Biomedical subjects

C Weisel

Publications and source records attributed to C Weisel.

12 recordsLinked to original sources

PubMed2003

Persistent organic pollutants in the dusts that settled across lower Manhattan after September 11, 2001.

The explosion and collapse of the World Trade Center (WTC) was a catastrophic event that produced an aerosol impacting many workers, residents, and commuters during the first few days after September 11, 2001. During the initial days that followed, 14 bulk samples of the settled dust were collected at locations surrounding the epicenter of the disaster, including one indoor location. Some samples were analyzed for many potential hazards, including inorganic and organic constituents as well as morphology. The results of the analyses for persistent organic pollutants are described herein, including polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and select organochlorine pesticides on settled dust samples. The sigma86-PCBs comprising less than 0.001% by mass of the bulk in the three bulk samples analyzed indicated that PCBs were of limited significance in the total settled dust across lower Manhattan. Likewise, organochlorine pesticides, including chlordanes, hexachlorobenzene, heptachlor, 4,4'-DDE, 2,4'-DDT, 4,4'-DDT, and Mirex, were found at low concentrations in the bulk samples. Conversely, the sigma37-PAHs comprised up to nearly 0.04% (<0.005-0.039%) by mass of the bulk settled dust in the six bulk samples. Further size segregation of these three initial bulk samples and seven additional samples indicates that sigma37-PAHs were found in higher concentrations on relatively large particles (10-53 microm), representing up to 0.04% of the total dust mass. Significant concentrations were also found on fine particles (<2.5 microm), often accounting for approximately 0.005% by mass. We estimate that approximately 100-1000 tons of sigma37-PAHs were spread over a localized area immediately after the WTC disaster on September 11.

Aircraft↗

PubMed2000

Controlled human exposure to methyl tertiary butyl ether in gasoline: symptoms, psychophysiologic and neurobehavioral responses of self-reported sensitive persons.

The 1990 Clean Air Act mandated oxygenation of gasoline in regions where carbon monoxide standards were not met. To achieve this standard, methyl tertiary butyl ether (MTBE) was increased to 15% by volume during winter months in many locations. Subsequent to the increase of MTBE in gasoline, commuters reported increases in symptoms such as headache, nausea, and eye, nose, and throat irritation. The present study compared 12 individuals selected based on self-report of symptoms (self-reported sensitives; SRSs) associated with MTBE to 19 controls without self-reported sensitivities. In a double-blind, repeated measures, controlled exposure, subjects were exposed for 15 min to clean air, gasoline, gasoline with 11% MTBE, and gasoline with 15% MTBE. Symptoms, odor ratings, neurobehavioral performance on a task of driving simulation, and psychophysiologic responses (heart and respiration rate, end-tidal CO(2), finger pulse volume, electromyograph, finger temperature) were measured before, during, and immediately after exposure. Relative to controls, SRSs reported significantly more total symptoms when exposed to gasoline with 15% MTBE than when exposed to gasoline with 11% MTBE or to clean air. However, these differences in symptoms were not accompanied by significant differences in neurobehavioral performance or psychophysiologic responses. No significant differences in symptoms or neurobehavioral or psychophysiologic responses were observed when exposure to gasoline with 11% MTBE was compared to clean air or to gasoline. Thus, the present study, although showing increased total symptoms among SRSs when exposed to gasoline with 15% MTBE, did not support a dose-response relationship for MTBE exposure nor the symptom specificity associated with MTBE in epidemiologic studies.

Adult↗

PubMed1997

Psychoneuroimmunology.

This paper develops hypotheses regarding the interactions among stress, immunity, and chemical sensitivities and gives an overview of the questions and hypotheses generated by a working group exploring the application of psychoneuroimmunology to chemical sensitivities. Consideration is given to prospective longitudinal studies designed to find cases among at-risk exposed populations. Relevant immune parameters to be measured longitudinally and in challenge studies for patients with MCS are discussed. Immune system changes in response to the chronic stress of having MCS and as primary responses to chemical exposure also are considered.

Environment, Controlled↗

PubMed1996

Biomarkers of environmental benzene exposure.

Environmental exposures to benzene result in increases in body burden that are reflected in various biomarkers of exposure, including benzene in exhaled breath, benzene in blood and urinary trans-trans-muconic acid and S-phenylmercapturic acid. A review of the literature indicates that these biomarkers can be used to distinguish populations with different levels of exposure (such as smokers from nonsmokers and occupationally exposed from environmentally exposed populations) and to determine differences in metabolism. Biomarkers in humans have shown that the percentage of benzene metabolized by the ring-opening pathway is greater at environmental exposures than that at higher occupational exposures, a trend similar to that found in animal studies. This suggests that the dose-response curve is nonlinear; that potential different metabolic mechanisms exist at high and low doses; and that the validity of a linear extrapolation of adverse effects measured at high doses to a population exposed to lower, environmental levels of benzene is uncertain. Time-series measurements of the biomarker, exhaled breath, were used to evaluate a physiologically based pharmacokinetic (PBPK) model. Biases were identified between the PBPK model predictions and experimental data that were adequately described using an empirical compartmental model. It is suggested that a mapping of the PBPK model to a compartmental model can be done to optimize the parameters in the PBPK model to provide a future framework for developing a population physiologically based pharmacokinetic model.

Air Pollutants↗

PubMed1995

Lead in house dust: relationships between exposure metrics.

This paper examines the quantitative relationships between dust loading, lead loading, and lead concentration in house dust. Bare floor, interior sill, and carpet dust samples were collected in 216 Jersey City, New Jersey, homes using quantitative wipe and vacuum sampling techniques. Comparison of wipe and vacuum sample distributions for these homes indicated that lead loading was more variable than dust loading or lead concentration measured on floors, sills, or carpets. These data also indicated that increased lead loading on carpets relative to sills or floors was due to higher dust loading on carpets. Correlation analysis of wipe samples indicated that dust loading was more strongly correlated with lead loading on floors (r = 0.73) than on sills (r = 0.53), that dust loading was not correlated with lead concentration on either surface, and that lead loading and lead concentration were more strongly correlated in samples collected from sills (r = 0.81) than from floors (r = 0.65). Most importantly, carpets and rugs served as large reservoirs for house dust and consequently were a large potential source of dust exposure in children's common microenvironments.

Air Pollutants↗

PubMed1995

Mercury release from dental amalgams: an in vitro study under controlled chewing and brushing in an artificial mouth.

The release of mercury vapor from class I amalgam restorations prepared in human molar teeth was studied during chewing simulations in an artificial mouth of a bi-axial servo-hydraulic mechanical test system. So that the total mercury released from the restoration over a fixed time could be determined, a closed chamber surrounded the envelope of chewing motion. In addition, the influence of sampling frequency on mercury release was corrected by the use of different sampling frequencies over a fixed time interval of mercury release measurement and extrapolation to zero sampling time. Thus, a combination of a closed environment and an extrapolation method to determine the mercury release under continuous sampling was used to determine the mercury released under normal breathing conditions. The measured mercury release rate data were used to calculate the potential daily mercury dose in a patient due to a single amalgam restoration, following the method previously outlined by Berglund. The mercury release from both a conventional and a high-copper amalgam was evaluated at different age intervals after the restoration was placed in the teeth. The results show that while the age of the amalgam and the amalgam type influence the extent of mercury release during the initial non-steady-state conditions, the steady-state value of mercury daily dose due to a single amalgam filling is 0.03 micrograms/day, which is well below the calculated threshold-limiting value (TLV) of 82.29 micrograms/day considered dangerous for occupational exposure in the United States.

Air Pollution, Indoor↗

PubMed1991

Soft plastic bread packaging: lead content and reuse by families.

The presence of lead in labels painted on soft plastic bread packaging was evaluated. Lead was detected on the outside of 17 of 18 soft plastic bread bags that were analyzed, with an average of 26 +/- 6 mg per bag with lead. Of 106 families questioned, 16 percent of respondents reported turning the bags inside out before reusing for food storage, thus putting food in contact with the lead paint. We estimate that a weak acid, such as vinegar, could readily leach 100 micrograms of lead from a painted plastic bag within 10 minutes. Further, lead and other metals painted on food packaging of any type becomes part of the municipal waste stream subject to incineration and to land-filling. The use of lead in packaging presents an unnecessary risk to public health.

Bread↗

PubMedDate not supplied

A field comparison of two methods for sampling lead in household dust.

Comparability of dust lead measurements has been a difficult problem due to different sampling and analysis techniques. This paper compares two dust sampling techniques, the U.S. Department of Housing and Urban Development (HUD) dust wipe method and the Lioy, Wainman, Weisel (LWW) sampler. The HUD method specifies using a moist towelette to pick up as much dust as possible in a specified area and estimates total lead loading. The LWW sampler collects the dust on preweighed wetted filter media, and provides greater standardization of the sampling path and pressure applied. LWW samples were analyzed using inductively coupled plasma mass spectronomy (no samples below minimum detection limit), while HUD samples were analyzed using flame atomic absorption (32% of samples below minimum detection limit). A bootstrapping technique was used in the analysis to contend with those HUD samples below the minimum detection limit. Mixed model equations were generated to predict HUD values from LWW results, and to examine the effects of sampling location, time, and method. The results indicate that the two samplers performed similarly under field conditions, although the LWW sampler produced consistently lower lead loading estimates. LWW values that predicted HUD lead clearance values of 100 micrograms/ft2 for floors and 500 micrograms/ft2 for window sills were 72 micrograms/ft2 and 275 micrograms/ft2, respectively. To examine internal reproducibility, duplicate samples were taken using both the HUD and LWW methods. Correlation results within paired samples indicated a statistically significantly higher (p < 0.001) internal reproducibility for lead loading, for the LWW sampler (r = 0.87), than for the HUD method (r = 0.71). Some of the differences appeared to be related to the analytical methods.

Child, Preschool↗

PubMedDate not supplied

The MTBE air concentrations in the cabin of automobiles while fueling.

Methyl tertiary-butyl ether (MTBE) is the most commonly used oxygenated compound added to gasoline to reduce ambient carbon monoxide levels. Complaints about perceived MTBE exposures and adverse health symptoms have been registered in several states, including New Jersey (NJ). Fueling automobiles is the activity thought to cause the highest environmental MTBE exposures. The current study was conducted to determine the MTBE concentrations inside automobile cabins during fueling, which represents the peak exposure that can occur at full service gasoline service stations, such as those that exist in NJ. Air samples were collected at service stations located on the NJ and PA turnpikes from March 1996 to July 1997 during which the MTBE content in gasoline varied. A bimodal distribution of MTBE concentrations was found in the cabin of the cars while fueling. The median MTBE, benzene and toluene in cabin concentrations were 100, 5.5 and 18 ppb, respectively, with the upper concentrations of the distribution exceeding 1 ppm for MTBE and 0.1 ppm for benzene and toluene. The highest in cabin concentrations occurred in a car that had a malfunctioning vapor recovery system and in a series of cars sampled on an unusually warm, calm winter day when the fuel volatility was high, the evaporation maximal and the dispersion by wind minimal. The in-cabin concentrations were typically higher when the car window was opened during the entire fueling process. Thus, exposure to MTBE during fueling can be reduced by properly maintaining the integrity of the fuel system and keeping the windows closed during fueling.

Air Pollution, Indoor↗

PubMedDate not supplied

Mercury and methylmercury exposure in the New Jersey pregnant population.

Methylmercury is a known fetal developmental neurotoxicant. The only significant source of fetal exposure is maternal fish consumption; however, few recent data on exposure of the pregnant population are available. The authors undertook a study of methylmercury exposure in the New Jersey pregnant population to investigate the distribution of exposure and to identify predictors of elevated exposure. Mainly first-trimester pregnant women were recruited through six New Jersey obstetric practices. Hair and blood samples were analyzed for total mercury, and a subset was analyzed for methylmercury. A questionnaire on demographics, life style, and fish-consumption practices was also administered. Although 85-90% of the pregnant population had hair mercury levels that were less than 1.0 microg/gm, 1-2% had levels in a range of possible concern for adverse developmental effects (> 4.0 microg/gm). Regression analysis suggested that blacks and individuals with some college education experienced lower exposures to methylmercury.

Adult↗

PubMedDate not supplied

A wipe sampler for the quantitative measurement of dust on smooth surfaces: laboratory performance studies.

A flat surface wipe sampler has been developed to quantitatively measure the concentration (micrograms/g) and surface loading (micrograms/cm2) of dust on flat surfaces. The Lioy-Weisel-Wainman (LWW) Sampler has been tested under conditions that controlled particle deposition in a chamber for two types of particles: road dust and potting soil, and for three different types of surfaces: painted shelving, formica, and wood paneling. The results for replicate analyses demonstrated that the sampler had > 90% efficiency for the capture of deposited dust and had a coefficient of variation of < 20% for replicate samples of the wooden shelving and formica. The wood paneling had a higher coefficient of variation, although it was less than 25%, due to its porosity. Operating procedures are presented and illustrated, and results from a study that used the technique to sample chromium from residential settings are also discussed.

Dust↗

PubMedDate not supplied

The effectiveness of a home cleaning intervention strategy in reducing potential dust and lead exposures.

The changes in dust loading, lead loading and lead concentration, determined from vacuum samples and wipe samples collected during the Childhood Lead Exposure Assessment and Reduction Study (CLEARS) were analyzed to determine the efficacy of the cleaning protocol in homes of children found to have moderate lead poisoning, e.g. levels between 10-20 micrograms/dL. The samples were collected at least twice, and in 65 homes three times, during the course of a year long intervention in homes where half were randomized into a group which received a standardized Lead Intervention program for lead reduction, and the other homes only received an Accident Intervention program. The homes with lead burdened children were located in Hudson County, New Jersey (primarily in Jersey City), and were referred to the CLEARS by a number of private and public sources. Each home had wipe sampling conducted with the LWW Sampler (patented), and vacuum sampling was completed using a device described by Wang et al. in Applied Occupational and Environmental Hygiene. The results were compared in two ways: (1) between the two intervention groups, and (2) over the time course of the intervention period. When compared to the values seen in the first visit vacuum sampling results showed statistically significant decreases in lead loading and dust loading by the third sampling visit for the Lead Intervention homes. Substantial reductions in lead loading and dust loading were also seen when the Lead Intervention values were compared to values obtained in the Accident Intervention homes over the course of the year long intervention. The wipe sampling results for the 65 homes with three visits found no significant reductions in dust loading and lead loading among any of the room surfaces sampled in the Accident Intervention homes. There were 75% and 50% reductions observed on the window sills and on the bedroom floors of the homes which participated in the Lead Intervention. The levels in the living room and the kitchen showed very little change in loadings. This appeared to be due to the fact these rooms were near a background or baseline value of 0.3 g/cm2 and 0.12 mg/cm2 for dust loading and lead, respectively. This was substantiated by the window sills and bedroom wipe sampling results since each surface approached these values by the third visit. Significant reductions in lead concentrations found in the wipe samples from the intervention homes appeared to be related to the absence of historically active sources of lead in these homes, rather than elimination of current sources. The results of the micro-environmental sampling program in CLEARS indicated that a year long cleaning protocol can significantly decrease lead levels in rugs and on other exposed surfaces. This will reduce the potential for exposure to lead among the occupants, especially children, that come in contact with such surfaces.

Air Pollution, Indoor↗