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.

Contribution from a eutrophic temperate estuary to the landscape flux of nitrous oxide.

For mitigation of climate change, all sources and sinks of greenhouse gases from the environment must be quantified and their driving factors identified. Nitrous oxide (N2O) is a strong greenhouse gas, and the contribution of aquatic systems to the global N2O budget remains poorly constrained. In this study, we measured N2O concentrations in a eutrophic coastal system, Roskilde Fjord (Denmark), and combined measurements with statistical modeling to quantify the N2O fluxes and budget in the system over a period of six months. To do so, we collected water at 15 sampling points and measured N2O concentrations along with physico-chemical water quality parameters, e.g. temperature, salinity, dissolved inorganic nitrogen and phosphorus, and silicon. We used mixed-effect regression models to predict N2O concentrations in the water from water quality parameters. We then derived N2O fluxes using well-established equations of N2O solubility and water-atmosphere exchanges. These fluxes were then put in perspective with those measured at the landscape scale by eddy-covariance at a 96 m nearby tall tower, and to those estimated from the agricultural land next to the fjord using Intergovernmental Panel on Climate Change (IPCC) guidelines. N2O concentrations in the Roskilde Fjord ranged between 2.40 and 8.05 nmol l-1. The best fitting model between water parameters and N2O concentrations in water included phosphorus and temperature. We estimated that (i) Roskilde Fjord was a sink of N2O, with a median inward flux of -0.04 nmol m-2 s-1, (ii) while the surrounding median agricultural flux was 0.13-0.18 nmol m-2 s-1, and (iii) the median landscape flux was 0.07 nmol m-2 s-1. All estimates of N2O fluxes were of the same magnitude and consistent with each other. These preliminary results need to be consolidated by further research.

Atmospheric particulate deposition in temperate deciduous forest ecosystems: interactions with the canopy and nutrient inputs in two beech stands of Northeastern France.

As wood harvests are expected to increase to satisfy the need for bio-energy in Europe, quantifying atmospheric nutrient inputs in forest ecosystems is essential for forest management. Current atmospheric measurements only take into account the <0.45 µm fraction and dry deposition is generally modeled. The aims of this study were to quantify atmospheric particulate deposition (APD), the >0.45 µm fraction of atmospheric deposition, below the canopy, to study the influence of the canopy on APD, and to determine the influence of APD below canopy to nutrient input-output budgets with a focus on base cations calcium, magnesium and potassium, and phosphorus. APD was sampled every four weeks by passive collectors. We divided APD into an organic and a mineral fraction, respectively POM and MDD. MDD was divided into a soluble and a hardly soluble fraction in hydrogen peroxide, referred to as S-MDD and H-MDD, respectively. In order to better understand the influence of the canopy on APD, we studied APD in three pathways below the canopy (litterfall, stemflow and throughfall), and in open field. Our results indicated that APD in throughfall (123 ± 64 kg ha(-1)year(-1)) was significantly higher and synchronic with that in open field (33 ±9 kg ha(-1)year(-1)) in the two study sites. This concerned both POM and MDD, suggesting a large interception of APD by foliar surfaces, which is rapidly washed off by rain within four weeks. Throughfall H-MDD was the main pathway with an average of 16 ± 2 kg ha(-1)year(-1). Stemflow and litterfall were neglected. In one study site, canopy intercepted about 8 kg ha(-1)year(-1) of S-MDD. Although base cations and phosphorus inputs by APD are lower than those of <0.45 µm deposition, they contributed from 5 to 32% to atmospheric deposition and improved the nutrient budget in one of the study sites.