Deborah H. Bennett

The Relationship of Urinary Metabolites of Carbaryl/Naphthalene and Chlorpyrifos with Human Semen Quality

Most of the general population is exposed to carbaryl and other contemporary-use insecticides at low levels. Studies of laboratory animals, in addition to limited human data, show an association between carbaryl exposure and decreased semen quality. In the present study we explored whether environmental exposures to 1-naphthol (1N), a metabolite of carbaryl and naphthalene, and 3,5,6-trichloro-2-pyridinol (TCPY), a metabolite of chlorpyrifos and chlorpyrifos-methyl, are associated with decreased semen quality in humans. Subjects (n = 272) were recruited through a Massachusetts infertility clinic. Individual exposures were measured as spot urinary concentrations of 1N and TCPY adjusted using specific gravity. Semen quality was assessed as sperm concentration, percent motile sperm, and percent sperm with normal morphology, along with sperm motion parameters (straight-line velocity, curvilinear velocity, and linearity). Median TCPY and 1N concentrations were 3.22 and 3.19 μg/L, respectively. For increasing 1N tertiles, adjusted odds ratios (ORs) were significantly elevated for below-reference sperm concentration (OR for low, medium, and high tertiles = 1.0, 4.2, 4.2, respectively; p-value for trend = 0.01) and percent motile sperm (1.0, 2.5, 2.4; p-value for trend = 0.01). The sperm motion parameter most strongly associated with 1N was straight-line velocity. There were suggestive, borderline-significant associations for TCPY with sperm concentration and motility, whereas sperm morphology was weakly and nonsignificantly associated with both TCPY and 1N. The observed associations between altered semen quality and 1N are consistent with previous studies of carbaryl exposure, although suggestive associations with TCPY are difficult to interpret because human and animal data are currently limited.

Ranking cancer risks of organic hazardous air pollutants in the United States.

Background In this study we compared cancer risks from organic hazardous air pollutants (HAPs) based on total personal exposure summed across different microenvironments and exposure pathways. Methods We developed distributions of personal exposure concentrations using field monitoring and modeling data for inhalation and, where relevant, ingestion pathways. We calculated risks for a nonoccupationally exposed and nonsmoking population using U.S. Environmental Protection Agency (EPA) and California Office of Environmental Health and Hazard Assessment (OEHHA) unit risks. We determined the contribution to risk from indoor versus outdoor sources using indoor/outdoor ratios for gaseous compounds and the infiltration factor for particle-bound compounds. Results With OEHHA’s unit risks, the highest ranking compounds based on the population median are 1,3-butadiene, formaldehyde, benzene, and dioxin, with risks on the order of 10−4–10−5. The highest risk compounds with the U.S. EPA unit risks were dioxin, benzene, formaldehyde, and chloroform, with risks on a similar order of magnitude. Although indoor exposures are responsible for nearly 70% of risk using OEHHA’s unit risks, when infiltration is accounted for, inhalation of outdoor sources contributed 50% to total risk, on average. Additionally, 15% of risk resulted from exposures through food, mainly due to dioxin. Conclusions Most of the polycyclic aromatic hydrocarbon, benzene, acetaldehyde, and 1,3-butadiene risk came from outdoor sources, whereas indoor sources were primarily responsible for chloroform, formaldehyde, and naphthalene risks. The infiltration of outdoor pollution into buildings, emissions from indoor sources, and uptake through food are all important to consider in reducing overall personal risk to HAPs.

Intake fraction for multimedia pollutants: A tool for life cycle analysis and comparative risk assessment

We employ the intake fraction (iF) as an effective tool for expressing the source-to-intake relationship for pollutant emissions in life cycle analysis (LCA) or comparative risk assessment. Intake fraction is the fraction of chemical mass emitted into the environment that eventually passes into a member of the population through inhalation, ingestion, or dermal exposure. To date, this concept has been primarily applied to pollutants whose primary route of exposure is inhalation. Here we extend the use of iF to multimedia pollutants with multiple exposure pathways. We use a level III multimedia model to calculate iF for TCDD and compare the result to one calculated from measured levels of dioxin toxic equivalents in the environment. We calculate iF for emissions to air and surface water for 308 chemicals. We correlate the primary exposure route with the magnitudes of the octanol-water partition coefficient, Kow, and of the air-water partitioning coefficient (dimensionless Henry constant), Kaw. This results in value ranges of Kow and Kaw where the chemical exposure route can be classified with limited input data requirements as primarily inhalation, primarily ingestion, or multipathway. For the inhalation and ingestion dominant pollutants, we also define empirical relationships based on chemical properties for quantifying the intake fraction. The empirical relationships facilitate rapid evaluation of many chemicals in terms of the intake. By defining a theoretical upper limit for iF in a multimedia environment we find that iF calculations provide insight into the multimedia model algorithms and help identify unusual patterns of exposure and questionable exposure model results.

Temporal variability of urinary levels of nonpersistent insecticides in adult men

Widespread application of contemporary-use insecticides results in low-level exposure for a majority of the population through a variety of pathways. Urinary insecticide biomarkers account for all exposure pathways, but failure to account for temporal within-subject variability of urinary levels can lead to exposure misclassification. To examine temporal variability in urinary markers of contemporary-use insecticides, nine repeated urine samples were collected over 3 months from 10 men participating in an ongoing study of male reproductive health. These 90 samples were analyzed for urinary metabolites of chlorpyrifos (3,5,6-trichloro-2-pyridinol (TCPY)) and carbaryl (1-naphthol (1N)). Volume- based (unadjusted), as well as creatinine (CRE)- and specific gravity (SG)-adjusted concentrations were measured. TCPY had low reliability with an intraclass correlation coefficient between 0.15 and 0.21, while 1N was moderately reliable with an intraclass correlation coefficient between 0.55 and 0.61. When the 10 men were divided into tertiles based on 3-month geometric mean TCPY and 1N levels, a single urine sample performed adequately in classifying a subject into the highest or lowest exposure tertiles. Sensitivity and specificity ranged from 0.44 to 0.84 for TCPY and from 0.56 to 0.89 for 1N. Some differences in the results between unadjusted metabolite concentrations and concentrations adjusted for CRE and SG were observed. Questionnaires were used to assess diet in the 24 h preceding the collection of each urine sample. In mixed-effects models, TCPY was significantly associated with season as well as with consuming grapes and cheese, while 1N levels were associated with consuming strawberries. In conclusion, although a single sample adequately predicted longer-term average exposure, a second sample collected at least 1 month following the first sample would reduce exposure measurement error.

PBDEs in 2−5 Year-Old Children from California and Associations with Diet and Indoor Environment

This study determined the body burden of PBDEs in 100 California children, and evaluated associations with sociodemographic, household, and dietary factors. In national and international comparisons, California dust, breast milk, and human serum samples contain higher concentrations of PBDEs. Higher levels in children suggest exposure pathways depend upon age. Plasma samples were analyzed for PBDEs using GC/MS. Circulating levels of PBDEs were 10-to 1000-fold higher than similar aged populations in Mexico and Europe, 5-times higher than similar aged children across the U.S., and 2- to 10-fold higher than U.S. adults. Increased levels of higher-brominated congeners were associated with the recent purchase of new upholstered furniture or mattresses and consumption of pork. Concentrations of lower-brominated congeners increased with frequency of poultry consumption. Lower maternal education was independently and significantly associated with higher levels of most congeners in the children.

Indoor carbon monoxide and PM2.5 concentrations by cooking fuels in Pakistan

UNLABELLED In developing countries biomass combustion is a frequently used source of domestic energy and may cause indoor air pollution. Carbon monoxide (CO)and particulate matter with an aerodynamic diameter of 2.5 lm or less (PM2.5)were measured in kitchens using wood or natural gas (NG) in a semi-rural community in Pakistan. Daytime CO and PM2.5 levels were measured for eight continuous hours in 51 wood and 44 NG users from December 2005 to April 2006. The laser photometer PM2.5 (Dustrak, TSI) was calibrated for field conditions and PM2.5 measurements were reduced by a factor of 2.77. CO was measured by an electrochemical monitor (Model T15v, Langan). The arithmetic mean for daytime CO concentration was 29.4 ppm in wood users; significantly higher than 7.5 ppm in NG users (P < 0.001). The arithmetic mean for daytime PM2.5 concentrations was 2.74 mg/m3 in wood users; significantly higher than 0.38 mg/m3 in NG users (P < 0.001). Higher peak levels of CO and PM2.5 were also observed in wood users. Time spent in the kitchen during fuel burning was significantly related to increasing CO and PM2.5 concentrations in wood users.These findings suggest that cooking with wood fuel may lead to hazardous concentrations of CO and PM2.5. PRACTICAL IMPLICATIONS Biomass combustion is frequently used in developing countries for cooking. This study showed very high level of air pollution in kitchens using wood as the cooking fuel. Many people, especially women and children, are vulnerable to exposure to very high levels of air pollutants as they spend time in the kitchen during cooking hours.

Pesticide loadings of select organophosphate and pyrethroid pesticides in urban public housing

We investigated the magnitude and distribution of pyrethroid and organophosphate pesticide loadings within public housing dwellings in Boston, Massachusetts and compared the results using various sampling methods. We collected dust matrices from living room and kitchen in 42 apartments and analyzed for eleven pyrethoids (e.g., permethrin and cyfluthrin) and two organophosphates (chlorpyrifos and diazinon) in house dust using GC/MS. Agreement between sampling methods were evaluated using Spearman correlations and Kappa statistics. Permethrin and chlorpyrifos were detected in kitchen floor wipes in all homes, followed in frequency of detects by diazinon (98%), cypermethrin (90%) and cyfluthrin (71%). At least six pesticides were detected in kitchen floor wipes in the majority of the homes (range 3–8). Positive and statistically significant correlations among dust matrices were observed between kitchen floor wipes and living room vacuum dust, including for diazinon (r=0.62) and cyfluthrin (r=0.69). Detection of several pesticides including banned or restricted use products in some public housing units, underscore the need for alternative pest management strategies that embrace the safe and judicious use of pest control products.

Influence of traffic patterns on particulate matter and polycyclic aromatic hydrocarbon concentrations in Roxbury, Massachusetts

Vehicle emissions have been associated with adverse health effects in multiple epidemiological studies, but the sources or constituents responsible have not been established. Characterization of vehicle-related exposures requires detailed information on spatial and temporal trends of various pollutants and the ability to predict exposures in unmonitored settings. To address these issues, in the summer of 2001 we measured continuously particle-bound polycyclic aromatic hydrocarbons (PAHs), ultrafine particles, and PM2.5 at a number of sites in Roxbury, a neighborhood of Boston, Massachusetts with significant diesel and gasoline-fueled traffic. We took measurements at the side of the road and at varying distances from the road, with simultaneous collection of traffic counts and meteorological conditions. Across all nine sites, median roadside concentrations were 8 ng/m3 of particle-bound PAHs (range: 4–57), 16,000 ultrafine particles/cm3 (range: 11,000–53,000), and 54 μg/m3 of PM2.5 as measured with a DustTrak (range: 12–86). Concentrations of all pollutants were lower at greater distances from the road, upwind, and at higher wind speeds, with greater concentration gradients for PAHs and ultrafine particles. In linear mixed effects regression models accounting for temporal autocorrelation, large diesel vehicle counts were significantly associated with roadside concentrations of PAHs (P=0.02), with a moderate association with ultrafine particles and little relation with PM2.5. Although more comprehensive information would be needed for epidemiological applications, these data demonstrate significant spatial and temporal heterogeneity for traffic-related pollutants during the summer in an urban center, with our monitoring and analytical methodology helping to inform source attribution.

Differences in source emission rates of volatile organic compounds in inner-city residences of New York City and Los Angeles.

The Toxics Exposure Assessment Columbia-Harvard (TEACH) Project characterized personal, indoor, and outdoor concentrations of a suite of volatile organic compounds (VOCs) for high school students living in New York City (NYC) and Los Angeles (LA). This paper presents the analysis of VOC measurements collected indoors and outdoors for 46 students’ homes in NYC and for 41 students’ homes in LA across two seasons. Dual-sorbent thermal desorption tubes were used for the collection of 15 VOCs and C18 2,4-dinitrophenylhydrazine-coated cartridges were used for the collection of seven aldehydes. Air-exchange rates (AERs) were also measured using a perfluorocarbon tracer gas method. The AERs were lower in the winter in both cities, averaging 1 h−1 in NYC and 1.4 h−1 in LA, compared with 1.8 h−1 in NYC in the summer and 2.5 h−1 in LA in the fall. Higher AERs were generally associated with lower indoor–outdoor ratios with significant differences for the compounds with indoor sources, including chloroform, 1,4-dichlorobenzene, and formaldehyde. Using a mass-balance model to account for AER and other housing parameters, effective source emission rates (SER) were calculated for each compound. Based on I/O ratios and source emission rates, VOCs could be divided into: (1) indoor-source-influenced compounds, (2) those with contributions from both indoor and outdoor sources, and (3) those with mostly outdoor sources. Significant indoor sources were found for the following six compounds (mean emission rates presented): chloroform (0.11 mg/h), 1,4-dichlorobenzene (19 mg/h), formaldehyde (5 mg/h), acetaldehyde (2 mg/h), benzaldehyde (0.6 mg/h), and hexaldehyde (2 mg/h). Although chloroform had variable I/O ratios across seasons, SERs, which accounted for AER, were similar in both cities for both seasons (e.g., LA means 0.12 and 0.11 mg/h in winter and fall, respectively). Formaldehyde had substantially higher indoor emission rates in the summer in NYC compared to winter (3.8 vs. 1.6 mg/h) but lower in the fall in LA compared to winter (4.3 vs. 5.0 mg/h). Uncertainty analysis determined that source strength calculations were not sensitive to measurement error for a subset of homes in LA.

A Cancer Risk Assessment of Inner-City Teenagers Living in New York City and Los Angeles

Background The Toxics Exposure Assessment Columbia–Harvard (TEACH) project assessed exposures and cancer risks from urban air pollutants in a population of high school teenagers in New York City (NYC) and Los Angeles (LA). Forty-six high school students participated in NYC and 41 in LA, most in two seasons in 1999 and 2000, respectively. Methods Personal, indoor home, and outdoor home 48-hr samples of volatile organic compounds (VOCs), aldehydes, particulate matter with aerodynamic diameter ≤ 2.5 μm, and particle-bound elements were collected. Individual cancer risks for 13 VOCs and 6 particle-bound elements were calculated from personal concentrations and published cancer unit risks. Results The median cumulative risk from personal VOC exposures for this sample of NYC high school students was 666 per million and was greater than the risks from ambient exposures by a factor of about 5. In the LA sample, median cancer risks from VOC personal exposures were 486 per million, about a factor of 4 greater than ambient exposure risks. The VOCs with the highest cancer risk included 1,4-dichlorobenzene, formaldehyde, chloroform, acetaldehyde, and benzene. Of these, benzene had the greatest contributions from outdoor sources. All others had high contributions from indoor sources. The cumulative risks from personal exposures to the elements were an order of magnitude lower than cancer risks from VOC exposures. Conclusions Most VOCs had median upper-bound lifetime cancer risks that exceeded the U.S. Environmental Protection Agency (EPA) benchmark of 1 × 10−6 and were generally greater than U.S. EPA modeled estimates, more so for compounds with predominant indoor sources. Chromium, nickel, and arsenic had median personal cancer risks above the U.S. EPA benchmark with exposures largely from outdoors and other microenvironments. The U.S. EPA–modeled concentrations tended to overestimate personal cancer risks for beryllium and chromium but underestimate risks for nickel and arsenic.