Detecting Illegal Intercountry Trade of Mercury Using Discrepancies in Mirrored Trade Data

Abstract

The ongoing international movement to phase out mercury, mainly led by the Minamata Convention on Mercury, raises concerns about illegal intercountry trade, including smuggling. This study aims to detect the existence of illegal intercountry mercury trade under the social mercury phase-out movement, focusing on discrepancies in each country’s trade statistics. To analyze the trends by year and country for discrepancies in intercountry mercury trade, an intraclass correlation coefficient (ICC) was applied to the mirrored exports and imports from trade statistics of each country provided by the UN Comtrade. The year-based ICC analysis identified a tendency to reduce the detection of discrepancies in the reported mirrored exports and imports for mercury at the intercountry level under the recent mercury phase-out movement. Through an ICC analysis focusing on exporting and importing countries, the validity of the ICC analysis was verified as a way to detect illegal intercountry trade of mercury. Our analyses detecting the illegal trade of related countries contribute to the effectiveness evaluation and custom capacity building required in the Minamata Convention by offering a data-driven method to enable the effective detection of illegal mercury trade.

Projected global mercury supply, demand, and excess to 2050 based on impacts of the Minamata Convention

“…It should be noted that this overview of the mercury trade does not include the transfer of mercury in the form of compounds or mercury-added products and illegal trade which cannot be seen in the official statistics. It should also be taken into account that, as the Nigerian case also shows, the UN trade data have been pointed out to be rather unreliable, including discrepancies between export and import data [49,50].…”

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

“…Data quality can be an often-overlooked bottleneck when using the UN Comtrade database, as the accuracy of individual data entries depends on the reporting country 23,43 . Importantly, erroneous reporting of trade volumes (for example, due to overinvoicing, underinvoicing or mislabelling 8,11,44 ) has been observed. For instance, as the major producer of perfluorooctane sulfonic acid (PFOS) and its salts in the past decade or two, China had a total production capacity of less than 250 tonnes per year 37 , but the export record of ammonium PFOS from Kuwait in 2018 was about 10.5 kilotonnes, which cannot be true.…”

“…Second, in addition to trade with records, illegal trade can occur in the form of smuggling, mislabelling or black markets. Such illegal trade of mercury has been demonstrated to exist widely, especially in Asia and Central and South America 11,45,46 , raising concerns and calling for more effective enforcement of the Minamata Convention. Currently, information on this type of illegal trade remains sparse for most chemicals 8 .…”

“…However, the effectiveness of this approach is limited because chemicals manufactured or consumed in one country may enter another via ever-intensified global trade of resources, chemicals, products and wastes, and/or via wind and water currents [8][9][10][11] . Also, many other countries have yet to establish their own frameworks 1,8 .…”

Mercury’s complex legacy

“…Trade data are increasingly used to better understand how mercury travels across the world, though it often contains discrepancies between country-specific import and export numbers ( 9 , 10 ). Much mercury is also smuggled illegally across national borders, particularly for use in artisanal and small-scale gold mining ( 10 ).…”