Inhalation and dermal absorption as dominant pathways of PCB exposure for residents of contaminated apartment buildings.

Applications of polychlorinated biphenyls (PCBs) in buildings and their persistence in indoor environments have led to cases of current and highly elevated exposure in humans, despite the global cease of production decades ago. Personal exposure to PCBs was assessed among residents in a social housing estate in Denmark containing both contaminated (n = 67) and non-contaminated (n = 23) apartments. Samples and estimated daily intakes (EDIs) were assessed for 15 PCB congeners, and body burden, which was limited by the dietary data availability, was compared across 7 indicator PCBs, with its sum (PCBsum7) often applied in European regulation of PCBs. Median PCBsum7 EDI across measured pathways for exposed residents was 101 ng· (kg bodyweight)-1· day-1, with the majority of exposure (60%) coming from inhalation of contaminated indoor air. Calculated from both PCBs measured in indoor air and on hand wipes, dermal absorption estimates showed comparable results and served as a secondary exposure pathway, accounting for 35% of personal exposure and considering selected assumptions and sources of physical-chemical parameters. Estimates revealed that diet was the primary PCB source among the reference group, accounting for over 75% of the PCBsum7 EDI across exposure routes. When evaluating overall EDIs across the two study groups and including dietary estimates, PCB exposure among exposed residents was around 10 times higher than the reference group. Solely within the exposed population, pathway-specific body burdens were calculated to account for exposure across years of residence in contaminated apartments, where lower chlorinated PCBs were dominant in indoor air. Among these dominant congeners, estimated body burdens of PCB-28 and -52 were significantly correlated with measured serum (rs = 0.49, 0.45; p < 0.001). This study demonstrates that inhalation and dermal absorption serve as dominant exposure pathways for residents of apartments contaminated with predominantly lower chlorinated PCBs and suggest that predictions of body burden from indoor environment measurements may be comparable to measured serum PCBs.

Cancer Risk following Residential Exposure to Airborne Polychlorinated Biphenyls: A Danish Register-Based Cohort Study.

BACKGROUND: Polychlorinated biphenyls (PCBs) are biopersistent chemicals classified as human carcinogens. This classification is primarily based on evidence on higher-chlorinated PCBs found in food. The carcinogenic potential of airborne lower-chlorinated PCBs remains largely unexplored. OBJECTIVES: We aimed to investigate cancer risk following residential exposure to airborne PCBs. METHODS: Cancer risk was examined in the Health Effects of PCBs in Indoor Air (HESPAIR) cohort of 38,613 residents of two partly PCB-contaminated residential areas in Greater Copenhagen, identified by nationwide registries. PCB exposure was based on relocation dates and indoor air PCB measurements in subsets of apartments. Cancer diagnoses were extracted from the Danish Cancer Registry for the follow-up period of 1970-2018. We estimated adjusted hazard ratios with time-varying cumulative exposure and a 10-y lag using Cox regression. RESULTS: Overall risk of cancer was not associated with PCByear, [hazard ratio (HR) for high-exposed vs. low-exposed =0.98; 95% confidence interval (CI): 0.88, 1.09], but residents exposed to ≥3,000 ng/m3 PCB×year had higher risk of liver cancer (HR =2.81; 95% CI: 1.28, 6.15) and meningiomas (HR =3.49; 95% CI: 1.84, 6.64), with indications of exposure-response relationships. Results were suggestive of a higher risk of pancreatic cancer (HR =1.59; 95% CI: 0.95, 2.64) at the highest aggregated PCB level. For testis cancer, a higher risk was observed among residents exposed to 300-949 ng/m3 PCB×year relative to residents exposed to <300 ng/m3 PCB×year (HR =2.97; 95% CI: 1.41, 6.28), but the risk was not higher for residents exposed to ≥950 ng/m3 PCB×year. Apart from this, the risk of specific cancers was similar across exposure groups. DISCUSSION: In this, to our knowledge, first population-based cohort study of residential exposure to airborne PCBs, we found no association between exposure to PCBs in indoor air in private homes and the risk for most of the specific cancers. Higher risk of liver cancer and meningiomas were observed. https://doi.org/10.1289/EHP10605.

Silicone wristbands as personal passive samplers of exposure to polychlorinated biphenyls in contaminated buildings.

Polychlorinated biphenyls (PCBs) were used in a number of industrial products from 1950 to 80s, including building materials. As a result, some buildings exhibit high levels of PCBs in the indoor environment. The aim of this study was to test silicone wristbands as a method for estimating personal exposure to PCBs in buildings both in controlled experiments and field settings. In the controlled study, the sampling kinetics of silicone wristbands were investigated in a 31-day uptake study. The field study focused on the application of wristbands as a personal exposure measure. It included 71 persons in a contaminated housing estate and 23 persons in a reference group. The linear uptake of PCBs ranged from 2 to 24 days for PCB-8, 18, 28, 31, 40, 44, 49, 52, 66, 99, and 101 under controlled conditions. A generic sampling rate (Rk) of 2.3 m3 d-1 corresponding to a mass transfer coefficient of 17 m h-1 was found in the controlled kinetic study. Partitioning coefficients were also determined for the nine congeners. In the field study, an apparent generic field sampling rate (Rf) of 2.6 m3 d-1 was found; when adjusted to reported hours exposed, it increased to 3.5 m3 d-1. The wristbands were shown to be a good tool for predicting airborne exposure, as there was a highly significant difference between the exposed and reference group as well as a clear trend when used for ranking of exposure. In correlation analyses, highly significant correlations were observed between air and wristband levels, though adjusting by self-reported exposure time only increased the correlation marginally in the field study. The obtained kinetic data can be used for estimating the magnitude of external exposure. The advantages provided by the wristbands in the form of easy use and handling are significant, though the limitations should also be acknowledged.

Sorption of PCB from air to settled house dust in a contaminated indoor environment.

Investigation of human exposure pathways to PCB in a high-rise estate in Denmark motivated an experiment with sorption of PCB from air to settled house dust. Three sieved house dust samples (<75 µm) of different origin were exposed to elevated air concentrations of PCB in a vacated apartment from seven to 40 days. Within the 40 days, most of the dust samples were close to equilibrium for the congeners PCB-8 to -101 and dust-air partition coefficients were determined. The dust samples of different origin showed comparable partitioning, though small differences were seen. The determined partition coefficients were in agreement with values found in literature. Further, the partition coefficients were compared to three sets of predicted estimates based on absorption of PCB into the organic matter of the dust and octanol-air partition coefficients derived from different sources. Comparing measured and predicted values (log-log), two sets of predicted values showed strong correlation, though overestimated 20-40%, while one set showed similar absolute levels, but with a few deviating congeners. Dust-air ratios were calculated for samples taken from a field investigation in homes with elevated air concentrations of PCB in the high-rises. The partitioning in the field samples were in agreement with the results from the exposure experiment and indicate near steady state conditions for the congeners in the dust from the homes. Dust exposed directly on the floorboards showed lower concentrations than samples placed on foil, indicating an ongoing sorption to the varnish being a tertiary source contaminated by the air.

PCB in air, dust and surface wipes in 73 Danish homes.

As part of an investigation of the total indoor exposure of residents in PCB contaminated apartments in a building estate in Denmark, 73 homes were visited. Samples of air, vacuum cleaner dust and surface wipes were taken and analysed for 15 PCB congeners. The 53 apartments located in high-rise buildings with indoor PCB containing sealants showed significant elevated total concentrations of PCB in air, dust and surface wipes compared to 20 reference homes. The average concentration in exposed homes was 2330 ng PCBtotal/m3 in air, 12.000 ng PCBsum15/g in dust and for surface wipes 529 ng PCBsum15/wipe. These values were respectively 40, 25 and 50 times higher than the averages found in reference homes. The air concentration in all exposed homes was higher than the lower recommended action level of 300 ng PCBtotal/m3 from the Danish Health Authority, whereas all reference homes were below. The air concentrations in exposed homes were variating, partly due to indoor temperature. The concentrations in air and dust samples were significantly correlated for PCBsum7 in exposed homes. No significant correlation was observed between samples of air and surface wipes, despite surface wipes from exposed homes were significantly different from wipes taken in reference homes. Both dust samples and surface wipes have a potential as screening tool for identifying elevated levels of the less chlorinated PCBs in air. Additional short-term measurements of air concentrations in a subgroup of exposed homes indicated limited diurnal variations within the individual homes. The congener patterns were rather uniform within the respective media from the exposed homes and dominated by tri- and tetraPCBs. The pattern of air differed from that of dust and surface wipes, which were more alike. The study demonstrates a wide spread PCB contamination of the indoor environment in buildings with PCB in indoor sealants and confirms the need for identifying and alleviate PCB in buildings causing a health concern to the occupants.

PCB in serum and hand wipes from exposed residents living in contaminated high-rise apartment buildings and a reference group.

Exposure to polychlorinated biphenyls (PCB) in buildings constructed with PCB-containing materials can lead to increased body burden of PCB for building users. Exposure to PCB from building related sources was assessed by measuring PCB in serum and hand wipes in two groups of tenants living in the same building estate in apartments constructed with and without PCB. The median serum levels of the sum of 19 PCB congeners was 777 ng/g lw (5-95th percentile: 219-2576 ng/g lw) for the exposed group and 282 ng/g lw (5-95th percentile: 49.8-797 ng/g lw) for the reference group. The congener pattern in serum of the exposed was shifted towards lower chlorinated congeners and was dominated by tri- and tetrachlorinated congeners. The largest difference in serum levels between the groups was observed for PCB-28, with median levels of the exposed being 70 times higher than in the reference group. For very persistent lower chlorinated congeners, like PCB-28, 66 and 74, an increase with residence times was observed as a result of accumulation over time. Less persistent congeners such as PCB-44 and 70 were also elevated in the exposed group -but independent of residence time. The less persistent congeners can therefore be used as markers of recent exposure to original PCB sources. The hand wipes also showed a large exposure contrast, e.g. PCB-28 being more than 60 times higher in the exposed group compared to the reference group (medians 14.4 and 0.23 ng/wipe, respectively) and no overlap between the groups. All measured di- to pentaPCB congeners were significantly higher in hand wipes from the exposed group compared with the reference group. Thus hand wipes seem to be a good, non-invasive screening tool for ongoing indoor exposure to PCB. Furthermore, the measured level of PCB on hand wipes was significantly correlated to PCB in blood for almost all congeners. In conclusion, PCB exposure in contaminated buildings can contribute significantly to the exposure and total body burden of PCB and the lower chlorinated congeners can make up the majority of the total PCB body burden.

Laboratory investigation of PCB bake-out from tertiary contaminated concrete for remediation of buildings.

Polychlorinated biphenyls (PCBs) have been used in flexible construction products from the 1950s to the 1970s. Despite a relatively low vapour pressure, PCBs have over the years emitted to the indoor air and adsorbed to other surfaces, creating tertiary sources. While necessary to protect the environment and health of building occupants, remediation of the contaminated buildings is an expensive and difficult process. The aim of this study was to investigate the effect of bake-out as a method for removing PCB from contaminated indoor surfaces. Four painted and four sandblasted samples of concrete wall were kept at 50 or 65 °C for 10 or 20 days in small scale chambers, which were ventilated with clean air at area specific rates comparable to full scale rooms. The air concentrations were measured several times during the bake-out. Concentrations of PCB in paint, plaster and concrete were measured before and after the experiment. For the painted samples, PCB28 and PCB52 followed by PCB138 and PCB153 were the predominant congeners measured in air. A significant reduction of the PCB concentration was only found for more volatile congeners in paint, while no significant effects were observed in the plaster or concrete. For the most effective setting (65 °C, 20 days), the concentration of PCB∑7 in the paint was reduced by 40%. For the sandblasted samples, the less volatile congeners PCB138 and PCB153 were predominant in the air during bake-out. No effect was observed on the initially low concentrations of the sandblasted samples, possibly due to analytical limitations.

Modelling the impact of room temperature on concentrations of polychlorinated biphenyls (PCBs) in indoor air.

Buildings contaminated with polychlorinated biphenyls (PCBs) are a health concern for the building occupants. Inhalation exposure is linked to indoor air concentrations of PCBs, which are known to be affected by indoor temperatures. In this study, a highly PCB contaminated room was heated to six temperature levels between 20 and 30 C, i.e. within the normal fluctuation of indoor temperatures, while the air exchange rate was constant. The steady-state air concentrations of seven PCBs were determined at each temperature level. A model based on Clausius-Clapeyron equation, ln(P) = -ΔH/RT + a(0), where changes in steady-state air concentrations in relation to temperature, was tested. The model was valid for PCB-28, PCB-52 and PCB-101; the four other congeners were sporadic or non-detected. For each congener, the model described a large proportion (R(2)>94%) of the variation in indoor air PCB levels. The results showed that one measured concentration of PCB at a known steady-state temperature can be used to predict the steady-state concentrations at other temperatures under circumstances where e.g. direct sunlight does not influence temperatures and the air exchange rate is constant. The model was also tested on field data from a PCB remediation case in an apartment in another contaminated building complex where PCB concentrations and temperature were measured simultaneously and regularly throughout one year. The model fitted relatively well with the regression of measured PCB air concentrations, ln(P) vs. 1/T, at varying temperature between 16.3 and 28.2 °C, even though the measurements were carried out under uncontrolled environmental condition.

Xanthoria parietina as a monitor of ground-level ambient ammonia concentrations.

Total nitrogen in transplanted and in situ lichen thalli of Xanthoria parietina were related to ambient ammonia air concentrations measured with passive ALPHA (Adapted Low-cost Passive High Absorption) diffusion samplers in Denmark. Transplants and ALPHA samplers were exposed four months in a transect on heathland close to a pig farm. Monthly mean ammonia concentrations declined exponentially approaching background levels after 300m. Nitrogen content of the lichen transplants tended to decline with distance, though only a few stations were significantly different from each other. Where ammonia concentrations were high, maximum content of nitrogen was reached after one month of exposure. Conversely, at sites with background concentrations, it took several months to reach a statistically significant uptake. The correlation between ammonia concentration in the air and in situ X. parietina was significant.

Estimation of emission fluxes from a horizontal flux budget method, exemplified with determination of pesticide volatilization.

The paper describes an experimental set-up designed to measure the volatilization of different pesticides after application under full-scale field conditions. The pesticides were sprayed around the circumference of a circle and measurements of meteorology and air concentrations of pesticides were taken in the centre of the circle. The paper describes how the dimensions like the radius of the circle and height of the mast in the experimental set-up are found from theoretical considerations. A method to increase the confidence of the flux calculations is described. It utilizes that several substances were applied simultaneously and that a certain parameter in the fitted concentration profiles depends on turbulence only and thus have the same value for all substances. The design was used during two campaigns, conducted on the same location, one during fall on bare soil and one in spring on a barley crop.

Personal exposure to PM2.5, black smoke and NO2 in Copenhagen: relationship to bedroom and outdoor concentrations covering seasonal variation.

Epidemiological studies have found negative associations between human health and particulate matter in urban air. In most studies outdoor monitoring of urban background has been used to assess exposure. In a field study, personal exposure as well as bedroom, front door and background concentrations of PM(2.5), black smoke (BS), and nitrogen dioxide (NO(2)) were measured during 2-day periods in 30 subjects (20-33 years old) living and studying in central parts of Copenhagen. The measurements were repeated in the four seasons. Information on indoor exposure sources such as environmental tobacco smoke (ETS) and burning of candles was collected by questionnaires. The personal exposure, the bedroom concentration and the front door concentration was set as outcome variable in separate models and analysed by mixed effect model regression methodology, regarding subject levels as a random factor. Seasons were defined as a dichotomised grouping of outdoor temperature (above and below 8 degrees C). For NO(2) there was a significant association between personal exposure and both the bedroom, the front door and the background concentrations, whereas for PM(2.5) and BS only the bedroom and the front door concentrations, and not the background concentration, were significantly associated to the personal exposure. The bedroom concentration was the strongest predictor of all three pollution measurements. The association between the bedroom and front door concentrations was significant for all three measurements, and the association between the front door and the background concentrations was significant for PM(2.5) and NO(2), but not for BS, indicating greater spatial variation for BS than for PM(2.5) and NO(2). For NO(2), the relationship between the personal exposure and the front door concentration was dependent upon the "season", with a stronger association in the warm season compared with the cold season, and for PM(2.5) and BS the same tendency was seen. Time exposed to burning of candles was a significant predictor of personal PM(2.5), BS and NO(2) exposure, and time exposed to ETS only associated with personal PM(2.5) exposure. These findings imply that the personal exposure to PM(2.5), BS and NO(2) depends on many factors besides the outdoor levels, and that information on, for example, time of season or outdoor temperature and residence exposure, could improve the accuracy of the personal exposure estimation.