Background: Between 1992 and 2010 in the Costa Rican Caribbean, a social movement coalition called Foro Emaús sought to change people's view on problems of high pesticide use in banana production.
Objective: To understand the formation and membership of Foro Emaús, its success period, and its decline.
Methods: Semi-structured interviews of 28 key actors; a questionnaire survey among school personnel (n = 475) in Siquirres, Matina, and Talamanca counties; and secondary data from newspapers, leaflets, and movement documents were used.
Results: Foro Emaús developed activism around pesticide issues and put pressure on governmental agencies and banana companies and shaped people's perception of pesticide risks. The success of the Foro Emaús movement led to the reinforcement of a counteracting social movement (Solidarismo) by conservative sectors of the Catholic Church and the banana companies. We found that the participation of unions in Foro Emaús is an early example of social movement unionism.
Conclusions: Scientific pesticide risk analysis is not the only force that shapes emerging societal perceptions of pesticide risk. Social movements influence the priority given to particular risks and can be crucial in putting health and environmental risk issues on the political and research agenda.