Long-term exposure to airborne metals and risk of cancer in the French cohort Gazel.

BACKGROUND: The specific compounds that make ambient fine particulate matter (PM2.5) carcinogen remain poorly identified. Some metals contribute to ambient PM2.5 and possibly to its adverse effects. But the challenge of assessing exposure to airborne metals limits epidemiological studies. OBJECTIVE: To analyze the relationships between several airborne metals and risk of cancer in a large population. METHODS: We estimated the individual exposure to 12 airborne metals of âˆ¼ 12,000 semi-urban and rural participants of the French population-based Gazel cohort using moss biomonitoring data from a 20-year national program. We used principal component analyses (PCA) to derive groups of metals, and focused on six single carcinogenic or toxic metals (arsenic, cadmium, chromium, lead, nickel, and vanadium). We used extended Cox models with attained age as time-scale and time-varying weighted average exposures, adjusted for individual and area-level covariables, to analyze the association between each exposure and all-site combined, bladder, lung, breast, and prostate cancer incidence. RESULTS: We identified 2,401 cases of all-site cancer between 2001 and 2015. Over the follow-up, median exposures varied from 0.22 (interquartile range (IQR): 0.18-0.28) to 8.68 (IQR: 6.62-11.79) µg.g-1 of dried moss for cadmium and lead, respectively. The PCA yielded three groups identified as "anthropogenic", "crustal", and "marine". Models yielded positive associations between most single and groups of metal and all-site cancer, with e.g. hazard ratios of 1.08 (95% CI: 1.03, 1.13) for cadmium or 1.06 (95% CI: 1.02,1.10) for lead, per interquartile range increase. These findings were consistent across supplementary analyses, albeit attenuated when accounting for total PM2.5. Regarding specific site cancers, we estimated positive associations mostly for bladder, and generally with large confidence intervals. CONCLUSION: Most single and groups of airborne metals, except vanadium, were associated with risk of cancer. These findings may help identify sources or components of PM2.5 that may be involved in its carcinogenicity.

Modeling exposure to airborne metals using moss biomonitoring in cemeteries in two urban areas around Paris and Lyon in France.

Exposure of the general population to airborne metals remains poorly estimated despite the potential health risks. Passive moss biomonitoring can proxy air quality at fine resolution over large areas, mainly in rural areas. We adapted the technique to urban areas to develop fine concentration maps for several metals for Constances cohort's participants. We sampled Grimmia pulvinata in 77 and 51 cemeteries within ∼50 km of Paris and Lyon city centers, respectively. We developed land-use regression models for 14 metals including cadmium, lead, and antimony; potential predictors included the amount of urban, agricultural, forest, and water around cemeteries, population density, altitude, and distance to major roads. We used both kriging with external drift and land use regression followed by residual kriging when necessary to derive concentration maps (500 × 500 m) for each metal and region. Both approaches led to similar results. The most frequent predictors were the amount of urban, agricultural, or forest areas. Depending on the metal, the models explained part of the spatial variability, from 6% for vanadium in Lyon to 84% for antimony in Paris, but mostly between 20% and 60%, with better results for metals emitted by human activities. Moss biomonitoring in cemeteries proves efficient for obtaining airborne metal exposures in urban areas for the most common metals.

[Metals, air pollution, and health: mosses to the rescue of epidemiology]. / Métaux, pollution de l'air et santé - Les mousses, des alliées originales en épidémiologie.

While evidence has accumulated about the links between long-term exposure to air pollution and health, little is known about the health effects of airborne metals. In France, the law makes it mandatory to monitor atmospheric concentrations and deposition of some airborne metals, through measurements or modelling. But the available data are either too scarce or irregular, making them difficult to use in large-scale epidemiology: using mosses in the wild offers a welcome alternative. Mosses belong to the few vegetal organisms able to accumulate airborne metals. As such, they have been used for decades in air quality survey networks in Europe. They provide data to assess population exposure to airborne metals and may complement classical research programmes on air pollution epidemiology. As an example, we estimated associations between exposure to airborne metals of anthropogenic origin and increased mortality in France.

TITLE: Métaux, pollution de l'air et santé - Les mousses, des alliées originales en épidémiologie. ABSTRACT: L'exposition à long terme aux particules atmosphériques a des effets bien documentés sur la santé humaine, mais le rôle des métaux reste à explorer. En France, la réglementation impose le suivi des teneurs ambiantes de certains métaux. Mais ces données, du fait d'un maillage trop large ou irrégulier, sont difficilement exploitables en épidémiologie à grande échelle. Les mousses, des végétaux capables d'accumuler les métaux atmosphériques, sont utilisées depuis plusieurs décennies en biosurveillance de la qualité de l'air. Elles fournissent des données exploitables en épidémiologie grâce auxquelles nous avons montré une association entre métaux d'origine anthropique et sur-risque de mortalité en France.

Long-term exposure to atmospheric metals assessed by mosses and mortality in France.

BACKGROUND: Long-term exposure to air pollution affects health, but little is known about exposure to atmospheric metals. Estimating exposure to atmospheric metals across large spatial areas remains challenging. Metal concentrations in mosses could constitute a useful proxy. Here, we linked moss biomonitoring and epidemiological data to investigate the associations between long-term exposure to metals and mortality. METHODS: We modelled and mapped 13 atmospheric metals from a 20-year national moss biomonitoring program to derive exposure estimates across France. In the population-based Gazel cohort, we included 11,382 participants from low to intermediate population density areas and assigned modelled metals to their residential addresses. We distinguished between airborne metals that are primarily of natural origin and those primarily of anthropogenic origin. Associations were estimated between exposure to metals and mortality (natural-cause, cardiovascular and respiratory), using Cox models, with confounder adjustment at individual level. FINDINGS: Between 1996 and 2017, there were 1313 deaths in the cohort (including 181 cardiovascular and 33 respiratory). Exposure to the anthropogenic metals was associated with an increased risk of natural-cause mortality (hazard ratio of 1.16 [1.08-1.24] per interquartile range of exposure), while metals from natural sources were not. INTERPRETATION: Some atmospheric anthropogenic metals may be associated with excess mortality - even in areas with relatively low levels of exposure to air pollution. Consistent with the previous literature, our findings support the use of moss biomonitoring as a tool to assess health effects of air pollution exposure at individual level.

Modelling spatial patterns of correlations between concentrations of heavy metals in mosses and atmospheric deposition in 2010 across Europe.

BACKGROUND: This paper aims to investigate the correlations between the concentrations of nine heavy metals in moss and atmospheric deposition within ecological land classes covering Europe. Additionally, it is examined to what extent the statistical relations are affected by the land use around the moss sampling sites. Based on moss data collected in 2010/2011 throughout Europe and data on total atmospheric deposition modelled by two chemical transport models (EMEP MSC-E, LOTOS-EUROS), correlation coefficients between concentrations of heavy metals in moss and in modelled atmospheric deposition were specified for spatial subsamples defined by ecological land classes of Europe (ELCE) as a spatial reference system. Linear discriminant analysis (LDA) and logistic regression (LR) were then used to separate moss sampling sites regarding their contribution to the strength of correlation considering the areal percentage of urban, agricultural and forestry land use around the sampling location. After verification LDA models by LR, LDA models were used to transform spatial information on the land use to maps of potential correlation levels, applicable for future network planning in the European Moss Survey. RESULTS: Correlations between concentrations of heavy metals in moss and in modelled atmospheric deposition were found to be specific for elements and ELCE units. Land use around the sampling sites mainly influences the correlation level. Small radiuses around the sampling sites examined (5 km) are more relevant for Cd, Cu, Ni, and Zn, while the areal percentage of urban and agricultural land use within large radiuses (75-100 km) is more relevant for As, Cr, Hg, Pb, and V. Most valid LDA models pattern with error rates of < 40% were found for As, Cr, Cu, Hg, Pb, and V. Land use-dependent predictions of spatial patterns split up Europe into investigation areas revealing potentially high (= above-average) or low (= below-average) correlation coefficients. CONCLUSIONS: LDA is an eligible method identifying and ranking boundary conditions of correlations between atmospheric deposition and respective concentrations of heavy metals in moss and related mapping considering the influence of the land use around moss sampling sites.

The coastal environment affects lead and sodium uptake by the moss Hypnum cupressiforme used as an air pollution biomonitor.

Several studies suggest that potential competition exists between marine cations and heavy metals for binding sites on the cell wall of mosses. This competition would impact the heavy metal concentration measured in mosses by biomonitoring programs, which may underestimate air pollution by heavy metals in a coastal environment. In the present study, we aim to identify possible mechanisms affecting lead uptake by mosses in a coastal environment, specifically, the competition between lead (Pb2+) and sodium (Na+) for binding sites in Hypnum cupressiforme (Hc). We also compared the response of continental and coastal Hc populations to Pb2+ exposure by immersing the moss samples in artificial solutions that comprised six experimental treatments and subsequently locating and quantifying Pb2+ and Na+ using the sequential elution technique and X-ray microanalyses with a scanning electron microscope. We demonstrated that high concentrations of Pb2+ prevented Na+ from binding to the cell wall. We also examined the effect of the salt acclimation of Hc on Pb2+ and Na+ accumulation. Coastal Hc populations accumulated more Na and less Pb than continental Hc populations in all treatments. Moreover, our results showed treatment effects on the intra/extracellular distribution of Na+, as well as site. This feedback on the influence of salt stress tolerance on Pb2+ uptake by mosses requires further study and can be investigated for other heavy metals, leading to a better use of mosses as biomonitoring tools.

Spatial analysis of trace elements in a moss bio-monitoring data over France by accounting for source, protocol and environmental parameters.

Air pollution in trace elements (TE) remains a concern for public health in Europe. For this reasons, networks of air pollution concentrations or exposure are deployed, including a moss bio-monitoring programme in Europe. Spatial determinants of TE concentrations in mosses remain unclear. In this study, the French dataset of TE in mosses is analyzed by spatial autoregressive model to account for spatial structure of the data and several variables proven or suspected to affect TE concentrations in mosses. Such variables include source (atmospheric deposition and soil concentrations), protocol (sampling month, collector, and moss species), and environment (forest type and canopy density, distance to the coast or the highway, and elevation). Modeled atmospheric deposition was only available for Cd and Pb and was one of the main explanatory variables of the concentrations in mosses. Predicted soil content was also an important explanatory variable except for Cr, Ni, and Zn. However, the moss species was the main factor for all the studied TE. The other environmental variables affected differently the TE. In particular, the forest type and canopy density were important in most cases. These results stress the need for further research on the effect of the moss species on the capture and retention of TE, as well as for accounting for several variables and the spatial structure of the data in statistical analyses.

Assessing temporal trends of trace metal concentrations in mosses over France between 1996 and 2011: A flexible and robust method to account for heterogeneous sampling strategies.

Air quality biomonitoring has been successfully assessed using mosses for decades in Europe, particularly regarding heavy metals (HM). Assessing robust temporal variations of HM concentrations in mosses requires to better understand to what extent they are affected by the sampling protocol and the moss species. This study used the concentrations of 14 elements measured during four surveys over 15 years in France. Analyses of variance (ANOVA) and a modeling approach were used to decipher temporal variations for each element and adjust them with parameters known to affect concentrations. ANOVA followed by post hoc analyses did not allow to estimate clear trends. A generalized additive mixed modeling approach including the sampling period, the collector and the moss species, plus quadratic effects, was used to analyze temporal variations on repeated sampling sites. This approach highlighted the importance of accounting for non-linear temporal variations in HM, and adjusting for confounding factors such as moss species, species-specific differences between sampling periods, collector and methodological differences in sampling campaigns. For instance, lead concentrations in mosses decreased between 1996 and 2011 following quadratic functions, with faster declines for the most contaminated sites in 1996. On the other hand, other HM showed double trends with U-shaped or hill-shaped curves. The effect of the moss was complex to handle and our results advocate for using one moss species by repeated site to better analyze temporal variations.

Spatially valid data of atmospheric deposition of heavy metals and nitrogen derived by moss surveys for pollution risk assessments of ecosystems.

For analysing element input into ecosystems and associated risks due to atmospheric deposition, element concentrations in moss provide complementary and time-integrated data at high spatial resolution every 5 years since 1990. The paper reviews (1) minimum sample sizes needed for reliable, statistical estimation of mean values at four different spatial scales (European and national level as well as landscape-specific level covering Europe and single countries); (2) trends of heavy metal (HM) and nitrogen (N) concentrations in moss in Europe (1990-2010); (3) correlations between concentrations of HM in moss and soil specimens collected across Norway (1990-2010); and (4) canopy drip-induced site-specific variation of N concentration in moss sampled in seven European countries (1990-2013). While the minimum sample sizes on the European and national level were achieved without exception, for some ecological land classes and elements, the coverage with sampling sites should be improved. The decline in emission and subsequent atmospheric deposition of HM across Europe has resulted in decreasing HM concentrations in moss between 1990 and 2010. In contrast, hardly any changes were observed for N in moss between 2005, when N was included into the survey for the first time, and 2010. In Norway, both, the moss and the soil survey data sets, were correlated, indicating a decrease of HM concentrations in moss and soil. At the site level, the average N deposition inside of forests was almost three times higher than the average N deposition outside of forests.

Relevance of canopy drip for the accumulation of nitrogen in moss used as biomonitors for atmospheric nitrogen deposition in Europe.

High atmospheric deposition of nitrogen (N) impacts functions and structures of N limited ecosystems. Due to filtering and related canopy drip effects forests are particularly exposed to N deposition. Up to now, this was proved by many studies using technical deposition samplers but there are only some few studies analysing the canopy drip effect on the accumulation of N in moss and related small scale atmospheric deposition patterns. Therefore, we investigated N deposition and related accumulation of N in forests and in (neighbouring) open fields by use of moss sampled across seven European countries. Sampling and chemical analyses were conducted according to the experimental protocol of the European Moss Survey. The ratios between the measured N content in moss sampled inside and outside of forests were computed and used to calculate estimates for non-sampled sites. Potentially influencing environmental factors were integrated in order to detect their relationships to the N content in moss. The overall average N content measured in moss was 20.0mgg(-1) inside and 11.9mgg(-1) outside of forests with highest N values in Germany inside of forests. Explaining more than 70% of the variance, the multivariate analyses confirmed that the sampling site category (site with/without canopy drip) showed the strongest correlation with the N content in moss. Spatial variances due to enhanced dry deposition in vegetation stands should be considered in future monitoring and modelling of atmospheric N deposition.

Relationship between site-specific nitrogen concentrations in mosses and measured wet bulk atmospheric nitrogen deposition across Europe.

To assess the relationship between nitrogen concentrations in mosses and wet bulk nitrogen deposition or concentrations in precipitation, moss tissue and deposition were sampled within a distance of 1 km of each other in seven European countries. Relationships for various forms of nitrogen appeared to be asymptotic, with data for different countries being positioned at different locations along the asymptotic relationship and saturation occurring at a wet bulk nitrogen deposition of ca. 20 kg N ha(-1) yr(-1). The asymptotic behaviour was more pronounced for ammonium-N than nitrate-N, with high ammonium deposition at German sites being most influential in providing evidence of the asymptotic behaviour. Within countries, relationships were only significant for Finland and Switzerland and were more or less linear. The results confirm previous relationships described for modelled total deposition. Nitrogen concentration in mosses can be applied to identify areas at risk of high nitrogen deposition at European scale.

Assessing spatial patterns of metal bioaccumulation in French mosses by means of an exposure index.

BACKGROUND, AIM AND SCOPE: The European Heavy Metals in Mosses Surveys (UNECE-ICP Vegetation) is a programme performed every 5 years since 1990 in at least 21 European countries. The moss surveys aim at uncovering the spatiotemporal patterns of metal and nitrogen bioaccumulation in mosses. In France, the moss survey was conducted for the third time in 2006. Five hundred thirty-six monitoring sites were sampled across the whole French territory. The aim of the presented study is to give an integrative picture of the metal bioaccumulation for the entire French territory without geographical gaps. Furthermore, confounding factors of the metal bioaccumulation in mosses should be investigated. MATERIALS AND METHODS: Element loads of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), nickel (Ni), lead (Pb), antimony (Sb), vanadium (V) and zinc (Zn) measured in the French campaign 2006 were aggregated to a multi-metal index (MMI). This index was first introduced in the German moss surveys and represents the mean rank of each monitoring site or estimated raster cell regarding all elements referred to. Hence, the spatial variability of the metal bioaccumulation in France could be assessed as a whole. A comparison of the MMI map with the spatial patterns of the Cu loads in mosses was then drawn, as Cu originates to a large extent from urban sources. Applying CHAID, the MMI and the Cu loads in the mosses were further investigated with regard to confounding factors. The said results were discussed on the basis of recent scientific publications. RESULTS: The MMI surface map shows high values in strongly industrialized and urbanized regions as well as at sites of high altitude, lying, for example in the Massif Central and the French Alps. Accordingly, the CHAID decision tree consequently shows the altitude to be the statistically most significant influencing factor of the MMI followed by the sampled moss species. As for the MMI map, the surface map for Cu mirrors urban agglomerations, as high values can be found in the areas of Greater Paris, Lyon and Marseille. The CHAID tree for Cu revealed the sampled moss species and the ratio of urban land uses within 5 km of the sampling sites to be the main influencing factors. DISCUSSION: The aggregation of metal bioaccumulation data was adopted for the French monitoring campaign. The influence of altitude, moss species-specific accumulation rates and urban emissions on the bioaccumulation is confirmed by international scientific publications. Nevertheless, the confounding factors in France differ from those derived from the German data, where the MMI was mainly associated to canopy drip effects and the growth patterns of the sampled mosses. CONCLUSIONS: The Cu and the MMI maps give a comprehensive overview of the metal bioaccumulation in France without geographical gaps. Hence, this approach allows summarising the spatial patterns of eleven element loads in mosses by use of geostatistics and percentile statistics. RECOMMENDATIONS AND PERSPECTIVES: The presented metal integrating approach should be applied on data from past French moss surveys and on those to come. Additionally, the decision tree analyses should be carried out to examine possibly changing boundary conditions of the metal accumulation in mosses over time.