Monitoring Methods for Polycyclic Aromatic Hydrocarbons and Their Distribution in House Dust and Track-in Soil

Quantitative characterization of resident' exposure to typical semi-volatile organic compounds (SVOCs) around a non-ferrous metal smelting plant

To comprehensively characterize residents' exposure to major semi-volatile organic compounds (SVOCs), samples of indoor floor wipes, size-segregated airborne particles, gaseous air, food, and paired skin wipes were simultaneously collected from residential areas around a large non-ferrous metal smelting plant as compared with the control areas, and three typical SVOCs (including polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and halogenated PAHs (HPAHs)) were determined. Comparison and correlation analysis among matrices indicated PAHs were the major contaminants emitted from metal smelting activities compared to HPAHs and PCBs, with naphthalene verified as the most important characteristic compound, and their accumulation on skin may be a comprehensive consequence of contact with floor dust and air. While patterns of human exposure pathways for the SVOCs were found to be clearly correlated to their vapor pressure, dermal absorption was the major contributor (51.1-76.3%) to total carcinogenic risk (TCR) of PAHs and HPAHs for surrounding residents, especially for low molecular weight PAHs, but dietary ingestion (98.6%) was the dominant exposure pathway to PCBs. The TCR of PAHs exceeded the acceptable level (1 × 10-4), implying smelting activities obviously elevated the health risk. This study will serve developing pertinent exposure and health risk prevention measures.

Polycyclic Aromatic Hydrocarbons in Indoor Dust Collected during the COVID-19 Pandemic Lockdown in Saudi Arabia: Status, Sources and Human Health Risks

To control the spread of coronavirus disease (COVID-19), Saudi Arabia's government imposed a strict lockdown during March-July 2020. As a result, the public was confined to indoors, and most of their daily activities were happening in their indoor places, which might have resulted in lower indoor environment quality. Polycyclic aromatic hydrocarbons (PAHs) were analyzed in household dust (n = 40) collected from different residential districts of Jeddah, Saudi Arabia, during the lockdown period. PAHs' levels were two folds higher than the previously reported PAHs in indoor dust from this region. We detected low molecular weight (LMW) with two to four aromatic ring PAHs in all the samples with a significant contribution from Phenanthrene (Phe), present at an average concentration of 1590 ng/g of dust. Although high molecular weight (HMW) (5-6 aromatic ring) PAHs were detected at lower concentrations than LMW PAHs, however, they contributed >90% in the carcinogenic index of PAHs. The estimated daily intake (EDI) of specific PAHs was above the reference dose (RfD) for young children in high-end exposure and the calculated Incremental Lifetime Cancer Risk (ILCR) was >1.00 × 10-4 for both Saudi adults and young children. The study highlighted that indoor pollution has increased significantly during lockdown due to the increased indoor activities and inversely affect human health. This study also warrants to conduct more studies involving different chemicals to understand the indoor environment quality during strict lockdown conditions.

Polycyclic aromatic compounds in particulate matter and indoor dust at preschools in Stockholm, Sweden: Occurrence, sources and genotoxic potential in vitro

Children spend a significant amount of their day in preschool; thus, environmental quality at preschools may have an impact on children's health. In the present study, we analyzed polycyclic aromatic compounds (PACs), including PAHs, alkylated PAHs and oxygenated PAHs (OPAHs), in indoor and outdoor air particulate matter (PM₁₀) and indoor dust at preschools in Stockholm, Sweden. There were significant correlations between PAC levels in outdoor and indoor PM₁₀, with in general higher PAC levels outdoors. Fluoranthene and pyrene were detected at highest levels in all sample types, although phenanthrene and methylated phenanthrene derivatives also were found at high levels in indoor dust. In addition, the highly carcinogenic PAHs 7H-benzo[c]fluorene, 7,12-dimethylbenz[a]anthracene, benz[j]aceanthrylene, and dibenzo[a,l]pyrene were detected in some samples. Benzanthrone was the most prevalent OPAH in PM₁₀ samples and 9,10-anthraquinone in indoor dust. Based on diagnostic ratios and Positive Matrix Factorization we identified vehicle emission and biomass burning as important PAC sources for all samples analyzed. However, poor correlation between PAC levels in indoor PM₁₀ and indoor dust suggested additional sources for the latter. Measuring activation of DNA damage signaling in human cells exposed to organic extracts of the samples indicated substantial genotoxic potential of outdoor PM₁₀ and indoor dust. Determination of benzo[a]pyrene equivalents demonstrated that the highly potent PAHs benz[j]aceanthrylene and dibenz[a,h]anthracene contributed more than 20% to the total carcinogenic potency of the samples. We conclude that PAC levels at Stockholm preschools are relatively low but that outdoor air quality may impact on the indoor environment.

Polycyclic aromatic hydrocarbons (PAHs) in indoor air and dust samples of different Saudi microenvironments; health and carcinogenic risk assessment for the general population

In this study, the presence of polycyclic aromatic hydrocarbons (PAHs) was studied in indoor air (PM10) and settled dust collected from different indoor microenvironments of Saudi Arabia. Limited data is available on the indoor quality of Saudi Arabia and to the best of our knowledge, this is the first study reporting PAHs in indoor air from Saudi Arabia. The main objectives were to study the levels and profile of selected PAHs in indoor dust and PM10 samples from different microenvironments of Saudi Arabia and to estimate health risk assessment to the local population via inhalation, dust ingestion and dermal contact. To study PAHs, indoor dust and PM10 samples were collected from different households, offices and hotel roomsPM10.Pyrene, benz(a)anthracene, chrysene, and phenanthrene were the major PAHs in both settled dust and PM10 samples. Profile of PAHs in dust samples was dominated by 3 and 4 ring PAHs while in PM10 sample 5-6 aromatic ring PAHs also contributed significantly. PM10 collected from kitchens and AC filter dust samples were the most contaminated with PAHs. PM10Health risk assessment was made for adults and young based on benzo(a)pyrene equivalent carcinogenic power (BaPE) and incremental lifetime cancer risk (ILCR). BaPE revealed major toxicity threat associated with PAHs is all microenvironments samples (dust and PM10) is from 5 and 6 aromatic rings PAHs. ILRC calculated using ingestion, inhalation and dermal contact was within the limits set by USEPA and although using max concentration it was up to 8.0E-05, which can have significant impact long term if other exposure pathways such as food and outdoor exposure, etc. are considered.

Polycyclic aromatic hydrocarbons in house dust and surface soil in major urban regions of Nepal: Implication on source apportionment and toxicological effect

Urban centers have turned to be the provincial store for resource consumptions and source releases of different types of semi-volatile organic compounds (SVOCs) including polycyclic aromatic hydrocarbons (PAHs), bringing about boundless environmental pollutions, among different issues. Human prosperity inside urban communities is unambiguously dependent on the status of urban soils and house dusts. However, environmental occurrence and sources of release of these SVOCs are challenging in Nepalese cities, as exceptionally very limited data are accessible. This motivated us to explore the environmental fate, their source/sink susceptibilities and health risk associated with PAHs. In this study, we investigated the contamination level, environmental fate and sources/sink of 16 EPA's priority pollutants in surface soil and house dusts from four major cities of Nepal. Additionally, the toxicological effect of individual PAH was studied to assess the health risk of PAHs. Generally, the concentrations of ∑₁₆PAHs in surface soil were 1.5 times higher than house dust, and ranged 767-6770ng/g dry weight (dw) (median 1810ng/g dw), and 747-4910 dw (median 1320ng/g dw), respectively. High molecular weight-PAHs both in soil and dust were more abundant than low molecular weight-PAHs, suggesting the dominance of pyrogenic source. Moderate to weak correlation of TOC and BC with PAHs in soil and dust suggested little or no role of soil organic carbon in sorption of PAHs. Source diagnostic ratio and principal component analysis indicated fossil fuel combustion, traffic/vehicular emissions and combustion of biomass are the principal sources of PAHs contamination in Nepalese urban environment. The high average TEQ value of PAHs in soil than dust suggested high risk of soil carcinogenicity compared to dust.

Polycyclic aromatic hydrocarbons (PAHs) in indoor dust samples from Cities of Jeddah and Kuwait: Levels, sources and non-dietary human exposure

This study reports levels and profiles of polycyclic aromatic hydrocarbons (PAHs) in dust samples collected from three different microenvironments (cars, air conditioner (AC) filters and household floor dust) of Jeddah, Saudi Arabia (KSA) and Kuwait. To the best of our knowledge, this is first study reporting PAHs in indoor microenvironments of KSA, which makes these findings important. Benzo(b)fluoranthene (BbF), benzo(a)pyrene (BaP), phenanthrene (Phe), and pyrene (Pyr) were found to be the major chemicals in dust samples from all selected microenvironments. ΣPAHs occurred at median concentrations (ng/g) of 3450, 2200, and 2650 in Saudi AC filter, car and household floor dust, respectively. The median levels (ng/g) of ΣPAHs in Kuwaiti car (950) and household floor (1675) dust samples were lower than Saudi dust. The PAHs profile in Saudi dust was dominated by high molecular weight (HMW) (4-5 ring) PAHs while in Kuwaiti dust 3 ring PAHs have marked contribution. BaP equivalent, a marker for carcinogenic PAHs, was high in Saudi household floor and AC filter dust with median levels (ng/g) of 370 and 455, respectively. Different exposure scenarios, using 5th percentile, median, mean, and 95th percentile levels, were estimated for adults and toddlers. For Saudi and Kuwaiti toddlers worst exposure scenario of ΣPAHs was calculated at 175 and 85ng/kg body weight/day (ng/kgbw/d), respectively. For Saudi toddlers, the calculated worst exposure scenarios for carcinogenic BaP (27.7) and BbF (29.3ng/kgbw/d) was 2-4 times higher than Kuwaiti toddlers. This study is based on small number of samples which necessitate more detailed studies for better understanding of dynamics of PAHs in the indoor environments of this region. Nevertheless, our finding supports the ongoing exposure of organic pollutants to population that accumulates indoor.

Molecular mechanisms of dust-induced toxicity in human corneal epithelial cells: Water and organic extract of office and house dust

Human corneal epithelial (HCE) cells are continually exposed to dust in the air, which may cause corneal epithelium damage. Both water and organic soluble contaminants in dust may contribute to cytotoxicity in HCE cells, however, the associated toxicity mechanisms are not fully elucidated. In this study, indoor dust from residential houses and commercial offices in Nanjing, China was collected and the effects of organic and water soluble fraction of dust on primary HCE cells were examined. The concentrations of heavy metals in the dust and dust extracts were determined by ICP-MS and PAHs by GC-MS, with office dust having greater concentrations of heavy metals and PAHs than house dust. Based on LC50, organic extract was more toxic than water extract, and office dust was more toxic than house dust. Accordingly, the organic extracts induced more ROS, malondialdehyde, and 8-Hydroxydeoxyguanosine and higher expression of inflammatory mediators (IL-1β, IL-6, and IL-8), and AhR inducible genes (CYP1A1, and CYP1B1) than water extracts (p<0.05). Extracts of office dust presented greater suppression of superoxide dismutase and catalase activity than those of house dust. In addition, exposure to dust extracts activated NF-κB signal pathway except water extract of house dust. The results suggested that both water and organic soluble fractions of dust caused cytotoxicity, oxidative damage, inflammatory response, and activation of AhR inducible genes, with organic extracts having higher potential to induce adverse effects on primary HCE cells. The results based on primary HCE cells demonstrated the importance of reducing contaminants in indoor dust to reduce their adverse impacts on human eyes.

Polycyclic aromatic hydrocarbons: determinants of residential carpet dust levels and risk of non-Hodgkin lymphoma

PURPOSE

To investigate the risk of non-Hodgkin lymphoma (NHL) associated with residential carpet dust measurements of polycyclic aromatic hydrocarbons (PAHs).

METHODS

We evaluated the relationship between residential carpet dust PAH concentrations (benz(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, chrysene, dibenz(a,h)anthracene, and indeno(1,2,3-c,d)pyrene, and their sum) and risk of NHL (676 cases, 511 controls) in the National Cancer Institute Surveillance Epidemiology and End Results multicenter case-control study. As a secondary aim, we investigated determinants of dust PAH concentrations. We computed odds ratios (OR) and 95 % confidence interval (CI) for associations between NHL and concentrations of individual and summed PAHs using unconditional logistic regression, adjusting for age, gender, and study center. Determinants of natural log-transformed PAHs were investigated using multivariate least-squares regression.

RESULTS

We observed some elevated risks for NHL overall and B cell lymphoma subtypes in association with quartiles or tertiles of PAH concentrations, but without a monotonic trend, and there was no association comparing the highest quartile or tertile to the lowest. In contrast, risk of T cell lymphoma was significantly increased among participants with the highest tertile of summed PAHs (OR = 3.04; 95 % CI, 1.09-8.47) and benzo(k)fluoranthene (OR = 3.20; 95 % CI, 1.13-9.11) compared with the lowest tertile. Predictors of PAH dust concentrations in homes included ambient air PAH concentrations and the proportion of developed land within 2 km of a residence. Older age, more years of education, and white race were also predictive of higher levels in homes.

CONCLUSION

Our results suggest a potential link between PAH exposure and risk of T cell lymphoma and demonstrate the importance of analyzing risk by NHL histologic type.

Spatiotemporal analysis and human exposure assessment on polycyclic aromatic hydrocarbons in indoor air, settled house dust, and diet: A review

This review summarizes the published literature on the presence of polycyclic aromatic hydrocarbons (PAH) in indoor air, settled house dust, and food, and highlights geographical and temporal trends in indoor PAH contamination. In both indoor air and dust, ΣPAH concentrations in North America have decreased over the past 30 years with a halving time of 6.7±1.9years in indoor air and 5.0±2.3 years in indoor dust. In contrast, indoor PAH concentrations in Asia have remained steady. Concentrations of ΣPAH in indoor air are significantly (p<0.01) higher in Asia than North America. In studies recording both vapor and particulate phases, the global average concentration in indoor air of ΣPAH excluding naphthalene is between 7 and 14,300 ng/m(3). Over a similar period, the average ΣPAH concentration in house dust ranges between 127 to 115,817ng/g. Indoor/outdoor ratios of atmospheric concentrations of ΣPAH have declined globally with a half-life of 6.3±2.3 years. While indoor/outdoor ratios for benzo[a]pyrene toxicity equivalents (BaPeq) declined in North America with a half-life of 12.2±3.2 years, no significant decline was observed when data from all regions were considered. Comparison of the global database, revealed that I/O ratios for ΣPAH (average=4.3±1.3), exceeded significantly those of BaPeq (average=1.7±0.4) in the same samples. The significant decline in global I/O ratios suggests that indoor sources of PAH have been controlled more effectively than outdoor sources. Moreover, the significantly higher I/O ratios for ΣPAH compared to BaPeq, imply that indoor sources of PAH emit proportionally more of the less carcinogenic PAH than outdoor sources. Dietary exposure to PAH ranges from 137 to 55,000 ng/day. Definitive spatiotemporal trends in dietary exposure were precluded due to relatively small number of relevant studies. However, although reported in only one study, PAH concentrations in Chinese diets exceeded those in diet from other parts of the world, a pattern consistent with the spatial trends observed for concentrations of PAH in indoor air. Evaluation of human exposure to ΣPAH via inhalation, dust and diet ingestion, suggests that while intake via diet and inhalation exceeds that via dust ingestion; all three pathways contribute and merit continued assessment.

Effect of land use activities on PAH contamination in urban soils of Rawalpindi and Islamabad, Pakistan

Urbanization can increase the vulnerability of soils to various types of contamination. Increased contamination of urban soils with polycyclic aromatic hydrocarbon (PAH) could relate to increased number of petrol pump stations and mechanical workshops-a phenomenon that needs to be constantly monitored. This study was undertaken to explore the soil PAH levels in Rawalpindi and Islamabad urban areas in relation to land use activities. Composite soil samples from petrol pump stations and mechanical workshops (n = 32) areas were evaluated for five PAHs--naphthalene, phenanthrene, pyrene, benzo[a]pyrene, and indeno(1,2,3-cd)pyrene-and compared with control area locations with minimum petroleum-related activity (n = 16). Surface samples up to 3 cm depth were collected and extraction of analytes was carried out using n-hexane and dichloromethane. Prior to running the samples, standards (100 μg ml(-1)) were run on HPLC to optimize signal to noise ratio using acetonitrile as mobile phase at a flow rate of 1.25 ml/min at 40 °C. Significant differences between petrol pump stations and mechanical workshop areas were observed for individual PAH as well as with control area soil samples. Naphthalene was found to be the most abundant PAH in soil, ranging from 2.47 to 24.36 mg kg(-1). Correlation between the benzo[a]pyrene (BaP) level in soil and the total PAH concentration (r = 0.82, P < 0.0001) revealed that BaP can be used as a potential marker for PAH pollution. A clear segregation between petrogenic and pyrogenic sources of contamination was observed when low molecular weight PAHs detected in soil was plotted against high molecular weight PAHs. The former source comprised lubricants and used engine oil found at mechanical workshops, whereas the latter could be mostly attributed to vehicular emission at petrol pumps. The results indicate that PAH contamination in urban areas of Rawalpindi and Islamabad has direct relevance with land use for petroleum activity. We conclude that in order to reduce the soil PAH exposure in urban environment, petrol pumps and mechanical workshops must be shifted to less densely populated areas because of their role as important point sources for PAH emission.

Environmental tobacco smoke as a source of polycyclic aromatic hydrocarbons in settled household dust

Environmental tobacco smoke is a major contributor to indoor air pollution. Dust and surfaces may remain contaminated long after active smoking has ceased (called 'thirdhand' smoke). Polycyclic aromatic hydrocarbons (PAHs) are known carcinogenic components of tobacco smoke found in settled house dust (SHD). We investigated whether tobacco smoke is a source of PAHs in SHD. House dust was collected from 132 homes in urban areas of Southern California. Total PAHs were significantly higher in smoker homes than nonsmoker homes (by concentration: 990 ng/g vs 756 ng/g, p = 0.025; by loading: 1650 ng/m(2) vs 796 ng/m(2), p = 0.012). We also found significant linear correlations between nicotine and total PAH levels in SHD (concentration, R(2) = 0.105; loading, R(2) = 0.385). Dust collected per square meter (g/m(2)) was significantly greater in smoker homes and might dilute PAH concentration in SHD inconsistently. Therefore, dust PAH loading (ng PAH/m(2)) is a better indicator of PAH content in SHD. House dust PAH loadings in the bedroom and living room in the same home were significantly correlated (R(2) = 0.468, p < 0.001) suggesting PAHs are distributed by tobacco smoke throughout a home. In conclusion, tobacco smoke is a source of PAHs in SHD, and tobacco smoke generated PAHs are a component of thirdhand smoke.

Polycyclic aromatic hydrocarbons in household dust near diesel transport routes

A river-dredging project has been undertaken in Nantou, Taiwan. A large number of diesel vehicles carrying gravel and sand shuttle back and forth on the main roads. Ten stations along major thoroughfares were selected as the exposure sites for testing, while a small village located about 9 km from a main traffic route was selected as the control site. Levels of household dust loading at the exposure sites (60.3 mg/m(2)) were significantly higher than those at the control site (38.2 mg/m(2)). The loading (μg/m(2)) of t-PAHs (total polycyclic aromatic hydrocarbons) in the household dust at the exposure sites was significantly higher (P < 0.05) than was the case at the control site. The diagnostic ratios of PAHs showed that diesel emissions were the dominant source of PAHs at the exposure sites. The lack of a significant correlation between the concentrations of Fe and t-PAHs suggested that the t-PAHs in household dust might come from diverse sources. However, a significant correlation (P = 0.003) between the concentrations of Mo and t-PAHs implied that the most of the t-PAHs in the household dust might have resulted from diesel emissions. The lifetime cancer risks of BaP(eq) from household dust exposure were markedly higher than those resulting from inhalation exposure.

Polycyclic aromatic hydrocarbons with molecular weight 302 in PM 2.5 at two industrial sites in South China

Daytime and nighttime PM(2.5) samples were collected between August 5 and 16, 2009 and between January 24 and February 4, 2010 in an industrial complex site (site A) and an electronic waste recycling site (site B) to determine the seasonal and diurnal variations of 19 individual polycyclic aromatic hydrocarbons (PAHs) with molecular weight 302 (MW302) including four highly carcinogenic dibenzopyrene (DBP) isomers dibenzo[a,l]pyrene (DBalP), dibenzo[a,e]pyrene (DBaeP), dibenzo[a,i]pyrene (DBaiP), and dibenzo[a,h]pyrene (DBahP). This is the first report on DBP isomers in air particles from South China. The total concentration of PAH MW302 isomers ranged from 1.65 to 3.60 ng m(-3) in summer and 3.82 to 9.81 ng m(-3) in winter. The strongest peaks in the chromatograms of the MW302 isomers were naphtha[2,1-a]pyrene (N21aP), dibenzo[j,l]fluoranthene (DBjlF), naphtha[1,2-b]fluoranthene (N12bF), naphtha[1,2-k]fluoranthene (N12kF) and dibenzo[a,e]fluoranthene (DBaeF), constituting 52.0 to 55.4% of the total MW302 isomers. All the MW302 isomers showed notable seasonal variations. Most of the MW302 isomers in site B showed distinctive diurnal variations with higher concentrations occurring in the night. Taking into account both concentration and potency equivalence factors (PEFs), the strongest carcinogen in the analyzed samples was DBaiP, and the ratios of sum carcinogenic potency of four highly carcinogenic DBP isomers to benzo[a]pyrene (BaP) was about 0.94 in winter to 1.89 in summer, indicating the importance of DBP isomers for the risk assessment. Health risk assessment indicated that on average, 1 in 100 000 residents in the two industrial sites may have an increased risk of cancer due to PAH exposure.

Mutagenicity, genotoxicity and carcinogenic risk assessment of indoor dust from three major cities around the Pearl River Delta

The mutagenicity and genotoxicity of workplace dust including commercial office, secondary school, shopping mall, hospital, electronics factory and manufacturing plant in Hong Kong and settled house dust from Hong Kong, Shenzhen and Guangzhou were measured. Results indicated that indoor dust contained both frameshift and base pair substitution mutagens. Dust from manufacturing plant showed highest mutagenic potency on TA98±S9 and TA100±S9 activation, whereas, electronics factory showed highest genotoxicity with and without S9 activation. TA100 (-S9) mutagenic potency was significantly correlated with genotoxicity expressed as SOSIP (-S9) of workplace dust (r(2)=0.37, p<0.01). The total PAHs concentration of settled house dust from PRD ranged from 1.63 to 29.2μg/g. Linear regression analyses indicated that the PAHs likely accounted for about 45% of the TA98 with S9 mutagenic activity of workplace dust. TA98 (-S9) mutagenicity (r(2)=0.27, p<0.05) and SOSIP (-S9) of house dust (r(2)=0.41, p<0.01) were both significantly correlated with the number of inhabitants in the house. To achieve a more accurate cancer risk assessment, the oral bioaccessibility of B(a)A, Chry, B(b+k)F, B(a)P, D(ah)A and I(cd)P in different dust ranging from 1.3% to 17% was taken into account. Risk assessments indicated that about 26% of house dust samples resulted in unacceptable cancer risk (>1×10(-6)) for preschool children.

Determinants of polycyclic aromatic hydrocarbon levels in house dust

Estimation of human exposures to polycyclic aromatic hydrocarbons (PAHs) is often desired for the epidemiological studies of cancer. One way to obtain information about indoor levels of PAHs is to measure these chemicals in house dust. In this study, we evaluated the predictive value of self-reported and geographic data for estimating measured levels of nine PAHs in house dust from 583 households in the Northern California Childhood Leukemia Study (NCCLS). Using multivariable linear regression models, we evaluated the effects on house-dust PAH concentrations from the following covariates: residential heating sources, smoking habits, house characteristics, and outdoor emission sources. House dust was collected from 2001 to 2007, using both high-volume surface samplers and household vacuum cleaners, and was analyzed for nine PAHs using gas chromatography-mass spectrometry. All nine PAHs were detected in more than 93% of dust samples, with median concentrations ranging from 14 to 94 ng/g dust. Statistically significant effects on PAH concentrations in house dust were found for gas heating, outdoor PAH concentrations, and residence age. Yet, the optimal regression model only explained 15% of the variation in PAH levels in house dust. As self-reported data and outdoor PAH sources were only marginally predictive of observed PAH levels, we recommend that PAH concentrations be measured directly in dust samples for use in epidemiological studies.

Spatial mapping of lead, arsenic, iron, and polycyclic aromatic hydrocarbon soil contamination in Sydney, Nova Scotia: community impact from the coke ovens and steel plant

This paper presents spatial maps of the arsenic, lead, and polycyclic aromatic hydrocarbon (PAH) soil contamination in Sydney, Nova Scotia, Canada. The spatial maps were designed to create exposure cohorts to help understand the observed increase in health effects. To assess whether contamination can be a proxy for exposures, the following hypothesis was tested: residential soils were impacted by the coke oven and steel plant industrial complex. The spatial map showed contaminants are centered on the industrial facility, significantly correlated, and exceed Canadian health risk-based soil quality guidelines. Core samples taken at 5-cm intervals suggest a consistent deposition over time. The concentrations in Sydney significantly exceed background Sydney soil concentrations, and are significantly elevated compared with North Sydney, an adjacent industrial community. The contaminant spatial maps will also be useful for developing cohorts of exposure and guiding risk management decisions.

Polycyclic aromatic hydrocarbons (PAHs) in different indoor dusts and their potential cytotoxicity based on two human cell lines

In this study, 55 air-conditioner filter dust samples from six different workplaces including commercial office, secondary school, shopping mall, hospital, electronic factory and manufacturing plant in Hong Kong were collected for analyses of PAH concentration and cytotoxicity. Chemical analyses showed that the total PAHs ranged from 1.17 to 25.5 microg/g, with the dust samples from manufacturing plant having the highest concentration. MTT (3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrasodium bromide) assay was performed to evaluate the cytotoxicity of organic dust extracts using human hepatocellular liver carcinoma cell line (HepG2) and human skin keratinocyte cell line (KERTr). Each organic dust extract showed marked dose-related response. Dust samples from the manufacturing plant showed the highest cytotoxicity. Curve estimation indicated that power model was fit for explaining the relationship between the total PAH concentration and lethal concentration 50 (LC(50)). In addition, a significant negative correlation was observed between the total PAH concentration and LC(50) both on HepG2 (r=-0.65, p<0.01) and KERTr (r=-0.63, p<0.01) cell lines. Source analyses demonstrated that the PAHs in dust were derived from pyrogenic origins.

Coal-tar-based parking lot sealcoat: an unrecognized source of PAH to settled house dust

Despite much speculation, the principal factors controlling concentrations of polycyclic aromatic hydrocarbons (PAH) in settled house dust (SHD) have not yet been identified. In response to recent reports that dust from pavement with coal-tar-based sealcoat contains extremely high concentrations of PAH, we measured PAH in SHD from 23 apartments and in dust from their associated parking lots, one-half of which had coal-tar-based sealcoat (CT). The median concentration of total PAH (T-PAH) in dust from CT parking lots (4760 microg/g, n = 11) was 530 times higher than that from parking lots with other pavement surface types (asphalt-based sealcoat, unsealed asphalt, concrete [median 9.0 microg/g, n = 12]). T-PAH in SHD from apartments with CT parking lots (median 129 microg/g) was 25 times higher than that in SHD from apartments with parking lots with other pavement surface types (median 5.1 microg/g). Presence or absence of CT on a parking lot explained 48% of the variance in log-transformed T-PAH in SHD. Urban land-use intensity near the residence also had a significant but weaker relation to T-PAH. No other variables tested, including carpeting, frequency of vacuuming, and indoor burning, were significant.

Evaluation of HEPA vacuum cleaning and dry steam cleaning in reducing levels of polycyclic aromatic hydrocarbons and house dust mite allergens in carpets

Dry steam cleaning, which has gained recent attention as an effective method to reduce house dust mite (HDM) allergen concentration and loading in carpets, was evaluated in this study for its efficacy in lowering levels of polycyclic aromatic hydrocarbons (PAHs) as well as HDM allergens. Fifty urban homes with wall-to-wall carpets, mostly low-income and with known lead contamination, were studied in 2003 and 2004. Two carpet-cleaning interventions were compared: Repeated HEPA (High Efficiency Particulate Air filtered) vacuuming alone and repeated HEPA vacuuming supplemented with dry steam cleaning. Vacuum samples were collected to measure carpet loading of dust and contaminants immediately before and after cleaning. Paired comparisons were conducted to evaluate the effectiveness of the cleaning protocols in reducing the levels of PAHs and HDM allergens in carpets. The results indicated that both cleaning methods substantially reduced the loading of PAHs and HDM allergens as well as dust in carpets (p < 0.0001). The reductions in loading of dust (64.4%), PAHs (69.1%), and HDM allergens (85.5%), by dry steam cleaning plus repetitive HEPA vacuuming were larger than the reductions by regular HEPA vacuuming alone: dust (55.5%), PAHs (58.6%), and HDM allergens (80.8%), although the difference was statistically significant only for dust and PAHs. We conclude that intensive HEPA vacuum cleaning substantially reduced the loading of PAHs and HDM allergens in carpets in these urban homes and that dry steam cleaning added modestly to cleaning effectiveness.

Distributions, sources and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in topsoil at Ji'nan city, China

Surface soil (0-5 cm) samples from 17 sampling sites including different functional areas at Ji'nan city in Shandong Province of China were collected and analyzed for 16 EPA priority polycyclic aromatic hydrocarbons (PAHs). The total PAH concentrations were in the range from 1.31 mg kg(-1) to 254.08 mg kg(-1) (dry weight), and the average level of total PAHs was 23.25 mg kg(-1). The highest total PAHs concentrations were found in steel and iron plant at industrial areas. The total PAHs concentrations in industrial areas were markedly higher than those in other different functional areas. According to comparing total PAHs concentration in Ji'nan city to that of other urban areas, it was found that total PAHs concentrations were 6 to 137 times higher than other areas because of some specific sampling sites such as steel and iron plant and one main roadside. The results showed that PAHs in topsoil of Ji'nan city were suffered from strong pyrogenic influence, especially in industrial areas. However about 52.9% soil samples were mainly originated from both pyrogenic and petrogenic mixed sources based on Flu/Pyr ratios and Phe/Ant ratios. Furthermore, It was found that all individual PAHs except Fle were significantly correlated (P < 0.01) with LMW, HMW, total PAHs and SOM, and individual PAHs except Fle in soils were significantly correlated (P < 0.01) with each other. The nemerow composite index to assess the environmental quality showed that the soil sample of steel and iron plant in industrial areas and one main roadside were heavy pollution of PAHs, and about 47% soil sampling sites were safety, about 53% soil sampling sites were got different grades of PAHs pollution.

Mutagenic and carcinogenic hazards of settled house dust. I: Polycyclic aromatic hydrocarbon content and excess lifetime cancer risk from preschool exposure

Settled house dust (SHD) may be a significant source of children's indoor exposure to hazardous substances including polycyclic aromatic hydrocarbons (PAHs). In this study, organic extracts of sieved vacuum cleaner dust from 51 homes were examined for the presence of 13 PAHs via GC/MS. PAHs were found in all samples with levels of total PAHs ranging between 1.5 and 325 microg g(-1). The PAH concentrations in the SHD were correlated with information contained in corresponding household questionnaires. Analyses showed levels of PAHs to be negatively associated with noncombustion activities such as vacuum cleaning frequency. A risk assessment was conducted to evaluate the excess lifetime cancer risks posed to preschool aged children who ingested PAHs in SHD. The assessment revealed that exposure to PAHs at levels found in 90% of the homes (< 40 microg g(-1)) would result in excess cancer risks that are considered acceptable (i.e., 1-100 x 10(-6)). However, exposure to higher levels of PAHs found in five homes yielded risks that could be higher than 1 x 10(-4).

Polycyclic aromatic hydrocarbons in indoor air and dust in Kuwait: implications for sources and nondietary human exposure

This study reports concentration of polycyclic aromatic hydrocarbons (PAHs) in indoor air and dust samples collected from 24 homes in Kuwait. Mean SigmaPAHs in indoor air ranged from 1.3 to 16 ng/m(3) with a geometric mean of 5.6 ng/m(3), whereas the dust concentrations varied over three orders of magnitude, from 3 to 2920 ng/g, with a geometric mean of 165 ng/g. The low-molecular-weight tricyclic and tetracyclic PAHs dominated the air profile constituting approximately 70-90 % of the measured compounds, with phenanthrene (51%), fluorene (13 %), fluoranthere (8 %), and pyrene (7 %) being the major contributors. The PAH profile in dust was dominated by the high-molecular-weight PAHs, with three compounds (benzo[a]pyrene, benzo[k]fluoranthene, and benzo[b]fluoranthene) contributing approximately 60% of the average SigmaPAHs measured in the samples. Indoor-to-outdoor (I/O) ratios for individual compounds were <1 for the majority of compounds, suggesting that there were no significant indoor sources for these compounds in these homes. Using the measured concentrations in air and dust, together with estimates of inhalation and inadvertent dust ingestion rates for children and adults, estimated human nondietary exposure on a BaP(equiv) basis were 547 pg/kg body weight/day and 205 pg/kg body weight/day for children and adults, respectively. Exposure from dust ingestion contributes about 42% of nondietary intake of SigmaPAHs in children, but only 11% for adults. The threefold difference in exposure estimates between children and adults in this study supports previous reports that children are at greater risk from pollutants that accumulate indoors.

Validation and calibration of a model used to reconstruct historical exposure to polycyclic aromatic hydrocarbons for use in epidemiologic studies

OBJECTIVES

We previously developed a historical reconstruction model to estimate exposure to airborne polycyclic aromatic hydrocarbons (PAHs) from traffic back to 1960 for use in case-control studies of breast cancer risk. Here we report the results of four exercises to validate and calibrate the model.

METHODS

Model predictions of benzo[a]pyrene (BaP) concentration in soil and carpet dust were tested against measurements collected at subjects' homes at interview. In addition, predictions of air intake of BaP were compared with blood PAH-DNA adducts. These same soil, carpet, and blood measurements were used for model optimization. In a separate test of the meteorological dispersion part of the model, predictions of hourly concentrations of carbon monoxide from traffic were compared with data collected at a U.S. Environmental Protection Agency monitoring station.

RESULTS

The data for soil, PAH-DNA adducts, and carbon monoxide concentrations were all consistent with model predictions. The carpet dust data were inconsistent, suggesting possible spatial confounding with PAH-containing contamination tracked in from outdoors or unmodeled cooking sources. BaP was found proportional to other PAHs in our soil and dust data, making it reasonable to use BaP historical data as a surrogate for other PAHs. Road intersections contributed 40-80% of both total emissions and average exposures, suggesting that the repertoire of simple markers of exposure, such as traffic counts and/or distance to nearest road, needs to be expanded to include distance to nearest intersection.

Employing dynamical and chemical processes for contaminant mixtures outdoors to the indoor environment: the implications for total human exposure analysis and prevention

There are many physical and chemical processes that affect the accumulation of outdoor pollutants. In recent years some of the information and concepts previously ascribed to outdoor pollution has been found to be useful in examining indoor dynamic and chemical processes. Further, becau se of the confining nature of the indoor environment, processes such as the "grasshopper effect" can lead to sustained higher levels of semivolatile chemicals indoors and affect multiroute (inhalation, dermal, incidental dietary, and nondietary ingestion) exposures. Such processes can also lead to a complex mixture of both semivolatile and volatile compounds in indoor air and on surfaces or within objects. This article specifically examines the above in combination with another indoor issue, indoor chemistry, and places the results into a context that can be used to evaluate (1) multipollutant cumulative or aggregate exposures and risks indoors, (2) exposure reduction strategies that can create healthy indoor environments. It is not a review of the entire field of the indoor environment or indoor air or the indoor environment, which has been covered in numerous volumes and reports. The complexities of the scientific issues are discussed by also placing them into our traditional approaches outdoor and indoor to pollution management, to indicate the difficulty in establishing the exposures that require mitigation or prevention. Further, some emerging issues are discussed as well as how to specifically address long-term single or multiroute exposures to semivolatile compounds within the "Total Indoor Environment."

Polycyclic aromatic hydrocarbon in urban soil from Beijing, China

Polycyclic aromatic hydrocarbons (EPA-PAHs) in the urban surface soils from Beijing were determined using gas chromatography and mass spectrometry (GC-MS). It is significantly complementary for understanding the PAHs pollution in soil of integrated Beijing city on the basis of the information known in the outskirts. The total concentration of 16 EPA-PAH was from 0.467 to 5.470 microg/g and was described by the contour map. Compound profiles presented that the 4-, 5- and 6-ring PAHs were major compositions. The correlation analysis showed that PAHs have the similar source in the most sampling sites and BaP might be considered as the indicator of PAHs. Characteristic ratios of anthracene (An)/(An+ phenanthrene (Phe)), fluoranthene (Flu)/(Flu+ pyrene (Pyr)) and benzo [a]pyrene (BaP)/benzo [g,h,i]perylene (BghiP) indicated that the PAHs pollutants probably mainly originated from the coal combustion and it was not negligible from vehicular emission. The level of PAHs in our study area was compared with other studies.

Characterizing exposures to nonpersistent pesticides during pregnancy and early childhood in the National Children's Study: a review of monitoring and measurement methodologies

The National Children's Study is a proposed longitudinal cohort study to evaluate the relationships between children's health and the environment. Enrollment is estimated to begin in September 2005, and 100,000 children will be followed from preconception or early pregnancy until adulthood. Among multiple health outcomes, the study is proposing to investigate whether pre- and/or postnatal exposures to nonpersistent pesticides increase the risk of poor performance on neurobehavioral and cognitive exams during infancy and early childhood. Characterization of exposures will be challenging. Nonpersistent pesticides include many chemicals with biologic half-lives on the order of hours or days. Exposures can occur through multiple pathways (e.g., food and residential or agriculture pesticide use) and by multiple routes (inhalation, ingestion, dermal). Effects may depend on the developmental stage when exposure occurs. Sequential sampling is likely to be required and may involve a combination of environmental and biologic monitoring as well as collection of questionnaire data. In this article we review measurements that can be used to characterize exposures. These include biologic markers, personal and indoor air sampling techniques, collection of dust, surface and dermal wipe samples, and dietary assessment tools. Criteria for sample selection will necessitate evaluation of the time frame of exposure captured by the measurement in relationship to critical windows of susceptibility, the cost and validity of the measurements, participant burden, and variability in exposure routes across populations and at different age periods.

The mutagenic hazards of settled house dust: a review

Given the large proportion of time people spend indoors, the potential health risks posed by chemical contaminants in the indoor environment are of concern. Research suggests that settled house dust (SHD) may be a significant source for indoor exposure to hazardous substances including polycyclic aromatic hydrocarbons (PAHs). Here, we summarize the literature on the mutagenic hazards of SHD and the presence of PAHs in dust. We assess the extent to which PAHs are estimated to contribute to the mutagenicity of SHD, and evaluate the carcinogenic risks associated with exposures to PAHs in SHD. Research demonstrates that SHD has a Salmonella TA98 mutagenic potency of 1000-7000 revertants/g, and contains between 0.5 and 500 microg/g of PAHs. Although they only account for a small proportion of the variability, analyses of pooled datasets suggest that cigarette smoking and an urban location contribute to higher levels of PAHs. Despite their presence, our calculations show that PAHs likely account for less than 25% of the overall mutagenic potency of dust. Nevertheless, carcinogenic PAHs in dust can pose potential health risks, particularly for children who play and crawl on dusty floors, and exhibit hand-to-mouth behaviour. Risk assessment calculations performed in this study reveal that the excess cancer risks from non-dietary ingestion of carcinogenic PAHs in SHD by preschool aged children is generally in the range of what is considered acceptable (1 x 10(-6) to 2 x 10(-6)). Substantially elevated risk estimates in the range 1.5 x 10(-4) to 2.5 x 10(-4) correspond only to situations where the PAH content is at or beyond the 95th percentile, and the risk estimates are adjusted for enhanced susceptibility at early life stages. Analyses of SHD and its contaminants provide an indication of indoor pollution and present important information for human exposure assessments.

Design and sampling methodology for a large study of preschool children's aggregate exposures to persistent organic pollutants in their everyday environments

Young children, because of their immaturity and their rapid development compared to adults, are considered to be more susceptible to the health effects of environmental pollutants. They are also more likely to be exposed to these pollutants, because of their continual exploration of their environments with all their senses. Although there has been increased emphasis in recent years on exposure research aimed at this specific susceptible population, there are still large gaps in the available data, especially in the area of chronic, low-level exposures of children in their home and school environments. A research program on preschool children's exposures was established in 1996 at the USEPA National Exposure Research Laboratory. The emphasis of this program is on children's aggregate exposures to common contaminants in their everyday environments, from multiple media, through all routes of exposure. The current research project, "Children's Total Exposure to Persistent Pesticides and Other Persistent Organic Pollutants," (CTEPP), is a pilot-scale study of the exposures of 257 children, ages 1(1/2)-5 years, and their primary adult caregivers to contaminants in their everyday surroundings. The contaminants of interest include several pesticides, phenols, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and phthalate esters. Field recruitment and data collection began in February 2000 in North Carolina and were completed in November 2001 in Ohio. This paper describes the design strategy, survey sampling, recruiting, and field methods for the CTEPP study.

Extraction and cleanup methods of dioxins in house dust from two cities in Japan using accelerated solvent extraction and a disposable multi-layer silica-gel cartridge

A simple and rapid method for the extraction and cleanup of dioxins from house dust was developed using an accelerated solvent extraction (ASE) method and a multi-layer silica-gel cartridge. It was found that the WHO-TEQ levels of dioxins extracted from the house dust obtained by both a conventional soxhlet extraction and the ASE were almost equal, when the data obtained by both methods were compared. As for the cleanup method, a multi-layer silica-gel cartridge yielded higher dioxin recoveries than the alkaline digestion method. The average values of the dioxins in house dust from Kumagaya city and Sendai city in Japan (Sendai city is bigger than Kumagaya city with respect to the population and industry), were 15.6 pg TEQ/g (8.6-26.0 pg TEQ/g, n=5, Kumagaya city) and 16.0 pg TEQ/g (5.9-30.5 pg TEQ/g, n=5, Sendai city), respectively.

Aggregate exposures of nine preschool children to persistent organic pollutants at day care and at home

In the summer of 1997, we measured the aggregate exposures of nine preschool children, aged 2-5 years, to a suite of organic pesticides and other persistent organic pollutants that are commonly found in the home and school environment. The children attended either of two child day care centers in the Raleigh-Durham-Chapel Hill area of North Carolina and were in day care at least 25 h/week. Over a 48-h period, we sampled indoor and outdoor air, play area soil and floor dust, as well as duplicate diets, hand surface wipes, and urine for each child at day care and at home. Our target analytes were several polycyclic aromatic hydrocarbons (PAH), organochlorine pesticides, and polychlorinated biphenyls (PCB); two organophosphate pesticides (chlorpyrifos and diazinon), the lawn herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), three phenols (pentachlorophenol (PCP), nonyl phenols, and bisphenol-A), 3,5,6-trichloro-2-pyridinol (TCP), and two phthalate esters (benzylbutyl and dibutyl phthalate). In urine, our target analytes were hydroxy-PAH, TCP, 2,4-D, and PCP. To allow estimation of each child's aggregate exposures over the 48-h sampling period, we also used time-activity diaries, which were filled out by each child's teacher at day care and the parent or other primary caregiver at home. In addition, we collected detailed household information that related to potential sources of exposure, such as pesticide use or smoking habits, through questionnaires and field observation. We found that the indoor exposures were greater than those outdoors, that exposures at day care and at home were of similar magnitudes, and that diet contributed greatly to the exposures. The children's potential aggregate doses, calculated from our data, were generally well below established reference doses (RfDs) for those compounds for which RfDs are available.

Extractable organic matter in PM10 from LiWan district of Guangzhou City, PR China

PM10 (particulate matter with aerodynamic diameter <10 microm) samples were collected at LiWan District of Guangzhou, PR China during April and July 2001 using a high volume air sampler to determine the distributions of homologous compounds and biomarkers. Polycyclic aromatic hydrocarbons (PAHs) including non-alkylated PAHs, methyl-alkylated PAHs, and some PAHs containing S/O atoms and n-alkanes were measured using gas chromatography/mass spectrometry analysis. The sigma(n)-alkane and sigmaPAHs ranged from 26.4 to 719.2 ng/m3 and 7.4 to 159.4 ng/m3, respectively. A seasonal fluctuation was clearly evident with higher concentrations occurring during the colder months (April). In addition, some compositional differences are observed for the organic compounds in samples collected from different heights above ground level. Higher sites had a significant contribution from vascular plant wax. The presence of petroleum products with no carbon number preference, pristane, phytane and a significant unresolved complex mixture (UCM) with unresolved to resolved components ratio (U/R) of 6.2-13.2 confirm the petroleum component. The relative distribution of n-alkanes and the values of molecular diagnostic ratio, such as carbon preference index (CPI) values ranging from 1.0 to 1.4 (for the whole range of n-alkanes), indicated the importance of petroleum and diesel residues and gasoline emissions, as well as the minor contribution of n-alkanes emitted directly from epicuticular waxes. Indeed, the percent contribution of leaf 'wax' n-alkanes (5.2-19.4%) indicated a low contribution of biogenic sources. The fossil fuel biomarkers, hopanes and steranes were observed in the PM10 samples, which indicate a petroleum origin. The distribution pattern of PAHs was characteristic of anthropogenic emissions. Coupling carbon number maximum (Cmax), CPI, U/R values, molecular marker and molecular diagnostic ratios for alkanes and PAHs revealed a classification of natural biogenic and anthropogenic components of atmospheric aerosols. These analyses support the conclusion that vehicular emission was the major source of organic compounds during the study period, while the contribution of epicuticular waxes emitted by terrestrial plants was minor.

Multipoint moss passive samplers assessment of urban airborne polycyclic aromatic hydrocarbons: concentrations profile and distribution along Warsaw main streets

Polycyclic aromatic hydrocarbons (PAHs) distribution along 28 km of Warsaw main street have been surveyed in July 2000 using moss passive samplers as a simple and economic surrogate of direct air sampling. Altogether 74 samplers at 39 crossroads with traffic lights were placed on the lamp post approximately/=3.5 m above ground. PAHs levels determined in samplers are in range from 828 to 3573 ng/g moss dry weight. The spatial spread of pollution within this range is statistically close to normal distribution with mean value of 2332 ng/g. Variability within and between study areas are rationalized in terms of urban environmental factors. PAHs concentrations profiles across the town have appeared uniform. The dominant compounds are phenantrene, fluoranthene and pyrene. Their contribution is 49-68% of total PAHs burden.

Levels of persistent organic pollutants in several child day care centers

The concentrations of a suite of persistent organic chemicals were measured in multiple media in 10 child day care centers located in central North Carolina. Five centers served mainly children from low-income families, as defined by the federal Women, Infants, and Children (WIC) assistance program, and five served mainly children from middle-income families. The targeted chemicals were chosen because of their probable carcinogenicity, acute or chronic toxicity, or hypothesized potential for endocrine system disruption. Targeted compounds included polycyclic aromatic hydrocarbons (PAHs), pentachloro- and nonyl-phenol, bisphenol-A, dibutyl and butylbenzyl phthalate, polychlorinated biphenyls (PCBs), organochlorine pesticides, the organophosphate pesticides diazinon and chlorpyrifos, and the herbicide 2,4-dichlorophenoxyacetic acid (2,4D). Sampled media were indoor and outdoor air, food and beverages, indoor dust, and outdoor play area soil. Concentrations of the targeted compounds were determined using a combination of extraction and analysis methods, depending on the media. Analysis was predominantly by gas chromatography/mass spectrometry (GC/MS) or gas chromatography with electron capture detection (GC/ECD). Concentrations of the targeted pollutants were low and well below the levels generally considered to be of concern as possible health hazards. Potential exposures to the target compounds were estimated from the concentrations in the various media, the children's daily time-activity schedules at day care, and the best currently available estimates of the inhalation rates (8.3 m(3)/day) and soil ingestion rates (100 mg/day) of children ages 3-5. The potential exposures for the target compounds differed depending on the compound class and the sampled media. Potential exposures through dietary ingestion were greater than those through inhalation, which were greater than those through nondietary ingestion, for the total of all PAHs, the phenols, the organophosphate pesticides, and the organochlorine pesticides. Potential exposures through dietary ingestion were greater than those through nondietary ingestion, which were greater than those through inhalation, for those PAHs that are probable human carcinogens (B2 PAH), the phthalate esters, and 2,4D. For the PCBs, exposures through inhalation were greater than those through nondietary ingestion, and exposures through dietary ingestion were smallest. Differences in targeted compound levels between the centers that serve mainly low-income clients and those that serve mainly middle-income clients were small and depended on the compound class and the medium.

Additive inhibitory action of chlorpyrifos and polycyclic aromatic hydrocarbons on acetylcholinesterase activity in vitro

This study tested the hypothesis that the inhibition of acetylcholinesterase is greater when the insecticide chlorpyrifos (CPF) is in the presence of several polycyclic aromatic hydrocarbons (PAHs) found in house dust. CPF-oxon (CPFO) inhibition curves of purified AChE (electric eel) were generated in the presence or absence of different concentrations of the PAHs pyrene, benzo(a)pyrene, anthracene, and fluoranthene. Without CPF-oxon, all four PAHs themselves inhibited AChE activity with IC50 values in the range 8.2-17 microM. The IC50 for benzo(a)pyrene with human recombinant AChE was 1.5 microM. When AChE was incubated with CPF-oxon together with the PAHs, the inhibitory effect on AChE was additive. This was exemplified by large (60-80%) and significant (P<0.01) inhibition in AChE activity by the PAHs when combined with nanomolar concentrations of CPF-oxon. Kinetic studies indicated that benzo(a)pyrene inhibited AChE in a noncompetitive manner, and the reduction in maximal velocity (Vmax) by benzo(a)pyrene and CPFO together was the sum of the inhibitory effect of the two inhibitors alone, further supporting an additive effect. These data suggest that some PAHs have anticholinesterase activity, and contribute in an additive manner to the inhibitory effect of CPFO on AChE in vitro. Further research is needed to determine the toxicological relevance of these findings.

Evaluation of enzyme-linked immunosorbent assay for the determination of polycyclic aromatic hydrocarbons in house dust and residential soil

Two commercially available enzyme-linked immunosorbent assays (ELISA) for total polycyclic aromatic hydrocarbon (PAH) and carcinogenic PAH (C-PAH) were evaluated. The testing procedures were refined for application to screening PAH and C-PAH in house dust and soil samples for human exposure studies. The overall method precision expressed as percent relative standard deviation (%RSD) of triplicate real world dust and soil samples was within +/- 29% (12-29%) for PAH ELISA and +/- 21% (5.9-21%) for C-PAH ELISA. Spike recoveries from real world dust/soil samples were 114 +/- 30% for phenanthrene from PAH ELISA and 120 +/- 8.2% for benzo[a]pyrene from C-PAH ELISA. The overall method accuracy for PAH and C-PAH assays cannot be assessed for multiple PAH components in dust/soil samples (which represent real-world samples), because of the assays' cross reactivities with other PAH components. Over 100 dust/soil samples from 13 North Carolina homes and 22 Arizona homes were analyzed by PAH and C-PAH assays, as well as by the conventional gas chromatography/mass spectrometry (GC/MS) method. Statistical analysis showed that dust/soil PAH data from ELISA and GC/MS methods are significantly different. In general PAH ELISA responses were higher than PAH GC/MS responses. The regression analysis showed that the linear relationship between ELISA and GC/MS measurements is not strong in the combined data. The relationship became stronger for the data from the same type of dust/soil samples. The screening performance of ELISA was evaluated based on the frequency distribution of ELISA and GC/MS data. The results indicated that the ELISA PAH and C-PAH assays cannot be used as a quantitative analytical tool for determining PAH in real-world dust/soil samples. However, the ELISA is an effective screening tool for ranking PAH concentrations in similar types of real world dust/soil samples.

Exposure of children to pollutants in house dust and indoor air

This review summarizes occurrence and exposure studies for pollutants in house dust and related indoor air exposures. A standard sampling method and control methods to reduce these exposures are discussed, including recommendations for future research. Infants and toddlers receive a broad and significant range of exposures to lead, pesticides, PAHs, allergens, and VOCs in house dust and indoor air. Carpet dust in eight Columbus and nine Seattle homes contained concentrations of potentially carcinogenic PAHs ranging from 3 to 290 micrograms/g, of lead from 250 to 2250 micrograms/g, and of PCBs from 210 to 1900 ng/g. Dust collected from ten used sofas in Seattle averaged 16.3, 37.2, and 229 micrograms/g for dust mite allergen, cat allergen, and lead, respectively; dust samples showed mutagenic activity. Biological and chemical pollutants in indoor dust and air have been associated with lead poisoning, cancer, allergy, asthma, damage to the nervous system, and sick building symptoms. The 11% of toddlers who have pica tend to have the highest exposures and risks. Further, the exposure of toddlers to lead via the dust pathway can be greater than by other routes. Standard method ASTM 5438.94 for sampling house dust has been used to characterize current and chronic exposure of toddlers in epidemiological studies. The accumulation of dust, dust mites, and tracked-in soil in old carpets, sofas, and mattresses appears to be a major source of exposure to lead, pesticides, allergens, PAHs, and VOCs. Remodeling and energy conservation can reduce ventilation and increase relative humidity, dust, dust mites, molds, VOCs, and other indoor air pollutants. The U.S. faces large and increasing costs from asthma and allergy. Asthma incidence in the U.S. has increased from 0.5% in 1930 to 8%-12% in 1991. Asthma hospitalization rates for children are increasing at the rate of 4%/yr in the U.S. and 14%/yr in Seattle. Such hospital visits would be rare with effective diagnosis, patient education, and control of home exposures. Asthma was estimated to cost $6.2 billion in 1990; hospital visits of children in Seattle cost $2,526,000 in 1993. Forty percent of the U.S. population has been sensitized to allergens; one in three homes has high relative humidity, which favors dust mites, molds, allergies, asthma, and other respiratory diseases. Reducing indoor allergens can reduce costs, severity, and the risk of being sensitized and developing allergic disease. Use of volunteer Master Home Environmentalists to do free in-home surveys and education in Seattle may reduce immediate health costs from allergens as well as long-term risks from lead, carcinogens, and home chemicals.(ABSTRACT TRUNCATED AT 400 WORDS)