Unravelling biosocial dynamics? The placenta as a postgenomic bio-object in environmental epigenetic research on air pollution.

Air pollution exposure and its health effects are a central concern of environmental epigenetic research with birth cohorts. This article explores why researchers have turned to the placenta as a research object to study the dynamic interactions between in utero exposure to air pollution and future child health. Drawing on Science and Technology Studies, particularly the bio-object concept, this article analyses the transformation of the placenta into a technologically manipulated postgenomic bio-object through scientific discourse and practice. Building on ethnographic fieldwork conducted at an institute of epidemiology and public health in Spain, we analyse how researchers deal with the tension between the placenta's promises for epigenetic research and the practical research realities in postgenomic sciences. First, researchers discursively call upon the placenta as a suitable research object that embodies air pollution exposure and becomes entangled with and responds to this exposure via epigenetic changes. Studying the placenta promises to elucidate the temporally dynamic and environmentally embedded process of disease development as one of postgenomics' core epistemic concerns. Second, in practice, however, accessing and preparing the postpartum placenta for epigenetic analysis defies its promise as a postgenomic bio-object. The constraints of research with birth cohorts, such as only having access to the postpartum placenta at birth, limit what researchers can know about the dynamic process of disease development. Third, we show how researchers deal with these limitations by assembling additional data in and around this organ to recontextualise the epigenetic analysis performed in the postpartum placenta and revive its postgenomic character. We conclude by discussing how ethnographies of epistemic practices provide entry points to collaboratively reflect upon the theoretical and methodological opportunities and challenges in birth cohort research to study biosocial dynamics. We suggest avenues for using qualitative social science perspectives for future biosocial research and collaboration between the social and life sciences.