Dangerous goods classes 1 to 9 according to ADR: Overview, labelling and obligation to order

The European Agreement concerning the International Carriage of Dangerous Goods by Road (ADR), as amended in 2025, divides all dangerous substances into nine main classes and several subclasses. This classification forms the basis for UN numbers, packaging instructions, labelling, transport documents and training requirements. It is equally relevant for shippers, carriers, shippers, packers and recipients. In Germany, the ADR is applied via the Dangerous Goods Transport Act (GGBefG) as well as the Dangerous Goods Ordinance on Roads, Railways and Inland Waterways (GGVSEB) and the Dangerous Goods Officer Ordinance (GbV), which largely harmonizes the regulations for national transport with the international requirements. The ADR is revised every two years, most recently on January 1, 2025.

This article explains the nine dangerous goods classes with their subclasses, the labelling requirement, the threshold values ​​for the obligation to appoint a dangerous goods representative according to Section 1 GbV and the typical risks of fines according to Section 37 GGVSEB. We will then show in which constellations an external dangerous goods officer via the CIVAC platform makes sense and which audit templates document shipping and storage operations in an audit-proof manner. You will receive an overview of the most common substances per class, an explanation of the UN number system with concrete examples and information on the annual reporting requirement in accordance with Section 8 GbV. The presentation follows the ADR version 2025 and the GbV version 2022 and is aimed at medium-sized companies who are looking for clarity about their obligations.

The ADR assigns each dangerous substance to a class, supplemented by a classification number, a UN number and a packaging group. The classification number describes the main hazard and possible secondary hazards, the UN number is the internationally unique substance identifier, and the packaging group (I, II or III) indicates the degree of hazard: I for very dangerous, II for dangerous and III for less dangerous. This structuring allows the systematic treatment of around 3,500 substances recorded by name and an open list for mixtures and new substances that are assigned to a class using classification tables. This means that previously unknown substances can also be transported according to their properties.

The main classes are not numbered according to increasing danger, but rather according to the type of danger, which often confuses beginners. Class 1 covers explosive substances, Class 2 gases, Class 3 flammable liquids, Class 4 flammable solids, Class 5 oxidants and so on. Within some classes there are subclasses, for example class 4 with the subclasses 4.1 (flammable solids), 4.2 (spontaneously ignitable substances) and 4.3 (substances which give off flammable gases when in contact with water). Class 6 is divided into 6.1 (toxic substances) and 6.2 (infectious substances), which is particularly relevant for hospitals, laboratories and medical care centres in daily practice.

Each substance is given a UN number with four digits in the ADR, for example UN 1203 for gasoline, UN 1789 for hydrochloric acid, UN 1950 for compressed gas packs, UN 3480 for lithium-ion batteries. The UN number must be stated on transport documents, packages and large packaging and controls the permitted types of packaging and the maximum shipping quantities per transport unit. The external appointment of a dangerous goods representative includes maintaining the company-specific substance list and updating it in the event of ADR changes every two years.

Class 1 covers all substances and objects that can have an explosive effect due to their chemical properties, from industrial explosives to pyrotechnic products to ammunition for military and civil applications. Subclasses 1.1 to 1.6 differentiate according to the type of explosion hazard and are used for packaging, transport and storage regulations. 1.1 covers substances with a mass explosion risk, i.e. an explosion that affects almost the entire load at the same time. 1.2 covers substances that cause danger from splinters, explosives or thrown pieces, but not from mass explosions. 1.3 covers substances with a fire hazard and low explosive effect. 1.4 covers substances with only minor danger in the event of ignition or triggering, including, for example, many smaller pyrotechnic products.

1.5 and 1.6 cover particularly low-sensitivity substances for military and industrial blasting work. Compatibility groups from A to S also structure permitted storage. Substances in compatibility group A (such as initial explosives) may not be transported or stored together with other substances, while group S (particularly securely packaged substances) are treated more flexibly. This differentiation is crucial for storage quantity calculations according to the 2nd SprengV and for approvals according to the Explosives Act and is often underestimated in medium-sized companies.

Shippers of class 1 substances are subject to special approval requirements, extended training of those involved in accordance with Chapter 1.3 ADR and a stricter reporting obligation to the supervisory authorities. The appointment of a dangerous goods representative is usually mandatory because the quantity thresholds are very low. Even a single kilogram of explosives triggers the order requirement, unlike in the case of mineral oil transports with high quantity thresholds. CIVAC offers Class 1 shippers and storage facilities an expanded GGB mandate with its own audit module, which maps the interface to explosives law and documents the reporting line to the supervisory authority in a versioned manner.

Class 2 covers gases in three subcategories: 2.1 flammable gases such as propane (UN 1978), hydrogen (UN 1049) and acetylene (UN 1001), 2.2 non-flammable, non-toxic gases such as nitrogen (UN 1066) and carbon dioxide (UN 1013) and 2.3 toxic gases such as chlorine (UN 1017) and ammonia (UN 1005). Transport takes place in compressed gas containers, pressure drums, cylinder bundles or tanks, each with its own testing, labelling and recurring testing rules in accordance with Chapter 6.2 ADR. Aerosols (UN 1950) also fall into class 2 and affect manufacturers and senders of cosmetics, paints and household products, which many e-commerce senders do not adequately document in practice.

Class 3 covers flammable liquids with a flash point of no more than 60 degrees Celsius. Typical substances are gasoline (UN 1203), diesel (UN 1202, only covered to a limited extent due to higher flash point), methanol (UN 1230), acetone (UN 1090) and solvent-based adhesives. The classification takes place across three packaging groups, graded according to flash point and initial boiling point. For shippers, the correct assignment of the packaging group is crucial because it determines the packaging requirements, the permissible filling levels and the choice of tanker vehicle type. Misclassification is one of the most common complaints during inspections.

Class 4 is divided into 4.1 (flammable solid substances such as sulfur UN 1350, self-reactive substances), 4.2 (self-igniting substances such as white phosphorus UN 1381) and 4.3 (substances that develop flammable gases with water, such as sodium UN 1428, calcium carbide UN 1402). Specific packaging, transport and storage regulations apply to each of these classes. Shippers and shippers require training in accordance with Chapter 1.3 ADR, supplemented by in-depth training for carriers. The CIVAC platform contains ready-made audit templates for the goods receipt, warehouse and loading interfaces, so that the reporting line to management is verifiable and documented in a version at all times.

Class 5 includes oxidants (5.1) and organic peroxides (5.2). Oxidizing agents such as ammonium nitrate (UN 1942), hydrogen peroxide in solution above 60 percent (UN 2014) and potassium permanganate (UN 1490) can initiate or intensify fires without being self-ignitable. They are subject to special separation regulations for storage and are relevant in many industries, particularly in chemistry, the fertilizer industry and water treatment. Transport usually takes place in packing group II or III, whereby particularly concentrated solutions are to be classified in packing group I and trigger correspondingly stricter packaging requirements.

Organic peroxides (5.2) are widely used as initiators in the plastics industry, for example as benzoyl peroxide (UN 3102 ff.) or dibenzoyl peroxide in various concentrations. They have particularly strict temperature requirements during transport, often requiring refrigeration and continuous temperature monitoring. The classification is based on a separate list in Chapter 2.2.52 ADR, and many peroxides may only be transported in certain packaging and under temperature control. Shippers must prove the cold chain and document delivery interruptions. Violations lead to complaints and can block shipping completely until clarification.

Class 6 is divided into 6.1 (toxic substances such as cyanides UN 1588, arsenic UN 1558) and 6.2 (infectious substances). Class 6.2 particularly affects medical facilities, diagnostic laboratories, research facilities and veterinary clinics. The UN numbers 2814 (Category A, infectious to humans), 2900 (Category A, for animals only) and 3373 (Biological substance Category B, less dangerous) are key reference points. Hospitals must document the training of shipping staff and appoint a dangerous goods officer or have him appointed externally. The CIVAC dangerous goods officer order covers the clinic-laboratory-shipping interface in a structured manner and provides packaging templates for UN 3373 as well as training modules for shipping staff.

Class 7 covers radioactive substances. It is subject to its own system of regulations, largely separate from the ADR, under the leadership of the IAEA and is further specified in Germany by the Radiation Protection Act and the Radiation Protection Ordinance. Typical UN numbers are UN 2910 (exempt packages), UN 2912 (LSA-I, substances with low specific activity), UN 3327 (fissile materials) and UN 2916 (Type B(U) packages). For most medium-sized companies, Class 7 is only relevant when shipping measuring instruments, medical devices, industrial testing devices or when disposing of low-level radioactive waste.

Class 8 includes corrosive substances such as sulfuric acid (UN 1830), hydrochloric acid (UN 1789), caustic soda (UN 1824) and many cleaning agents in the industrial sector. Class 8 is the most widely used class in medium-sized businesses because corrosive substances occur in almost every industry, from electroplating and food hygiene to the construction industry and water treatment. Shippers often underestimate the fact that battery acids, bleach and descalers also need to be labelled as Class 8 dangerous goods if they are shipped in larger packaging. The shipping obligations apply above the exemption limits according to Chapter 3.4 ADR.

Class 9 covers other dangerous substances and objects that do not fit into other classes. These include lithium-ion batteries (UN 3480, 3481), asbestos (UN 2212, 2590), dry ice (UN 1845), environmentally hazardous substances (UN 3077, 3082) and airbag modules (UN 0503). Lithium batteries are the most economically significant subgroup of Class 9 and are shipped in smartphones, laptops, e-bikes, electric vehicles and stationary storage. The labelling requirement and the training of shipping staff are often underestimated, especially by e-commerce senders with end customer business. Licence the workspace for your internal representatives, or have our representatives order it.

The ADR marking follows a three-stage logic: on the package, on the means of transport and in the transport document. The danger labels (e.g. flame for class 3, skull for class 6.1, lithium battery symbol for class 9) and the UN number preceded by UN must be attached to the package. The size of the danger labels is at least 100 by 100 millimeters, in rare exceptions 50 by 50 millimeters for small shipments such as diagnostic samples. Incorrect or missing labelling is subject to a fine according to Section 37 GGVSEB, with amounts typically between 50 and 5,000 euros per violation and a correspondingly high total for mass shipments.

Orange warning signs with the UN number in the lower half and the danger number (Kemler number) in the upper half must be attached to the means of transport, plus large danger labels (large labels, placards) with at least 250 copies 250 millimeters. The warning signs are attached to the front and rear of the vehicle and, in the case of tanks and tank containers, also to the side of each tank chamber. When transporting in packages (not tanks), the orange warning sign without labelling is sufficient, which saves effort for shippers with mixed cargo.

The transport document must contain six pieces of information: UN number, official shipping name, class, packing group, number and description of packages and total quantity. For lithium batteries, additional information on watt-hour capacity or lithium content is required. Senders are liable for the accuracy of the information, carriers for checking plausibility. A complete transport document is a prerequisite for shipping and must be presented in the event of a police or customs inspection. CIVAC provides ready-to-use transport document templates for each class in the workspace, so that shippers can record the mandatory information in a structured manner, reduce typos and present the entire historical shipping documentation in the audit trail.

According to Section 1 Paragraph 1 GbV (Dangerous Goods Officer Ordinance), every company that transports, packs, fills, loads, unloads or ships dangerous goods is obliged to appoint at least one dangerous goods officer in writing. The obligation applies regardless of the size of the company and applies to almost every activity to which dangerous goods law is linked. According to Section 2 GbV, exceptions exist for small quantities (so-called exemption limits according to Chapter 1.1.3.6 ADR), for purely occasional transport and for cases in which the activity plays a very minor role. In practice, however, these exceptions are interpreted restrictively.

The threshold values ​​for the exemption limits are graded according to transport category 0 to 4. Substances in transport category 0 (particularly dangerous, such as some class 1 substances) trigger the obligation from the first kilogram. Substances in category 4 (particularly harmless) are generally exempt from the transport obligation until large quantities are reached. For most medium-sized companies with class 3, class 8 or class 9 shipping, the ordering obligation is regularly fulfilled because the quantity thresholds are exceeded in just a few shipping processes per quarter, especially in e-commerce and wholesale.

The dangerous goods officer must present a valid training certificate from the IHK in accordance with Section 4 GbV, which is valid for five years and is extended by a refresher test. Tasks include monitoring compliance with dangerous goods regulations, advising management, preparing the annual report in accordance with Section 8 GbV and investigating accidents and near misses with a written report. In the event of violations, there is a risk of fines of up to 50,000 euros per incident according to Section 37 GGVSEB. CIVAC offers the external appointment of a dangerous goods representative within two working days with an appointment certificate and notification to the authorities as well as platform maintenance of the annual report and accident files.

According to Section 8 GbV, the dangerous goods officer is obliged to prepare a written annual report on the company's activities with regard to the transport of dangerous goods. The report must contain at least the following content: the quantities transported per class during the reporting period, identified deficiencies and deviations, internal audits carried out, training measures for the personnel involved and recommendations for improving compliance. The report is presented to management and retained for at least five years. In the case of supervisory authority inspections by BAG or the responsible state authorities, it must be presented on request, often at short notice.

The training of the personnel involved in the transport of dangerous goods in accordance with Chapter 1.3 ADR is mandatory regardless of the appointment of the dangerous goods representative. The training includes a general introduction to dangerous goods law, task-related in-depth training and safety training with instructions on how to behave in the event of an accident. It must be repeated regularly; refresher training is usual every two years, and for some classes even annually. For activities with a higher risk, such as when shipping Class 1 or Class 7 substances, stricter requirements apply with the obligation to provide a documented knowledge test and list of participants.

In practice, audit evidence is the central element for audit-proof documentation. Anyone who can present the list of transports, proof of training, the transport document archive and the annual report digitally and in version in the audit to the district government or the BAG (Federal Office for Logistics and Mobility) will usually complete the audit within a few hours. Anyone who relies on paper folders and Excel files risks inquiries lasting several days and higher complaint rates. The CIVAC platform for the dangerous goods officer bundles these four areas of evidence in one interface with an audit trail and EU data residence, which significantly reduces the preparation time for controls.

The nine dangerous goods classes according to ADR are the basis of all obligations in dangerous goods law, from packaging to labelling and the transport document to the training of staff and the appointment of the dangerous goods representative. Anyone in medium-sized businesses who deals with Class 3 (flammable liquids), Class 8 (corrosive substances) or Class 9 (lithium batteries and others) is generally required to order in accordance with Section 1 GbV and is subject to training and reporting requirements. The operational load can be reduced in a structured manner if the appointment certificate, training certificates and annual report are available digitally and maintained in a versioned workspace. Audit-proof, documented, § 1-GbV-proof is the short formula.

CIVAC is a German compliance platform and officer-as-a-service. We offer the external dangerous goods officer in two models. In the platform model, you licence the workspace, keep your internal GGB and use 490 audit templates, the ADR 2025-compliant transport document templates, EU data residency and an automated annual report generator in accordance with Section 8 GbV. In the service model, CIVAC also appoints a named natural person with a valid IHK training certificate as an external dangerous goods representative, with an appointment certificate within two working days instead of the industry-standard four to eight weeks. Both models can be combined with other representative roles.

If you are looking for a documented hazardous goods representative for your shipping or warehouse operations, get an offer with a specific class overview. The auditor calls, the evidence is ready. Send a short inquiry to info@civac.de or using the contact form on civac.de, stating the classes you transport and approximate annual quantities per class. We will respond within one working day with an initial indication and a suggestion for a 30-minute initial consultation to clarify your needs. Turn reading into an assignment.