John A. Liddle

Epidemic lead absorption near an ore smelter. The role of particulate lead.

Blood lead levels were determined on a random sample of persons in all age groups living near a lead-emitting smelter in El Paso, Texas. A blood lead level of greater than or equal to 40 mug per 100 ml, which was considered indicative of undue lead absorption, was found in 53 per cent of the children one to nine years old living within 1.6 km of the smelter and in 18 per cent of those from 1.6 to 6.6 km; beyond that distance in older persons levels were lower. Children in the first 1.6 km with blood levels of greater than or equal to mug per 100 ml were exposed to 3.1 times as much lead in dust as children there with lower blood values (6447 vs 2067 ppm). There was also airborne lead exposure (8 to 10 mug per cubic meter, annual mean). Paint, water, food, and pottery were less important as sources. The data suggest that particulate lead in dust and air accounted for most of the lead absorption in El Paso children. The smelter was the principal source of this lead, especially within 1.6km of itself.

Human adipose data for 2,3,7,8-tetrachlorodibenzo-p-dioxin in certain U.S. samples

Abstract We report the results of analyses of human adipose from 35 autopsy cases from Georgia and Utah for 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD). We also report the effect of storing the samples and our quality control plan. The geometric mean of values for 2,3,7,8-TCDD in these samples on a whole-weight basis was 7.1 ppt. The geometric mean of values for 2,3,7,8-TCDD in 31 of these samples on a lipid basis was 9.6 ppt.

Environmental and biomarker measurements in nine homes in the Lower Rio Grande Valley: Multimedia results for Pesticides, metals, PAHs, and VOCs

Residential environmental and biomarker measurements were made of multiple pollutants during two seasons (spring and summer, 1993) in order to assess human exposure for a purposeful sample of 18 nonsmoking adults residing within nine homes (a primary and secondary subject in each home) in the Lower Rio Grande Valley (LRGV) near Brownsville, TX. Pesticides, metals, PAHs, VOCs, and PCBs were measured in drinking water, food, air, soil, and house dust over a one- to two-day period in each season. Biomarker measurements were made in blood, breath, and urine. A total of 375 measurements across five pollutant classes (227 pesticides, 44 trace elements, 78 VOCs, 18 PAHs, and 8 PCBs) was possible for each home in one or more media. A large percentage of the measurements was below the method limit of detection ranging from 0–37% for pesticides, 22–61% for metals, 6% and 90% for VOCs in water and air, respectively, and 0–74% for PAHs. The total number of analytes measurable in blood, urine, or breath was considerably less, i.e., 58 (21 pesticides, 1 PCB, 4 metals, 31 VOCs, and 1 PAH) with the percentage above the method limit of detection for pesticides and metals ranging from 40 to 100%, while for VOCs, PAHs, and PCBs, this percentage ranged from 2 to 33%. A significant seasonal difference (p≤0.10) was found in the biomarker levels of two of seven nonpersistent pesticides (3,5,6-trichloro-2-pyridinol and 2,5-dichlorophenol) and 3 of 3 metals (arsenic, cadmium, and mercury) and the pyrene metabolite, 1-hydroxypyrene, measured in urine. In all cases, levels were higher in the summer relative to the spring. For the persistent pesticides and PCBs in blood serum, a seasonal effect could be evaluated for 5 of 10 analytes; a significant difference (p≤0.10) was observed only for hexachlorobenzene, which like the urine biomarkers, was higher in the summer. In contrast to the urine metals, blood-Pb concentrations did not change significantly (p≤0.05) from spring to summer. Biological results from the current study are compared to the reference range furnished by the Third National Health and Nutrition Examination Survey (NHANES III). Comparisons are only suggestive due to limitations in comparability between the two studies. Based on the percentage of measurements above the detection limit, a significant elevation (p≤0.10) in 2 of 12 nonpersistent pesticides (4-nitrophenol and 2,4-D) was observed for the LRGV study subjects. The VOC carbon tetrachloride was found in the blood (monitored only in spring) with greater prevalence (p≤0.10) than would be expected from NHANES III results. Blood serum levels of two persistent pesticides (4,4′-DDE, and trans-nonachlor) and PCB exceeded median and/or 95th percentile reference levels as did arsenic in urine. Where seasonal differences were identified or for compounds exceeding reference levels, environmental monitoring results were investigated to identify potential contributing pathways and sources of exposure. However, because environmental sampling did not always coincide with the biological sampling and because of the high frequency of analytes measured below the limit of detection, sources and pathways of exposure in many cases could not be explained. Chlorpyrifos was an exception where urine metabolite (3,5,6-TCP) levels were found to be significantly correlated with air (R2=0.55; p≤0.01) and dust (R2=0.46; p≤0.01) concentrations. Based on the results of biomarker and residential environmental measurements over two seasons, this scoping study shows a seasonal effect for some analytes and suggests where exposures may be high for others. This information may be useful in considering future studies in the region.

Determination of paraquat in sunflower seeds by reversed-phase high-performance liquid chromatography.

The herbicide paraquat was determined with extracts from 1-g samples of sunflower seeds. The liquid chromatography procedure utilized a microparticle (10 micron) C18 reversed-phase column and isocratic elution with 27% acetonitrile in water, 10 mM in the sodium salt of octanesulfonic acid. Eluted paraquat was detected at 254 and 280 nm and quantitated by paraquat internal standard peak height ratios. This procedure provided linear working curves over the concentration range of 0-20 microgram/g of paraquat. Recovery of paraquat varied from 89-101%, with an average recovery of 93%. Good agreement was obtained in the comparison of results of the described procedure with those from a well established UV procedure.

Electron-capture, capillary column gas chromatographic determination of low-molecular-weight diols in serum

Research on alcoholism has revealed that concentrations of 1,2-propanediol, d,1-2,3-butanediol and meso-2,3-butanediol may be greater in the serum of chronic alcoholics than in the serum of social drinkers and nondrinkers. In connection with one of these studies, we developed methodology to determine these diols at the micromolar levels in 500 serum samples. The procedure consisted primarily of extraction of the serum with acetonitrile containing internal standard. The extract was then concentrated to dryness and reacted with p-bromophenylboric acid. The reaction mixture was injected into a gas chromatograph fitted with a capillary column and an electron-capture detector. The total coefficients of variation were best for 1,2-propanediol, 6.82 and 10.00%, and worst for d,1-2,3-butanediol, 13.64 and 19.22%. The observed means for the analytes were all within 10% of the spiked level.

Investigation of hyperkeratotic activity of polybrominated biphenyls in Firemaster FF-1.

A polybrominated biphenyl (PBB) mixture was fractionated by normal-phase preparative high-performance liquid chromatography. The hexane fractions were concentrated and applied to rabbit ears. Only the most polar fraction produced hyperkeratosis on the rabbit ears. This active fraction was subfractionated by using the same procedure. Again, the extent of hyperkeratotic activity increased with increasing polarity. The PBBs of the largest concentration levels in the active fraction were purified by preparative gas chromatography and tested on rabbit ears. The major compounds did not demonstrate hyperkeratotic activity.

Hereditary cholinesterase deficiency: A report of a family with two rare genotypes

Cholinesterase deficiency was detected in a young girl following an episode of post‐anesthesia apnea. Subsequently, plasma and serum cholinesterase levels and dibucaine numbers were determined on blood samples from 56 members of her extended family. Including the proband, three individuals were identified with severe cholinesterase deficiency and 12 were found to have mild abnormalities. The occurrence of two genetic variants regulating cholinesterase production, the “silent” gene and the atypical enzyme, is postulated to account for the unusual pattern of inheritance in this family. Screening family members of confirmed cases is essential to prevent the potentially fatal consequences of this hereditary disorder.

A Laboratory for Handling Chemical Toxicants Safely

The Centers for Disease Control has a special Chemical Toxicant Laboratory (CTL) for handling very hazardous chemicals. It is designed to protect the workers, prevent the release of the chemical toxicant into the surrounding environment, and provide for the scientific integrity of the experiments conducted. A discussion of laboratory ventilation and special containment devices is presented. The design of the CTL, coupled with a realistic set of safety guidelines, provides for the safe conduct of research involving highly toxic chemicals.

THE LABORATORY'S ROLE IN ENVIRONMENTAL HEALTH EMERGENCY INVESTIGATIONS

An emergency environmental health investigation of a mass poisoning of unknown origin is a multidiscipline effort that requires the cooperation and close communication of epidemiologists, toxicologists, and chemists. The laboratorys role in this effort is important; special instruments, knowledge, and experience are needed. Our approach to such an investigation is discussed and past cases are used as illustrations. The role of the analytical chemist is presented, and the major resources needed for these investigations are described.

TETRACHLORODIBENZODIOXIN, AN ACCIDENTAL POISENING EPISODE IN HORSE ARENAS

Tetrachlorodibenzodioxin was identified as the apparent cause of an outbreak of poisoning in humans, horses, and other animals. Exposure was related to the spraying of contaminated waste oil on riding arenas for dust control. The contamination resulted from improper disposal of a toxic industrial waste. The pathologic effects and chemical identification of tetrachlorodibenzodioxin are described.