Gaseous elemental mercury as an indoor air pollutant

Mercury accumulation efficiency of different biomonitors in indoor environments: the case study of the Central Italian Herbarium (Florence, Italy)

Biomonitoring studies are often employed to track airborne pollutants both in outdoor and indoor environments. In this study, the mercury (Hg) sorption by three biomonitors, i.e., Pinus nigra bark, Pseudovernia furfuracea lichen, and Hypnum cupressiforme moss, was investigated in controlled (indoor) conditions. In comparison to outdoor environments, controlled conditions offer the opportunity to investigate more in detail the variables (humidity, temperature, pollutants speciation, etc.) that control Hg uptake. The biomonitors were exposed in two distinct periods of the year for 2 and 12 months respectively, in the halls of the Central Italian Herbarium (Natural History Museum of the University of Florence, Italy), which are polluted by Hg, due to past plant sample treatments. The Hg sorption trend was monitored every 3 weeks by recording: (i) the Hg content in the substrata, (ii) gaseous elemental mercury (GEM) concentrations in the exposition halls, (iii) temperature, (iv) humidity, and (v) particulate matter (PM) concentrations. At the end of the experiment, Hg concentrations in the biomonitors range from 1130 ± 201 to 293 ± 45 μg kg-1 (max-min) in barks, from 3470 ± 571 to 648 ± 40 μg kg-1 in lichens, and from 3052 ± 483 to 750 ± 127 μg kg-1 in mosses. All the biomonitors showed the highest Hg accumulation after the first 3 weeks of exposure. Mercury concentrations increased over time showing a continuous accumulation during the experiments. The biomonitors demonstrated different Hg accumulation trends in response to GEM concentrations and to the different climatic conditions (temperature and humidity) of the Herbarium halls. Barks strictly reflected the gaseous Hg pollution, while lichen and moss accumulation was also influenced by the climatic conditions of the indoor environment. Mercury bound to PM seemed to provide a negligible contribution to the biomonitors final uptake.

Characteristics and Health Risk Assessment of Mercury Exposure via Indoor and Outdoor Household Dust in Three Iranian Cities

This study aims to increase our current knowledge on the concentration of particulate-bound mercury (PBM) in urban environments of three Iranian cities, where high concentrations of dust particles can act as carriers for mercury transport and deposition. A total of 172 dust samples were collected from Ahvaz, Asaluyeh, and Zabol residential houses and in outdoor air and were analyzed for total mercury content. Ahvaz is a highly industrialized city with large metallurgical plants, refineries, and major oil-related activities, which were assumed to contribute to elevated contents of PBM in this city. Very high levels of Hg contamination in Ahvaz indoor dust samples were calculated (Contamination Factor: CF > 6). Sampling sites in Asaluyeh are influenced by Hg emissions from the South Pars Gas Field. However, the results revealed a relatively lower concentration of PBM in Asaluyeh, with a low-to-moderate level of Hg contamination. This is likely ascribed to the lower content of total mercury in hydrocarbon gases than crude oil, in addition to the absence of metal smelting plants in this city compared to Ahvaz. Zabol, as a city devoid of industrial activity, presented the lowest levels of PBM concentration and contamination. Indoor dust in Ahvaz showed considerable potential to cause a non-carcinogenic health risk for children, mainly through the inhalation of PBM, while the health risk for other cities was below safe limits. The trend of health risk was found in the order of indoor > outdoor and children > adults in all studied cities.

Outstanding performance of ZnS/TiO2 for the urgent disposal of liquid mercury leakage indoors: Novel support effect, reaction mechanism and kinetics

Effectively weakening the bond strength of Zn-S in S-Zn-S on ZnS is of great significance to the improvement of its performance for the urgent disposal of liquid Hg⁰ leakage indoors. In this work, ZnS was loaded on three common supports (i.e., TiO₂, SiO₂, and Al₂O₃) to further improve its performance for capturing high concentrations of Hg⁰ indoors. After being loaded on TiO₂, the S-Zn-O bond was present on ZnS, and the bond strength of Zn-S in S-Zn-O was significantly weaker than that in S-Zn-S because Zn²⁺ preferred to O^2- than S^2-. Hence, physically adsorbed Hg⁰ was much easier to bond with S in S-Zn-O than that in S-Zn-S to form HgS. Therefore, TiO₂ showed a novel support effect on ZnS for Hg⁰ capture, and the Hg⁰ capture performance of ZnS/TiO₂ was greatly better than those of ZnS, ZnS/SiO₂, and ZnS/Al₂O₃. Moreover, the promotion mechanism of ZnO loading on Hg⁰ adsorption onto TiO₂-S was discovered after comparing the Hg⁰ adsorption kinetic parameters of TiO₂-S and ZnS/TiO₂. The promotion of ZnO loading was primarily related to the notable increase in the content of S^2- that can bond with physically adsorbed Hg⁰, which predominantly resulted from the strong interaction of ZnO/TiO₂ with H₂S.

Concurrently Measured Concentrations of Atmospheric Mercury in Indoor (household) and Outdoor Air of Basel, Switzerland

Indoor air pollution can be a major health risk because urban populations spend up to 90% of their time in closed rooms. Gaseous elemental mercury (GEM) has not been measured as routinely as other indoor air pollutants due to the high costs and limited mobility of active Hg analyzers. However, household GEM concentrations may exceed Hg air quality guidelines as a result of potential indoor GEM sources like broken Hg thermometers. Here we deploy novel low-cost mercury passive air samplers (MerPAS) in 27 households (7 days) and at 14 outdoor locations (29-31 days) in Basel, Switzerland. Average Hg concentrations ranged from 2.0 to 10.8 ng m^-3 indoors and from 1.8 to 2.5 ng m^-3 outdoors. These results reveal that households are a net source of Hg to the urban atmosphere and exceed outdoor Hg levels by a factor of 2 on average. We estimated an average weekly intake rate of 0.01 μg of Hg/kg of body weight for adult residents in Basel, which is usually lower than Hg exposure of people with dental amalgam fillings. Our campaign demonstrates that air monitoring programs can easily be complemented by straightforward Hg measurements using MerPAS.

Human health risk assessment of exposure to indoor mercury vapour in a Ghanaian artisanal small-scale gold mining community

People living or working in and around artisanal small-scale gold mining communities can be exposed to mercury vapour, which may negatively affect their health. In this study, the human exposure to air borne mercury in an artisanal mining community in the Upper East region of Ghana was investigated using Lumex RA 915 M mercury analyser, an active sampler. The concentration of mercury in air was measured inside and outside households and was related to human health risk standards. For each household, one measurement was taken from outside and three from inside at different positions. About 91% of the households where amalgam burning was reported had concentrations higher than the USEPA reference dose of 300 ng m^-3 whereas 64% of the households where amalgam burning was not reported exceeded the reference dose above. The maximal (upper) instrumental limit (50,000 ng m^-3) was passed for the highest concentrations, so, the upper 97.5% concentration was estimated, using censored statistics, to exceed 800,000 ng m^-3 for the fireplaces. This exceeds any reported indoor household air concentration of Hg, identified by the literature review in this paper. Estimated hazard quotients were found to range from <1 to 108 within the households that are reported not to burn amalgam. In the households where amalgam burning reportedly takes place, the hazard quotient had a range of 0.01-160. Mercury concentrations measured in households with reported amalgam burning are approximately ten times higher than those households with no reported burning of amalgam. The censored data predicted hazard quotients up to 966. The results indicate that both miners and non-miners of the community are at risk of adverse health effects resulting from inhalation of mercury vapour.

Mercury emission from industrially contaminated soils in relation to chemical, microbial, and meteorological factors

The Minamata Convention entered into force in 2017 with the aim to phase-out the use of mercury (Hg) in manufacturing processes such as the chlor-alkali or vinyl chloride monomer production. However, past industrial use of Hg had already resulted in extensive soil pollution, which poses a potential environmental threat. We investigated the emission of gaseous elemental mercury (Hg⁰) from Hg polluted soils in settlement areas in the canton of Valais, Switzerland, and its impact on local air Hg concentrations. Most soil Hg was found as soil matrix-bound divalent Hg (Hg^II). Elemental mercury (Hg⁰) was undetectable in soils, yet we observed substantial Hg⁰ emission (20-1392 ng m^-2 h^-1) from 27 soil plots contaminated with Hg (0.2-390 mg Hg kg^-1). The emissions of Hg⁰ were calculated for 1274 parcels covering an area of 8.6 km² of which 12% exceeded the Swiss soil remediation threshold of 2 mg Hg kg^-1. The annual Hg⁰ emission from this area was approximately 6 kg a^-1, which is almost 1% of the total atmospheric Hg emissions in Switzerland based on emission inventory estimates. Our results show a higher abundance of Hg resistance genes (merA) in soil microbial communities with increasing soil Hg concentrations, indicating that biotic reduction of Hg^II is likely an important pathway to form volatile Hg⁰ in these soils. The total soil Hg pool in the top 20 cm of the investigated area was 4288 kg; hence, if not remediated, these contaminated soils remain a long-term source of atmospheric Hg, which is prone to long-range atmospheric transport.

Automated Stable Isotope Sampling of Gaseous Elemental Mercury (ISO-GEM): Insights into GEM Emissions from Building Surfaces

Atmospheric monitoring networks quantify gaseous elemental mercury (GEM) concentrations, but not isotopic compositions. Here, we present a new method for automated and quantitative stable isotope sampling of GEM (ISO-GEM) at the outlet of a commercial Hg analyzer. A programmable multivalve manifold selects Hg at the analyzer inlet and outlet based on specific criteria (location, time, GEM concentration, auxiliary threshold). Outlet Hg recovery was tested for gold traps, oxidizing acidic solution traps, and activated carbon traps. We illustrate the ISO-GEM method in an exploratory study on the effect of building walls on local GEM. We find that GEM concentrations directly at the building surface (wall inlet) are significantly enhanced (mean 3.8 ± 1.8 ng/m³) compared to 3 m from the building wall (free inlet) (mean 1.5 ± 0.4 ng/m³). GEM δ²⁰²Hg (-1.26‰ ± 0.41‰, 1 SD, n = 16) and Δ¹⁹⁹Hg (-0.05‰ ± 0.10‰, 1 SD, n = 16) at the wall inlet were different from ambient GEM δ²⁰²Hg (0.76‰ ± 0.09‰, 1 SD, n = 16) and Δ¹⁹⁹Hg (-0.21‰ ± 0.05‰, 1 SD, n = 16) at the free inlet. The isotopic fingerprint of GEM at the wall inlet suggests that GEM emission from the aluminum building surface affected local GEM concentration measurements. These results illustrate the versatility of the automated Hg isotope sampling.

Factors determining dry deposition of total mercury and organic carbon in house dust of residents of the Tri-city and the surrounding area (Baltic Sea coast)

The purpose of this study was to find out what factors determine the deposition levels of mercury and organic carbon in household dust in the Tri-city region (southern Baltic Sea coast). Analyses were performed on samples collected over the period of 2 years, from 2013 to 2015, always in the heating season. The deposition of organic carbon was between 4and 210 mg m^-2 month^-1, while mercury deposition ranged from 4 to 1336 ng m^-2 month^-1. Deposition of mercury in household dust during the heating season was three times lower and deposition of organic carbon one and a half times lower than outdoor deposition obtained in the Baltic Sea region by other researchers. In the non-heating period, deposition of mercury in household dust was similar to outdoor deposition while deposition of OC was one and a half times higher. Both of the analyzed dust components reached higher deposition in rural areas than in cities, and both mercury and organic carbon were found to have higher deposition in single-family houses than in buildings housing several families. The increased level of OC was conditioned by the vicinity of the building to a road or street with a high level of traffic, and dust collected on the ground floor had higher Hg depositions. The presence of plants and pets, as well as smoking more than ten cigarettes per day, resulted in higher depositions of both the compounds present in household dust within the Tri-city region.

Indoor and outdoor elemental mercury: a comparison of three different cases

Gaseous elemental mercury (GEM) concentrations were determined in three different indoor environments: an office in a building with no indoor sources of mercury (Bldg. I), an office affected by indoor mercury emissions from an adjacent laboratory (Bldg. II), and finally, an office where an outdoor mercury spill occurred accidentally (Bldg. III). The maximum recorded indoor GEM concentrations, with the largest variation in time, were observed in Bldg. II, with a continuous indoor mercury source (lower to upper quartile 15 to 62 ng m^-3). The lowest values were recorded in Bldg. I (lower to upper quartile 3 to 5 ng m^-3), where indoor GEM levels were affected mainly by the exhaust of vehicles in the parking lot of the building. The monitoring of GEM indoors (lower to upper quartile 15 to 42 ng m^-3), and outdoors (in several heights) of the Bldg. III, revealed that the cleaning up procedure that followed the spill was not adequate. Auxiliary measurements in the first two cases were the indoor microclimatic conditions, as well as the indoor CO₂ concentrations, and in the third case the outdoor meteorological data. The exhaust of vehicles, the chemical reagents, and an outdoor mercury spill were found to mainly affect the observed indoor GEM levels. People in Bldg. II and people walking through the area, where Hg⁰ was spilled, were found to be exposed to concentrations above some guide values.

Knowledge, attitudes and practices regarding handling mercury containing medical devices among nurses in a tertiary care paediatric hospital in Sri Lanka

BACKGROUND

Mercury is a highly toxic heavy metal used in many medical devices in the healthcare sector, making nurses one of the vulnerable occupational groups.

OBJECTIVE

To assess knowledge, attitudes and practices regarding handling mercury containing devices and factors associated with knowledge among nurses in a paediatric hospital in Sri Lanka.

METHODS

A descriptive cross-sectional study was conducted among nurses (n = 538) working in Lady Ridgeway Hospital, Sri Lanka. Information on the use of mercury containing medical devices, accidental exposure, management of spillage and disposal was gathered using a self-administered questionnaire.

RESULTS

A total of 472 nurses responded with a response rate of 87.7%. Of the 347 mercury thermometer users, 67.1% had experienced breakages while among 405 mercury sphygmomanometer users, 20.0% had experienced mercury spillages, during a three months period prior to the study. A majority (56.8%) had 'good' overall knowledge regarding mercury and its adverse effects while 94.1% had favorable attitudes towards protecting themselves/others from mercury. Practices related to managing a mercury spill were poor. Work experience >10 years (p = 0.032) and favorable attitude (p = 0.007) were associated with good knowledge while having a training on managing a mercury spillage was not (p = 0.850).

CONCLUSIONS

Gaps in practices on managing a mercury spillage were evident. Current training programmes were not found to be effective.

Awareness assessment of harmful effects of mercury in a health care set-up in India: A survey-based study

Mercury, one of the most toxic heavy metals, is ubiquitous in environment. The adverse health impact of mercury on living organisms is well known. The health care facilities are one of the important sources of mercury release into the atmosphere as mercury items are extensively used in hospitals. To assess the awareness about mercury toxicity and the knowledge of proper handling and disposal of mercury-containing items in health care set-up, a questionnaire-based survey was carried out amongst doctors (n = 835), nurses (n = 610) and technicians (n = 393) in government hospitals, corporate hospitals and primary health care centres in the Indian states of Delhi, Uttar Pradesh and Haryana. The study was conducted using a tool-containing pretested structured multiple-choice questionnaire. Analysis of the results using STATA 11.1 software highlighted that overall awareness was more in corporate sector. However, percentage range of knowledge of respondents irrespective of health care sector was only between 20 and 40%. Despite the commitment of various hospitals to be mercury free, mercury containing-thermometer/sphygmomanometer are still preferred by health professionals. The likely reasons are availability, affordability, accuracy and convenience in use. There is an urgent need for source reduction, recycling and waste minimization. Emphasis must be laid on mercury alternative products, education and training of health personnel and public at large, about correct handling and proper clean up of spills.

Exposure analysis of accidental release of mercury from compact fluorescent lamps (CFLs)

Mercury release after breakage of compact fluorescent lamps (CFLs) has recently become an issue of public health concern, especially in the case of early life infants. Preliminary, screening type calculations have indicated that there is potential for increased intake of mercury vapor by inhalation after breakage of a CFL. Several experimental and computational studies have shown that, when modeling the breakage of a CFL, the room space must be segregated into different zones, according to the potential of mercury vapor to accumulate in them after accidental release. In this study, a detailed two-zone model that captures the physicochemical processes that govern mercury vapor formation and dispersion in the indoor environment was developed. The mercury fate model was coupled to a population exposure model that accounts for age and gender-related differences in time-activity patterns, as well as country differences in body weight and age distribution. The parameters above are used to determine the intake through inhalation (gas phase and particles) and non-dietary ingestion (settled dust) for each age, gender group and ethnicity. Results showed that the critical period for intake covers the first 4h after the CFL breaks and that room air temperature significantly affects the intake rate. Indoor air concentration of mercury vapor may exceed toxicological thresholds of concern such as the acute Reference Exposure Limit (REL) for mercury vapor set by the Environmental Protection Agency of California. Ingestion intake through hand-to-mouth behavior is significant for infants and toddlers, counting for about 20% of the overall intake. Simple risk reduction measures including increased indoor ventilation followed by careful clean-up of the accident site, may limit dramatically the estimated health risk.

Estimating human indoor exposure to elemental mercury from broken compact fluorescent lamps (CFLs)

The 2008 EU regulation, which prohibits conventional incandescent light bulbs, is to be implemented in phases, completing in 2012. One of the possible substitutes is the compact fluorescent lamp (CFL), which, however, does contain up to 5 mg of mercury in its elemental or amalgamated form. The question arises as to the possible exposure of individuals to mercury as a result of lamp breakage during operation or when disconnected from the power supply. Therefore, an apparatus was built to shatter CFLs and drop the shards onto glycol-modified polyethylene terephthalate, a carpeted floor, or laminate floor under defined climatic parameters and operating conditions. Six CFLs of different types and mercury content were studied. After the breakage of a common CFL containing liquid mercury, concentrations up to 8000 ng/m(3) were reached in the chamber. Much lower peak values were obtained with amalgam-type lamps (414 ng/m(3)) or with lamps with a shatter-proof coating (60 ng/m(3)). It was found that ventilation can considerably reduce the indoor air concentration within 20 min. Acute health effects would only be expected if the mercury is not removed immediately. Careful collection and disposal of the lamp fragments would also prevent dwellers from the risk of long-term exposure.

PRACTICAL IMPLICATIONS

After accidental breakage of a compact fluorescent lamp (CFL) indoors, dwellers could be exposed to high mercury concentrations. From the results of our studies in test chambers and real rooms using different lamp types and scenarios, it was possible to estimate the possible human uptake of mercury by inhalation. Immediate action is important to reduce indoor mercury concentrations to a minimum level. The first step is to maximize ventilation followed by careful collection of spilled mercury.

Mercury levels in road dust and household TSP/PM₂.₅ related to concentrations in hair in Guangzhou, China

Road dust, household total suspended particulate matters (TSP) and PM₂.₅ were collected in urban area of Guangzhou, south of China, to investigate the concentrations of total mercury (THg) and methyl mercury (MeHg). The household PM₂.₅ concentrations varied between 16.2 and 623 μg/m³. The average PM₂.₅ level (174 μg/m³) from all of the locations exceeded 24-h concentration from WHO air quality guideline The average concentrations of THg and MeHg were: 235 μg/kg and 0.392 μg/kg in road dust, 600 μg/kg and 1.49 μg/kg in TSP; 1006 μg/kg (104 pg/m³) and 1.40 μg/kg (0.134 pg/m³) in PM₂.₅. Risk assessment showed that the Hazardous quotients (HQs) of exposure to Hg and MeHg via road dust and TSP were less than 1, indicating that no adverse risk was manifested. Ingestion of dust was found to constitute a relatively minor pathway of Guangzhou residents' exposure to Hg. Furthermore, human hair samples from 88 Guangzhou citizens were also analyzed to investigate the mercury accumulation in human body in Guangzhou. The average concentrations of THg and MeHg in human hair samples were 869±831 μg/kg and 104±108 μg/kg respectively. However, no significant correlations of the mercury species were noted between human hair and road dust, TSP and PM₂.₅.

Source, concentration, and distribution of elemental mercury in the atmosphere in Toronto, Canada

Atmospheric gaseous elemental mercury [GEM] at 1.8, 4, and 59 m above ground, in parking lots, and in indoor and outdoor air was measured in Toronto City, Canada from May 2008-July 2009. The average GEM value at 1.8 m was 1.89 ± 0.62 ng m(-3). The GEM values increased with elevation. The average GEM in underground parking lots ranged from 1.37 to 7.86 ng m(-3) and was higher than those observed from the surface parking lots. The GEM in the indoor air ranged from 1.21 to 28.50 ng m(-3), was higher in the laboratories than in the offices, and was much higher than that in the outdoor air. All these indicate that buildings serve as sources of mercury to the urban atmosphere. More studies are needed to estimate the contribution of urban areas to the atmospheric mercury budget and the impact of indoor air on outdoor air quality and human health.

Concentrations of gaseous elemental mercury in ambient air within an academic chemistry building

Gaseous elemental mercury (GEM) concentrations were determined within an academic chemistry building by cold vapor atomic fluorescence spectrometry. Concentrations varied depending on the room activity, with night time and weekend levels the lowest and most stable (typically between 10 and 20 ng/m(3)), and daytime weekday levels the highest (averaging about 3-5 times higher). Laboratory air exhibited daytime concentration spikes as high as 1,600 ng/m(3). Office levels were similar to weekend laboratory concentrations, suggesting a general building-wide mercury background. However, concentration spikes suggest GEM levels may be exacerbated by foot traffic which may cause motion-induced wafting from higher concentration areas. Based on current regulations the GEM levels do not present a health hazard.

Indoor air concentrations of mercury species in incineration plants for municipal solid waste (MSW) and hospital waste (HW)

Until now, there is limited information about mercury exposures inside solid waste incineration plants although incineration has been considered as one of major solid waste treatments. This study investigated indoor air concentrations of gaseous elemental mercury (GEM), reactive gaseous mercury (RGM) and particulate mercury (Hgp) and indoor dust mercury concentrations in a municipal solid waste incineration (MSWI) plant and a hospital waste incineration (HWI) plant during December 2003 and July 2004. The final results showed that the employees in incineration plants are not only exposed to GEM, but also to RGM and Hgp. For the HWI plant, only concentration of total mercury (HgT) in operation center in summer was below 1000ngm(-3) due to frequent ventilation, while those of GEM and HgT in hospital waste depot exceeded 3000ngm(-3). For the MSWI plant, only concentration of HgT in workplace in winter exceeded 1000ngm(-3). Therefore, more attention should be paid to mercury exposures in HWI plants than in MSWI plants. Indoor dust containing approximately 3968microgHgTkg(-1) (dry matter) possibly served as the potential source for indoor air mercury pollution, especially in the HWI plant.

Evaluation of potential for mercury volatilization from natural and FGD gypsum products using flux-chamber tests

Synthetic gypsum produced by flue-gas desulfurization (FGD) in coal-fired power plants (FGD gypsum) is put to productive use in manufacturing wallboard. FGD gypsum wallboard is widely used, accounting for nearly 30% of wallboard sold in the United States. Mercury is captured in flue gas and thus is one of the trace metals present in FGD gypsum; raising questions about the potential for mercury exposure from wallboard. Mercury is also one of the trace metals present in "natural" mined gypsum used to make wall board. Data available in the literature were not adequate to assess whether mercury in wallboard from either FGD or natural gypsum could volatilize into indoor air. In this study, mercury volatilization was evaluated using small-scale (5 L) glass and Teflon flux chambers, with samples collected using both iodated carbon and gold-coated sand traps. Mercury flux measurements made using iodated carbon traps (n=6) were below the detection limit of 11.5 ng/m2-day for all natural and synthetic gypsum wallboard samples. Mercury flux measurements made using gold-coated sand traps (n=6) were 0.92 +/- 0.11 ng/m2-day for natural gypsum wallboard and 5.9 +/- 2.4 ng/m2-day for synthetic gypsum wallboard. Room air mercury concentrations between 0.028 and 0.28 ng/m3 and between 0.13 and 2.2 ng/m3 were estimated based on the flux-rate data for natural and synthetic gypsum wallboard samples, respectively, and were calculated assuming a 3 m x 4 m x 5 m room, and 10th and 90th percentile air exchange rates of 0.18/hour and 1.26/hour. The resulting concentration estimates are well below the U.S. Environmental Protection Agency (EPA) reference concentration for indoor air elemental mercury of 300 ng/m3 and the Agency for Toxic Substances and Disease Registry minimal risk level (MRL) of 200 ng/m3. Further, these estimates are below background mercury concentrations in indoor air and within or below the range of typical background mercury concentrations in outdoor air.

Assessment of exposure to mercury from industrial emissions: comparing "distance as a proxy" and dispersion modelling approaches

BACKGROUND

The Runcorn area, north-west England, contains many pollution sources, the health effects of which have been under discussion for over 100 years. Preliminary investigations revealed an excess risk of mortality from kidney disease in people living nearest to several point sources of pollution, using distance as a proxy for exposure. Ongoing epidemiological investigations into the effect of ambient mercury exposure on dose and renal effect required a more refined assessment of exposure.

METHODS

Atmospheric dispersion modelling was used to assess mercury dispersion from three mercury-emitting sources (including a large chlor alkali plant), based on knowledge of emissions, local meteorology and topography.

RESULTS

The model was sensitive to various input parameters, with different dispersion patterns and ground-level concentrations, and therefore different exposed populations identified when different input parameters were defined. The different approaches to exposure assessment also had an impact on the epidemiological findings. The model output correlated well with weekly monitoring data collected in the local area, although the model underestimated concentrations in close proximity to the chlor alkali plant. The model identified that one point source did not contribute significantly to ground-level mercury concentrations, so that inclusion of this source when using the "distance as a proxy" approach led to significant exposure misclassification.

CONCLUSIONS

The model output indicates that assessment of ambient exposure should give consideration to the magnitude of emissions, point source characteristics, local meteorology and topography to ensure that the most appropriate exposure classification is reached. Even if dispersion modelling cannot be undertaken, these data can be used to inform and improve the distance as a proxy approach, and improve the interpretability of the epidemiological findings.

Incorporating ethnographic methods in multidisciplinary approaches to risk assessment and communication: cultural and religious uses of mercury in Latino and Caribbean communities

The potential risk from cultural and religious practices involving mercury in Latino and Caribbean communities raises central methodological and ethical questions for risk assessment and risk communication. Here, specific cultural practices unfamiliar to most risk professionals carry significant inherent risks in the eyes of those professionals but not necessarily in the eyes of practitioners. Practitioners' past experience and history as targets of religious suppression and anti-immigrant sentiment create a reluctance to engage with researchers or public health officials in risk assessment or preventive risk communication efforts. The potential for the risk--in this case mercury contamination in dwellings--to extend beyond the practicing community to future occupants adds to public health concern. Understanding the risks of these practices requires both an understanding of the cultural and political context, beliefs, and behaviors of mercury users and an understanding of the fate and transport of mercury in typical use scenarios. In this study, we employed ethnographic methods (interviews and participant observation) to understand beliefs and behavior about mercury use as well as quantitative modeling and measurement to estimate and assess potential exposures. This represents a new methodology tailored to situations in which traditional activities or observances that are integral components of cultural identity pose risks in and of themselves. Our findings indicate that there are different types of mercury use stemming from different cultural and religious traditions that result in different levels of exposure. Many of the mercury uses that can result in the highest exposures to mercury vapors have previously been attributed to the religious tradition of Santeria, but appear instead to have their roots outside of the religion.

Mercury use and exposure among Santeria practitioners: religious versus folk practice in Northern New Jersey, USA

OBJECTIVE

To understand and characterize exposure to and use of elemental mercury among practitioners of Afro-Cuban religions in Hudson County, New Jersey, USA.

DESIGN

Participant observation and open-ended interviews with 22 religious supply store employees and practitioners of Santeria, Espiritismo or Palo Mayombe probed respondents' knowledge and use of mercury, as well as their beliefs about its benefits and risks. Including a cultural and religious insider as part of the research team was crucial in working with this relatively closed community.

RESULTS

Seventeen of the 21 practitioners reported using mercury or mercury compounds in various forms of practice and in services that they provide to clients. The contained nature of these uses suggests that accidental spills, as opposed to the practices themselves, emerge as the greatest exposure concern for this population. Mercury was never recommended to clients for individual use. This restriction appears to be rooted in the way the religion is practiced and in the way santeros receive compensation, not in a perception of mercury as hazardous. Most practitioners were aware that mercury can be hazardous, but were not familiar with the most significant exposure pathway, inhalation of mercury vapor. A climate of fear surrounds the use of mercury in this community, so that health concerns pale in comparison to fear of reprisal from authorities. Among those who sell or formerly sold mercury, several shared the erroneous belief that it was illegal to sell mercury in New Jersey.

CONCLUSION

Despite widespread reported use, there were no reports of practices believed to result in the highest exposures. To reduce exposure in the community, interventions presenting general information on mercury hazards and instructions for cleaning up spills are recommended. To address insider-outsider dynamics and the climate of fear, educational materials should be accessible to the community and avoid any mention of religious practice.

Residential mercury spills from gas regulators

Many older homes are equipped with mercury-containing gas regulators that reduce the pressure of natural gas in the mains to the low pressure used in home gas piping. Removal of these regulators can result in elemental mercury spills inside the home. In the summer of 2000, mercury spills were discovered in the basements of several Chicago-area homes after removal of gas regulators by gas company contractors. Subsequent inspections of approximately 361,000 homes by two northern Illinois gas companies showed that 1,363 homes had residential mercury contamination. Urine mercury screening was offered to concerned residents, and results of urine bioassays and indoor mercury air measurements were available for 171 homes. Six of these 171 homes (3.5%) had a cumulative total of nine residents with a urine mercury > or = 10 microg/L. The highest urine mercury concentration observed in a resident was 26 microg/L. Positive bioassays were most strongly associated with mercury air concentrations > 10 microg/m3 on the first floor [odds ratio (OR) = 21.4 ; 95% confidence interval (CI) , 3.6-125.9] rather than in the basement (OR = 3.0 ; 95% CI, 0.3-26) , and first-floor air samples were more predictive of positive bioassays than were basement samples. Overall, the risk of residential mercury contamination after gas regulator removal ranged from 0.9/1,000 to 4.3/1,000 homes, depending on the gas company, although the risk was considerably higher (20 of 120 homes, 16.7%) for one of the contractors performing removal work for one of the gas companies. Gas companies, their contractors, and residents should be aware of these risks and should take appropriate actions to prevent these spills from occurring and remediate them if they occur.

Comparison of indoor mercury vapor in common areas of residential buildings with outdoor levels in a community where mercury is used for cultural purposes

Elemental mercury has been imbued with magical properties for millennia, and various cultures use elemental mercury in a variety of superstitious and cultural practices, raising health concerns for users and residents in buildings where it is used. As a first step in assessing this phenomenon, we compared mercury vapor concentration in common areas of residential buildings versus outdoor air, in two New Jersey cities where mercury is available and is used in cultural practices. We measured mercury using a portable atomic absorption spectrometer capable of quantitative measurement from 2 ng/m3 mercury vapor. We evaluated the interior hallways in 34 multifamily buildings and the vestibule in an additional 33 buildings. Outdoor mercury vapor averaged 5 ng/m3; indoor mercury was significantly higher (mean 25 ng/m3; p<0.001); 21% of buildings had mean mercury vapor concentration in hallways that exceeded the 95th percentile of outdoor mercury vapor concentration (17 ng/m3), whereas 35% of buildings had a maximum mercury vapor concentration that exceeded the 95th percentile of outdoor mercury concentration. The highest indoor average mercury vapor concentration was 299 ng/m3, and the maximum point concentration was 2,022 ng/m3. In some instances, we were able to locate the source, but we could not specifically attribute the elevated levels of mercury vapor to cultural use or other specific mercury releases. However, these findings provide sufficient evidence of indoor mercury source(s) to warrant further investigation.

Mercury policy and science in northeastern North America: the Mercury Action Plan of the New England Governors and Eastern Canadian Premiers

In June 1998 the New England Governors and Eastern Canadian Premiers (NEG-ECP) adopted a comprehensive regional Mercury Action Plan (MAP) with aggressive emission reduction and pollution prevention goals for the New England States, the Atlantic Provinces and Quebec. New Jersey and New York have also been active participants. The NEG-ECP MAP was motivated by, and based on, extensive data demonstrating the widespread and serious nature of mercury impacts in the region and the existence of many preventable sources of mercury pollution. The plan established a long-term goal of virtually eliminating anthropogenic mercury releases in the region with interim goals of a 50% reduction by 2003 and 75% by 2010. Policy and regulatory initiatives implemented under the NEG-ECP MAP have exceeded federal efforts addressing mercury and have resulted in substantial regional progress in reducing mercury pollution. Recent data indicates that the region has reduced mercury emissions by approximately 55% since the NEGECP MAP was adopted. The NEG-ECP MAP provides an important demonstration of what can be technologically, economically and politically accomplished and has influenced mercury reduction programs at the global scale. Scientific information played important roles in developing and implementing this plan. Key research areas where regional policy makers would benefit from additional information include improved: environmental indicators for tracking progress; mercury release inventories, especially on mercury product breakage and mobile sources; deposition sources, including in-region and out-of-region contributors; elemental mercury exposure and impact data; determinants of mercury levels in fish; ecological impacts of mercury; and data on the effectiveness of outreach efforts.

Mercury persistence in indoor environments in the Amazon region, Brazil

We evaluated the indoor atmospheric Hg contamination in gold trade shops in two Brazilian cities of the Legal Amazon area using the Spanish moss (Tillandsia usneoides, Bromeliaceae) as a sentinel species. Plants inside plastic cages were exposed to a controlled atmosphere to evaluate the rate of Hg retention over time and then distributed in several stores with different characteristics to enable a relative comparison. Hg concentrations were determined by cold vapor atomic absorption spectrophotometry. Plants exposed in active stores with good air circulation exhibited lower levels. Ex-gold trade shops that were kept closed for long periods exhibited higher values. Stores that have been restored before being transformed into new businesses exhibited lower values than nonrestored ones. Direct measurements suggest that indoor Hg air concentrations were below the threshold limit recommended by the World Health Organization to occupational exposure; nevertheless, restoring ex-gold trade shops could ensure a healthier working environment.

The mercury's falling: the Massachusetts approach to reducing mercury in the environment

Mercury is a persistent, bioaccumulative toxin that adversely affects human beings and wildlife. Mercury, like many such toxins, is a multimedia pollutant that can readily transfer among air, water, and soils, and thus crosses the boundaries of traditional regulatory programs. Mercury can also be transported long distances in the atmosphere, creating transboundary issues that are regional and global in scope. Human exposure to mercury is largely attributable to the consumption of contaminated fish, with women of childbearing age, infants, and children at greatest risk. Because mercury persists in the environment, the risk of neurological or other impairments can span generations. Mercury, largely from anthropogenic sources, enters aquatic systems through a variety of pathways including direct deposition from the atmosphere, runoff, and wastewater discharges.

Characterization of polymer coated glass as a passive air sampler for persistent organic pollutants

The use of thin-film polymer-coated glass surfaces or POGs as passive air samplers was investigated during an uptake experiment in an indoor environment with high levels of gas-phase polychlorinated biphenyls (PCBs). POGs consisted of a micron thick layer of ethylene vinyl acetate (EVA) coated onto glass cylinders. The uptake was initially linear with time and governed by the air-side mass transfer coefficient and surface area of the sampler. This was followed by a curvilinear region and finally a constant phase when equilibrium was established between air and EVA. The high surface area-to-volume ratio of the POGs allowed rapid equilibrium with gas-phase PCBs; equilibration times were on the order of hours for the low molecular weight congeners. The equilibrium concentration was dependent on the EVA-air partition coefficient, K(EVA-A), which was shown to be very well correlated to the octanol-air partition coefficient, K(OA). When POGs of varying thickness were equilibrated with air, the amount of PCB accumulated increased with increasing thickness of the EVA, indicating that uptake was by absorption into the entire polymer matrix. A wind field of 4 m s(-1) resulted in an increased uptake rate by a factor of approximately six compared to uptake in relatively still air. This wind speed effect was diminished, however, when POGs were housed in deployment chambers consisting of inverted stainless steel bowls. Relationships based on the air-side mass transfer coefficient and K(EVA-A) were developed for PCBs that describe the entire uptake profile and allow air concentrations to be determined from the amount of chemical accumulated in the POG. It is believed that these relationships are also valid when POGs are used to detect other classes of persistent organic pollutants.