Continuing large-scale global trade and illegal trade of highly hazardous chemicals

Anthropogenic chemicals significantly impact human health and ecosystems, contributing to planetary crises alongside climate change and biodiversity loss. Exposure to chemicals such as lead and certain carcinogens leads to substantial premature deaths and disability-adjusted life years globally. Chemical pollution is a major driver of biodiversity loss, further exacerbating the planetary crisis. While national and regional frameworks exist to manage chemicals, their effectiveness is limited by intensified global trade and the lack of frameworks in many countries. The Rotterdam Convention, a key global treaty, aims to improve the handling of international trade in hazardous chemicals through the prior informed consent (PIC) procedure. This procedure doesn't ban chemicals but assists countries in making informed import decisions. Prior research on the Convention's effectiveness is limited by data quality issues in the UN Comtrade database. This study addresses these limitations to provide a comprehensive analysis of global trade in highly hazardous chemicals listed under the Rotterdam Convention, examining geographical patterns and illegal trade.

Previous research examining the effectiveness of the Rotterdam Convention has been scarce and limited by data quality issues. Núñez-Rocha and Martínez-Zarzoso analyzed trade data from 1995-2012 using the BACI database (derived from the UN Comtrade database), but their study was limited by its geographical scope (only 88 countries) and the failure to identify and exclude erroneous trade records. This study aims to address these limitations by using a more comprehensive dataset and workflow to analyze global trade patterns and illegal trade in highly hazardous chemicals.

The study analyzed 66,156 trade records from the UN Comtrade database (after data cleaning) for 46 chemicals listed under the Rotterdam Convention. A workflow was developed to address data-quality issues, integrating outlier analysis (using clustering and statistical methods) to identify and remove erroneous records, and mirror analysis to reconcile asymmetric bilateral transactions. The analysis covers the period from 2004 (when the Convention entered into force) to 2019. 'Illegal trade' was defined as trade between parties to the Convention where the import was explicitly not consented to by the importing country. The study provides a minimum estimate of global and illegal trade, taking a conservative approach and excluding chemicals without dedicated Harmonized System (HS) codes. The analysis considered various aspects of geographical patterns of trade, focusing on the top importers and exporters of pesticides, industrial chemicals, and multi-use chemicals. Countries were divided into 15 regions for a detailed analysis of interregional trade relationships. The data were then analyzed to determine the prevalence of ‘illegal’ trade – specifically instances where listed chemicals were imported/exported between signatory countries despite an import response of ‘no consent’ being issued by the importing country. The EU PIC Regulation, which implements the Rotterdam Convention within the EU, was used to further examine the defaulting situation within the EU and identify discrepancies compared to data in the UN Comtrade database. Additional data treatment techniques such as extrapolating missing values or applying weighted-average methods were not applied to avoid potential bias and uncertainties.

The cumulative global trade of the 46 listed chemicals between 2004 and 2019 reached 64.5 megatonnes, with ethylene dichloride and ethylene oxide contributing significantly. The annual trade volume has been steadily increasing, mainly driven by ethylene dichloride, despite a slight decrease observed in some chemicals in recent years. Surprisingly, substantial amounts of largely banned legacy chemicals like tetraethyl and tetramethyl lead and tributyltin compounds (TBTs) are still traded globally. This indicates continued usage, potentially in niche applications or illegally. Tris(2,3-dibromopropyl) phosphate, a phased-out flame retardant, also shows continued trade. The trade of these chemicals is concentrated in certain regions like the USA, Western Europe, Central Europe, Canada (import), and China (export). The study also reveals a prevalent illegal trade, representing at least 25.7 megatonnes (40% of the total trade volume), with considerable volume across borders with weak controls, especially in certain regions. The defaulting phenomenon was widespread, particularly in Europe, Asia, and the Middle East. The analysis also suggests even higher levels of illegal trade by incorporating the data from EU PIC Regulation which indicates more stringent reporting within the EU. Trade data for specific chemicals show a decline consistent with their listing under the Rotterdam Convention, but the large-scale continued trade of others, and the prevalence of illegal trade across borders, indicate significant shortcomings in the Convention's effectiveness. The study also identified a total of 13,038 probably erroneous import/export records (out of 79,194 original records), mainly in South and Southeast Asia, Central and Western Europe, the USA, and the Middle East. These errors involved chemicals such as alachlor, ethylene dichloride, ethylene oxide, and pentachlorophenol and its salts and esters. Nearly 10,000 trade records were missing, primarily for exports, and were filled using mirror analysis.

The findings indicate that while the Rotterdam Convention has had a positive impact on reducing the trade of some hazardous chemicals, significant challenges remain. The persistent large-scale global trade of some highly hazardous substances, coupled with the widespread prevalence of illegal trade, highlights the need for substantial improvements in the Convention's effectiveness. The study’s conservative approach likely underestimates the true extent of both legal and illegal trade. Two types of illegal trade were not accounted for: trade between parties and non-parties to the Convention (due to the difficulty in compiling domestic legislation from many countries), and illegal trade through smuggling, mislabeling, or black markets. The significant discrepancies between the UN Comtrade database and EU PIC Regulation further highlight the challenges in accurately monitoring and regulating the global trade of these chemicals. Therefore, despite the positive role of the Rotterdam Convention, urgent action is required to improve global, regional, and national strategies related to the trade of highly hazardous chemicals.

This study highlights the continued large-scale global trade and the substantial levels of illegal trade in highly hazardous chemicals, despite the Rotterdam Convention. The Convention shows some positive impact, but more concerted efforts are needed to enhance enforcement, address illegal activities, and swiftly list problematic chemicals. Future research should focus on understanding and addressing the supply and demand of these chemicals in key regions and countries, improving data quality and accessibility, and exploring synergies with other international treaties to improve harmonized policymaking and strengthen regional and national control measures.

The study's estimates of global and illegal trade are conservative, potentially underestimating the true extent due to the exclusion of chemicals without dedicated HS codes, the focus solely on trade between Convention parties, and the lack of data on illegal trade via smuggling or black markets. The reliance on self-reported data in the UN Comtrade database may introduce inaccuracies. The regions defined for analysis might not fully capture specific trade flows or patterns. Additional data treatment techniques were not used to avoid introducing arbitrary estimations and uncertainties. Finally, the study did not delve into the reasons behind the discrepancies between reported trade volumes under the Rotterdam Convention and EU PIC Regulation.