Which event caused significant economic losses due to a PCB leak from an electrical transformer?

The event associated with significant economic losses due to a PCB leak from an electrical transformer is indeed linked to Montana. In this case, the presence of polychlorinated biphenyls (PCBs) in electrical equipment has been historically problematic due to their environmental and health effects, leading to contamination and significant cleanup efforts.

Montana experienced a substantial PCB leak which resulted in both environmental degradation and extensive costs related to remediation. These events typically involve the contamination of soil and waterways, requiring significant investment for cleanup and also impacting local economies due to the repercussions on businesses and public health.

This historical incident highlights the broader implications of PCB contamination, not only in terms of environmental health but also in economic terms for the regions affected, which were necessary to address lingering pollution and ensure public safety.