The Metha-BioSol project aims to assess the impact of anaerobic digestion residues (digestates) on the biological and ecological quality of soils using an operational dashboard of indicators. This dashboard includes measurements of soil physical and chemical status, bio-indicators of soil biological communities and indicators of soil biological functions and soil health status. The project consisted of two parts: 1) To evaluate, under controlled conditions, the impact of different types of digestates taking into account the soil type, and on experimental sites, the impact of repeated digestate applications; and 2) To establish a national network of agricultural farms and conduct an assessment of the impact of digestate application combined with various agronomic practices in different pedoclimatic contexts. The results obtained from both controlled conditions and experimental sites showed that the response of bio-indicators to digestate application was dependent on the type of digestate, the pedoclimatic context, and the recurrence of these applications. The establishment of the farm network also provided the first elements for creating a reference framework for interpreting the impact of digestate use in varied territorial and sociotechnical contexts.
Abstract Background: Acrylamide is classified as a probable human carcinogen by the IARC but epidemiological evidence on the carcinogenicity of acrylamide from dietary sources is limited. This study aimed to investigate the associations between dietary acrylamide and breast cancer risk in the NutriNet-Santé cohort. Methods: This prospective cohort study included 80,597 French women (mean [SD] age at baseline: 40.8 [14] years) during a mean (SD) follow-up of 8.8 (2.3) years. Acrylamide intake was evaluated using repeated 24h dietary records (n= 5.5 [SD 3.0]), linked to a comprehensive food composition database. Associations between acrylamide intake and breast cancer risk (overall, premenopausal and post-menopausal) were assessed by Cox hazard models adjusted for known risk factors. Results: The mean (SD) dietary acrylamide intake was 30.1 (21.9) µg/d (main contributors: coffee, potato fries and chips, pastries and cakes, and bread). During follow-up, 1016 first incident breast cancer cases were diagnosed (431 premenopausal, 585 postmenopausal). A borderline significant positive association was observed between acrylamide intake and breast cancer risk overall (HRQ4 vs Q1= 1.21 [95% CI: 1.00-1.47]) and a positive association was observed with premenopausal cancer (HRQ4 vs Q1= 1.40 [95% CI: 1.04-1.88]). Restricted cubic spline analyses suggested evidence for non-linearity of these associations, with higher HR for intermediate (Q2) and high (Q4) exposures. Receptor-specific analyses revealed a positive association with estrogen receptor-positive breast cancer, which represented 86% of total cancer cases. Acrylamide intake was not associated with post-menopausal breast cancer. Conclusions: Results from this large prospective cohort study suggest the potential deleterious role of dietary acrylamide in breast cancer etiology, especially in premenopausal women, and provide new insights that should encourage further mitigation strategies to reduce the content of acrylamide in food. Citation Format: Alice Bellicha, Gaëlle Wendeu-Foyet, Xavier Coumoul, Meriem Koual, Fabrice Pierre, Françoise Guéraud, Laurent Zelek, Charlotte Debras, Bernard Srour, Laury Sellem, Emmanuelle Kesse-Guyot, Chantal Julia, Pilar Galan, Serge Hercberg, Mélanie Deschasaux-Tanguy, Mathilde Touvier. Dietary exposure to acrylamide and breast cancer risk: results from the NutriNet-Santé cohort [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-06-03.
Anaerobic digestion of organic waste is considered as a key process to produce renewable energy and meet the growing demand for sustainable energy. The residues of anaerobic digestion – called digestates – can be used as soil amendments and improve crop yields. However, the effect of digestates on the soil biota, especially on microorganisms, is still debated and needs to be better documented before they can be used at a large scale in agriculture. We designed a microcosm experiment to compare the short-term (42 days) effects of four different digestates derived from cattle manure, energy crop, food residues or slurry with bio-waste on the soil microbial communities; a control microcosm made of undigested cattle manure was also used. Each digestate was applied on three contrasting soils representing contrasted pedo-climatic conditions (especially soil type and climate). The effect of digestate inputs on the soil microbial communities was assessed using molecular DNA-based tools (quantification of extracted soil DNA and high-throughput sequencing) to measure microbial biomass and diversity, respectively. The three soils presented different prokaryotic and fungal communities structures without organic material application. Our results show that 42 days after biogas residue application, the effect of digestates on the soil microbial community depends on both the soil type and the digestate characteristics. Thus, in the silty clay loam soil, no effect of digestates was observed on soil microbial biomass or diversity (P > 0.05), as compared to the undigested cattle manure. In the other soil types (loam and sandy loam), application of digestates having a lower total organic carbon content compared to undigested manure, led to a decrease of soil microbial biomass. The soil prokaryotic diversity was not influenced by the soil type or the quality of digestate applied. For the soil fungal diversity, variation observed were driven by only the soil C/N ratio, where lower soil C/N induced a higher soil fungal diversity. The microbial community structure from coarse-textured soil appeared more impacted by organic inputs. To conclude, our results show that different soil types, harboring distinct microbial community structures, responded differently to different digestates application. This response was also digestate-dependent.
