HazMat Tool — substance information

Toxic solids, self-heating, n.o.s.

HMT May 2026

UN / ID: UN 3124
Hazard class: 6.1
Packing group: I (multiple — see tabs)
ERG guide: ERG 136
Special provisions: SP A5, SP T6, SP TP33
Source: 49 CFR §172 (2026/05)

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Toxic solids, self-heating, n.o.s.

Toxic or poisonous material is a material, other than a gas, known to be so toxic to humans that it presents a health hazard during transportation. More Information

Emergency Response Guide No. 136

Hazardous Materials Table

Source: 49 CFR §172 (2026/05)

Packing group I
Packing group II

(3) Hazard Class

6.1
Poisonous Material

This entry is signed with "G". The letter "G" identifies proper shipping names for which one or more technical names of the hazardous material must be entered in parentheses, in association with the basic description. (See §172.203(k)).

(7) Special Provisions (§172.102)

×Note:
Special provisions may be very complex. The extracts are taken from 49 CFR §172.102. Please be careful with the information, as necessary, additional conditions may be applied that are not written here. Please check the original source and report bugs.

Solids having an inhalation toxicity of Packing Group I are not permitted on passenger aircraft and may not exceed a maximum net quantity per package of 15 kg (33 pounds) on cargo aircraft.

Browse special provision A5

Minimum test pressure (bar)	4
Minimum shell thickness	§ 178.274(d)(2)
Pressure-relief requirements	Normal
Bottom opening requirements	§ 178.275(d)(2)

Browse special provision T6

TP33

The portable tank instruction assigned for this substance applies for granular and powdered solids and for solids which are filled and discharged at temperatures above their melting point which are cooled and transported as a solid mass. Solid substances transported or offered for transport above their melting point are authorized for transportation in portable tanks conforming to the provisions of portable tank instruction T4 for solid substances of packing group III or T7 for solid substances of packing group II, unless a tank with more stringent requirements for minimum shell thickness, maximum allowable working pressure, pressure-relief devices or bottom outlets are assigned in which case the more stringent tank instruction and special provisions shall apply. Filling limits must be in accordance with portable tank special provision TP3. Solids meeting the definition of an elevated temperature material must be transported in accordance with the applicable requirements of this subchapter.

Browse special provision TP33

(8) Packing Authorizations (§173.***)

(8A) Exceptions	None
(8B) Non-bulk	211	see 49 CFR §173.211
(8C) Bulk	242	see 49 CFR §173.242

(9) Quantity Limits

(9A) Passenger aircraft/rail	5 kg
(9B) Cargo aircraft only	15 kg

(10) Vessel stowage

(10A) Location

Stowage category “D” means the material must be stowed “on deck only” on a cargo vessel or on a passenger vessel carrying a number of passengers limited to not more than the larger of 25 passengers or one passenger per each 3 m of overall vessel length, but the material is prohibited on a passenger vessel in which the limiting number of passengers is exceeded.

Source: 49 CFR §172.101(k)

(10B) Other

40	see 49 CFR §176.84

Source: 49 CFR §176.84

(3) Hazard Class

6.1
Poisonous Material

(4) Identification number

UN 3124

(5) Packing Group

Comparison View of PG

(6) Labels

Spontaneously combustible materials (4.2)

(1) Symbols

(7) Special Provisions (§172.102)

IB6

Authorized IBCs: Metal (11A, 11B, 11N, 21A, 21B, 21N, 31A, 31B and 31N); Rigid plastics (11H1, 11H2, 21H1, 21H2, 31H1 and 31H2); Composite (11HZ1, 11HZ2, 21HZ1, 21HZ2 and 31HZ1).
Additional Requirement: Composite IBCs 11HZ2 and 21HZ2 may not be used when the hazardous materials being transported may become liquid during transport.

Browse special provision IB6

IP2

When IBCs other than metal or rigid plastics IBCs are used, they must be offered for transportation in a closed freight container or a closed transport vehicle.

Browse special provision IP2

Minimum test pressure (bar)	2.65
Minimum shell thickness	§ 178.274(d)(2)
Pressure-relief requirements	Normal
Bottom opening requirements	§ 178.275(d)(2)

Browse special provision T3

TP33

Browse special provision TP33

(8) Packing Authorizations (§173.***)

(8A) Exceptions	None
(8B) Non-bulk	212	see 49 CFR §173.212
(8C) Bulk	242	see 49 CFR §173.242

(9) Quantity Limits

(9A) Passenger aircraft/rail	15 kg
(9B) Cargo aircraft only	50 kg

(10) Vessel stowage

(10A) Location

Source: 49 CFR §172.101(k)

(10B) Other

40	see 49 CFR §176.84

Source: 49 CFR §176.84

Packing group comparison

Multiple packing groups apply to this entry. See assignment criteria in 49 CFR §173 Subpart D. Details are in the tabs above; differences are highlighted.

	PG I	PG II
1	G	G
2	Toxic solids, self-heating, n.o.s.	Toxic solids, self-heating, n.o.s.
3	6.1	6.1
4	UN 3124	UN 3124
5	I	II
6	6.1, 4.2	6.1, 4.2
7	A5, T6, TP33	IB6, IP2, T3, TP33
8A	None	None
8B	211	212
8C	242	242
9A	5 kg	15 kg
9B	15 kg	50 kg
10A	D	D
10B	40	40

Segregation chart for load, transport, and storage

This chart shows whether loading, transport, or storage with other hazard classes is permitted, prohibited, or restricted. Based on 49 CFR §177.848.

Note: The HMR prohibit only those Division 6.1 liquids that meet the definition of a Packing Group (PG) I and Hazard Zone A. See special provision 1 and PHMSA Interpretation #09-0252.

Packages with POISON or POISON INHALATION HAZARD labels, or a POISON label displaying “PG III,” or “PG III” marked next to a POISON label may not be transported with foodstuffs, feed or any other edible material, intended for humans or animals. For exceptions see 49 CFR §177.841(e).

Scope & sources (important)Click to show CFR references

This check evaluates segregation per 49 CFR §177.848. Additional loading/unloading and handling requirements may still apply; see 49 CFR §177 Subpart B (Loading and Unloading):

§177.834 - General requirements
§177.835 - Class 1 materials
§177.837 - Class 3 materials
§177.838 - Class 4 (flammable solid) materials, Class 5 (oxidizing) materials, and Division 4.2 (pyroforic liquid) materials
§177.839 - Class 8 (corrosive) materials
§177.840 - Class 2 (gases) materials
§177.841 - Division 6.1 and Division 2.3 materials
§177.842 - Class 7 (radioactive) material
§177.843 - Contamination of vehicles

Similar substances

UN / ID	Proper shipping name	Hazard class
UN 2793	Ferrous metal borings or Ferrous metal shavings or Ferrous metal turnings or Ferrous metal cuttings in a form liable to self-heating	4.2
UN 2968	Maneb stabilized or Maneb preparations, stabilized against self-heating	4.3
UN 3187	Self-heating liquid, toxic, inorganic, n.o.s	4.2
UN 3184	Self-heating liquid, toxic, organic, n.o.s	4.2
UN 3128	Self-heating solid, toxic, organic, n.o.s	4.2
UN 3191	Self-heating solid, toxic, inorganic, n.o.s.	4.2
UN 3397	Organometallic substance, solid, water-reactive, self-heating	4.3
UN 3188	Self-heating liquid, corrosive, inorganic, n.o.s	4.2
UN 3185	Self-heating liquid, corrosive, organic, n.o.s	4.2
UN 3126	Self-heating solid, corrosive, organic, n.o.s	4.2
UN 3206	Alkali metal alcoholates, self-heating, corrosive, n.o.s.	4.2
UN 3209	Metallic substance, water-reactive, self-heating, n.o.s	4.3
UN 3400	Organometallic substance, solid, self-heating	4.2
UN 3186	Self-heating liquid, inorganic, n.o.s	4.2
UN 3183	Self-heating liquid, organic, n.o.s	4.2