This paper examines the ethical review of innovative biotechnologies under conditions of deep uncertainty regarding their long-term consequences. Traditional models of biomedical ethics, developed primarily for clinical contexts, presuppose a relatively well-defined and localized type of risk. Genome editing, synthetic biology, and cellular therapies, however, alter the epistemic status of risk: its effects may be delayed, difficult to reverse, distributed across populations, intergenerational, and poorly characterized. The paper argues for a reconceptualization of the principle of non-maleficence under uncertainty: from a logic of prohibition to a logic of precaution; from risk estimation to the management of uncertainty; and from individual consent to collective participation in decision-making.