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D A Kalman

Publications and source records attributed to D A Kalman.

36 records · Page 2Linked to original sources
PubMed1995

Pesticides in household dust and soil: exposure pathways for children of agricultural families.

Child of agriculture families are likely to be exposed to agricultural chemicals, even if they are not involved in farm activities. This study was designed to determine whether such children are exposed to higher levels of pesticides than children whose parents are not involved in agriculture and whose homes are not close to farms. Household dust and soil samples were collected in children's play areas from 59 residences in eastern Washington State (26 farming, 22 farmworker, and 11 nonfarming families). The majority of the farm families lived within 200 feet of an operating apple or pear orchard, whereas all reference homes were located at least a quarter of a mile from an orchard. Four organophosphorous (OP) insecticides commonly used on tree fruit were targeted for analysis: azinphosmethyl, chlorpyrifos, parathion, and phosmet. Samples were extracted and analyzed by gas chromatography/mass selective detection. Pesticide concentrations in household dust were significantly higher than in soil for all groups. OP levels for farmer/farm-worker families ranged from nondetectable to 930 ng/g in soil (0.93 ppm) and from nondetectable to 17,000 ng/g in dust (17 ppm); all four OP compounds were found in 62% of household dust samples, and two-thirds of the farm homes contained at least one OP above 1000 ng/g. Residues were found less frequently in reference homes and all levels were below 1000 ng/g. Household dust concentrations for all four target compounds were significantly lower in reference homes when compared to farmer/farmworker homes (Mann Whitney, U test; p < 0.05). These results demonstrate that children of agricultural families have a higher potential for exposure to OP pesticides than children of nonfarm families in this region. Measurable residues of a toxicity, I compound registered exclusively for agricultural use, azcnphosmettyl were found in household dust samples from all study homes, suggesting that low level exposure to such chemicals occurs throughout the region. Children's total and cumulative exposure to this pesticide class from household dust, soil, and other sources warrants further investigation.

Adult↗
PubMed1993

Evaluation of stable isotope-labeled probes in the study of solvent pharmacokinetics in human subjects.

The relationship between biomarkers of exposure (such as concentrations of toxicants in blood or breath, or metabolites in urine) and toxicant dose for individuals is influenced by many person- and episode-specific factors which contribute to overall variability in biomarker level for a given dose. This variability results in imprecise biological marker-based estimates of dose for individuals. We hypothesize that pharmacokinetic data from stable-isotope (deuterated) analogs can be used with a pharmacokinetic model to account for individual-related sources of variation, leading to more precise methods of dose estimation for individuals. To establish the degree of similarity in the pharmacokinetics of unlabeled (d0-) and fully deuterated (D8-) toluene, 21 men (ages 20-45) inhaled an equal molar mixture for 2h. Washout kinetics for both compounds were followed for 4 d in alveolar air and blood. Both compounds exhibited three-phase elimination kinetics in both fluids. The third phase was not always definable for d0-toluene because of concurrent uncontrolled environmental exposures. Considering data from only the first two phases, concentrations of d0- and d8-toluene in alveolar air and blood were well correlated for all subjects, even though pharmacokinetic parameters varied among individuals by 5-9 folds. Further experiments are needed to discern whether correlations between d0- and d8-toluene for the third phase are influenced by an isotope effect; present data support use of d8-toluene as a suitable probe for d0-kinetics.

Adult↗
PubMed1991

Capillary gas chromatographic method for mandelic and phenylglyoxylic acids in urine.

In support of an occupational investigation of styrene exposure, a capillary gas chromatographic method was developed for the quantitation of the styrene metabolites mandelic and phenylglyoxylic acids. The method was based on that of Guillemin and Bauer, in which phenylglyoxylic acid was converted to mandelic acid by reduction before instrumental analysis. The earlier method had to be modified for use with capillary columns; the resulting method was sensitive, selective and reproducible. The detection limit was approximately 0.001 mg/ml urine. Approximately less than 5% relative precision was achieved in the range of 0.05-2 mg/ml urine. Mandelic acid was resolved from other components of urine and from by-products of derivatization.

Air Pollutants, Occupational↗
PubMed1990

Pathways of human exposure to arsenic in a community surrounding a copper smelter.

Several studies have found elevated levels of urinary arsenic among residents living near a copper smelter in Tacoma, Washington. To assess pathways of exposure to arsenic from the smelter, biological and environmental samples were collected longitudinally from 121 households up to 8 miles from the smelter. The concentration of inorganic and methylated arsenic compounds in spot urine samples was used as the primary measure of exposure to environmental arsenic. Urinary concentration of arsenic dropped off to a constant background level within one-half mile of the smelter in contrast to environmental concentrations, which decreased more steadily with increasing distance. Among all age-sex-specific groups in all areas, only children ages 0-6 living within one-half mile of the smelter had elevated levels of arsenic in urine. A separate analysis of data for these children suggests that hand-to-mouth activity was the primary source of exposure. Inhalation of ambient air and resuspension of contaminated soil were not important sources of exposure for children or adults.

Adolescent↗
PubMed1990

The effect of variable environmental arsenic contamination on urinary concentrations of arsenic species.

Urinary arsenic species have been determined for approximately 3000 urine samples obtained from residents of a community surrounding an arsenic-emitting copper smelter. Levels of inorganic, monomethylated and dimethylated arsenic species ranged from less than 1 microgram/L (the instrumental detection limit) to 180 micrograms/L seen for dimethyl arsenic. Comparison of a subsample of this population that had the least environmental contamination with the subsample having highest environmental arsenic concentrations showed small but statistically significant differences in urinary arsenic levels for all species except dimethylated arsenic. However, for children under 7 years of age living in areas with increased environmental arsenic contamination, there was a larger and equally significant (p less than 0.001) increase in all urinary species. This effect was more pronounced in males (5-fold increase in median sum of species concentration over control group) than in females (2-fold increase in median sum of species concentration over control group) and was observed as a weaker effect in the next higher age group (7-13 years of age). Reported consumption of seafood also was significantly related to increased urinary dimethyl arsenic, but changes in distribution among the urinary arsenic species detected was not a sensitive indicator of recent seafood consumption.

Arsenic↗
PubMed1987

Micronutrient assay for cancer prevention clinical trials: serum retinol, retinyl palmitate, alpha-carotene, and beta-carotene with the use of high-performance liquid chromatography.

Assay of serum levels of retinol, retinyl palmitate, alpha-carotene, and beta-carotene to assess nutritional status, to trials of retinol and/or beta-carotene to assess nutritional status, to monitor compliance with medication schedules, and to conduct toxicity surveillance. The optimal assay method for clinical trial use represents a balance between analytical power and speed/simplicity. Three such methods were evaluated by means of shared samples between two laboratories. Each method required less than 15 minutes per assay and detected all of the analytes of interest. Careful evaluation of calibration materials and procedures permitted different laboratories using different methods to produce results with an interlaboratory variability smaller than the within-laboratory variability for each separate method. Typical precisions for the analytes in serum samples are: retinol, 0.06 relative standard deviation (RSD; standard deviation divided by mean value); retinyl palmitate, 0.08 RSD; alpha-carotene, 0.15 RSD; and beta-carotene, 0.11 RSD. Application of these methods to several hundred samples indicated that retinyl palmitate and beta-carotene levels were indicative of administered retinol and beta-carotene, whereas retinol itself was not. Population variability in pretreatment serum levels of these micronutrients expressed as RSD (retinol, 0.24; alpha-carotene, 1.11; and beta-carotene, 0.98) far exceeded the analytical imprecision in these determinations, confirming that the present assays could meet the needs of current clinical intervention trials.

Carotenoids↗
PubMed1986

Survey analysis of volatile organics released from plastics under thermal stress.

Irritating or toxic vapors can be produced from plastic process materials by a variety of operations, such as injection molding, hot wire cutting, bandsawing and milling. These components typically are not reported in the combustion toxicology literature for the materials used, but rather represent the volatilization of plasticizers, unreacted monomer, mold-release agents or other additives, or lubricants. A method for the characterization of the complex mixtures that can result from thermal stressing of plastic and of relating quantitatively to process temperatures and amounts of plastic used is presented. The method utilizes both Thermo-Gravimetric analysis (TGA) and dynamic headspace GC/MS with on-column cryogenic focusing. Application to actual occupational situations is illustrated with three examples.

Air Pollutants, Occupational↗
PubMed1986

Industrial hygiene, chemical and biological assessments of exposures to a chlorinated phenolic sapstain control agent.

A two-year study of the occupational exposure of workers in a lumber mill to a wood preservative containing chlorophenol has been conducted. The methods were biological (urine) monitoring, industrial hygiene assessment and a questionnaire related to worker-perceived health effects. Approximately 40 workers exposed to the wood preservative and 40 unexposed controls working in other locations of the plant participated in the study. Evaluation of work conditions, assessment of urinary levels of tetra- and pentachlorophenol, and administration of a medical questionnaire were performed at a six-month intervals over a two-year period. Industrial hygiene ratings of exposures and adequacy of protection were evaluated in relation to the results of biological monitoring. Workers who came into contact with freshly treated and still wet wood had consistently higher urinary levels of tetrachlorophenol. Workers stationed adjacent to the spray applicator also had higher tetrachlorophenol levels. There was no statistically significant relationship between the subjective ratings by the industrial hygienist of exposure and adequacy of worker protection with the urinary levels of tetrachlorophenol. Nor was there a consistent pattern linking exposure ratings with adequacy of protection. The short half-life of tetrachlorophenol in the urine makes this a good indicator of only the most recent exposure. The differences in urinary levels between controls and exposed workers were large, with averages of 240.4 ppb for exposed workers and 14.6 for controls. Traditional industrial hygiene evaluation techniques, in conjunction with biological monitoring, proved to be the most effective method of assessing both exposure and work practices. Exposed workers reported a statistically significant increase of positive answers to known signs and symptoms of chlorophenol exposure compared with the controls. There was no statistically significant relationship between the number of these health problems reported and the mean urinary levels of tetra- or pentachlorophenol for the exposed group; however, for certain variables (heavy vs. light exposure, inadequate vs. adequate protection, greater than 100 ppb urinary tetrachlorophenol vs. less than 100 ppb), those with heavier exposure, inadequate protection or higher urinary tetrachlorophenol reported on the average more health problems over the two-year period. Firm statistical conclusions could not be drawn because of the small size of the study population.

Chlorophenols↗
PubMed1985

Hazardous lead release from glazed dinnerware: a cautionary note.

Numerous pieces of contemporary glazed pottery dinnerware made in Italy and Mexico have been shown to release excessive amounts of lead, greater than 1000 ppm in several instances. Extended use with frequent scouring increased the lead release. This pottery, manufactured under obsolete conditions, may be imported into the United States by tourists, retail merchants and immigrants, and used for daily cooking and storage of food and beverages. Our findings demonstrate a potentially widespread health hazard both in the countries of origin of the pottery and the countries of importation.

Adult↗
PubMed1984

Determination of pentachlorophenol and 2,3,4,6-tetrachlorophenol in human urine by high resolution gas chromatography.

A method for the determination of pentachlorophenol, 2,3,4,6-tetrachlorophenol, and their salts or hydrolyzable biological conjugates in urine, water, serum, or fish tissue is reported. The method utilizes fused silica capillary gas chromatography (GC) with electron capture detection of the free phenols following hydrolysis and extraction into toluene. A recovery standard (4-chloro-2-nitrophenol) and an internal standard for GC (1-nitro-2,3,5,6-tetrachlorobenzene) are used to monitor recovery and GC performance. The detection limit for TCP and PCP is 0.5 ppb and the precision observed for each sample in the 1- to 100-ppb range is between 3 and 12% relative standard deviation for both components.

Chlorophenols↗
PubMed1983

Persistence of tetrachlorophenol and pentachlorophenol in exposed woodworkers.

The decline in urinary concentrations of pentachlorophenol (PCP) and 2,3,4,6-tetrachlorophenol (TCP) were observed for a group of woodworkers chronically exposed to Permatox 100 (3% PCP, 21% TCP) during a 16 day vacation and plant shutdown. The group was monitored annually for two years, with sampling occurring on the last working day prior to shutdown and on the first day after the shutdown. Among those workers with the highest pre-shutdown levels, uniform TCP reductions of 90 +/- 6% were observed, indicating elimination rates similar to those reported for PCP in a single dose human exposure study. Four workers were sampled on alternate days during the shutdown in the second year. Of these, two workers had significant pre-shutdown levels, and showed declines in urine TCP levels over this period consistent with simple one-compartment first order decay. The possible effect of environmental PCP exposure on observed biological decay rates when occupational PCP exposures are low was indicated by the wide variation in urinary PCP reduction and slight decreases or actual increases observed over the shutdown period.

Chlorophenols↗
PubMedDate not supplied

Identification of a novel dihydroxy metabolite of aflatoxin B1 produced in vitro and in vivo in rats and mice.

HPLC analysis of bile obtained from rats given aflatoxin B1 (AFB) demonstrates the presence of numerous polar metabolites. The glutathione conjugate derived from AFB 8,9-epoxide and the glucuronide conjugate of aflatoxin P1 (AFP) have previously been identified as the two major polar metabolites. The most polar peak present in bile from AFB-treated rats is converted to a less polar peak upon incubation with beta-glucuronidase, which has a parent ion m/e of 314 amu. Treatment of this aglycon with diazomethane produced a product which cochromatographs with aflatoxin M1 (AFM). From these data it is concluded that the most polar peak in bile from AFB-treated rats is the glucuronide conjugate of 4,9a-dihydroxyaflatoxin B1. This dihydroxy AFB metabolite was produced in vitro in mouse microsomal incubations, and time-course studies of its production suggest that it is largely formed by 9a-hydroxylation of AFP, although some may be formed by 4-O-demethylation of AFM. Direct incubation of AFP and AFM with mouse microsomes confirmed that this metabolite can be formed from both AFP and AFM. An HPLC method is described which is capable of base line resolution of this novel dihydroxyaflatoxin metabolite and eight other hydroxylated metabolites of AFB, as well as the glutathione conjugate of AFB 8,9-epoxide.

Aflatoxin B1↗
PubMedDate not supplied

Selective determination of inorganic mercury and methylmercury in tissues by continuous flow and cold vapor atomic absorption spectrometry.

A method has been developed for the determination of inorganic (InHg) and methylmercury (MeHg) in solubilized tissues with continuous-flow (flow injection) cold vapor atomic absorption spectrometry. Kidney, liver, and brain tissues were spiked with MeHg and InHg and solubilized at an elevated temperature in a solution containing 90 g/L NaOH, 2 g/L L-cysteine, and 4 g/L NaCl. Total mercury determination was achieved by continuous-flow cold vapor atomic absorption spectrometry using an inlet system containing a flow through photo-oxidation reactor and sodium borohydride as the mercury reductant. InHg was selectively determined in the presence of MeHg with this method when using stannous chloride as the reductant. MeHg concentrations were computed as the difference between the values obtained from the two analyses. Recoveries for spiked tissues were above 95% for InHg and MeHg. Quantitation limits for InHg and total mercury in tissues were 0.4 and 0.6 microgram/g, respectively. MeHg chloride levels from kidney tissues of exposed rats were evaluated using the present method in comparison with another method in which MeHg was measured using solvent extraction and capillary gas chromatography with electron capture detection.

Animals↗
PubMedDate not supplied

Improved cleanup and determination of dialkyl phosphates in the urine of children exposed to organophosphorus insecticides.

Analysis of dialkylphosphate urinary metabolites of organophosphorus insecticides has been used to estimate dose in nonoccupationally exposed populations, including children. Analytical methods must continue to be improved in order to accurately and reproducibly measure less than 10 ng/mL of these metabolites. Dialkyl phosphates are commonly determined as their pentafluorobenzyl bromide derivatives via gas chromatography (GC) with flame photometric detection. Presented here is an improved method for precleanup of urine using solid-phase extraction, followed by derivatization and GC analysis. The method includes the quantitative determination of the following dialkyl phosphate metabolites: dimethylphosphate, diethylphosphate, dimethylthiophosphate, diethylthiophosphate, and dimethyldithiophosphate. Additional cleanup of urine samples allows for increasing sample size and improving sensitivity while minimizing interferences and variability associated with derivatization. Sample aliquot size was 5 mL with limits of quantitation of 10 ng/mL of urine for dimethylphosphate and diethylphosphate and 2 ng/mL of urine for dimethylthiophosphate, diethylthiophosphate, and dimethyldithiophosphate. This level of method sensitivity allows for quantitative determination of trace dialkyl phosphates in approximately 75% of individuals in nonoccupationally exposed populations. This streamlined method increases sample throughput, provides a clean extract for analysis, and requires no custom glassware.

Alkylation↗
PubMedDate not supplied

Inter-individual variability in blood/air partitioning of volatile organic compounds and correlation with blood chemistry.

In vitro blood/air partition coefficients (KB/A) for acetone, 1,1,1-trichloroethane, toluene, and styrene were measured in blood samples from 73 human subjects and correlated with blood chemistry parameters (hematocrit, total cholesterol, serum triglycerides, serum albumin, total plasma proteins, Na+, K+, Cl-, and HCO3-). Statistically significant inter-individual variation existed in KB/A between some subjects. Substitution of group or generic in vitro KB/A values for values determined in some individuals could introduce errors of up to 50%. However, most subjects could be well represented by group averages (mean +/- SD; acetone, 301 +/- 22; 1,1,1-trichloroethane, 6.0 +/- 0.8; toluene, 19 +/- 3; styrene, 62 +/- 10). The KB/A values for acetone, 1,1,1-trichloroethane and toluene were normally distributed. The data for styrene appeared to deviate from a normal distribution and may have been bimodal. The KB/A values for the two structurally related compounds, toluene and styrene, were strongly correlated within individuals, while the KB/A values for compounds with less structural similarity, such as acetone and styrene, were poorly correlated. At most, 15% of the variation in KB/A among individuals could be explained by variation in the measured blood chemistry parameters. When the entire sample group was considered, blood chemistry parameters were not significantly correlated with KB/A for any compound. The KB/A of 1,1,1-trichloroethane was significantly correlated with the concentration of cholesterol and triglycerides in females. Sex was a significant grouping variable for the correlation of albumin concentration with the KB/A of styrene. Age was not a significant correlation variable. Blood chemistry parameters which previously have been correlated with KB/A in small sample groups do not appear to be significantly correlated in our larger sample group.

Acetone↗
PubMedDate not supplied

Increased micronuclei in exfoliated bladder cells of individuals who chronically ingest arsenic-contaminated water in Nevada.

It is well established that inorganic arsenic is causally associated with lung cancer via inhalation and skin cancer via ingestion. Epidemiological evidence based on studies in Taiwan suggests that ingestion of inorganic arsenic may also cause other more fatal internal cancers, with the highest relative risks reported for bladder cancer. Here, we have used a biological marker of response, the micronucleus assay in exfoliated bladder cells, to evaluate the possible genotoxic effects of chronic arsenic ingestion on the bladder. The overall objective of this study was to compare the frequency of micronucleated cells in exfoliated bladder and buccal cells between a group of 18 individuals in Nevada who chronically ingested high levels of inorganic arsenic from their well water (average level, 1,312 micrograms/liter) and an individually matched control group with low exposure to arsenic (average level, 16 micrograms/liter). A 1.8-fold increase (90% confidence interval, 1.06-2.99) was observed in the weighted mean frequency of micronucleated bladder cells in the exposed group (2.79 per 1000 cells) compared with the unexposed group (1.57 per 1000 cells). In addition, the frequency of micronucleated bladder cells was positively associated with the urinary concentration of inorganic arsenic plus its methylated metabolites (Spearman correlation = 0.33; P = 0.03). In contrast, there was no increase in micronucleated buccal cells associated with arsenic ingestion (frequency ratio = 1.0; 90% confidence interval, 0.65-1.53). The results of this study provide evidence that chronic ingestion of high levels of inorganic arsenic in drinking water is associated with an increased frequency of micronucleated bladder cells. These findings are consistent with a genotoxic effect of arsenic on bladder cells, but a larger study is needed to confirm them.

Adolescent↗
PubMedDate not supplied

Blood/air partition coefficient determinations: automation and improvement of the equilibrium partitioning in closed systems method.

The equilibrium partitioning in closed systems method has been frequently used for determining partition coefficients between liquid and gas phases. We developed several improvements in this method: preparation of test atmospheres with a dynamic solvent vapor generator, automation of gas phase analysis, and estimation of the precision of the partition coefficients using a statistical procedure that did not require pairing of test and reference measurements. Blood/air partition coefficients measured in a blood-bank blood sample for acetone, 1,1,1-trichloroethane, toluene, and styrene were: 309 +/- 2, 5.6 +/- 0.1, 16.2 +/- 0.5 and 49 +/- 2 (geometric mean +/- estimated SE, respectively). Water/air partition coefficients were: 361 +/- 7, 2.9 +/- 0.3, 4.6 +/- 0.5, and 6.9 +/- 0.9 for acetone, 1,1,1-trichloroethane, toluene, and styrene.

Acetone↗