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Biomedical subjects

D B Barr

Publications and source records attributed to D B Barr.

At least 19 recordsLinked to original sources
PubMed2005

Biomarkers in assessing residential insecticide exposures during pregnancy and effects on fetal growth.

The Columbia Center for Children's Environmental Health is using a combination of environmental and biologic measures to evaluate the effects of prenatal insecticide exposures among urban minorities in New York City. Of the 571 women enrolled, 85% report using some form of pest control during pregnancy and 46% report using exterminators, can sprays, and/or pest bombs. Chlorpyrifos, diazinon, and propoxur were detected in 99.7-100% of 48-h personal air samples collected from the mothers during pregnancy (n = 394) and in 39-70% of blood samples collected from the mothers (n = 326) and/or newborns (n = 341) at delivery. Maternal and newborn blood levels are similar and highly correlated (r = 0.4-08, P < 0.001). Levels of insecticides in blood samples and/or personal air samples decreased significantly following the 2000-2001 U.S. Environmental Protection Agency's regulatory actions to phase out residential use of chlorpyrifos and diazinon. Among infants born prior to 1/1/01, birth weight decreased by 67.3 g (95% confidence interval (CI) -116.6 to -17.8, P = 0.008) and birth length decreased by 0.43 centimeters (95% CI, -0.73 to -0.14, P = 0.004) for each unit increase in log-transformed cord plasma chlorpyrifos levels. Combined measures of (ln)cord plasma chlorpyrifos and diazinon (adjusted for relative potency) were also inversely associated with birth weight and length (P </= 0.007). Birth weight averaged 215.1 g less (95% CI -384.7 to -45.5) among those with the highest exposures compared to those without detectable levels. No association was seen between birth weight and length and cord plasma chlorpyrifos or diazinon among newborns born after 1/1/01 (P > 0.8). Results support recent regulatory action to phase out residential uses of these insecticides.

Adolescent↗
PubMed2005

The presence of dialkylphosphates in fresh fruit juices: implication for organophosphorus pesticide exposure and risk assessments.

This study was designed to determine whether dialkylphosphates (DAPs) are present in fresh fruit juices, as a result of organophosphorus (OP) pesticides degradation. Fresh conventional and organic fruit (apple and orange) juices were purchased from local grocery stores. DAPs were found in both conventional and organic juices, and the original levels were higher, for both apple and orange juices, in conventional than in organic juices. Additional DAPs were found in OP pesticide fortified juices after 72 h of storage at 4 degrees C, suggesting a degradation of OP pesticides in juices. Overall, 12% and 36.2% of fortified azinphosmethyl, a dimethyl OP pesticide, and the combination of fortified diazinon and chlorpyrifos, both diethyl OP pesticides, were degraded to dimethyl and diethyl DAPs, respectively. Although the exact mechanism of the degradation is unknown, hydrolysis is likely the cause of OP pesticide degradation in juice. The presence of DAPs in fresh fruit juices clouds the validity of using urinary DAP measurements for estimating OP pesticide exposures in humans, particularly in children. The overestimated OP pesticide exposures based on urinary DAPs reported in other studies is likely due to the coexistence of preformed DAPs and DAPs resulting from OP pesticide exposures. Thus, before urinary DAP concentrations can be reliably used in exposure and risk assessment, the proportion of the concentration attributable to environmental DAP exposure, particularly through the diet, must be ascertained. In conclusion, urinary DAPs have many limitations when being used as biomarkers for OP pesticides in exposure and risk assessment, and caution should be exercised when interpreting DAPs results.

Beverages↗
PubMed2005

A summary of recent findings on birth outcomes and developmental effects of prenatal ETS, PAH, and pesticide exposures.

Inner-city minority populations are high-risk groups for adverse birth outcomes and also more likely to be exposed to environmental contaminants, including environmental tobacco smoke (ETS), benzo[a]pyrene B[a]P, other ambient polycyclic aromatic hydrocarbons (global PAHs), and residential pesticides. The Columbia Center for Children's Environmental Health (CCCEH) is conducting a prospective cohort study of 700 northern Manhattan pregnant women and newborns to examine the effects of prenatal exposure to these common toxicants on fetal growth, early neurodevelopment, and respiratory health. This paper summarizes results of three published studies demonstrating the effects of prenatal ETS, PAH, and pesticides on birth outcomes and/or neurocognitive development [Perera FP, Rauh V, Whyatt RM, Tsai WY, Bernert JT, Tu YH, et al. Molecular evidence of an interaction between prenatal environment exposures on birth outcomes in a multiethnic population. Environ Health Perspect 2004;12:630-62; Rauh VA, Whyatt RM, Garfinkel R, Andrews H, Hoepner L, Reyes A, et al. Developmental effects of exposure to environmental tobacco smoke and material hardship among inner-city children. Neurotoxicol Teratol 2004;26:373-85; Whyatt RM, Rauh V, Barr DB, Camann DE, Andrews HF, Garfinkel R, et al. Prenatal insecticide exposures, birth weight and length among an urban minority cohort. Environ Health Perspect, in press]. To evaluate the effects of prenatal exposure to ETS, PAHs, and pesticides, researchers analyzed questionnaire data, cord blood plasma (including biomarkers of ETS and pesticide exposure), and B[a]P-DNA adducts (a molecular dosimeter of PAHs). Self-reported ETS was associated with decreased head circumference (P = 0.04), and there was a significant interaction between ETS and adducts such that combined exposure had a significant multiplicative effect on birth weight (P = 0.04) and head circumference (P = 0.01) after adjusting for confounders. A second analysis examined the neurotoxic effects of prenatal ETS exposure and postpartum material hardship (unmet basic needs in the areas of food, housing, and clothing) on 2-year cognitive development. Both exposures depressed cognitive development (P < 0.05), and there was a significant interaction such that children with exposure to both ETS and material hardship exhibited the greatest cognitive deficit (7.1 points). A third analysis found that cord chlorpyrifos, and a combined measure of cord chlorpyrifos, diazinon, and propoxur-metabolite, were inversely associated with birth weight and/or length (P < 0.05). These results underscore the importance of policies that reduce exposure to ETS, air pollution, and pesticides with potentially adverse effects on fetal growth and child neurodevelopment.

Child↗
PubMed2001

Measurement of organophosphate metabolites in postpartum meconium as a potential biomarker of prenatal exposure: a validation study.

Experimental data have linked exposure to prenatal organophosphates to adverse neurocognitive sequalae. However, epidemiologic research has been hampered by lack of reliable dosimeters. Existing biomarkers reflect short-term exposure only. Measurements of pesticides in postpartum meconium may yield a longer-term dosimeter of prenatal exposure. As the initial step in biomarker validation, this research determined background levels, detection limits, and stabilities of six organophosphate metabolites in meconium: diethylphosphate (DEP), diethylthiophosphate (DETP), diethyldithiophosphate (DEDTP), dimethylphosphate (DMP), dimethylthiophosphate (DMTP), and dimethyldithiophosphate (DMDTP). Calibration curves were also constructed. The meconium was collected from 20 newborns at New York Presbyterian Hospital; analyses were undertaken at the Centers for Disease Control and Prevention (CDC). DEP was detected in 19/20 samples (range 0.8-3.2 microg/g) and DETP was detected in 20/20 (range 2.0-5.6 microg/g). DMP and DEDTP were each detected in 1/20 (at 16 and 1.8 microg/g, respectively). DMTP and DMDTP were not detected. Detection limits were comparable to or lower than those in urine; levels were similar to those seen in adult urine in population-based research. Metabolites were stable at room temperature over 12 hr. Calibration curves were linear over the range tested (0.5-400 microg/g); recoveries ranged from 18% to 66%. Using isotope dilution, recoveries of each analyte in individual samples can be corrected automatically based on the recovery of the respective stable isotope-labeled analogue, making this method fully quantitative. Results indicate that measurements of organophosphate metabolites in meconium have promise as biomarkers of prenatal exposure. Further research is needed to determine the time frame of exposure represented by pesticide levels in meconium and to evaluate the dose-response relationship.

Adult↗
PubMed2001

Biomarker correlations of urinary 2,4-D levels in foresters: genomic instability and endocrine disruption.

Forest pesticide applicators constitute a unique pesticide use group. Aerial, mechanical-ground, and focal weed control by application of herbicides, in particular chlorophenoxy herbicides, yield diverse exposure scenarios. In the present work, we analyzed aberrations in G-banded chromosomes, reproductive hormone levels, and polymerase chain reaction-based V(D)J rearrangement frequencies in applicators whose exposures were mostly limited to chlorophenoxy herbicides. Data from appliers where chlorophenoxy use was less frequent were also examined. The biomarker outcome data were compared to urinary levels of 2,4-dichlorophenoxyacetic acid (2,4-D) obtained at the time of maximum 2,4-D use. Further comparisons of outcome data were made to the total volume of herbicides applied during the entire pesticide-use season.Twenty-four applicators and 15 minimally exposed foresters (control) subjects were studied. Categorized by applicator method, men who used a hand-held, backpack sprayer in their applications showed the highest average level (453.6 ppb) of 2,4-D in urine. Serum luteinizing hormone (LH) values were correlated with urinary 2,4-D levels, but follicle-stimulating hormone and free and total testosterone were not. At the height of the application season; 6/7 backpack sprayers, 3/4 applicators who used multinozzle mechanical (boom) sprayers, 4/8 aerial applicators, and 2/5 skidder-radiarc (closed cab) appliers had two or more V(D)J region rearrangements per microgram of DNA. Only 5 of 15 minimally exposed (control) foresters had two or more rearrangements, and 3 of these 5 subjects demonstrated detectable levels of 2,4-D in the urine. Only 8/24 DNA samples obtained from the exposed group 10 months or more after their last chlorophenoxy use had two rearrangements per microgram of DNA, suggesting that the exposure-related effects observed were reversible and temporary. Although urinary 2,4-D levels were not correlated with chromosome aberration frequency, chromosome aberration frequencies were correlated with the total volume of herbicides applied, including products other than 2,4-D. In summary, herbicide applicators with high urinary levels of 2,4-D (backpack and boom spray applications) exhibited elevated LH levels. They also exhibited altered genomic stability as measured by V(D)J rearrangement frequency, which appears reversible months after peak exposure. Though highly detailed, the limited sample size warrants cautious interpretation of the data.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2001

Measurement of children's exposure to pesticides: analysis of urinary metabolite levels in a probability-based sample.

The Minnesota Children's Pesticide Exposure Study is a probability-based sample of 102 children 3-13 years old who were monitored for commonly used pesticides. During the summer of 1997, first-morning-void urine samples (1-3 per child) were obtained for 88% of study children and analyzed for metabolites of insecticides and herbicides: carbamates and related compounds (1-NAP), atrazine (AM), malathion (MDA), and chlorpyrifos and related compounds (TCPy). TCPy was present in 93% of the samples, whereas 1-NAP, MDA, and AM were detected in 45%, 37%, and 2% of samples, respectively. Measured intrachild means ranged from 1.4 microg/L for MDA to 9.2 microg/L for TCPy, and there was considerable intrachild variability. For children providing three urine samples, geometric mean TCPy levels were greater than the detection limit in 98% of the samples, and nearly half the children had geometric mean 1-NAP and MDA levels greater than the detection limit. Interchild variability was significantly greater than intrachild variability for 1-NAP (p = 0.0037) and TCPy (p < 0.0001). The four metabolites measured were not correlated within urine samples, and children's metabolite levels did not vary systematically by sex, age, race, household income, or putative household pesticide use. On a log scale, mean TCPy levels were significantly higher in urban than in nonurban children (7.2 vs. 4.7 microg/L; p = 0.036). Weighted population mean concentrations were 3.9 [standard error (SE) = 0.7; 95% confidence interval (CI), 2.5, 5.3] microg/L for 1-NAP, 1.7 (SE = 0.3; 95% CI, 1.1, 2.3) microg/L for MDA, and 9.6 (SE = 0.9; 95% CI, 7.8, 11) microg/L for TCPy. The weighted population results estimate the overall mean and variability of metabolite levels for more than 84,000 children in the census tracts sampled. Levels of 1-NAP were lower than reported adult reference range concentrations, whereas TCPy concentrations were substantially higher. Concentrations of MDA were detected more frequently and found at higher levels in children than in a recent nonprobability-based sample of adults. Overall, Minnesota children's TCPy and MDA levels were higher than in recent population-based studies of adults in the United States, but the relative magnitude of intraindividual variability was similar for adults and children.

Adolescent↗
PubMed2000

Mass psychogenic illness attributed to toxic exposure at a high school.

BACKGROUND AND METHODS: Mass psychogenic illness may be difficult to differentiate from illness caused by bioterrorism, rapidly spreading infection, or toxic substances. We investigated symptoms attributed to exposure to toxic gas at a high school in Tennessee. In November 1998, a teacher noticed a 'gasoline-like' smell in her classroom, and soon thereafter she had a headache, nausea, shortness of breath, and dizziness. The school was evacuated, and 80 students and 19 staff members went to the emergency room at the local hospital; 38 persons were hospitalized overnight. Five days later, after the school had reopened, another 71 persons went to the emergency room. An extensive investigation was performed by several government agencies. RESULTS: We were unable to find a medical or environmental explanation for the reported illnesses. The persons who reported symptoms on the first day came from 36 classrooms scattered throughout the school. The most frequent symptoms (in this group and the group of people who reported symptoms five days later) were headache, dizziness, nausea, and drowsiness. Blood and urine specimens showed no evidence of carbon monoxide, volatile organic compounds, pesticides, polychlorinated biphenyls, paraquat, or mercury. There was no evidence of toxic compounds in the environment. A questionnaire administered a month later showed that the reported symptoms were significantly associated with female sex, seeing another ill person, knowing that a classmate was ill, and reporting an unusual odor at the school. CONCLUSIONS: The illness attributed to toxic exposure had features of mass psychogenic illness - notably, widespread subjective symptoms thought to be associated with environmental exposure to a toxic substance in the absence of objective evidence of an environmental cause. Alleviation of the anxiety surrounding an episode of mass psychogenic illness requires prompt recognition and a detailed investigation.

Disease Outbreaks↗
PubMed2000

Simplified urinary immunoassay for 2,4-D: validation and exposure assessment.

Urinary monitoring of exposed workers by either analytic chemical methods or radioimmunoassay suggests that urinary levels of 2,4-dichlorophenoxyacetic acid (2,4-D) exceeding 30 ppb are indicative of occupational exposure. However, the current methods do not lend themselves to clinical laboratory use in the rural medical setting. The major goal of this project was to provide medical practitioners who care for members of the agricultural community with a cost-efficient way to conduct exposure assessment. This project used a direct 2,4-D enzyme immunoassay (EIA) and measurement of the ratio between 2,4-D-spiked and non-spiked samples of the same urine to quantify 2,4-D levels. This simplified approach minimizes the effects of non-specific interfering substances in urine and eliminates the need for sample extraction and clean-up. Possible urine co-contaminants (2,4-dichlorophenol and 2,5-dichlorophenol) do not significantly interfere with this immunoassay. Twenty-two forest pesticide applicators who apply and use chlorophenoxy herbicides in their work and 14 comparable control subjects were studied to validate the assay in the occupational setting. Coded urine specimens were examined for levels of 2,4-D by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) and compared with immunoassay results from the same specimens. A correlation coefficient of r = 0.982 with a P value of .0001 for a plot of HPLC-MS/MS versus immunoassay demonstrated that the results from these methods were comparable over urinary dose levels ranging from not detectable (<19 ppb) to 1700 ppb 2,4-D, as determined by immunoassay.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2000

Levels of methyleugenol in a subset of adults in the general U.S. population as determined by high resolution mass spectrometry.

We developed a sensitive and accurate analytical method for quantifying methyleugenol (ME) in human serum. Our method uses a simple solid-phase extraction followed by a highly specific analysis using isotope dilution gas chromatography-high resolution mass spectrometry. Our method is very accurate; its limit of detection is 3.1 pg/g and its average coefficient of variation is 14% over a 200-pg/g range. We applied this method to measure serum ME concentrations in adults in the general U.S. population. ME was detected in 98% of our samples, with a mean ME concentration of 24 pg/g (range < 3.1-390 pg/g). Lipid adjustment of the data did not alter the distribution. Bivariate and multivariate analyses using selected demographic variables showed only marginal relationships between race/ethnicity and sex/fasting status with serum ME concentrations. Although no demographic variable was a good predictor of ME exposure or dose, our data indicate prevalent exposure of U.S. adults to ME. Detailed pharmacokinetic studies are required to determine the relationship between ME intake and human serum ME concentrations.

Adolescent↗
PubMed1999

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

We have developed an isotope dilution high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) method for quantifying the urinary metabolites of the pesticides atrazine, malathion, and 2,4-dichlorophenoxyacetic acid (2,4-D). Urine samples are extracted with an organic solvent, and the organic fraction is concentrated. The concentrate is then analyzed using HPLC/MS/MS. The limits of detection for the metabolites are less than 0.5 microgram/L (parts per billion) in 10 mL of urine, with a high degree of accuracy and precision.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1999

An appraisal of the disc-macula distance to disc diameter ratio in the assessment of optic disc size.

The disc-macula distance to disc diameter ratio (DM:DD ratio) has been advocated as a method of supporting the diagnosis of optic nerve hypoplasia. A DM:DD ratio of 3.00 has been claimed to be a satisfactory threshold value for this purpose. This study has critically evaluated the above claim and found a value of 3.00 to be too low. The threshold DM:DD ratio values for the diagnosis of unequivocal ONH for an adult population, 5 and 2 years of age were found to be respectively 4.20, 3.93 and 3.70, the values for the diagnosis of mild ONH being 3.68, 3.44 and 3.23. Lower computed values reduce the predictive power. The method of computation of the DM:DD ratio was modified to abolish potential error due to disc rotation and foveal displacement. In an adult population, there was no correlation between the DM:DD ratio and amblyopia or disc ovalness. There was a trend of increasing DM:DD ratio towards myopia and decreasing DM:DD ratio towards hypermetropia; the DM:DD ratio may therefore be falsely high in high myopia. DM:DD ratio values below threshold should therefore be interpreted with care until formal optic disc biometry can be performed.

Adolescent↗
PubMed1999

Functional magnetic resonance imaging in the visual system.

Functional magnetic resonance imaging (fMRI) is a relatively new technique for measuring brain function during resting and activated conditions with good spatial and temporal resolution. Because of a robust and reproducible activation response to visual stimuli in the occipital cortex, many studies have been directed at visual function. The methodology has been refined progressively to allow more accurate detection of the small activation signal, and using computational mapping foci of cerebral activity have been displayed in a two-dimensional format. Several factors modifying the activation signal have been identified. fMRI has been used to define the retinotopic representation of areal boundaries and the localization of higher visual functions in the occipital cortex. Motion perception in area middle temporal (MT) is well-recognized, but eye movement studies are limited. The activated signal may have significant implications for our understanding of brain metabolism, but cerebral blood flow and oxygenation sensitive recordings after prolonged visual stimulation have given conflicting results. Clinically, fMRI can follow changes in cerebral activity during a progressive neurologic illness and measure responses to treatment. Neurosurgical planning in disorders such as epilepsy may be facilitated.

Color Perception↗
PubMed1998

Epidemic of pediatric deaths from acute renal failure caused by diethylene glycol poisoning. Acute Renal Failure Investigation Team.

CONTEXT: Contaminated pharmaceutical products can result in substantial morbidity and mortality and should be included in the differential diagnosis of deaths of unknown origin. OBJECTIVE: To investigate an outbreak of deaths among children from acute renal failure in Haiti to determine the etiology and institute control measures. DESIGN: Case-control study, cohort study, and laboratory toxicologic evaluation. SETTING: Pediatric population of Haiti. PARTICIPANTS: Cases were defined as Haitian residents younger than 18 years with idiopathic anuria or severe oliguria for 24 hours or longer. Febrile hospitalized children without renal failure were enrolled as control subjects. MAIN OUTCOME MEASURE: The odds of exposure to suspected etiologic agents among cases and controls. RESULTS: We identified 109 cases of acute renal failure among children. The clinical syndrome included renal failure, hepatitis, pancreatitis, central nervous system impairment, coma, and death. Of 87 patients with follow-up information who remained in Haiti for treatment, 85 (98%) died; 3 (27%) of 11 patients transported to the United States for intensive care unit management died before hospital discharge. A locally manufactured acetaminophen syrup was highly associated with disease (odds ratio, 52.7; 95% confidence interval, 15.2-197.2). Diethylene glycol (DEG) was found in patients' bottles in a median concentration of 14.4%. The median estimated toxic dose of DEG was 1.34 mL/kg (range, 0.22-4.42 mL/kg). Glycerin, a raw material imported to Haiti and used in the acetaminophen formulation, was contaminated with 24% DEG. CONCLUSIONS: An epidemic of severe systemic toxicity and deaths from DEG-contaminated acetaminophen syrup occurred in Haiti. Good manufacturing practice regulations should be used by all pharmaceutical manufacturers to prevent such tragedies.

Acetaminophen↗
PubMed1995

An appraisal of the accuracy of Littmann's method of determining the real dimension of a retinal object.

Estimation of the neuroretinal rim area in absolute units is becoming increasingly desirable in the evaluation of optic discs of glaucoma suspects. There are various methods of optic disc biometry, photogrammetric techniques being the most commonly reported. Any method of estimation of the real dimension of a retinal object must consider magnification due to the patient's eye. Photogrammetric techniques use Littmann's method extensively in this respect, assuming that it is an accurate way of performing the necessary correction. The accuracy of Littmann's method has not yet been assessed in a physiological setting. This study has found that, when the normal distributions of the optical elements eye are considered, in estimating the neuroretinal rim area, the method is at least 86% accurate (95% confidence interval) within an ametropia range -4 to +4 dioptres. This level of accuracy should be considered when drawing conclusions from any study in which Littmann's method is used.

Algorithms↗