Ceiling (attic) dust: a "museum" of contamination and potential hazard

Distribution and impacts of contamination by natural and artificial radionuclides in attic dust and urban soil samples from a former industrial Hungarian city: A case study from Salgótarján

Primordial radionuclides can be found in all environmental compartments. Since coal-fired power plants (CFPP) can be a source of additional radionuclide contamination because coal contains natural radioactive isotopes such as 238U (226Ra) and 232Th. This study investigated the impact of such possible radionuclide contamination from former heavy industrial activities, namely a former local coal-fired power plant, in urban soils and attic dust in Salgótarján, Hungary. Even today, industrial by-products, e.g., coal ash, in this city represent significant threat to its residents. A total of 36 attic dust samples (family houses, kindergartens, churches and blockhouses) were collected and 19 urban soil samples (playgrounds, kindergartens, parks and others) were selected no further than 500 m from the corresponding attic dust sampling sites. Additionally, a coal ash and a brown forest soil sample were also collected to differentiate between the anthropogenic and geogenic sources in the residential area. The sampled houses, built between 1890 and 1990, are considered to be representative sampling sites for long-term accumulations of attic dust. The mean values of the total U, Th and Cs (mg kg-1) concentrations as well as those of K (m/m %) in attic dust and urban soil samples are 2.4, 3.6, 1.7 and 0.6 and 1.1, 4.4, 1.2 and 0.3, respectively, measured using ICP-MS. The mean activity concentrations of 226Ra, 232Th, 40K and 137Cs in attic dust and urban soil samples are 43.3, 34.0, 534.4 and 88.5 and 25.1, 32.8, 386.4 and 5.6 Bq kg-1, respectively, by using a low-background iron chamber with a well-type HPGe and a n-type coaxial HPGe detector. The elemental compositions (U, Th) and activity concentrations (226Ra, 232Th) along with their abundances in coal ash from the CFPP increase in both studied media as the distance of the sampling sites from the CFPP decreases. Two outlier attic dust samples in particular show significantly high activity concentrations of 226Ra: 145 and 143, of 232Th: 83 and 94 Bq kg-1, which can be considered as a proxy of unweathered coal ash. The calculated total absorbed gamma dose rate (D) and annual effective dose (E) received from urban soils indicate that the presence of the CFPP, coal ash cone and slag dumps does not cause an increase in the level of background radiation in Salgótarján. However, the concentrations of the studied radionuclides are much higher (except for 232Th) and exhibit higher degree of variability in the samples of attic dustthan in those of urban soils. The study suggests that attic dust preserves the undisturbed 'fingerprints' of long-term atmospheric deposition thanks to its chemical and physical properties unlike urban soil.

Sentinel animals for monitoring the environmental lead exposure: combination of traditional review and visualization analysis

In nature, certain animals share a common living environment with humans, thus these animals have become biomonitors of health effects related to various environmental exposures. As one of the most toxic environmental chemicals, lead (Pb) can cause detriment health effects to animals, plants, and even humans through different exposure pathways such as atmosphere, soil, food, water, and dust, etc. Sentinel animals played an "indicative" role in the researches of environmental pollution monitoring and human health. In order to comprehend the usage of sentinel animals in the indication of environmental Pb pollution and human Pb exposure completely, a combination of traditional review and visualization analysis based on CiteSpace literature was used to review earlier researches in this study. In the first instance, present researches on exposure sources and exposure pathways of Pb were summarized briefly, and then the studies using sentinel animals to monitor environmental heavy metal pollution and human health were combed. Finally, visualization software CiteSpace 5.8.R3 was used to explore and analyze the hotspots and frontiers of lead exposure and sentinel animals researches at home and abroad. The results showed that certain mammals were good indicators for human lead exposure. Sentinel animals had been widely used to monitor the ecological environment and human lead exposure. Among them, the blood lead levels of small mammals, particularly for domestic dogs and cats, had a significant correlation with the blood lead levels of human living in the same environment. It indicated that certain biological indicators in animals can be used as surrogates to monitor human body exposure to heavy metals. This study also explored the challenges and perspectives that may be faced in sentinel animal research, in order to provide a certain theoretical basis and train of thought guidance for future research.

Sources, pathways and concentrations of potentially toxic trace metals in home environments

Despite ongoing concerns about trace metal and metalloid (trace metals) exposure risks from indoor dust, there has been limited research examining their sources and relationship to outdoor soils. Here we determine the concentrations and sources for potentially toxic trace metals arsenic (As), chromium (Cr), copper (Cu), manganese (Mn), lead (Pb) and zinc (Zn) and their pathways into homes in Sydney, Australia, using home-matched indoor dust (n = 166), garden soil (n = 166), and road dust samples (n = 51). All trace metals were more elevated indoors versus their matched garden soil counterparts. Indoor Cu and Zn dust concentrations were significantly more enriched than outdoor dusts and soils, indicating indoor sources were more relevant for these elements. By contrast, even though Pb was elevated in indoor dust, garden soil concentrations were correspondingly high, indicating that it remains an important source and pathway for indoor contamination. Elevated concentrations of As, Pb and Zn in garden soil and indoor dust were associated with home age (>50 years), construction materials, recent renovations and deteriorating interior paint. Significant correlations (p < 0.05) between road dust and garden soil Cu concentrations, and those of As and Zn in soil and indoor dust, and Pb across all three media suggest common sources. Scanning electron microscopy (SEM) analysis of indoor dust samples (n = 6) showed that 57% of particles were derived from outdoor sources. Lead isotopic compositions of soil (n = 21) and indoor dust (n = 21) were moderately correlated, confirming the relevance of outdoor contaminants to indoor environments. This study illustrates the source, relationship and fate of trace metals between outdoor and indoor environments. The findings provide insight into understanding and responding to potentially toxic trace metal exposures in the home environment.

Activity concentration of 137Cs in undisturbed attic dust collected from Salgótarján and Ózd (northern Hungary)

Due to the Chernobyl nuclear power plant accident, contaminated air masses, containing ¹³⁷Cs, were widely propagated across all of Europe. Cesium-137 is easily adsorbed on aerosol particles as it returns to the lithosphere/pedosphere/via wet and dry deposition in the form of a radioactive fallout component. Following the nuclear accident, primary attention was paid to agricultural areas and less to urban environments. Our ¹³⁷Cs activity study using undisturbed attic dust samples has been carried out from two residential areas (city of Salgótarján and Ózd) in northern Hungary, approx. 1000 km away from Chernobyl. A total of 61 attic dust samples were collected in 2016 and 2018 from houses (>30 years) functioning as family house, kindergarten, blockhouse and church. Activity concentration of ¹³⁷Cs was determined for 1-2 g homogenized (<125 μm) attic dust samples in a low background iron chamber with a well-type HPGe detector. The mean ¹³⁷Cs activity concentrations in attic dust samples are 88.5 ± 5.1 Bq kg^-1 and 87.8 ± 4.5 Bq kg^-1 in Salgótarján and Ózd, respectively. The dependence between ¹³⁷Cs activities and the age of the houses was found to be significant (p=0.02), which could be explained by Chernobyl nuclear accident-causing elevated activity concentrations in location built prior to the accident. Three outliers in Ózd (>223 Bq kg^-1), are probably related to the first rainfall event after the Chernobyl accident. Isotopic landscapes (isoscapes) of ¹³⁷Cs were derived for both cities by means of kriging interpolation. In Salgótarján the ¹³⁷Cs activity concentrations were higher than in Ózd which might have been due to redistribution loadings and local topographical features. We concluded that components of attic dust are highly useful indicators of home exposure to pollution events and remain detectable after several decades.

Attic dust: an archive of historical air contamination of the urban environment and potential hazard to health?

A comprehensive study of attic dust in an urban area is presented. Its entire life cycle, from determining historical emission sources to recognising the processes that take place in attic dust and its potential to impact human health is discussed. Its chemical composition and morphological characteristics of individual solid particles reflect past anthropogenic activities. High levels of Be-Cd-Cu-Sb-Sn-Pb-Te-Zn and occurrence of Cu-Zn shavings are typical for an industrial zone characterised by a foundry and a battery factory. High levels of Co-Fe-Mo-Ni-W-Ba-Cr-Mg-Mn-Nb-Ti and occurrence of various solid Fe-oxides, particularly spherical particles, were identified in another industrial zone, which was dominated by the automotive and metal-processing industries. Emissions from coal combustion affected the distribution of S-Se-Hg-Tl-As-Ag-U. The predominant mineral in attic dust is gypsum, which was presumably formed in situ by the reaction of carbonate dust particles and atmospheric SO₂ gas. The high oral bioaccessibility of As-Cd-Cu-Pb-Zn in the gastric phase and high bioaccessibility of As-Cu-Cd-Ni in the gastrointestinal phase were identified. Determined characteristics of attic dust and identified possibilities of prolonged human exposure to it indicate that attic dust should be treated as an excellent proxy for historical air contamination as well as a potentially hazardous material for human health.

Distribution of potentially harmful elements in attic dust from the City of Coronel (Chile)

Attic dusts provide an indirect measure of airborne pollutants deposited in the urban environment. The objectives of this study are: (1) to determine the concentrations of As, Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sr, V and Zn in attic dust in the City of Coronel, (2) to evaluate the source apportionment of PHE and (3) to assess the risk of health effects from exposure in adults and children. In the City of Coronel, attic dust samples were collected in 19 houses. The concentrations of As, Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sr, V and Zn were measured in ICP-OES after Aqua Regia digestion of < 75 µm dust sample. The median (and the range) concentration (mg kg^-1) of potentially harmful elements was: As 16 (7-72), Ba 154 (53-251), Cd 0.8 (0.25-14.5), Co 12, (8-22), Cr 38 (22-482), Cu 107 (44-1641), Mn 698 (364-1245), Ni 51 (24-1734), Pb 66 (18-393), Sr 131 (52-252), V 129 (57-376) and Zn 815 (107-9761). The exploratory data analysis shows that Ni, Cu, Cr, Zn, Pb and As distribution is dominated by anthropogenic sources and characterized by high extreme values. Principal component analysis shows four factors. One factor is geogenic, while the other three factors are associated with transport emissions and the industrial park. The resulting median of cumulative noncarcinogenic risk (HI_s) value for attic dust was 3.49 for children. This is significant, as any value greater than one indicates an elevated risk.

Spatial Analysis and Lead-Risk Assessment of Philadelphia, USA

Childhood lead poisoning is an issue that continues to plague major U.S. cities. Despite efforts by the Philadelphia Department of Public Health to curtail systemic childhood lead poisoning, children continue to be identified with elevated blood lead levels. The persistence of elevated blood lead levels in children is concerning because lead poisoning has been linked to decreases in academic achievement and IQ, with associated repercussions for entire communities. This paper reports the results of an analysis of the spatial distribution of houses with lead paint (i.e., pre-1978), demolitions, and occurrence of historic smelters, in West and North Philadelphia, relative to elevated blood lead level data, to determine which lead sources act as primary lead-risk factors. The presence of lead paint in homes and the number of demolitions of older properties were found to have the highest correlations to elevated blood lead levels for children in Philadelphia. Using lead-risk factors including lead paint, housing code violations, demolitions, and owner-occupied housing units, a lead-risk assessment was performed at the census tract level to identify future soil sampling sites and high-risk neighborhoods in Philadelphia. These sites of high risk for lead exposure, and in particular the census tracts 175 and 172, should be prioritized for lead poisoning prevention initiatives.

Nontuberculous Mycobacteria Prevalence in Bats' Guano from Caves and Attics of Buildings Studied by Culture and qPCR Examinations

A total of 281 guano samples were collected from caves (N = 181) in eight European countries (Bulgaria, Czech Republic, France, Hungary, Italy, Romania, Slovakia and Slovenia) and attics in the Czech R. (N = 100). The correlation of detection of mycobacteria between Ziehl-Neelsen (ZN) microscopy and culture examination and qPCR was strong. ZN microscopy was positive in guano from caves (58.6%) more than double than positivity in guano from attics (21.0%; p < 0.01). From 89 mycobacterial isolates (73 isolates from cave guano and 16 isolates from attics' guano), 68 (76.4%) isolates of 19 sp., ssp. and complex were identified as members of three Groups (M. fortuitum, M.chelonae, and M. mucogenicum) and four complexes (M. avium, M. terrae, M.vaccae, and M.smegmatis). A total of 20 isolates (22.5%) belonged to risk group 1 (environmental saprophytes), 48 isolates (53.9%) belonged to risk group 2 (potential pathogens), and none of the isolates belonged to risk group 3 (obligatory pathogens). When comparing bat guano collected from caves and attics, differences (p < 0.01; Mann-Whitney test) were observed for the electrical conductivity, total carbon, total organic, and total inorganic carbon. No difference (p > 0.05; Mann-Whitney test) was found for pH and oxidation-reduction potential parameters.

Quantitative filter forensics: Size distribution and particulate matter concentrations in residential buildings

We applied filter forensics, the analysis of dust from the heating, ventilation, and air-conditioning (HVAC) filters, to measure particle size distribution in 21 residences in Toronto, Canada over a year. Four filters with different nominal efficiencies (Minimum Efficiency Reporting Value (MERV) 8-14 from ASHRAE Standard 52.2) were deployed in each residence each for three months, while the effective filtration volumes (the product of flow rate, runtime, and in-situ filter efficiency) were characterized over each filter lifetime. Using extraction and laser diffraction, we found that approximately 90% of the volumetric distributions were >10 µm and the volume median diameter (VMD) ranged from 23.4 to 75.1 µm. Using quantitative filter forensics (QFF), total suspended particle (TSP) concentrations ranged from 2.9 to 823.7 µg/m³ (median = 89.8 µg/m³ ) with a moderate correlation with the content of TSP on the filters (in terms of g) and with the TSP effective filtration volume (m³ ) indicating the importance of both filter forensics and HVAC metadata parameters to QFF concentration estimates. There was no strong correlation between PM₁₀ or PM_2.5 concentrations and hourly airborne particle number concentrations measured by low-cost sensors suggesting an evaluation of QFF is warranted, particularly for the exploration of smaller particles.

Towards a holistic approach to the geochemistry of solid inorganic particles in the urban environment

Airborne particulate matter (PM) has a major impact on the biogeochemical cycles of chemical elements in the urban environment. Anthropogenic-derived PM emissions are the cause of some of the most severe environmental and health problems. The presented study aims to improve our knowledge of PM dynamics by introducing a multi-media, multi-analytical and multi-elemental holistic approach to geochemical studies of inorganic PM in the urban environment. The importance of the holistic approach is highlighted and its application in a case study of Maribor (Slovenia) is presented. The chemical composition and individual particulate characteristics of street, attic and household dust were determined and compared with the characteristics of airborne PM, and PM deposited in snow, together with the chemical composition of the soil. We found that the mineralogical and chemical composition and the individual solid particle characteristics of the studied media differ considerably. Nevertheless, minerals of geogenic origin are present in all media. The highest levels of potentially toxic elements (PTEs) in all media, except household dust, are typical for industrial areas. Street dust primarily reflects the influence of winter road maintenance and industrial activities, while characteristics of household dust are predominantly influenced by indoor activities and properties of dwellings. The comparison of the chemical composition of attic and street dust indicates that emissions of As, Cd, Pb, S and Zn were higher in the past. The characterisation of airborne PM and PM deposited in snow is essential for the identification of the most recent sources of PTE-bearing particles. Several industrial sources and the fate of some particle types in the environment have been determined based on the findings of the SEM/EDS analyses. This study confirms that various environmental media are carriers of diverse geochemical information and highlights the importance of a holistic approach in geochemistry of PM in urban areas.

HVAC filtration of particles and trace metals: Airborne measurements and the evaluation of quantitative filter forensics

Filters installed in the heating, ventilation, and air-conditioning (HVAC) systems can serve as air-cleaning and sampling devices for indoor particles. The purpose of this article is to evaluate these dual roles. An occupied home with a central HVAC system equipped with a Minimum Efficiency Reporting Value (MERV, from ASHRAE Standard 52.2) 11 filter was monitored for six weeks. Weekly airborne gravimetric and real-time sampling was performed to measure the particle size distribution and the concentration of total suspended particles (TSP), PM₁₀, PM_2.5, PM₁, and 12 trace metals. The weekly system runtimes were intentionally changed to provide a wide range of weekly filtration volumes. The quantitative filter forensics (QFF) concentrations of particulate matter (PM) and trace metals were calculated using the analysis of the dust collected on the HVAC filter, the filtration volume, and filter in-situ efficiency. The results indicated that filtration was not influential to remove PM and trace metals as the concentrations during the weeks with continuous HVAC operation were not consistently lower than those during the other weeks. This suggests the dominance of other particle and trace metal source and loss mechanisms weakens the influence of filtration in this home. The QFF evaluation results indicated that the concentration of TSP and over half of the tested trace metals (e.g., Pb, Cd, Ni, V, Sb, K, and Sr) could be estimated by QFF within a factor of two when compared to airborne sampling results. PM₁₀, PM_2.5, and PM₁ concentrations were significantly underestimated by QFF potentially due to the limitations of size distribution analysis by a laser diffraction particle sizer (LDPS) for the detection of <1 μm particles. Overall, while QFF was promising for TSP and some trace metals, improvement in size distribution analysis could extend the application of QFF for airborne sampling.

A 25-year record of childhood blood lead exposure and its relationship to environmental sources

Broken Hill, the oldest silver (Ag)-zinc (Zn)-lead (Pb) mining community in Australia, has a legacy and ongoing problem of environmental Pb exposure that was identified as early as 1893. To reduce Pb exposure risks, identifying potential exposure pathways and related factors is a critical first step. This study examined blood lead (PbB) levels of children ≤60 months old (n = 24,106 samples), along with Pb concentrations in corresponding soil (n = 10,160 samples), petri-dish dust (n = 106 houses) and ceiling dust (n = 80 houses) over a 25-year period from 1991 to 2015. Regression analysis was used to examine the relationships between environmental Pb sources and children's blood lead (PbB) outcomes. Analysis of the dataset showed Aboriginal children in Broken Hill had a geometric mean PbB of 7.4 μg/dL (95% CI: 6.7-7.4) being significantly higher (p < 0.01) than non-Aboriginal children (PbB 6.2 μg/dL, 95% CI: 6.2-6.3) for all years between 1991 and 2015. Children at the age of 24-36 months had a higher PbB compared with other age groups. Higher PbB levels were also statistically associated with lower socio-economic status and children living in houses built before 1940 (p < 0.01). Blood Pb was also significantly correlated with both soil Pb and indoor petri-dish dust Pb loadings, confirming that these are important pathways for exposure in Broken Hill. A 100 mg/kg increase in soil Pb was associated with a 0.12 μg/dL increase in childhood PbB. In addition, PbB concentrations increased with indoor petri-dish dust Pb loadings (i.e., 0.08 μg/dL per 100 μg/m²/30 days). The 25-year data show that the risk of exposure at ≥ 10 μg/dL was seemingly unavoidable irrespective of residential address (i.e., children of all ages presenting with a ≥10 μg/dL across the whole city area). In terms of moving forward and mitigating harmful early-life Pb exposures, all children aged 24-36 months should be prioritised for feasible and effective intervention practices. Primary intervention must focus on mitigating contemporary ongoing dust emissions from the mining operations and the associated mine-lease areas along with household soil remediation, to help prevent recontamination of homes. Additional practices of dust cleaning using wet mopping and wiping techniques, vacuuming of carpets and furnishings, ongoing monitoring of children and household dust remain important but short-lived abatement strategies. Overall, the key goal should be to eliminate risk by removing contamination in the wider environment as well as in individual homes.

Roof cavity dust as an exposure proxy for extreme air pollution events

Understanding exposure to air pollution during extreme events such as fire emergencies is critical for assessing their potential health impacts. However, air pollution emergencies often affect places without a network of air quality monitoring and characterising exposure retrospectively is methodologically challenging due to the complex behaviour of smoke and other air pollutants. Here we test the potential of roof cavity (attic) dust to act as a robust household-level exposure proxy, using a major air pollution event associated with a coal mine fire in the Latrobe Valley, Australia, as an illustrative study. To assess the relationship between roof cavity dust composition and mine fire exposure, we analysed the elemental and polycyclic aromatic hydrocarbon composition of roof cavity dust (<150μm) from 39 homes along a gradient of exposure to the mine fire plume. These homes were grouped into 12 zones along this exposure gradient: eight zones across Morwell, where mine fire impacts were greatest, and four in other Latrobe Valley towns at increasing distance from the fire. We identified two elements-barium and magnesium-as 'chemical markers' that show a clear and theoretically grounded relationship with the brown coal mine fire plume exposure. This relationship is robust to the influence of plausible confounders and contrasts with other, non-mine fire related elements, which showed distinct and varied distributional patterns. We conclude that targeted components of roof cavity dust can be a useful empirical marker of household exposure to severe air pollution events and their use could support epidemiological studies by providing spatially-resolved exposure estimates post-event.

Enchasing anthropogenic element trackers for evidence of long-term atmospheric depositions in mine environs

In this work attic dust was examined as historical archive of anthropogenic emissions, with the aim of elucidating the pathways of enrichments associated with exploitation of Cu, Pb, and Zn minerals in the Bregalnica river basin region. Attic dust samples were collected from 84 settlements. At each location for attic dust sampling, topsoil samples from the house yards were also collected. Mass spectrometry with inductively coupled plasma (ICP-MS) was applied as analytical technique for determination of Ag, Bi, Cd, Cu, In, Mn, Pb, Sb, Te, W, and Zn. The Universal Kriging method with linear variogram interpolation was applied for the construction of spatial distribution maps. Thеsе elements are normally associated with air pollution (Cd-Pb-Zn), and usually are not influenced by lithological background. This investigation fortifies an extended anthropogenic association (Ag, Bi, In, and Mn) that implement some other anthropogenic activities such as agricultural activities (use of urban sludge, manure and fertilizers) or their occurrence can be a secondary affection from mine poly-metallic pollution. Spatial patterns showed intensive deposition in the areas of Pb-Zn mining activities ("Sasa" and "Zletovo" mines) and copper mine "Bučim". Long-distance distributions of higher contents of these elements from the mines were not detected.

Sources of lead exposure in various countries

This review evaluates the sources of lead exposure worldwide. Studies from searches relating to sources of lead exposure in various countries within different regional zones were reviewed. Results indicated that in Nigeria, exposure sources include electronic waste, paint and batteries. In Mexico exposure sources include glazed ceramics, lead contaminated utensils and lead contaminated water, for India lead sources include cosmetics and traditional medicines. Sources of lead exposure in China include e-waste, traditional medicines and industrial emissions. In France, exposure sources included lead paint from older homes, imported ceramics and cosmetics and industrial emissions. Australia's exposure sources include paint, dust, imported toys and traditional medicines. Finally, in the United States exposure sources included paint, the industrial legacy of lead exposure and batteries. In high-income countries (HICs) the legacy of lead exposure keeps populations continuously exposed. In lower- and middle-income countries (LMICs), in addition to the legacy of lead exposure, lack of regulations or the inability to enforce regulations keeps populations exposed. In all, evidence suggests that lead exposure remains an issue of public health significance in both HIC and LMIC.

Tracing natural and industrial contamination and lead isotopic compositions in an Australian native bee species

This study investigates trace element concentrations (arsenic (As), manganese (Mn), lead (Pb) and zinc (Zn)) and Pb isotopic compositions in an Australian native bee species, Tetragonula carbonaria, and its products of honey and wax. Co-located soil and dust samples were simultaneously analysed with the objective of determining if the bees or their products had potential application as a proxy for monitoring environmental contamination. The most significant relationships were found between Pb concentrations in honey (r = 0.814, p = 0.014) and wax (r = 0.883, p = 0.004) and those in co-located dust samples. In addition, Zn concentrations in honey and soil were significantly associated (r = 0.709, p = 0.049). Lead isotopic compositions of native bee products collected from background sites adjacent to Sydney national parks (²⁰⁶Pb/²⁰⁷Pb = 1.144, ²⁰⁸Pb/²⁰⁷Pb = 2.437) corresponded to local geogenic rock and soil values (²⁰⁶Pb/²⁰⁷Pb = 1.123-1.176, ²⁰⁸Pb/²⁰⁷Pb = 2.413-2.500). By contrast, inner Sydney metropolitan samples, including native bees and wax (²⁰⁶Pb/²⁰⁷Pb = 1.072-1.121, ²⁰⁸Pb/²⁰⁷Pb = 2.348-2.409), co-located soil and dust (²⁰⁶Pb/²⁰⁷Pb = 1.090-1.122, ²⁰⁸Pb/²⁰⁷Pb = 2.368-2.403), corresponded most closely to aerosols collected during the period of leaded petrol use (²⁰⁶Pb/²⁰⁷Pb = 1.067-1.148, ²⁰⁸Pb/²⁰⁷Pb = 2.341-2.410). A large range of Pb isotopic compositions in beehive samples suggests that other legacy sources, such as Pb-based paints and industrials, may have also contributed to Pb contamination in beehive samples. Native bee data were compared to corresponding samples from the more common European honey bee (Apis mellifera). Although Pb isotopic compositions were similar in both species, significant differences in trace element concentrations were evident across the trace element suite, the bees and their products. The statistical association between T. carbonaria and co-located environmental contaminant concentrations were stronger than those in European honey bees, which may be attributable to its smaller foraging distance (0.3-0.7 km versus 5-9 km, respectively). This implies that T. carbonaria may be more suitable for assessing small spatial scale variations of trace element concentrations than European honey bees.

The pro-inflammatory effects of particulate matter on epithelial cells are associated with elemental composition

BACKGROUND

Adverse health effects of particulate matter (PM) vary with chemical composition; however, evidence regarding which elements are the most detrimental is limited. The roof space area provides an open and stable environment for outdoor PM to settle and deposit. Therefore, this study used roof space PM samples as a proxy of residential cumulative exposure to outdoor air pollution to investigate their pro-inflammatory effects on human lung cells and the contribution of the endotoxin and chemical content.

METHODS

Roof space PM samples of 36 different homes were collected and analysed using standardised techniques. We evaluated cytotoxicity and cytokine production of BEAS-2B cells after PM exposure using MTS and ELISA, respectively. Principle component analysis (PCA) and linear regression analyses were employed to assess the associations between cytokine production and the PM components.

RESULTS

PM caused significant time- and dose-dependent increases in cellular cytokine production (p < 0.05). PCA identified four factors that explained 68.33% of the variance in the chemical composition. An increase in Factor 1 (+Fe, +Al, +Mn) score and a decrease in Factor 2 (-Ca, +Pb, +PAH) score were associated with increased interleukin (IL)-6 (Factor 1; p = 0.010; Factor 2; p = 0.006) and IL-8 (Factor 1; p = 0.003; Factor 2; p = 0.020) production, however, only the association with Factor 1 was evident after correcting for endotoxin and particle size.

CONCLUSIONS

Our study provides novel insight into the positive associations between pro-inflammatory effects of roof space PM samples with Fe, Al and Mn levels.

A simple lead dust fall method predicts children's blood lead level: New evidence from Australia

We have measured dust fall accumulation in petri dishes (PDD) collected 6 monthly from inside residences in Sydney urban area, New South Wales, Australia as part of a 5-year longitudinal study to determine environmental associations, including soil. with blood lead (PbB) levels. The Pb loading in the dishes (n = 706) had geometric means (GM) of 24µg/m²/30d, a median value of 22µg/m²/30d with a range from 0.2 to 11,390µg/m²/30d. Observed geometric mean PbB was 2.4µg/dL at ages 2-3 years. Regression analyses showed a statistically significant relationship between predicted PbB and PDD. The predicted PbB values from dust in our study are consistent with similar analyses from the US in which floor dust was collected by wipes. Predicted PbB values from PDD indicate that an increase in PDD of about 100µg/m²/30d would increase PbB by about 1.5µg/dL or a doubling PbB at the low levels currently observed in many countries. Predicted PbB values from soil indicate that a change from 0 to 1000mg Pb/kg results in an increase of 1.7µg/dL in PbB, consistent with earlier investigations. Blood Pb levels can be predicted from dust fall accumulation (and soil) in cases where blood sampling is not always possible, especially in young children. Petri dish loading data could provide an alternative or complementary "action level" at about 100µg Pb/m²/30 days, similar to the suggested level of about 110µg Pb/m² for surface wipes, for use in monitoring activities such as housing rehabilitation, demolition or soil resuspension.

Long-term Geochemical Evolution of Lithogenic Versus Anthropogenic Distribution of Macro and Trace Elements in Household Attic Dust

Attic dusts were examined as historical archives of anthropogenic emissions, with the goal of elucidating the enrichment pathways associated with hydrothermal exploitation of Cu, Pb, and Zn minerals in the Bregalnica River basin in the eastern part of the Republic of Macedonia. Dust samples were collected from 84 settlements. Atomic emission spectrometry and mass spectrometry with inductively coupled plasma were applied as analytical techniques for the determination of 69 element contents. Multivariate analysis was applied for the extraction of dominant geochemical markers. The lithogenic distribution was simplified to six dominant geochemical markers: F1: Ga-Nb-Ta-Y-(La-Gd)-(Eu-Lu); F2: Be-Cr-Li-Mg-Ni; F3: Ag-Bi-Cd-Cu-In-Mn-Pb-Sb-Te-W-Zn; F4: Ba-Cs-Hf-Pd-Rb-Sr-Tl-Zr; F5: As-Co-Ge-V; and F6: К-Na-Sc-Ti. The anthropogenic effects on the air pollution were marked by a dominance of F3 and secondary dominance of F5. The fifth factor also was determined as a lithogenic marker for the occurrence of the very old Rifeous shales. The first factor also presents a very unique association that despite the heterogeneity relays on natural phenomena of tracking the deposition in areas of Proterosoic gneisses; related to the distribution of fine particles was associated with carbonate-silicate volcanic rocks. Intensive poly-metallic dust depositions were recorded only in the surroundings of localities where the hydrothermal extractions are implemented. Long-term deposition can be considered as pollution indexes for these hot spots. This mainly affects the Cd, Pb, and Zn deposition that is as high as 25, 3900, and 3200 mg/kg, respectively.

Corrigendum to "Undisturbed dust as a metric of long-term indoor insecticide exposure: Residential DDT contamination from indoor residual spraying and its association with serum levels in the VHEMBE cohort" [Environ. Int. 85C (2015) 163-167]

Although approximately 123 million people may be exposed to high levels of insecticides through the use of indoor residual spraying (IRS) for malaria control, few studies exist on indoor insecticide contamination due to IRS and its relationship with human exposure. In the present study, we developed a sampling method to collect undisturbed dust from 50 homes in Limpopo, South Africa, a region where dichlorodiphenyltrichloroethane (DDT) has been used in IRS programs to prevent malaria for ~70years. We quantified DDT and its degradation products, dichlorodiphenyldichloroethylene (DDE), and dichlorodiphenyldichloroethane (DDD) in dust samples to determine dust loading levels and compared these levels to paired serum concentrations of p,p'-DDT and p,p'-DDE in women residents. p,p'-DDT and p,p'-DDE had the highest detection frequencies in both dust (58% and 34% detection, respectively) and serum samples (100% detection). Significantly higher detection frequencies for o,p'-DDT, p,p'-DDE, and p,p'-DDD were observed in dust samples collected in buildings that had been previously sprayed for malaria control. We also observed a significant, positive association between dust loading and serum concentrations of p,p'-DDT and p,p'-DDE (Spearman's rho=0.68 and 0.54, respectively). Despite the low detection frequency in dust, our results indicate that undisturbed dust may be a good metric to quantify long-term home exposure to DDT-related compounds and that contamination of the home environment may be an important determinant/source of DDT and DDE exposure.

Children's Blood Lead Seasonality in Flint, Michigan (USA), and Soil-Sourced Lead Hazard Risks

In Flint; MI; USA; a public health crisis resulted from the switching of the water supply from Lake Huron to a more corrosive source from the Flint River in April 2014; which caused lead to leach from water lines. Between 2010 and 2015; Flint area children’s average blood lead patterns display consistent peaks in the third quarter of the year. The third quarter blood lead peaks displayed a declining trend between 2010 and 2013; then rose abruptly between the third quarters of 2013 from 3.6% blood lead levels ≥5 µg/dL to a peak of about 7% in the third quarter of 2014; an increase of approximately 50%. The percentage of blood lead level ≥5 µg/dL in the first quarter of 2015 then dropped to 2.3%; which was the same percentage as the first quarter of 2014 (prior to the Flint River water source change). The Flint quarterly blood lead level peak then rose to about 6% blood lead levels ≥ 5 µg/dL in the third quarter of 2015; and then declined to about 2.5% in the fourth quarter of 2015. Soil lead data collected by Edible Flint food collaborative reveal generally higher soil lead values in the metropolitan center for Flint; with lower values in the outskirts of the city. The questions that are not being asked is why did children’s blood lead levels display a seasonal blood lead pattern before the introduction of the new water supply in Flint; and what are the implications of these seasonal blood lead patterns? Based upon previous findings in Detroit and other North American cities we infer that resuspension to the air of lead in the form of dust from lead contaminated soils in Flint appears to be a persistent contribution to lead exposure of Flint children even before the change in the water supply from Lake Huron to the Flint River.

Australian atmospheric lead deposition reconstructed using lead concentrations and isotopic compositions of archival lichen and fungi

Lead concentrations and their isotopic compositions were measured in lichen genera Cladonia and Usnea and fungi genus Trametes from the Greater Sydney region (New South Wales, Australia) that had been collected and archived over the past 120 years. The median lead contents were elevated in lichens and fungi prior to the introduction of leaded petrol (Cladonia 12.5 mg/kg; Usnea 15.6 mg/kg; Trametes 1.85 mg/kg) corresponding to early industrial development. During the use of leaded petrol for automobiles in Australia from 1932 to 2002, total median lead concentrations rose: Cladonia 18.8 mg/kg; Usnea 21.5 mg/kg; Trametes 4.3 mg/kg. Following the cessation of leaded petrol use, median total lead concentrations decreased sharply in the 2000s: Cladonia 4.8 mg/kg; Usnea 1.7 mg/kg. The lichen and fungi isotopic compositions reveal a significant decrease in (206)Pb/(207)Pb values from the end of 19th century to the 1970s. The following decades were characterised by lower allowable levels of lead additive in fuel and the introduction of unleaded petrol in 1985. The environmental response to these regulatory changes was that lichen and fungi (206)Pb/(207)Pb values increased, particularly from 1995 onwards. Although the lead isotope ratios of lichens continued to increase in the 2000s they do not return to pre-leaded petrol values. This demonstrates that historic leaded petrol emissions, inter alia other sources, remain a persistent source of anthropogenic contamination in the Greater Sydney region.

Undisturbed dust as a metric of long-term indoor insecticide exposure: Residential DDT contamination from indoor residual spraying and its association with serum levels in the VHEMBE cohort

Although approximately 123 million people may be exposed to high levels of insecticides through the use of indoor residual spraying (IRS) for malaria control, few studies exist on indoor insecticide contamination due to IRS and its relationship with human exposure. In the present study, we developed a sampling method to collect undisturbed dust from 50 homes in Limpopo, South Africa, a region where dichlorodiphenyltrichloroethane (DDT) has been used in IRS programs to prevent malaria for ~70years. We quantified DDT and its degradation products, dichlorodiphenyldichloroethylene (DDE), and dichlorodiphenyldichloroethane (DDD) in dust samples to determine dust loading levels and compared these levels to paired serum concentrations of p,p'-DDT and p,p'-DDE in women residents. p,p'-DDT and p,p'-DDE had the highest detection frequencies in both dust (58% and 34% detection, respectively) and serum samples (98% and 100% detection, respectively). Significantly higher detection frequencies for o,p'-DDT, p,p'-DDE, and p,p'-DDD were observed in dust samples collected in buildings that had been previously sprayed for malaria control. We also observed a significant, positive association between dust loading and serum concentrations of p,p'-DDT and p,p'-DDE (Spearman's rho=0.68 and 0.54, respectively). Despite the low detection frequency in dust, our results indicate that undisturbed dust may be a good metric to quantify long-term home exposure to DDT-related compounds and that contamination of the home environment may be an important determinant/source of DDT and DDE exposure.

Lead in Chinese villager house dust: Geographical variation and influencing factors

House dust has been recognized as an important contributor to Pb exposure of children. Here we conducted a comprehensive study to investigate geographical variation of Pb in Chinese villager house dust. The influences of outdoor soil Pb concentrations, dates of construction, house decoration materials, heating types, and site specific pollution on Pb concentrations in house dust were evaluated. The concentrations of Pb in 477 house dust samples collected from twenty eight areas throughout China varied from 12 to 2510 mg/kg, with a median concentration of 42 mg/kg. The median Pb concentrations in different geographical areas ranged from 16 (Zhangjiakou, Hebei) to 195 mg/kg (Loudi, Hunan). No correlations were found between the house dust Pb concentrations and the age of houses, as well as house decoration materials. Whereas outdoor soil, coal combustion, and site specific pollution may be potential Pb sources. Principal component analysis (PCA) confirmed that elemental compositions of the house dust were controlled by both anthropogenic and geogenic sources. Using scanning electron microscopy (SEM), the Pb bearing particles in the house dust were also studied.

Characterization of particulate matter in attic and settled dusts collected from two buildings in Budapest, Hungary

We have investigated two buildings covered with Zsolnay glazed architectural ceramics in Budapest (Hungary), one located in the densely built-up area of the city centre with a high traffic rate and one in a city quarter with moderate traffic and more open space. A black crust layer, containing a large amount of artificial particulate matter with different size and chemical composition, was observed on the ceramic material of both buildings, whereas weathered glaze was detected only on the ceramics of the building situated in the city centre. In this paper, our goal is to reveal the role of the particulate matter in the degradation of architectural ceramics. For this reason the attic dust and settled dust from the roofs of the studied buildings were collected. In the attic dust, besides the natural particles of geological origin, three types of artificial particles typically with spherical shape (spherules) were also distinguished: aluminosilicate (two subtypes), carbonaceous, and iron-rich fly-ash. The appearance of gypsum crystallites around the particulate matter in association with all spherule types suggests that the particulate matter greatly contributes to the degradation process.

Attic dust assessment near a wood treatment plant: past air pollution and potential exposure

The wood treatment process uses substances that generate hazardous compounds that may contaminate environmental compartments. In the present study, an area under influence of a deactivated wood treatment plant was investigated to evaluate past air pollution and to try to understand local air dispersion. Attic dust samples were collected from eight residences around the plant and from two residences outside this area, as reference samples. The presence of copper, chromium, arsenic, pentachlorophenol, sixteen priority polycyclic aromatic hydrocarbons and mutagenic activity using Salmonella/microsome assay was evaluated. The residences close to the entrance to the plant were the most affected, according to potentially toxic elements analysis. The PCP concentration was 0.49 mg/kg and the total PAHs content ranged from 0.40 to 13.31 μg/g with greater dispersion than potentially toxic elements. The highest mutagenesis values were 15,905 and 10,399 revertants/g of dust in the absence and presence of S9 mix (mammalian metabolic activation), respectively. Samples in which the total PAHs concentration was less than 2 μg/g no mutagenic effects were observed, including the residences in the reference area. The contribution of PAHs to mutagenesis was 10 percent, indicating that other compounds may contribute to the mutagenic effect. These results suggest that the population was or is potentially exposed to substances with strong effects on health.

Assessment of indirect human exposure to environmental sources of nickel: oral exposure and risk characterization for systemic effects

This paper describes the indirect human exposure to Ni via the oral route for the regional scale in the EU, together with a method to assess additional local exposure from industrial emissions. The approach fills a gap in the generic REACH guidance which is inadequate for assessing indirect environmental exposure of metals. Estimates of regional scale Ni dietary intake were derived from Ni dietary studies performed in the EU. Typical and Reasonable Worst Case dietary Ni intakes for the general population in the EU were below the oral Derived No Effect Level (DNEL) of Ni sulfate for systemic effects. Estimates for the Ni dietary intake at the local scale take into account the influence of aerial Ni deposition and transfer from soil to crops grown near industrial plants emitting Ni. The additional dietary exposure via this local contribution was small. Despite the use of conservative parameters for these processes, this method may underestimate dietary exposure around older industrial sites because REACH guidance does not account for historical soil contamination. Nevertheless, the method developed here can also be used as a screening tool for community-based risk assessment, as it accounts for historical soil pollution. Nickel exposure via drinking water was derived from databases on Ni tap water quality. A small proportion of the EU population (<5%) is likely to be exposed to tap water exceeding the EU standard (20 μg Ni/l). Taking into account the relative gastrointestinal absorption of Ni from water (30%) versus from solid matrices (5%), water intake constitutes, after dietary intake, the second most important pathway for oral Ni intake. Incidental ingestion of Ni from soil/dust at the regional scale, and also at the local scale, was low in comparison with dietary intake.

Distribution of chemical elements in attic dust as reflection of their geogenic and anthropogenic sources in the vicinity of the copper mine and flotation plant

The main aim of this article was to assess the atmospheric pollution with heavy metals due to copper mining Bučim near Radoviš, the Republic of Macedonia. The open pit and mine waste and flotation tailings are continually exposed to open air, which leads to winds carrying the fine particles into the atmosphere. Samples of attic dust were examined as historical archives of mine emissions, with the aim of elucidating the pathways of pollution. Dust was collected from the attics of 29 houses, built between 1920 and 1970. Nineteen elements (Ag, Al, As, Ba, Ca, Cd, Co, Cr, Cu, Li, Fe, K, Mg, Mn, Na, Ni, Pb, Sr, and Zn) were analyzed by atomic emission spectrometry with inductively coupled plasma. The obtained values of the investigated elements in attic dust samples were statistically processed using nonparametric and parametric analysis. Factor analysis revealed three factors governing the source of individual chemical elements. Two of them grouping Ca, Li, Mg, Mn, and Sr (Factor 1) and Co, Cr, and Ni (Factor 2) can be characterized as geogenic. The third factor grouping As, Cu, and Pb is anthropogenic and mirrors dust fallout from mining operation and from flotation tailings. Maps of areal deposition were prepared for this group of elements, from which correlation of these anthropogenic born elements was confirmed.

Canadian house dust study: lead bioaccessibility and speciation

Vacuum samples were collected from 1025 randomly selected urban Canadian homes to investigate bioaccessible Pb (Pb(S)) concentrations in settled house dust. Results indicate a polymodal frequency distribution, consisting of three lognormally distributed subpopulations defined as "urban background" (geomean 58 μg g(-1)), "elevated" (geomean 447 μg g(-1)), and "anomalous" (geomean 1730 μg g(-1)). Dust Pb(S) concentrations in 924 homes (90%) fall into the "urban background" category. The elevated and anomalous subpopulations predominantly consist of older homes located in central core areas of cities. The influence of house age is evidenced by a moderate correlation between house age and dust Pb(S) content (R(2) = 0.34; n = 1025; p < 0.01), but it is notable that more than 10% of homes in the elevated/anomalous category were built after 1980. Conversely, the benefit of home remediation is evidenced by the large number of homes (33%) in the background category that were built before 1960. The dominant dust Pb species determined using X-ray Absorption Spectroscopy were as follows: Pb carbonate, Pb hydroxyl carbonate, Pb sulfate, Pb chromate, Pb oxide, Pb citrate, Pb metal, Pb adsorbed to Fe- and Al-oxyhydroxides, and Pb adsorbed to humate. Pb bioaccessibility estimated from solid phase speciation predicts Pb bioaccessibility measured using a simulated gastric extraction (R(2) = 0.85; n = 12; p < 0.0001). The trend toward increased Pb bioaccessibility in the elevated and anomalous subpopulations (75% ± 18% and 81% ± 8%, respectively) compared to background (63% ± 18%) is explained by the higher proportion of bioaccessible compounds used as pigments in older paints (Pb carbonate and Pb hydroxyl carbonate). This population-based study provides a nationally representative urban baseline for applications in human health risk assessment and risk management.

Childhood lead poisoning from the smelter in Torreón, México

Lead concentrations and isotopic compositions in blood samples of 34 children (ages 2-17 years) living within a 113 km(2) area of a silver-zinc-lead smelter plant in Torreón, México were compared to those of associated environmental samples (soil, aerosols, and outdoor and indoor dust) to identify the principal source(s) of environmental and human lead contamination in the area. Lead concentrations of soil and outdoor dust ranged 130-12,050 and 150-14,365 μg g(-1), respectively. Concentrations were greatest near the smelter, with the highest levels corresponding with the prevailing wind direction, and orders of magnitude above background concentrations of 7.3-33.3 μg g(-1). Atmospheric lead depositions in the city varied between 130 and 1350 μg m(-2) d(-1), again with highest rates <1 km from the smelter. Blood lead (PbB) concentrations (11.0±5.3 μg dl(-1)) levels in the children ranged 5.0-25.8 μg dl(-1), which is 3-14 times higher than the current average (1.9 μg dl(-1)) of children (ages 1-5 years) in the US. Lead isotopic ratios ((206)Pb/(207)Pb, (208)Pb/(207)Pb) of the urban dust and soil (1.200±0.009, 2.467±0.003), aerosols (1.200±0.002, 2.466±0.002), and PbB (1.199±0.001, 2.468±0.002) were indistinguishable from each other, as well as those of the lead ores processed at the smelter (1.199±0.007, 2.473±0.007). Consequently, an elevated PbB concentrations of the children in Torreón, as well as in their environment, are still dominated by industrial emissions from the smelter located within the city, in spite of new controls on atmospheric releases from the facility.

Potential for childhood lead poisoning in the inner cities of Australia due to exposure to lead in soil dust

This article presents evidence demonstrating that the historical use of leaded gasoline and lead (Pb) in exterior paints in Australia has contaminated urban soils in the older inner suburbs of large cities such as Sydney and Melbourne. While significant attention has been focused on Pb poisoning in mining and smelting towns in Australia, relatively little research has focused on exposure to Pb originating from inner-city soil dust and its potential for childhood Pb exposures. Due to a lack of systematic blood lead (PbB) screening and geochemical soil Pb mapping in the inner cities of Australia, the risks from environmental Pb exposure remain unconstrained within urban population centres.

Comparison of lead isotopes with source apportionment models, including SOM, for air particulates

We have measured high precision lead isotopes in PM(2.5) particulates from a highly-trafficked site (Mascot) and rural site (Richmond) in the Sydney Basin, New South Wales, Australia to compare with isotopic data from total suspended particulates (TSP) from other sites in the Sydney Basin and evaluate relationships with source fingerprints obtained from multi-element PM(2.5) data. The isotopic data for the period 1998 to 2004 show seasonal peaks and troughs that are more pronounced in the rural site for the PM(2.5).samples but are consistent with the TSP. The Self Organising Map (SOM) method has been applied to the multi-element PM(2.5) data to evaluate its use in obtaining fingerprints for comparison with standard statistical procedures (ANSTO model). As seasonal effects are also significant for the multi-element data, the SOM modelling is reported as site and season dependent. At the Mascot site, the ANSTO model exhibits decreasing (206)Pb/(204)Pb ratios with increasing contributions of fingerprints for "secondary smoke" (industry), "soil", "smoke" and "seaspray". Similar patterns were shown by SOM winter fingerprints for both sites. At the rural site, there are large isotopic variations but for the majority of samples these are not associated with increased contributions from the main sources with the ANSTO model. For two winter sampling times, there are increased contributions from "secondary industry", "smoke", "soil" and seaspray with one time having a source or sources of Pb similar to that of Mascot. The only positive relationship between increasing (206)Pb/(204)Pb ratio and source contributions is found at the rural site using the SOM summer fingerprints, both of which show a significant contribution from sulphur. Several of the fingerprints using either model have significant contributions from black carbon (BC) and/or sulphur (S) that probably derive from diesel fuels and industrial sources. Increased contributions from sources with the SOM summer fingerprints could explain the summer-time peaks in isotopic ratio at both sites and, at the rural site, be associated with meteorological influences. Nevertheless, the SOM results indicate that there are multiple overlapping 'weak' sources.

Chemical constituents of fugitive dust

Wind erosion selectively winnows the fine, most chemically concentrated portions of surface soils and results in the inter-regional transport of fugitive dust containing plant nutrients, trace elements and other soil-borne contaminants. We sampled and analyzed surface soils, sediments in transport over eroding fields, and attic dust from a small area of the Southern High Plains of Texas to characterize the physical nature and chemical constituents of these materials and to investigate techniques that would allow relatively rapid, low cost techniques for estimating the chemical constituents of fugitive dust from an eroding field. From chemical analyses of actively eroding sediments, it would appear that Ca is the only chemical species that is enriched more than others during the process of fugitive dust production. We found surface soil sieved to produce a sub-sample with particle diameters in the range of 53-74 microm to be a reasonably good surrogate for fugitive dust very near the source field, that sieved sub-samples with particle diameters <10 microm have a crustal enrichment factor of approximately 6, and that this factor, multiplied by the chemical contents of source soils, may be a reasonable estimator of fugitive PM(10) chemistry from the soils of interest. We also found that dust from tractor air cleaners provided a good surrogate for dust entrained by tillage and harvesting operations if the chemical species resulting from engine wear and exhaust were removed from the data set or scaled back to the average of enrichment factors noted for chemical species with no known anthropogenic sources. Chemical analyses of dust samples collected from attics approximately 4 km from the nearest source fields indicated that anthropogenic sources of several environmentally important nutrient and trace element species are much larger contributors, by up to nearly two orders of magnitude, to atmospheric loading and subsequent deposition than fugitive dust from eroding soils.