRACT:

The accuracy of the exposure assessment is a critical factor in epidemiological investigations of pesticide exposures and health in agricultural populations. However, few studies have been conducted to evaluate questionnaire-based exposure metrics. The Agricultural Health Study (AHS) is a prospective cohort study of pesticide applicators who provided detailed questionnaire information on their use of specific pesticides. A field study was conducted for a subset of the applicators enrolled in the AHS to assess a pesticide exposure algorithm through comparison of algorithm intensity scores with measured exposures. Pre- and post-application urinary biomarker measurements were made for 2,4-D (n=69) and chlorpyrifos (n=17) applicators. Dermal patch, hand wipe, and personal air samples were also collected. Intensity scores were calculated using information from technician observations and an interviewer-administered questionnaire. Correlations between observer and questionnaire intensity scores were high (Spearman’s r=0.92 and 0.84 for 2,4-D and chlorpyrifos, respectively). Intensity scores from questionnaires for individual applications were significantly correlated with post-application urinary concentrations for both 2,4-D (r=0.42, P<0.001) and chlorpyrifos (r=0.53, P=0.035) applicators. Significant correlations were also found between intensity scores and estimated hand loading, estimated body loading, and air concentrations for 2,4-D applicators (r-values 0.28-0.50, P-values<0.025). Correlations between intensity scores and dermal and air measures were generally lower for chlorpyrifos applicators using granular products. A linear regression model indicated that the algorithm factors for individual applications explained 24% of the variability in post-application urinary 2,4-D concentration, which increased to 60% when the pre-application urine concentration was included. The results of the measurements support the use of the algorithm for estimating questionnaire-based exposure intensities in the AHS for liquid pesticide products. Refinement of the algorithm may be possible using the results from this and other measurement studies. FULL TEXT

Hoppin et al., 2002

Hoppin, J. A., Yucel, F., Dosemeci, M., & Sandler, D. P.; “Accuracy of self-reported pesticide use duration information from licensed pesticide applicators in the Agricultural Health Study;” Journal of Exposure Analysis and Environmental Epidemiology, 2002, 12(5), 313-318; DOI: 10.1038/sj.jea.7500232.

ABSTRACT:

Epidemiologists frequently rely on self-reported information regarding a variety of exposures including smoking history, medication use, and occupational exposure because other sources of information are either unavailable or difficult to obtain. One way to evaluate the accuracy of self-reported information is through logic checks using other sources. To assess the quality of the self-reported pesticide product use history of 57,311 licensed pesticide applicators in the Agricultural Health Study (AHS), we compared the self-reported decade of first use and total years of use to the year the pesticide active ingredient was first registered for use. We obtained pesticide active ingredient registration information from the United States Environmental Protection Agency (USEPA) and other publicly available sources for the 52 pesticides on the AHS initial questionnaires administered from 1994 to 1997. Based on the registration year, we assessed 19 pesticides for potential inaccuracies regarding duration of use or decade of first use. When calculating potential total years of use, we did not consider the impact of chemicals being removed from the market, since the possibility for continued use existed. The majority of respondents provided plausible responses for both decade of first use and total duration of use. On average, 1% of the subjects overestimated total possible duration of use, ranging from less than 1% for carbofuran and chlorpyrifos to 5% for imazethapyr. Decade of first use was also reasonably reported, although more subjects did not report decade of first use than duration of use, with an average of 6% of subjects missing decade information for an individual chemical. For subjects who reported a decade of first use, 98% gave plausible responses on average, with overestimates highest for cyanazine, introduced in 1971 (6% reported earlier use), and chlorimuron ethyl, introduced in 1985 (7% reported earlier use). This analysis provided the opportunity to consider only one source of potential overreporting of exposure, and while underreporting may have also occurred, we cannot evaluate its role nor the balance between these potential inaccuracies. While we are unable to validate directly the accuracy of a respondent’s use of pesticides, this analysis suggests that participants provide plausible information regarding their pesticide use. FULL TEXT

Coble et al., 2011

Coble, J., Thomas, K. W., Hines, C. J., Hoppin, J. A., Dosemeci, M., Curwin, B., Lubin, J. H., Beane Freeman, L. E., Blair, A., Sandler, D. P., & Alavanja, M. C.; “An updated algorithm for estimation of pesticide exposure intensity in the agricultural health study;” International Journal of Environmental Research and Public Health, 2011, 8(12), 4608-4622; DOI: 10.3390/ijerph8124608.

ABSTRACT:

An algorithm developed to estimate pesticide exposure intensity for use in epidemiologic analyses was revised based on data from two exposure monitoring studies. In the first study, we estimated relative exposure intensity based on the results of measurements taken during the application of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) (n = 88) and the insecticide chlorpyrifos (n = 17). Modifications to the algorithm weighting factors were based on geometric means (GM) of post-application urine concentrations for applicators grouped by application method and use of chemically-resistant (CR) gloves. Measurement data from a second study were also used to evaluate relative exposure levels associated with airblast as compared to hand spray application methods. Algorithm modifications included an increase in the exposure reduction factor for use of CR gloves from 40% to 60%, an increase in the application method weight for boom spray relative to in-furrow and for air blast relative to hand spray, and a decrease in the weight for mixing relative to the new weights assigned for application methods. The weighting factors for the revised algorithm now incorporate exposure measurements taken on Agricultural Health Study (AHS) participants for the application methods and personal protective equipment (PPE) commonly reported by study participants. FULL TEXT

Blair et al., 2011

Blair, A., Thomas, K., Coble, J., Sandler, D. P., Hines, C. J., Lynch, C. F., Knott, C., Purdue, M. P., Zahm, S. H., Alavanja, M. C., Dosemeci, M., Kamel, F., Hoppin, J. A., Freeman, L. B., & Lubin, J. H.; “Impact of pesticide exposure misclassification on estimates of relative risks in the Agricultural Health Study;” Occupational and Environmental Medicine, 2011, 68(7), 537-541; DOI: 10.1136/oem.2010.059469.

ABSTRACT:

BACKGROUND: The Agricultural Health Study (AHS) is a prospective study of licensed pesticide applicators and their spouses in Iowa and North Carolina. We evaluate the impact of occupational pesticide exposure misclassification on relative risks using data from the cohort and the AHS Pesticide Exposure Study (AHS/PES).

METHODS: We assessed the impact of exposure misclassification on relative risks using the range of correlation coefficients observed between measured post-application urinary levels of 2,4-dichlorophenoxyacetic acid (2,4-D) and a chlorpyrifos metabolite and exposure estimates based on an algorithm from 83 AHS pesticide applications.

RESULTS: Correlations between urinary levels of 2,4-D and a chlorpyrifos metabolite and algorithm estimated intensity scores were about 0.4 for 2,4-D (n=64), 0.8 for liquid chlorpyrifos (n=4) and 0.6 for granular chlorpyrifos (n=12). Correlations of urinary levels with kilograms of active ingredient used, duration of application, or number of acres treated were lower and ranged from -0.36 to 0.19. These findings indicate that a priori expert-derived algorithm scores were more closely related to measured urinary levels than individual exposure determinants evaluated here. Estimates of potential bias in relative risks based on the correlations from the AHS/PES indicate that non-differential misclassification of exposure using the algorithm would bias estimates towards the null, but less than that from individual exposure determinants.

CONCLUSIONS: Although correlations between algorithm scores and urinary levels were quite good (ie, correlations between 0.4 and 0.8), exposure misclassification would still bias relative risk estimates in the AHS towards the null and diminish study power.

FULL TEXT

Coble et al., 2005

Coble, J., Arbuckle, T., Lee, W., Alavanja, M., & Dosemeci, M.; “The validation of a pesticide exposure algorithm using biological monitoring results;” Journal of Occupational and Environmental Hygiene, 2005, 2(3), 194-201; DOI: 10.1080/15459620590923343.

ABSTRACT:

A pesticide exposure algorithm was developed to calculate pesticide exposure intensity scores based on responses to questions about pesticide handling procedures and application methods in a self-administered questionnaire. The validity of the algorithm was evaluated through comparison of the algorithm scores with biological monitoring data from a study of 126 pesticide applicators who applied the herbicides MCPA or 2,4-D. The variability in the algorithm scores calculated for these applicators was due primarily to differences in their use of personal protective equipment (PPE). Rubber gloves were worn by 75% of applicators when mixing and 22% when applying pesticides, rubber boots were worn by 33% when mixing and 23% when applying, and goggles were worn by 33% and 17% of applicators when mixing and when applying, respectively. Only 2% of applicators wore all three types of PPE when both mixing and applying, and 15% wore none of these three types of PPE when either mixing or applying. Substantial variability was also observed in the concentrations of pesticides detected in the post application urine samples. The concentration of MCPA detected in urine samples collected on the second day after the application ranged from less than < 1.0 to 610 microg/L among 84 of the applicators who applied MCPA. The concentrations of 2,4-D detected in the urine samples ranged from less than < 1.0 to 514 microg/L among 41 of the applicators who applied 2,4-D. When categorized into three groups based on the algorithm scores, the geometric mean in the highest exposure group was 20 microg/L compared with 5 microg/L in the lowest exposure group for the MCPA applicators, and 29 microg/L in highest exposure group compared with 2 microg/L in the low exposure group for the 2,4-D applicators. A regression analysis detected statistically significant trends in the geometric mean of the urine concentrations across the exposure categories for both the 2,4-D and the MCPA applicators. The algorithm scores, based primarily on the use of PPE, appear to provide a reasonably valid measure of exposure intensity for these applicators, however, further studies are needed to generalize these results to other types of pesticides and application methods. FULL TEXT

Thomas et al., 2010

Thomas, K. W., Dosemeci, M., Hoppin, J. A., Sheldon, L. S., Croghan, C. W., Gordon, S. M., Jones, M. L., Reynolds, S. J., Raymer, J. H., Akland, G. G., Lynch, C. F., Knott, C. E., Sandler, D. P., Blair, A. E., & Alavanja, M. C.; “Urinary biomarker, dermal, and air measurement results for 2,4-D and chlorpyrifos farm applicators in the Agricultural Health Study;” Journal of Exposure Science and Environmental Epidemiology, 2010, 20(2), 119-134; DOI: 10.1038/jes.2009.6.

ABSTRACT:

A subset of private pesticide applicators in the Agricultural Health Study (AHS) epidemiological cohort was monitored around the time of their agricultural use of 2,4-dichlorophenoxyacetic acid (2,4-D) and O,O-diethyl-O-3,5,6-trichloro-2-pyridyl phosphorothioate (chlorpyrifos) to assess exposure levels and potential determinants of exposure. Measurements included pre- and post-application urine samples, and patch, hand wipe, and personal air samples. Boom spray or hand spray application methods were used by applicators for 2,4-D products. Chlorpyrifos products were applied using spray applications and in-furrow application of granular products. Geometric mean (GM) values for 69 2,4-D applicators were 7.8 and 25 microg/l in pre- and post-application urine, respectively (P<0.05 for difference); 0.39 mg for estimated hand loading; 2.9 mg for estimated body loading; and 0.37 microg/m(3) for concentration in personal air. Significant correlations were found between all media for 2,4-D. GM values for 17 chlorpyrifos applicators were 11 microg/l in both pre- and post-application urine for the 3,5,6-trichloro-2-pyridinol metabolite, 0.28 mg for body loading, and 0.49 microg/m(3) for air concentration. Only 53% of the chlorpyrifos applicators had measurable hand loading results; their median hand loading being 0.02 mg. Factors associated with differences in 2,4-D measurements included application method and glove use, and, for hand spray applicators, use of adjuvants, equipment repair, duration of use, and contact with treated vegetation. Spray applications of liquid chlorpyrifos products were associated with higher measurements than in-furrow granular product applications. This study provides information on exposures and possible exposure determinants for several application methods commonly used by farmers in the cohort and will provide information to assess and refine exposure classification in the AHS. Results may also be of use in pesticide safety education for reducing exposures to pesticide applicators. FULL TEXT

Dosemeci et al., 2002

Dosemeci, M., Alavanja, M. C., Rowland, A. S., Mage, D., Zahm, S. H., Rothman, N., Lubin, J. H., Hoppin, J. A., Sandler, D. P., & Blair, A.; “A quantitative approach for estimating exposure to pesticides in the Agricultural Health Study;” Annals of Occupational Hygiene, 2002, 46(2), 245-260; DOI: 10.1093/annhyg/mef011.

ABSTRACT:

We developed a quantitative method to estimate long-term chemical-specific pesticide exposures in a large prospective cohort study of more than 58000 pesticide applicators in North Carolina and Iowa. An enrollment questionnaire was administered to applicators to collect basic time- and intensity-related information on pesticide exposure such as mixing condition, duration and frequency of application, application methods and personal protective equipment used. In addition, a detailed take-home questionnaire was administered to collect further intensity-related exposure information such as maintenance or repair of mixing and application equipment, work practices and personal hygiene. More than 40% of the enrolled applicators responded to this detailed take-home questionnaire. Two algorithms were developed to identify applicators’ exposure scenarios using information from the enrollment and take-home questionnaires separately in the calculation of subject-specific intensity of exposure score to individual pesticides. The ‘general algorithm’ used four basic variables (i.e. mixing status, application method, equipment repair status and personal protective equipment use) from the enrollment questionnaire and measurement data from the published pesticide exposure literature to calculate estimated intensity of exposure to individual pesticides for each applicator. The ‘detailed’ algorithm was based on variables in the general algorithm plus additional exposure information from the take-home questionnaire, including types of mixing system used (i.e. enclosed or open), having a tractor with enclosed cab and/or charcoal filter, frequency of washing equipment after application, frequency of replacing old gloves, personal hygiene and changing clothes after a spill. Weighting factors applied in both algorithms were estimated using measurement data from the published pesticide exposure literature and professional judgment. For each study subject, chemical-specific lifetime cumulative pesticide exposure levels were derived by combining intensity of pesticide exposure as calculated by the two algorithms independently and duration/frequency of pesticide use from the questionnaire. Distributions of duration, intensity and cumulative exposure levels of 2,4-D and chlorpyrifos are presented by state, gender, age group and applicator type (i.e. farmer or commercial applicator) for the entire enrollment cohort and for the sub-cohort of applicators who responded to the take-home questionnaire. The distribution patterns of all basic exposure indices (i.e. intensity, duration and cumulative exposure to 2,4-D and chlorpyrifos) by state, gender, age and applicator type were almost identical in two study populations, indicating that the take-home questionnaire sub-cohort of applicators is representative of the entire cohort in terms of exposure. FULL TEXT

Lerro et al., 2020

Lerro, C. C., Andreotti, G., Wong, J. Y., Blair, A., Rothman, N., & Beane Freeman, L. E.; “2,4-D exposure and urinary markers of oxidative DNA damage and lipid peroxidation: a longitudinal study;” Occupational and Environmental Medicine, 2020, 77(4), 276-280; DOI: 10.1136/oemed-2019-106267.

ABSTRACT:

OBJECTIVE: 2,4-Dichlorophenoxyacetic acid (2,4-D) is a herbicide that is commonly used commercially, agriculturally and residentially worldwide. There is concern about its potential for carcinogenicity based on studies in laboratory animals demonstrating the potential for induction of oxidative stress. We conducted a longitudinal biomarker study of 31 pesticide applicators in Kansas who heavily applied 2,4-D and 34 non-applicator controls.

METHODS: We used multivariable generalised linear mixed-effect models to evaluate the association between urinary 2,4-D and natural log-transformed 8-iso prostaglandin F2alpha (8-isoprostane) and 8-hydroxy-2′-deoxyguanosine (8-OHdG), adjusting for urinary creatinine, age, tobacco use and concomitant use of the herbicide picloram.

RESULTS: Compared with non-applicator controls, urinary 2,4-D in the third quartile of exposure was associated with elevated 8-isoprostane (e (beta)=1.38, 95% CI 1.03 to 1.84). There was no association among the highest exposed and no exposure-response trend. 2,4-D exposure was not associated with 8-OHdG. Results were unchanged when restricted to participants who only applied 2,4-D (no picloram use).

CONCLUSIONS: We did not find evidence that increasing 2,4-D exposure was associated with 8-isoprostane or 8-OHdG. Future work should carefully evaluate potential confounders of this association, such as diet and physical activity, as well as additional biological markers of oxidative stress and damage. FULL TEXT

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