Liboiron’s Pollution Is Colonialism advances a radical reconfiguration of environmental thought by arguing that pollution is not merely an ecological problem, a regrettable by-product of capitalism, or a metaphor for colonial violence, but an active enactment of colonial relations to Land. The book’s central intervention lies in its critique of the dominant “threshold theory of pollution”, derived from models such as assimilative capacity, which assumes that bodies, rivers, ecosystems and territories can absorb a calculable quantity of contamination before harm becomes scientifically legible. For Liboiron, this assumption is not neutral: it presupposes access to Indigenous Land as a sink, a storage site, a resource, or an expendable medium for settler and industrial futures. Plastic pollution becomes a particularly revealing case because plastics do not assimilate neatly, do not disappear into ecological cycles, and cannot be adequately addressed through conventional environmental solutions such as recycling, clean-up campaigns or improved waste management. These approaches may remain colonial when they continue to presume the availability of Land for processing, disposal, extraction or remediation. The book therefore distinguishes colonialism from capitalism and environmentalism without denying their entanglement: capitalism seeks accumulation, environmentalism may seek conservation, but colonialism is fundamentally organised through entitlement to Land. Liboiron’s case study of plastic pollution in Newfoundland and Labrador, developed through the Civic Laboratory for Environmental Action Research, illustrates how an anticolonial pollution science must begin from place-based obligation rather than universal method. This entails refusing toxic laboratory practices, foregrounding food sovereignty, rethinking sampling protocols, and treating methodology itself as a relation rather than a technical procedure. The text’s broader conclusion is that science is never outside politics, ethics or Land relations; it either reproduces colonial access or helps cultivate accountable alternatives. Consequently, pollution must be understood not only as environmental damage, but as a structure of permission that authorises some worlds to contaminate others.