Daily Archives: September 12, 2013

Domestic radon exposure not associated with childhood cancer in Switzerland

Dimitri Hauri, Ben Spycher, Anke Huss, Frank Zimmermann, Michael Grotzer, Nicolas von der Weid, Damien Weber, Adrian Spoerri, Claudia E. Kuehni, and Martin Röösli, for the Swiss National Cohort and the Swiss Paediatric Oncology Group (SPOG). Domestic Radon Exposure and Risk of Childhood Cancer: A Prospective Census-Based Cohort Study. Environ Health Perspect; DOI:10.1289/ehp.1306500

Background: In contrast with established evidence linking high doses of ionizing radiation with childhood cancer, research on low dose ionizing radiation and childhood cancer has produced inconsistent results.

Objective: To investigate the association between domestic radon exposure and childhood cancers, particularly leukemia and central nervous system (CNS) tumors.

Methods: We conducted a nationwide census-based cohort study including all children < 16 years of age living in Switzerland on 5 December 2000, the date of the 2000 census. Follow-up lasted until the date of diagnosis, death, emigration, a child’s 16th birthday, or 31 December 2008. Domestic radon levels were estimated for each individual home address using a model developed and validated based on approximately 45,000 measurements taken throughout Switzerland. Data were analyzed by Cox proportional hazard models adjusted for age, gender, birth order, parents’ socio-economic status, environmental gamma radiation, and period effects.

Results: In total, 997 childhood cancer cases were included in the study. Compared with children exposed to a radon concentration below the median (< 77.7 Bq/m3), adjusted hazard ratios for children with exposure ≥ the 90th percentile (≥ 139.9 Bq/m3) were 0.93 (95% CI: 0.74, 1.16) for all cancers, 0.95 (95% CI: 0.63, 1.43) for all leukemias, 0.90 (95% CI: 0.56, 1.43) for acute lymphoblastic leukemia, and 1.05 (95% CI: 0.68, 1.61) for CNS tumors.

Conclusions: We did not find evidence that domestic radon exposure is associated with childhood cancer, despite relatively high radon levels in Switzerland.

Click here for full paper (Open Source).

Biological activity at air-ocean confounds prior global carbon cycle calculations?

Maria Ll. Calleja, Carlos M. Duarte, Marta Álvarez, Raquel Vaquer-Sunyer, Susana Agustí, Gerhard J. Herndl. Prevalence of strong vertical CO2 and O2 variability in the top meters of the ocean. Global Biogeochemical Cycles. DOI: 10.1002/gbc.20081

The gradient in the partial pressure of carbon dioxide (pCO2) across the air-sea boundary layer is the main driving force for the air-sea CO2 flux. Global data-bases for surface seawater pCO2 are actually based on pCO2 measurements from several meters below the sea surface, assuming a homogeneous distribution between the diffusive boundary layer and the upper top meters of the ocean. Compiling vertical profiles of pCO2, Temperature and dissolved oxygen in the upper 5-8 meters of the ocean from different biogeographical areas, we detected a mean difference between the boundary layer and 5 m pCO2 of 13 ± 1 µatm. Temperature gradients accounted for only 11 % of this pCO2 gradient in the top meters of the ocean, thus, pointing to a heterogeneous biological activity underneath the air-sea boundary layer as the main factor controlling the top meters pCO2 variability. Observations of pCO2 just beneath the air-sea boundary layer should be further investigated in order to estimate possible biases in calculating global air-sea CO2 fluxes.

click here for full paper (fee).