Serap Erdal

A Quantitative Look at Fluorosis, Fluoride Exposure, and Intake in Children Using a Health Risk Assessment Approach

The prevalence of dental fluorosis in the United States has increased during the last 30 years. In this study, we used a mathematical model commonly employed by the U.S. Environmental Protection Agency to estimate average daily intake of fluoride via all applicable exposure pathways contributing to fluorosis risk for infants and children living in hypothetical fluoridated and non-fluoridated communities. We also estimated hazard quotients for each exposure pathway and hazard indices for exposure conditions representative of central tendency exposure (CTE) and reasonable maximum exposure (RME) conditions. The exposure pathways considered were uptake of fluoride via fluoridated drinking water, beverages, cow’s milk, foods, and fluoride supplements for both age groups. Additionally, consumption of infant formula for infants and inadvertent swallowing of toothpaste while brushing and incidental ingestion of soil for children were also considered. The cumulative daily fluoride intake in fluoridated areas was estimated as 0.20 and 0.11 mg/kg-day for RME and CTE scenarios, respectively, for infants. On the other hand, the RME and CTE estimates for children were 0.23 and 0.06 mg/kg-day, respectively. In areas where municipal water is not fluoridated, our RME and CTE estimates for cumulative daily average intake were, respectively, 0.11 and 0.08 mg/kg-day for infants and 0.21 and 0.06 mg/kg-day for children. Our theoretical estimates are in good agreement with measurement-based estimates reported in the literature. Although CTE estimates were within the optimum range for dental caries prevention, the RME estimates were above the upper tolerable intake limit. This suggests that some children may be at risk for fluorosis.

Urinary 1-Hydroxypyrene as a Biomarker of PAH Exposure in 3-Year-Old Ukrainian Children

Urinary 1-hydroxypyrene (1-OHP) is a biomarker of polycyclic aromatic hydrocarbon (PAH) exposure. We measured urinary 1-OHP in 48 children 3 years of age in Mariupol, Ukraine, who lived near a steel mill and coking facility and compared these with 1-OHP concentrations measured in 42 children of the same age living in the capital city of Kiev, Ukraine. Children living in Mariupol had significantly higher urinary 1-OHP and creatinine-adjusted urinary 1-OHP than did children living in Kiev (adjusted: 0.69 vs. 0.34 μmol/mol creatinine, p < 0.001; unadjusted: 0.42 vs. 0.30 ng/mL, p = 0.002). Combined, children in both cities exposed to environmental tobacco smoke in their homes had higher 1-OHP than did children not exposed (0.61 vs. 0.42 μmol/mol creatinine; p = 0.04; p = 0.07 after adjusting for city). In addition, no significant differences were seen with sex of the children. Our sample of children in Mariupol has the highest reported mean urinary 1-OHP concentrations in children studied to date, most likely due to their proximity to a large industrial point source of PAHs.

Comparing the reliability of responses to telephone-administered versus self-administered Web-based surveys in a case-control study of adult malignant brain cancer.

Introduction: To determine whether a Web-based survey was an acceptable method of data collection for a clinic-based case-control study of adult brain cancer, the authors compared the reliability of paired responses to a main and resurvey for participants completing surveys by telephone (n = 74) or self-administered on the Web (n = 465) between 2003 and 2006. Methods: Recruitment of cases was done at the Evanston Northwestern Healthcare Kellogg Cancer Care Center and the Duke University Medical Center Cancer Control division, and controls were friends and siblings of cases. Twenty-five variables were examined, including smoking, oral contraceptive and residential histories, water sources, meat preparation, fruit and vegetable consumption, and pesticide use. Weighted and simple κs were estimated for categorical and binary variables, respectively. Results: The number of concordant paired responses was summed for use in linear regression. Respondents were 97% White and 85% had postsecondary education. Kappas for individual questions ranged from 0.31 (duration of residence in a single family house) to 0.96 (ever smoked), with a median of 0.57 (95% confidence interval, 0.47-0.64). The median number of concordant responses was 16.2 (range, 5-22). Reliability was greater for controls than cases, Web-based versus telephone responders, females, and higher-income responders. Frequency of e-mail and Internet use was not associated with reliability. Conclusions: A self-administered, Web-based survey was a feasible and appropriate mode of interview in this study. The comparable reliability of Web compared with telephone responses suggest that Web-based self-interviews could be a cost-effective alternative to traditional modes of interview. (Cancer Epidemiol Biomarkers Prev 2008;17(10):2639–46)

Particle size fractionation and human exposure of polybrominated diphenyl ethers in indoor dust from Chicago

The objective of this study was to investigate the concentration level, the mass distribution based on dust particle size, and the associated human exposure of polybrominated diphenyl ethers (PBDEs) in indoor dust. The total concentration of 13 PBDEs Σ13(BDEs) was found to be 500–6,944 ng/g in indoor dusts, 4,000 ng/g in car interior dust, 260–300 ng/g in outdoor ambient air particles, 30 ng/g in carpet fibers, and as high as 0.5% in carpet padding. Selected dust samples were fractionated based on particle size, and over 80% of the Σ13BDEs were associated with particles < 150 μm in diameter. Mass ratios of BDE206/BDE209 are higher in both indoor and outdoor samples than in commercial deca products; and mass ratio BDE47/BDEs(85+99+100) was much higher in outdoor than in indoor samples. Using EPA software ProUCL, the exposure of Americans to PBDEs via hand-to-mouth transfer of house dust was estimated under the central tendency exposure and reasonable maximum exposure scenarios. The results suggest that ingestion of PBDE-laden house dust via hand-to-mouth contact is likely a significant exposure pathway, especially for children.

Assessment of type of allergy and antihistamine use in the development of glioma

Background: Allergies have been associated with decreased risk of glioma; but, associations between duration and timing of allergies, and antihistamine use and glioma risk have been less consistent. The objective was to investigate this association by analyzing types, number, years since diagnosis, and age at diagnosis of allergies, and information on antihistamine usage, including type, duration, and frequency of exposure. Methods: Self-report data on medically diagnosed allergies and antihistamine use were obtained for 419 glioma cases and 612 hospital-based controls from Duke University and NorthShore University HealthSystem. Results: High- and low-grade glioma cases were statistically significantly less likely to report any allergy than controls (OR = 0.66, 95% CI: 0.49–0.87 and OR = 0.44, 95% CI: 0.25–0.76, respectively). The number of types of allergies (seasonal, medication, pet, food, and other) was inversely associated with glioma risk in a dose–response manner (P value for trend < 0.05). Age at diagnosis and years since diagnosis of allergies were not associated with glioma risk. Oral antihistamine use was statistically significantly inversely associated with glioma risk, but when stratified by allergy status, remained significant only for those with high-grade glioma and no medically diagnosed allergy. Conclusions: All types of allergies appear to be protective with reduced risk for those with more types of allergies. Antihistamine use, other than in relationship with allergy status, may not influence glioma risk. Impact: A comprehensive study of allergies and antihistamine use using standardized questions and biological markers will be essential to further delineate the biological mechanism that may be involved in brain tumor development. Cancer Epidemiol Biomarkers Prev; 20(2); 370–8. ©2011 AACR.

Demolition of High-Rise Public Housing Increases Particulate Matter Air Pollution in Communities of High-Risk Asthmatics

Abstract Public housing developments across the United States are being demolished, potentially increasing local concentrations of particulate matter (PM) in communities with high burdens of severe asthma. Little is known about the impact of demolition on local air quality. At three public housing developments in Chicago, IL, PM with an aerodynamic diameter <10 μm (PM10) and <2.5 μm were measured before and during high-rise demolition. Additionally, size-selective sampling and real-time monitoring were concurrently performed upwind and downwind of one demolition site. The concentration of particulates attributable to demolition was estimated after accounting for background urban air pollution. Particle microscopy was performed on a small number of samples. Substantial increases of PM10 occurred during demolition, with the magnitude of that increase varying based on sampler distance, wind direction, and averaging time. During structural demolition, local concentrations of PM10 42 m downwind of a demolition site increased 4- to 9-fold above upwind concentrations (6-hr averaging time). After adjusting for background PM10, the presence of dusty conditions was associated with a 74% increase in PM10 100 m downwind of demolition sites (24-hr averaging times). During structural demolition, short-term peaks in real-time PM10 (30-sec averaging time) occasionally exceeded 500 μg/m3. The median particle size downwind of a demolition site (17.3 μm) was significantly larger than background (3 μm). Specific activities are associated with real-time particulate measures. Microscopy did not identify asbestos or high concentrations of mold spores. In conclusion, individuals living near sites of public housing demolition are at risk for exposure to high particulate concentrations. This increase is characterized by relatively large particles and high short-term peaks in PM concentration.

Human head model as an aerosol sampler: calculation of aspiration efficiencies for coarse particles using an idealized human head model facing the wind

Abstract Theoretical quantification of the entry of coarse particles to the human mouth or nose under different inhalation rates and ambient wind velocities is an important topic in understanding inhalability, in extrapolating empirical results and designing inhalable aerosol samplers. Using an idealized human head model facing the wind and potential flow approximation for the velocity fields, coarse particle aspiration efficiencies were calculated for a set of inhalation and external fluid motion parameters. The inhalation parameters are orifice size, the frequency and the tidal volume of breathing which depend upon the level of exertion assumed as well as interpersonal variabilities. The external fluid motion parameters are introduced by the fluid motion external to the head and the orientation of the orifice axis with respect to the flow axis. The total velocity field was modeled by superimposing the velocity field generated by breathing onto the external velocity field generated by an ambient wind. In this three-dimensional velocity field around the idealized human head figure, the particle equations of motion for coarse particles result in a set of coupled ordinary differential equations. The numerical solution of this set can be used to obtain particle trajectories and particle aspiration efficiency. The aspiration efficiency calculation for 25–200 μm particle aerodynamic equivalent diameters, for tidal volumes of 750, 1450, 2250 cm 3 and for 0.5–9 m/s ambient wind speed conform to the main trends observed in the experimental studies. Thus they may be used to extrapolate the experimental findings. Most importantly, the calculations did not suggest an evidence of zero aspiration efficiency (cutoff) for aerodynamic equivalent diameters up to 200 μm for the range of inhalation and external fluid motion parameters examined.

Lead and other heavy metals in dust fall from single-family housing demolition

Objective. We measured lead and other heavy metals in dust during older housing demolition and effectiveness of dust suppression. Methods. We used American Public Housing Association Method 502 and U.S. Environmental Protection Agency Methods SW3050B and SW6020 at 97 single-family housing demolition events with intermittent (or no) use of water to suppress dust at perimeter, non-perimeter, and locations without demolition, with nested mixed modeling and tobit modeling with left censoring. Results. The geometric mean (GM) lead dust fall during demolition was 6.01 micrograms of lead per square foot per hour (μg Pb/ft2/hour). GM lead dust fall was 14.18 μg Pb/ft2/hour without dust suppression, but declined to 5.48 μg Pb/ft2/hour (p=0.057) when buildings and debris were wetted. Significant predictors included distance, wind direction, and main street location. At 400 feet, lead dust fall was not significantly different from background. GM lead concentration at demolition (2,406 parts per million [ppm]) was significantly greater than background (GM = 579 ppm, p=0.05). Arsenic, chromium, copper, iron, and manganese demolition dust fall was significantly higher than background (p<0.001). Demolition of approximately 400 old housing units elsewhere with more dust suppression was only 0.25 μg Pb/ft2/hour. Conclusions. Lead dust suppression is feasible and important in single-family housing demolition where distances between houses are smaller and community exposures are higher. Neighbor notification should be expanded to at least 400 feet away from single-family housing demolition, not just adjacent properties. Further research is needed on effects of distance, potential water contamination, occupational exposures, and water application.

Human exposure to selected animal neurocarcinogens: a biomarker-based assessment and implications for brain tumor epidemiology.

This review is based on the proceedings from the Second Lebow Conference, held in Chicago in 2007. The conference concentrated on developing a framework for innovative studies in the epidemiology of environmental exposures, focusing specifically on the potential relationship with brain tumors. Researchers with different perspectives, including toxicology, pharmacokinetics, and epidemiological exposure assessment, exchanged information and ideas on the use of biomarkers of exposure in molecular epidemiology studies and summarized the current knowledge on methods and approaches for biomarker-based exposure assessment. This report presents the state of science regarding biomarker-based exposure assessment of the four most common neurocarcinogens: acrylamide, 1,3-butadiene, N-nitroso compounds, and polycyclic aromatic hydrocarbons. Importantly, these chemicals are also carcinogenic in other organs; therefore, this discussion is useful for environmental epidemiologists studying all cancer types.

Groundwater arsenic in Chimaltenango, Guatemala

In the Municipality of Chimaltenango, Guatemala, we sampled groundwater for total inorganic arsenic. In total, 42 samples were collected from 27 (43.5%) of the 62 wells in the municipality, with sites chosen to achieve spatial representation throughout the municipality. Samples were collected from household faucets used for drinking water, and sent to the USA for analysis. The only site found to have a concentration above the 10 μg/L World Health Organization provisional guideline for arsenic in drinking water was Cerro Alto, where the average concentration was 47.5 μg/L. A health risk assessment based on the arsenic levels found in Cerro Alto showed an increase in noncarcinogenic and carcinogenic risks for residents as a result of consuming groundwater as their primary drinking water source. Using data from the US Geological Survey and our global positioning system data of the sample locations, we found Cerro Alto to be the only site sampled within the tertiary volcanic rock layer, a known source of naturally occurring arsenic. Recommendations were made to reduce the levels of arsenic found in the communitys drinking water so that the health risks can be managed.