Jed M. Waldman

The Total Human Environmental Exposure Study (THEES) to Benzo(a)pyrene: Comparison of the Inhalation and Food Pathways

The assessment of human exposure to an environmental contaminant requires the measurement of levels present in each pathway of possible contact. In this paper, the design considerations and Phase I results of a human exposure study focused on Benzo(a)pyrene (BaP) are discussed. This study site, located in Phillipsburg, New Jersey, is a city that contains a metal pipe foundry, which is a suspected major source of BaP. Three outdoor PM-10 samplers (used to collect BaP-containing particles with an aerodynamic size of less than or equal to 10 micron) were located in residential areas surrounding the foundry. Ten homes were sampled indoors for PM-10. Some homes have indoor combustion sources, e.g., cigarette smoke or a coal burning stove. The indoor and outdoor samples were 24 hr in duration. The mean outdoor concentration of BaP was 0.9 ng/m3, and the indoor concentrations ranged from 0.1-8.1 ng/m3. Food samples were acquired from family meals each day. They represented a one-third portion of each meal eaten at home. The range of BaP per gram of wet weight of food was between 0.004 and 1.2 ng/g. Of the 20 wk of exposure (10 x 2 wk), 10 had higher food exposures and the other 10 had higher inhalation exposures. Of the two groups, the higher food exposures usually had a greater number of ng of BaP/wk. The dominance of one or the other pathway appeared to depend upon personal eating habits and indoor combustion source use. In some instances, outdoor air pollution led to a major portion of indoor air BaP exposures. Water appears to be a minor source of BaP exposures in the study area.

Assessment of carcinogenic risk from personal exposure to benzo(a)pyrene in the Total Human Environmental Exposure Study (THEES)

The Total Human Environmental Exposure Study (THEES) was an investigation of multimedia exposure to the ubiquitous environmental carcinogen, benzo(a)pyrene (BaP). The three-phase study was conducted in Phillipsburg, New Jersey and involved the participation of 14-15 individuals (8-10 homes) during each 14-day monitoring period. Microenvironmental sampling of air, food, water and soil indicated that environmental exposure to BaP was primarily through air and food. Exposure and risk estimates were, therefore, based on the results of personal monitoring of breathing zone air and prepared food samples. Based on a comparison of the range and magnitude of inhalation and dietary BaP exposures, food ingestion was clearly the predominant exposure to pathway. The relative contributions of other potential sources of community exposure to BaP (e.g., soil and drinking water ingestion) were also assessed. The excess cancer risk estimates for food ingestion were consistently greater than those for personal air, reflecting both the predominantly higher BaP exposures through the diet and the higher carcinogenic potency value for oral exposure. Overall, the total lifetime risk from personal exposure to BaP for nonsmokers in the community was estimated at 10(-5). In identifying risk reduction options, it is important to account for the observation that personal activities, lifestyle, and diet strongly influenced individual exposures to BaP.

The personal, indoor and outdoor concentrations of PM-10 measured in an industrial community during the winter

The concentrations of PM-10 were measured for 2 weeks in the winter of 1988 as part of the Total Human Environmental Exposure Study (THEES). Samples were taken simultaneously in a small city, Phillipsburg, NJ for outdoor and indoor microenvironments, and with personal monitors on non-smokers. There were four outdoor sites, eight indoor sites and fourteen individuals wearing personal monitors. The mean concentrations were 66, 48 and 42 μg m−3 for the personal, outdoor and indoor sites, respectively, with the personal samplers having 8.8% of the 24h averages above 150 μg m−3. The higher outdoor averages with respect to indoors were suspected to be related to more prevalent outdoor sources of coarse particles < 10 μm in diameter, and the lack of residential smokers to contribute to the indoor respirable subfraction. There was one day during the period when all the outdoor sites exceeded the 24 h PM-10 standard. Increased outdoor levels were also reflected in elevated indoor samples and the personal samples on that day. These would be a result of direct outdoor exposures and the penetration of outdoor PM-10 to the indoors.

An assessment of a urinary biomarker for total human environmental exposure to benzo[a]pyrene

Urinary banzo[a]pyrene (BaP) metabolite levels were compared to human environmental exposure to BaP through inhalation and dietary ingestion to assess the predictive validity of the exposure biomarker. These measurements were made for 14 adult volunteers over 14 consecutive days, once during summer/fall, again during winter periods. Based on personal air monitoring, median potential inhalation doses of 11.0 and 2.3 ng/day were estimated for the winter and summer/fall studies, respectively. A median potential ingested dose of 176 ng/day, estimated from “duplicate plate” sampling, exceeded inhalation by 6-and 122-fold for the winter and summer/fall studies, respectively. “Total” urinary BaP metabolites were measured using a published “reverse metabolism” (BaP) method of analysis. Median rates of urinary BaP metabolite elimination for the winter and summer/fall studies were 121 and 129 ng/day, respectively. The changes in inhaled and ingested potential doses were regressed on the change in urinary metabolite elimination from week 1 to week 2 to test the predictive validity of the biomarker measurement. The regression was statistically significant (r = 0.620, p = 0.015, n = 25) when body weight was included and two extreme values were removed. Consistent with the exposure measurements showing diet as the dominant route of exposure, most of the variation in urinary metabolite elimination was explained by the ingested dose. It is concluded that the measurement of urinary BaP by “reverse metabolism” is qualitative and of marginal predictive validity as an exposure biomarker due to the methods low recoveries and the large unexplained variance.

Breath Ammonia Depletion and Its Relevance to Acidic Aerosol Exposure Studies

It is thought that gaseous ammonia in breath neutralizes acidic air pollution and thereby potentially mitigates the pulmonary effects of pollution. The efficacy of breath ammonia depletion methods reported in recent acid aerosol exposure-health response studies was investigated. Fourteen subjects (21 to 54 y of age) performed one or more of the following hygiene maneuvers: (a) acidic oral rinse (pH 2.5); (b) tooth brushing, followed by acidic oral rinse; (c) tooth brushing, followed by distilled water rinse; and (d) distilled water rinse. Initial ammonia levels ranged from 120 to 1,280 ppb (147-1,570 micrograms/m3). Acidic rinsing resulted in an immediate 90% reduction in exhaled ammonia in all subjects, and a return to 50% of baseline levels occurred within 1 h. Depletion that resulted from tooth brushing or distilled water alone was not significant. It was concluded that acidic oral rinsing is an effective method of reducing airway ammonia, but repeated oral rinsing may be required to maintain consistent, low-breath-ammonia conditions during acid aerosol exposure studies.

Wintertime measurements of aerosol acidity and trace elements in Wuhan, a city in central China

A 2-week intensive ambient aerosol study was conducted in December 1988 in Wuhan (Hubei Province), a city of nearly 2 million located on the Yangtze River in central China (P.R.C.). This is an industrial region where soft coal burning is widespread, and emission controls for vehicles and industrial facilities are minimal. The sampling site was located in one of the civic centers where residential and commercial density is highest. An Andersen dichotomous sampler was operated with Teflon membrane filters to collect fine (dp < 2.5 μmad) and coarse (2.5 ⩽ dp < 10 μmad) particles for total mass and element determinations. An annular denuder system (ADS) was used to collect fine fraction aerosols for analyses of ionic species including strong acidity (H+). The study was conducted between 18 and 30 December, which was rainless, consistently cool (3–10°C) and overcast, but without fog or acute stagnation. Fine particulate mass (PM, as μ m−3) averaged 139 (range 54–207); coarse PM averaged 86 (range 29–179). Trace element concentrations were also high. Crustal elements (Si, Al, Ca and Fe) were found primarily in the coarse fraction, while elements associated with combustion (S, K, Cl, Zn and Se) were enriched in the fine fraction. The concentrations of arsenic and selenium were evidence of a large source of coal burning, while vanadium levels (associated with fuel oil use) were not especially enriched. Despite the seemingly high PM loadings, ionic concentrations were not especially high. The average composition of soluble fine aerosol species (in neq m−3) were SO42−: 520 (range 180–980), NO3−: 225 (range 50–470), Cl−: 215 (range 20–640), and NH4+: 760 (range 280–1660). A deficit in accountable FP components (total mass compared to the total of ionic plus element masses) as well as the black appearance of collected materials indicate an abundance of carbonaceous aerosol, as high as 100 μ m−3. (total mass compared to the total of ionic plus element masses) as well as the black appearance of collected materials indicate an abundance of carbonaceous aerosol, as high as 100 μ m−3 Aerosol acidity was negligible during most monitoring periods, H+: 14 (range 0–50 neq m−3, equivalent to 0–2.5 μm m−3 as H2SO4). Sulfur dioxide, measured by the West-Gaeke method for part of the study, concentrations were low. Although not directly measured, the aerosol measurments suggested that gaseous HCl (from refuse incineration) and NH3 (animal wastes) concentrations might have been high. Higher aerosol acidity might be expected if HCl sources were more prominent and not neutralized by local ammonia or other base components.

Spatial and temporal patterns in summertime sulfate aerosol acidity and neutralization within a metropolitan area.

Abstract A study of sulfate aerosol acidity in Metropolitan Toronto was conducted during the summer of 1986. Fine-fraction aerosol ( 0.9 for 24-h data). However, spatial variations in the magnitude of aerosol acidity were observed during sulfate episodes. For example, the peak concentrations for all sites occurred on 25–26 July 1986. While the 24-h data for sulfate were quite uniform at the three sites (34, 34 and 35 μg m−3), H+ concentrations were 9.4, 8.3 and 6.0 μg m−3 (as H2SO4) for the NE, WNW and Center City sites, respectively. For most of the summertime episodes, the downtown area also had lower aerosol acidity compared to the two sites in suburban areas.

Nutrient leaching from pine needles impacted by acidic cloudwater

In coastral and mountainous environments, fog and cloud droplets are frequently deposited onto terrestrial surfaces; this deposition pathway may account for a large fraction of both moisture and chemical loading. Stratus cloudwater was collected for chemical analyses at Henninger Flats (870 m MSL), a site in the foothills of the San Gabriel Mountains, 25 km northeast of downtown Los Angeles. Concurrent samples of intercepted cloudwater were manually removed, drop-by-drop, from needles on various species of pine trees upon which it had deposited. Samples were analyzed for pH, major cations, and anions. Solute concentrations were substantially higher in samples removed from pine needles compared to the suspended cloudwater. For example, cloudwater concentrations for nitrate and sulfate were measured between 0.25 and 4.5 meq L−1 while deposited samples were 0.4 to 90 meq L−1. This solute enhancement was due to evaporation following droplet deposition and to nutrient leaching. Nutrient leaching was indicated by (a) a disproportionate increase in the concentrations of cations such as K and Mg (a factor of 2 to 15 enrichment relative to sulfate), and (b) reductions in the leachate acidity and ammonium relative to the incident droplets. A relationship was observed between the enhancement of Na, Ca, and nitrate in pine needle leachate. This suggests that reactions at the foliar surfaces are occurring which involve gaseous HNO3 and accumulated soil dust and sea-salt particles.

Investigations of Indoor and Outdoor Levels of Benzo(a) Pyrene in a Community of Older Homes

Abstract Indoor and outdoor air measurements of PM-10 (particulate mass dp < 10 μm) and its benzo (a)pyrene (Bap) content were made daily in 13 residences and 5 nearby sites during one or more of three 14-day periods (Winters 1987 and 1988, and Fall 1988). These are a population of older homes (60+ years) adjacent to a gray-iron foundry. Winter BaP values were ∼ 10 × higher than fall values. Indoor BaP sources in several homes (e.g., cooking, cigarette smoke, a coal stove) led to contaminant levels higher than the ambient concentrations. However, in homes without strong sources, concentrations were very close to outdoor levels. Periods of elevated ambient pollution were readily discernible in the record of virtually all homes. Correlations for indoor-outdoor concentrations (PM-10 and BaP) were statistically significant (p < 0.01) in the majority of homes. Higher BaP concentrations were associated with periods of lower temperatures. There were high degrees of correlation for BaP and PM-10 among outdoor sit...

Human Exposures to Particle Strong Acidity

AbstractThis article reviews the findings of recent research programs and attempts to present an update of our current understanding about human exposures to particle strong acidity (PSA). This review tells the key steps in our recent progress, such as aerosol chemistry and physics, improvements in samplers and measurement techniques, increases in the databases, and exposure assessments. Remedying an earlier paucity in direct measurements of PSA, there has been a great increase in the database from several recent field studies. These studies have shown that where appreciable PSA exists, virtually all exposures occur in the warmer months, and the highest PSA levels are specifically associated with summertime, regional stagnation periods. Frequently, PSA episodes are coincident with photochemical smog and high ozone levels, although the converse is not always the case. A number of new studies have shown that the effect of the indoors on human exposures to PSA is entirely protective. That is, there are rarel...