The Customs Laboratories European Network (CLEN) is a network of 79 customs laboratories and 27 mobile laboratories spread over 25 EU countries.
Role of CLEN
Since 1999, CLEN aims to rationalise, coordinate and optimise the use of human and technical resources among European customs laboratories. CLEN activities are carried out on an ad-hoc and voluntary basis by customs laboratories themselves. Third countries’ customs laboratories sometimes also participate in CLEN activities.
One of CLEN’s most important missions is to anticipate changes in the customs environment and ensure that customs laboratories are sufficiently prepared to meet both current and future challenges. Through networking, training, meetings and conferences, CLEN enables the exchange of experience and sharing of good laboratory practices.
CLEN coordinates its activities through six actions, which are closely linked to each other.
CLEN Action 1
Inter Laboratory Inventory of Analytical Determination (ILIADe)
ILIADe is a database of analytical methods, initially developed as a shared directory by the Italian Customs Agency and currently hosted by the European Commission.
Its main purpose is to improve the effectiveness of customs laboratories by providing them with an easily accessible and up-to-date compilation of analytical methods they are required to use for customs and excise purposes, as well as for authenticity and quality controls, consumer health protection and environmental controls.
The database contains official analytical methods, international standards and in-house developed methods. Its content is discussed and validated by a project group.
The full ILIADe database is accessible to EU countries’ customs laboratories. Methods and contacts are also available to third countries upon special request sent to TAXUD-CLEN
ec [dot] europa [dot] eu (TAXUD-CLEN[at]ec[dot]europa[dot]eu).
Mineral oils - Euromarker
Food and beverages
Denatured alcohols
Tobacco products
Drugs and unknown substances
CLEN Action 2
Inter-comparisons and method validations
CLEN Action 2 ensures uniform application of the control of goods in the European Union through the harmonisation and validation of methods used by customs laboratories.
European customs laboratories participate in Proficiency Testing Schemes to assess their own performances and efficiency, as well as to confirm that the results they obtain are similar to those of other laboratories.
Participation is also essential to achieve accreditation, which is a guarantee of quality for laboratories. Most of the customs laboratories are accredited according to ISO 17025, which is an international standard guaranteeing laboratories’ competence of testing.
The design of each Proficiency Testing Scheme depends on its purpose, i.e. whether the aim is:
- to carry out collaborative trials for the validation of a specific method,
- to carry out a comparison of different methods or analytical protocols used to measure the same parameter,
- to assess laboratories’ performance.
Proficiency tests and ring tests organised within the CLEN usually:
- gather between 10 and 50 participating laboratories,
- deal with 2 to 10 samples, and
- are carried out on 1 to 20 different parameters for each sample.
Examples of tests that have been organised over the past years:
| Ring test on ceramics and pottery | Proficiency test related to Meursing table |
| Ring test on milk products | Proficiency test on mineral oils |
| Ring test on nuts and seeds | Proficiency test on starch and sugars in pet-food |
| Proficiency test on rice | Inter-laboratory test on BPE Euromarker |
| Proficiency test on spirits, alcoholic beverages and alcohol-based preparations | Proficiency test on sugars and sugar containing products |
| Proficiency test on Textiles | Proficiency test on Tobacco |
| Ring Test on Cannabinoids | Test on Handheld Raman equipment |
| Proficiency test on palm oils, texturation proof | Test on XRD for inorganics |
CLEN Action 3
Networking on quality
CLEN Action 3 aims to create a common quality approach applying to all EU customs laboratories through the following activities.
Aim: Development of guidelines on “measurement uncertainty and decision rules in compliance assessment”
Although quality requirements are the same for all Member States’ customs laboratories, their implementation may vary because of specific quality systems. Therefore, the Project Group has been developing guidelines using statistics for processing precision data and other performance characteristics obtained in proficiency tests.
These guidelines support all customs laboratories to interpret analytical results. They also ensure uniform interpretation of new standards and mutual acceptability of test data without the need to further re-test products.
The increasing number of methods of analysis accredited according to ISO 17025 (an international standard guaranteeing laboratories’ competence of testing) clearly shows the constant effort made by customs laboratories to improve their skills and ensure quality of testing.
Project Group on Sampling (Samancta)
Aim: Development and maintenance of Samancta, the Sampling Manual for Customs and Tax Authorities
Samancta is an online sampling manual providing a consistent set of sampling instructions for officers in all Member States and beyond. It is available in English and is freely accessible. An automatic translation tool is available at the top of each page, but it should be used with precaution as technical terms may not be translated accurately.
The aim of Samancta is:
- to improve the quality of samples received for analysis at laboratories,
- to harmonise procedures across Member States, and
- to provide constructive guidance to officers on the sampling methods to be used for each type of product.
The manual consists of six main parts:
- Background information
- General information about Health & Safety in sampling situations
- General information on taking samples, planning, procedures, handling and storage of samples.
- Specific procedures for sampling different products
- Sampling equipment and containers
- Training material and visual examples of sampling in live situations
Samancta is also used for training purposes.
An eLearning course providing guidance on how to navigate through Samancta has been developed by the European Commission, with support of a project team of national experts under the Customs 2020 Programme.
This course is aimed at helping EU customs officers to develop the competencies needed to correctly take and handle samples for laboratory testing. It is currently available in 13 languages.
CLEN Triennial survey
Every three years, a comprehensive survey is conducted in all EU customs laboratories to gather detailed information about their organisation, activities and capabilities. This survey provides a valuable snapshot of laboratories’ work and helps to identify trends.
The most recent survey was conducted in 2025, collecting data from 2024.
CLEN Action 4
Communication and Strategy
CLEN Action 4 is a multiple action focused on scientific and technical communication and exchanges. It facilitates collaboration between EU customs laboratories as well as between the CLEN and other institutional partners (i.e., other European Commission services, customs administrations and third countries’ customs laboratories).
Major conferences have been organised every three years since 2000, bringing together customs chemists from the whole world (EU countries, Candidate and Third Countries). Representatives from the World Customs Organisation (WCO), industry, trade and environmental sectors also participated.
These events are an excellent opportunity to inform the wider public on the activities of customs laboratories globally. They also offer a forum for customs chemists to meet, exchange views, share experience and compare practices operating in their respective laboratories.
| Events | |
|---|---|
9th Seminar of European Customs Chemists Stockholm, Sweden 1 - 3 July 2026 Theme: “Fostering unity in uncertain times” |  |
8th Seminar of European Customs Chemists Berlin, Germany 4 – 6 July 2023 – 210 participants from 40 countries Theme: “Working together: Smart Efficient Competent Committed” More information about this Seminar Customs Laboratories European Network holds its 8th International Seminar. |  |
7th Seminar of European Customs Chemists Budapest, Hungary 2 – 4 July 2019 – 282 participants from 54 countries Theme: “Combating Fraud through cooperation and innovation” |  |
6th Seminar of European Customs Chemists Amsterdam, The Netherlands 22-24 June 2016 – 320 participants from 55 countries Theme: "Sharing knowledge beyond borders" |  |
5th Seminar of European Customs Chemists Paris, France 10-12 July 2013 - 259 participants from 49 countries Theme: "Working together for all of us, today and tomorrow" |  |
4th Seminar of European Customs Chemists Helsinki, Finland 2-4 June 2010 - 182 participants from 36 countries Theme: "Safe & Ecological commerce: How do Customs meet the challenge?" |  |
3rd Conference of European Customs Chemists Athens, Greece 27-29 June 2007 - 170 participants from 42 countries Theme: "The role of customs control in facilitating trade and guaranteeing safety and security" |  |
2nd Conference of European Customs Chemists Prague, Czech Republic 22-24 October 2003 - 137 participants from 28 countries Theme: "Safeguarding the European citizens and protecting the environment in the context of globalisation" |  |
1st Conference of European Customs Chemists Fiuggi-Fonte, Italy 18-20 October 2000 - 95 participants from 34 countries Theme: "Customs, commerce and industry - a unified approach" |  |
CLEN Action 5
Scientific expertise
CLEN Action 5 is dedicated to studying and solving new challenges faced by customs laboratories, such as emerging threats and evolving trade patterns. It also seeks to assist customs officers in any fields requiring scientific support.
Through this Action, significant steps have been made towards developing a robust scientific capacity in customs laboratories, enabling them to quickly provide support across the EU. To achieve this, workshops, training sessions, and working groups are regularly organised to train customs officers on real-life situations.
| Activities | Summary of the activity |
|---|---|
| Technical Meetings on the Use of Handheld Devices | 4 – 7 March 2025 in Amsterdam (NL) Organised by the Dutch customs laboratory for the sixth time, this technical meeting aimed to exchange experiences on how mobile detection equipment are used in practice. Participants had the opportunity to carry out physical inspection of containers, search a vehicle, analyse different samples in various packages, etc. |
| Training session on cast iron | 12 – 13 February 2025 in Cologne (DE)
Organised by the German customs laboratory, the training included a theoretical presentation on the analysis of cast iron and practical hands-on training in the laboratory, with analyses on cast iron by Spark EOS and metallography (embedding, polishing, microscopy). The objectives of the session were to gain practice on the analysis of cast iron and define the correct tariff classification. |
| Training on sampling of confiscated substances for quantitative analysis | 21 – 22 January 2025 in Hamburg (DE) Organised by the German customs laboratory, the training focused on sampling procedures with regard to quantitative analysis aspects. Theoretical presentations were enriched by sampling experiments by participants. |
| Trainings in Nuclear Magnetic Resonance (NMR) | 15 – 22 July and 25 – 29 July 2024 in Ispra (IT) Organised by the Joint Research Centre (JRC), the trainings included both theoretical and practical aspects of Nuclear Magnetic Resonance (NMR) with a focus on the main application of interest for application for customs controls. Harmonisation of methods, especially for quantification of target compounds (e.g. cocaine, MDMA, methamphetamine, tadalafil, sildenafil in mixtures) were also discussed. |
| Workshop on textiles | 20 – 21 March 2024 in Amsterdam (NL) Organised by the Dutch customs laboratory, the workshop aimed to solve issues regarding the identification and classification of textile products (coated, covered, laminated or impregnated) and to share experience, with practical sessions dedicated to the observation of selected samples. |
| Training Session on Gemmology | 24-25 October and 14-15, 28-29 November 2023 – Turin (IT) – 6 participants per session from 13 Member States Organised by the Italian customs laboratory, these workshops aimed at increasing participants’ knowledge on the characteristics needed to identify gemstones and diamonds, as well as distinguishing nature gemstones and diamonds from their synthetic counterparts or imitations. Participants had the opportunity to work hands-on with main gemmological instruments. |
| Technical Meetings on the Use of Handheld Devices | 4-7 and 11-14 October 2022 – Amsterdam (NL) – 14 participants per session from 10 Member States Organised by the Dutch customs laboratory, these technical meetings aimed at exchanging experiences on how mobile detection equipment are used in practice. Participants had the opportunity to carry out physical inspection of containers, search a vehicle, analyse different samples in various packages, etc. |
| Webinar on Gemmology | 30 November 2021 - 65 participants from 29 countries (21 Member States, 2 EU Candidate Countries, 2 other European countries and 4 Asian countries) The aim of the webinar was to expand the customs laboratories’ knowledge on gems, concentrating on theoretical aspects and traditional fields of application of gemmology, as well as sharing good practices. |
| Webinar on Cannabis and Cannabinoids | 20-22 October 2020 – 99 participants from 31 countries (24 Member States, 2 EU Candidate Countries, 2 other European countries, 2 American countries and 1 Asian country) The main objectives of the webinar were: |
CLEN Action 6
European Customs Inventory of Chemical Substances (ECICS)
CLEN Action 6 develops a guide to classify chemical products in the Combined Nomenclature (CN) and the Harmonised System (HS) at global level. ECICS is a database managed by the European Commission's Directorate-General for Taxation and Customs Union (DG TAXUD). It allows users to:
- identify chemicals;
- classify chemicals in the Combined Nomenclature (CN);
- name chemicals in all EU languages for regulatory purposes.
ECICS is publicly available and currently contains more than 87 000 chemical products, serving as a repository of knowledge of traded chemicals. First published in 1974, it became ‘CLEN Action 6’ in 2009.
Any goods imported or exported in or out of the EU must be classified for customs purposes, according to the Combined Nomenclature (eight-digit CN codes). This tariff classification determines the rate of customs duties, if any, as well as any non-tariff measures that may apply to the imported products.
ECICS has therefore become a cornerstone for customs authorities, customs laboratories and economic operators trading all kinds of chemicals. As the CN codes are based on the ‘Harmonized Commodity Description and Coding System’ emanating from the World Customs Organization (WCO), the tariff classifications found in ECICS are helpful across the world.
Each product listed in ECICS is identified by the CUS code, assigned by DG TAXUD, which is an easy identifier to search the database and to communicate with customs. Products are also identified by CAS RN (Chemical Abstracts Service Registry Number), as well as by other identifiers such as EC numbers and UN numbers, where these identifiers are available.
ECICS lists various chemical names in several EU languages. These names are usually recognised internationally like International Non-proprietary Names for pharmaceuticals (INN), International Organization for Standardization names for pesticides and chemical names constructed according to the International Union of Pure and Applied Chemistry (IUPAC) nomenclatures. ECICS is also equipped with a module aimed at translating chemical names from English into other EU languages. It currently focuses on IUPAC names, but other types of names are in development.
The inventory mainly covers pure chemicals such as pharmaceuticals, pesticides, chemical weapons precursors, narcotic drugs and precursors, ozone-depleting substances or hazardous chemicals for the health and environment.
In particular, it covers:
| Pesticides and other plant protection products listed by the International Organization for Standardization under ISO 1750; |
| International Non-proprietary Names (INN) assigned to pharmaceuticals by the World Health Organization; |
| Salts and esters of INNs, known as INNMs ("M" standing for "Modified"); |
| Pharmaceuticals intermediates, i.e. compounds used in the manufacture of pharmaceuticals; |
| Narcotic and psychotropic substances and their precursors; |
| Ozone-depleting substances; |
| Chemicals controlled under the International Chemical Weapons Convention; |
| Chemicals subject to other international conventions e.g. Rotterdam prior informed consent (PIC) procedure, Stockholm convention for the control of Persistent Organic Pollutants (POPs); |
| Other products subject to import/export controls; |
| Colour Index dyes and pigments; |
| Chemicals subject to EU legislation (e.g REACH, RoHS, food additives) |
| Other commercially significant products. |
The content of the database is regularly enriched by DG TAXUD, assisted by EU countries’ representatives in the Customs Code Committee – Tariff and Statistical Nomenclature Section (Agriculture/Chemical sector). Its coverage is also progressively extended to regulated mixtures.
To help users get the most out of the database, a nano learning course provides tips and guidance on searching and using ECICS effectively. The course is available free: European Customs Inventory of Chemical Substances (ECICS).
A list of Frequently Asked Questions is also available in ECICS and provides answers to the most commonly received questions from stakeholders and customs authorities regarding the use of the database.
Note: The information provided in ECICS is not binding and does not give rise to protection of any kind. For any question, suggestion or correction of information found in the database, please do not hesitate to contact us via our mailbox taxud-dds-ecicsec [dot] europa [dot] eu (taxud-dds-ecics[at]ec[dot]europa[dot]eu) with the maximum of information about your request (i.e., description of the product, CAS RN, chemical name and structure, uses, exact composition with components, Safety Data Sheet, etc.).