3.2 Class 6: Toxic and Infectious Substances
Key Takeaways
Division 6.1 toxic substances cause death, severe injury, or serious harm to health through oral ingestion, dermal absorption, or vapor/dust inhalation.
Packing Groups I, II, and III are defined by oral LD50, dermal LD50, and inhalation LC50 thresholds, with Packing Group I indicating extreme lethality (oral LD50 <= 5 mg/kg).
ADR 8.1.5.3 mandates an emergency escape mask for each crew member on transport units carrying Division 6.1 toxic goods.
ADR 7.5.4 enforces strict segregation prohibitions between Class 6 packages and food, foodstuffs, or animal feed.
Division 6.2 categorizes pathogens into Category A (life-threatening diseases, UN 2814/2900, P620 packaging) and Category B (biological specimens, UN 3373, P650 packaging).
3.2 Class 6: Toxic and Infectious Substances
Quick Answer: ADR Class 6 encompasses chemical and biological threats to human and animal life. Division 6.1 comprises toxic substances classified into Packing Groups I, II, and III based on oral, dermal, and inhalation exposure criteria (LD50 and LC50). Division 6.2 covers infectious pathogens split into Category A (life-threatening pathogens under UN 2814/2900 requiring certified P620 packaging) and Category B (biological diagnostic specimens under UN 3373 and P650 packaging).
Division 6.1: Toxic Substances — Definition and Exposure Routes
Under ADR 2.2.61.1.1, toxic substances are substances known by experience or animal testing to be liable, in relatively small quantities, to cause damage to human health or death by ingestion, inhalation, or skin absorption.
Toxicity manifests through three primary physiological routes:
- Oral ingestion: Ingestion of chemical residues from contaminated hands, food, or drink.
- Dermal absorption: Direct penetration through intact skin into the bloodstream (e.g., organophosphates, cyanide compounds, and aniline).
- Inhalation: Inhaling toxic vapors, fine aerosols, mists, or respirable dusts directly into lung alveoli, facilitating instant systemic absorption.
Toxicity Criteria and Packing Group Classification (LD50 and LC50)
ADR classifies Division 6.1 substances into three packing groups using standardized quantitative testing criteria:
- Oral LD50 (Lethal Dose 50%): Single dose causing death within 14 days in 50% of young adult albino rats (mg/kg body weight).
- Dermal LD50: Dose in continuous contact for 24 hours with bare rabbit skin causing death within 14 days in 50% of test animals (mg/kg).
- Inhalation LC50 (Lethal Concentration 50%): Continuous inhalation concentration causing death in 50% of test rats (mg/L for dusts/mists, ml/m3 for vapors, one-hour ADR LC50 values; conversion rules apply when data use other durations).
| Packing Group | Danger Level | Oral LD50 (mg/kg) | Dermal LD50 (mg/kg) | Inhalation Dust/Mist LC50 (mg/L) | Inhalation Vapor Criteria |
|---|---|---|---|---|---|
| Packing Group I | Highly toxic | <= 5 | <= 50 | <= 0.2 | V >= 10 LC50 and LC50 <= 1,000 ml/m3 |
| Packing Group II | Toxic | > 5 to <= 50 | > 50 to <= 200 | > 0.2 to <= 2.0 | V >= LC50 and LC50 <= 3,000 ml/m3 (not PG I) |
| Packing Group III | Slightly toxic / Harmful | > 50 to <= 300 | > 200 to <= 1,000 | > 2.0 to <= 10.0 | V >= 0.2 LC50 and LC50 <= 5,000 ml/m3 (not PG I/II) |
(Note: V is the saturated vapor concentration in ml/m3 air at 20°C and standard atmospheric pressure.)
Operational Precautions: Emergency Escape Masks (ADR 8.1.5)
Under ADR 8.1.5.3, for each member of the vehicle crew, an emergency escape mask is mandatory on any transport unit carrying goods bearing Division 6.1 (toxic substances) or Division 2.3 (toxic gases) labels.
Operational rules for escape masks include:
- Filter capability: The mask must include an appropriate combined gas and particulate filter (such as an A1B1E1K1-P1 or A2B2E2K2-P2 combination filter) effective against organic, inorganic, acid, and basic toxic gases and hazardous dusts.
- Escape function only: The mask is strictly engineered for rapid self-rescue and immediate evacuation from an accidental release zone. It must never be used for firefighting, entering enclosed cargo holds, or chemical salvage.
- Accessibility: Escape masks must be stored in the driver's cab where they can be reached immediately without opening the cargo area.
Segregation from Foodstuffs and Animal Feed (ADR 7.5.4)
ADR 7.5.4 applies to packages and uncleaned empty packagings bearing labels 6.1 or 6.2 and the specified Class 9 entries (UN 2212, 2315, 2590, 3151, 3152, 3245). They must not be stacked on or loaded in immediate proximity to food and feed. Permitted separation includes a complete partition of the required height, intervening non-relevant packages, or at least 0.8 m. An additional packaging or complete covering of the relevant dangerous goods is another specified exception. These are alternatives, not “overpack plus 0.8 m” in every case. See section 7.1 for application.
If any toxic or infectious package leaks, the cargo space must be thoroughly unloaded, decontaminated, and inspected before any subsequent cargo can be loaded.
Division 6.2: Recognising Infectious Substances
Infectious substances are known or reasonably expected to contain pathogens. Category A concerns material carried in a form capable, on exposure, of causing permanent disability or life-threatening or fatal disease in otherwise healthy humans or animals. Category B does not meet those criteria. The sender determines the correct entry and preparation under the applicable rules; a routine diagnostic sample is not automatically category B solely because a clinic sent it.
UN 2814 concerns infectious substances affecting humans, and UN 2900 those affecting animals only. UN 3373 identifies biological substance, category B, with its specific mark and P650 provisions. Some medical wastes have other assigned entries. Class 6.2 has no packing groups. Detailed preparation of specialist infectious consignments is outside basic driver training.
What the driver actually checks
- Match the shipment description and package count to the information supplied.
- Check externally for damage, leakage or missing required identification without opening packages.
- Keep packages secure and protect them against crushing, falling and unauthorised access.
- Use the assigned route, delivery arrangements and any applicable security procedure.
- Stop and obtain expert instructions if the description, marks and intended handling are inconsistent.
A damaged-package scenario
At collection, a driver sees a wet stain spreading from a specialist medical consignment. The correct response is to stop loading, prevent others from handling it and notify the responsible consignor and carrier. Ordinary driving gloves and an emergency escape mask do not make investigation safe. The driver must not open the outer packaging, transfer its contents or try to identify the biological agent.
If damage becomes apparent during carriage, use the Instructions in Writing, move away from exposure and contact the emergency services and carrier from safety. Tell responders what the transport information says and distinguish observations from guesses. Do not touch leaked material, clean it with cab supplies or carry contaminated clothing into the cab. Specialist arrangements govern recovery, decontamination and disposal.
For food segregation, apply 7.5.4 when the prescribed label conditions are present. A UN 3373 mark is different from a danger label 6.2; do not assume every medical parcel has identical ADR documentation, equipment or mixed-loading requirements. The role of a basic driver is to recognise these boundaries and obtain the correct instructions before acceptance.
Source check: 17 October 2026 — ADR 2025, English text published by the Slovak Ministry of Transport, 2.2.61, 2.2.62, 7.5.4 and 8.1.5.
Under ADR 2.2.61 criteria, what is the acute oral toxicity threshold defining a Division 6.1 substance as Packing Group I?
An oral LD50 of 5 mg/kg or less
An oral LD50 between 50 mg/kg and 300 mg/kg
An oral LD50 between 300 mg/kg and 2,000 mg/kg
An oral LD50 exceeding 5,000 mg/kg
Under ADR 8.1.5.3, what specialized item of personal safety equipment is mandatory for every crew member on a transport unit carrying Division 6.1 toxic substances?
A full-body lead-lined radiation suit
An emergency escape mask with a combination gas and particulate filter
A positive-pressure scuba diving apparatus
A portable high-pressure chemical decontamination shower
Which classification criteria and UN numbers correctly distinguish Category A from Category B infectious substances?
Category A consists of clinical diagnostic specimens under UN 3291, whereas Category B consists of animal carcasses under UN 2900
Category A consists of genetically modified crops under UN 3245, whereas Category B consists of human vaccines under UN 2814
Category A pathogens can cause permanent disability or fatal disease (UN 2814/2900), whereas Category B pathogens do not meet those criteria (UN 3373)
Category A substances require standard cardboard boxes under P650, whereas Category B substances require steel cylinders under P620
What loading segregation rule applies when carrying Class 6.1 toxic substances on the same transport unit as foodstuffs under ADR 7.5.4?
Uncovered toxic packages may be stacked directly on loose bags of grain
Foodstuffs and toxic chemicals may be interlocked on the same wooden pallet to maximize payload
Toxic goods may be transported with food provided the vehicle travels only during daylight hours
Prevent immediate proximity to food by applying a permitted 7.5.4 separation arrangement, such as at least 0.8 metres
Sections you finish are checked off in the contents.