Historic Trends in the Concentrations of Persistent Organohalogenated Pollutants in Australian Butter and the Impact of Regulation

Analysis of historically sealed dairy products offers a novel method for tracking persistent organic pollutant (POP) contamination over time. This study examined Australian canned butter samples from 1944, 1958, 1969, and 1987, sourced from museum collections, Antarctic expeditions, and storage facilities. Samples were analyzed for a broad range of POPs, including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), polybrominated diphenyl ethers (PBDEs), and polychlorinated alkanes (PCAs). OCP concentrations peaked in the 1950s and 1960s, before sharply declining post-1980s bans. Similar declining trends occurred for PCBs and PCAs, although at lower concentrations than for OCPs. PBDEs were consistently not detected in all of the historic samples. In contrast, highly chlorinated dioxins exhibited unique behavior, where their concentrations peaked in the 1944 sample, remained at high levels through the 1950s–1960s, and decreased to current levels afterward. The source of these elevated levels of dioxins remains unknown. The study revealed distinct temporal pollution patterns influenced by chemical properties, environmental behavior, and regulatory effectiveness. All monitored POPs exhibited declining trends, following regulatory restrictions on their production. These findings highlight the value of archived food samples in reconstructing contamination timelines.