Based on a presentation by Joshua O. Babayemi (PhD), University of Medical Sciences Ondo, Nigeria, at the GGKP webinar “Strengthening the Collaboration with National Statistical Offices to Address Gaps in POPs Data and Related Information,” 19 November 2024.
Trade Statistics as a Foundation for Tier II POPs Inventories
For countries updating their National Implementation Plans (NIPs) under the Stockholm Convention, one of the most demanding tasks is quantifying how many products containing persistent organic pollutants (POPs) have entered their markets. Electrical and electronic equipment (EEE), and the waste streams that follow them (WEEE), are particularly challenging because they involve multiple product categories, complex trade flows, and plastics embedded with POPs and other chemicals of concern. While countries collaborate closely with the national customs authorities on the import and export data, there are still limitations in obtaining full dataset.
The United Nations Commodity Trade Statistics Database (UN Comtrade) provides a powerful starting point for Tier II POPs inventory in EEE. As the most comprehensive repository of global trade data, classified by the Harmonized System (HS) codes, it allows governments and researchers to track imports and exports of EEE. Yet, the data in Comtrade is raw trade information — it does not directly tell us how much plastic or POPs those products contain. Research in Nigeria’s shows how this gap can be bridged.
Why Nigeria Looked at EEE and WEEE
Nigeria is a major importer of EEE and WEEE in Africa, and this translates into significant downstream challenges in managing WEEE. To better understand the scope of the issue, Dr. Joshua Babayemi and colleagues analysed 32 years of import data, from 1990 to 2022, to estimate both the total plastics and the POPs contained within them.
The study focused on 28 product groups that account for over 90% of officially recorded EEE imports. Lamps and other products with negligible plastic content were excluded. Instead, the analysis concentrated on categories like televisions, computers, and household appliances, which are most relevant for POPs management.
How Nigeria Processed the Data
The study began by selecting relevant product categories using established classifications (UNU-KEYs and EU-6) and matching them to their HS codes. Trade data for these categories was then extracted directly from the UN Comtrade database.
Next, the researchers estimated how much plastic was embedded in each category. To do this, they relied on plastic fractions from GGKP’s sectoral POP inventory guidance and scientific literature. Finally, these fractions were multiplied by impact factors from the GGKP sectoral guidance and UNEP PBDE inventory for chemicals such as PBDEs, HBCD, SCCPs, MCCPs, and Dechlorane Plus.
The result was a structured process for transforming trade data into chemical estimates — a method that other countries can replicate.
Methodology Snapshot: Turning Comtrade Data into POPs Estimates
Using UN Comtrade data for POPs inventories involves three key stages:
- Selecting relevant product groups (UNU-KEYs/EU-6) and identifying their HS codes.
- Downloading trade data (imports, weights, values, partners) for those HS codes.
- Applying fractions and chemical concentrations to estimate plastics and POPs.
The Nigerian team applied straightforward formulas:
- For plastics content:
Pm = Em × f
(Pm = plastic content; Em = imported quantity; f = plastic fraction) - For PBDEs content:
Br = Em × f × C
(Br = PBDEs; C = average PBDE concentration) - For other POPs content:
POPc = Em × f × Cpop
(POPc = other POPs; Cpop = average concentration)
Looking at the above, it is understood that Comtrade provides the raw import volumes, while inventories are built by applying guidance and factors to interpret those numbers.
Key Findings from the Nigerian Analysis
Applying this method to more than three decades of trade data yielded a clear picture. Between 1990 and 2022, Nigeria officially imported about 4,568 kilotonnes of EEE, of which 1,337 kilotonnes were plastics. When estimated informal imports of WEEE are included, the figure rises dramatically: around 12,259 kilotonnes of EEE/WEEE, containing 3,644 kilotonnes of plastics.
These plastics were estimated to contain:
- 8,511 tonnes of DecaBDE
- 1,043 tonnes of HexaBDE/HeptaBDE
- 154 tonnes of HBCD
- 91 tonnes of SCCPs
- 364 tonnes of MCCPs
- 146 tonnes of Dechlorane Plus
This represents the first systematic estimate of major POPs in EEE/WEEE plastics for a low-income country, providing Nigeria with critical evidence for waste planning and POPs management.
Lessons Beyond Nigeria
Nigeria’s experience offers valuable practical steps to other countries. First, it confirms that UN Comtrade is not ready-made inventory data: it must be combined with plastic fractions, impact factors, and contextual knowledge. Second, the methodology is replicable and can be adapted to national circumstances, making it an essential tool for Parties developing their POPs inventories as a part of NIPs. For governments preparing their NIPs under the Stockholm Convention, the lesson is clear: the data exists, but it requires methodological rigor and local expertise to become actionable. Nigeria’s example shows that with the right approach, even raw trade flows can be turned into evidence that can support safer waste management, stronger compliance, and more informed policy decisions.
Equally important is the role of national statistical offices, and national customs authorities, which ensure that HS codes are correctly applied and that the trade data feeding into the UN Comtrade database is accurate. Without this collaboration, the reliability of inventories may be undermined.
To learn more about the Global NIP Update project, visit Global NIP Update | Green Policy Platform
For a deeper dive into the GGKP webinar on the collaboration with National Statistical Offices, you can access the full recordings and materials here: Strengthening the Collaboration with National Statistical Offices to Address Gaps in POPs Data and Related Information | Green Policy Platform
Related publication of authors: Babayemi JO, Nnorom IC, Weber R. (2025) Comprehensive inventory of imports of electrical and electronic equipment and related plastics and POPs plastic additives into Nigeria in the past 32 years (1990–2022). Emerging Contaminants. 11(1), 100423. https://doi.org/10.1016/j.emcon.2024.100423
Authors:
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Joshua O. Babayemi, University of Medical Sciences Ondo, Nigeria |
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Roland Weber, POPs and NIP expert, POPs Environmental Consulting
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