Global emissions of polychlorinated naphthalenes (PCNs) have recently been estimated, providing insight on the environmental burden imposed by these persistent organic pollutants. A study published by researchers revealed comprehensive emission estimates from PCN production and usage from 1912 through 2020, with projections extending to 2050. The findings highlight the significant historical emissions contributed mainly by product usage, and they suggest fluctuative trends for future emissions largely driven by waste management practices worldwide.
PCNs, which consist of one to eight chlorine atoms per naphthalene molecule, have been shown to cause various health issues, including neurotoxicity and endocrine disruption. Due to their toxicity and persistence, PCNs were added to the list of regulated substances under the Stockholm Convention, marking them as hazardous to human health and the environment. This research builds on earlier studies by providing the first global inventory of PCN emissions after the Stockholm Convention was enacted.
From 1912 to 1987, cumulative PCN production reached approximately 1,042,790 tons, leading to historical emissions of 468,014 tons. The vast majority of these emissions—over 99%—entered the atmosphere during the product usage phase, highlighting the need for monitoring and tracking these pollutants. The legacy of historical production remains significant, as many areas still experience elevated levels of PCNs due to past industrial activities.
For the years 2000 to 2020, researchers monitored unintentional emissions from 20 identified sources which amounted to 11,534 tons. Municipal waste incineration emerged as the primary source, accounting for approximately 94.5% of global emissions, followed by cement production. Regions like Kazakhstan, which was identified as the largest emitter, demonstrated the negative effects of inadequate waste management practices, where 99.95% of local PCN emissions stemmed from incineration.
To project future emissions from 2020 to 2050, the researchers employed advanced modeling techniques, including random forest regression models. These methods take various economic parameters, such as GDP and population growth, to simulate potential outcomes under different scenarios. Future emissions are expected to fluctuate significantly, with projections indicating changes could range from decreases of 29% to increases of 347% depending on technological changes and waste management improvements.
This emission inventory is pivotal for informing policymakers as they seek to mitigate the global environmental and health risks posed by PCNs. By establishing the extent and sources of these emissions, targeted strategies can be developed to reduce their prevalence. The emphasis on reducing unintentional emissions, especially from waste incineration, is likely to dictate future regulatory frameworks.
According to the study, the incorporation of thorough models and databases offers insights necessary for both regional assessments of PCN emissions and global strategies to combat their release. This research acts as both a means of tracking the historical impacts of PCNs and as guidance for future environmental legislation aimed at protecting public health and the planet.