Hazard class 4.3

Class 4.3: Dangerous when wet

Materials that give off flammable or toxic gas when they contact water. Below is every Class 4.3 entry in 49 CFR §172.101 that has a UN/NA number — 89 entries.

ID	Proper shipping name	Class	PG
UN1183	Ethyldichlorosilane	4.3	I
UN1242	Methyldichlorosilane	4.3	I
UN1295	Trichlorosilane	4.3	I
UN1340	Phosphorus pentasulfide, free from yellow or white phosphorus	4.3	II
UN1360	Calcium phosphide	4.3	I
UN1389	Alkali metal amalgam, liquid	4.3	I
UN1390	Alkali metal amides	4.3	II
UN1391	Alkali metal dispersions, or Alkaline earth metal dispersions	4.3	I
UN1392	Alkaline earth metal amalgams, liquid	4.3	I
UN1393	Alkaline earth metal alloys, n.o.s	4.3	II
UN1394	Aluminum carbide	4.3	II
UN1395	Aluminum ferrosilicon powder	4.3	II
UN1396	Aluminum powder, uncoated	4.3	II
UN1397	Aluminum phosphide	4.3	I
UN1398	Aluminum silicon powder, uncoated	4.3	III
UN1400	Barium	4.3	II
UN1401	Calcium	4.3	II
UN1402	Calcium carbide	4.3	I
UN1403	Calcium cyanamide with more than 0.1 percent of calcium carbide	4.3	III
UN1404	Calcium hydride	4.3	I
UN1405	Calcium silicide	4.3	II
UN1407	Cesium or Caesium	4.3	I
UN1408	Ferrosilicon with 30 percent or more but less than 90 percent silicon	4.3	III
UN1409	Metal hydrides, water reactive, n.o.s	4.3	I
UN1410	Lithium aluminum hydride	4.3	I
UN1411	Lithium aluminum hydride, ethereal	4.3	I
UN1413	Lithium borohydride	4.3	I
UN1414	Lithium hydride	4.3	I
UN1415	Lithium	4.3	I
UN1417	Lithium silicon	4.3	II
UN1418	Magnesium, powder or Magnesium alloys, powder	4.3	I
UN1419	Magnesium aluminum phosphide	4.3	I
UN1420	Potassium, metal alloys, liquid	4.3	I
UN1421	Alkali metal alloys, liquid, n.o.s	4.3	I
UN1422	Potassium sodium alloys, liquid	4.3	I
UN1423	Rubidium	4.3	I
UN1426	Sodium borohydride	4.3	I
UN1427	Sodium hydride	4.3	I
UN1428	Sodium	4.3	I
UN1432	Sodium phosphide	4.3	I
UN1433	Stannic phosphide	4.3	I
UN1435	Zinc ashes	4.3	III
UN1436	Zinc powder or Zinc dust	4.3	I
UN1714	Zinc phosphide	4.3	I
UN1870	Potassium borohydride	4.3	I
UN1928	Methyl magnesium bromide, in ethyl ether	4.3	I
UN2010	Magnesium hydride	4.3	I
UN2011	Magnesium phosphide	4.3	I
UN2012	Potassium phosphide	4.3	I
UN2013	Strontium phosphide	4.3	I
UN2257	Potassium	4.3	I
UN2463	Aluminum hydride	4.3	I
UN2624	Magnesium silicide	4.3	II
UN2805	Lithium hydride, fused solid	4.3	II
UN2806	Lithium nitride	4.3	I
UN2813	Water-reactive solid, n.o.s	4.3	I
UN2830	Lithium ferrosilicon	4.3	II
UN2835	Sodium aluminum hydride	4.3	II
UN2844	Calcium manganese silicon	4.3	III
UN2950	Magnesium granules, coated, particle size not less than 149 microns	4.3	III
UN2965	Boron trifluoride dimethyl etherate	4.3	I
UN2968	Maneb stabilized or Maneb preparations, stabilized against self-heating	4.3	III
UN2988	Chlorosilanes, water-reactive, flammable, corrosive, n.o.s	4.3	I
UN3078	Cerium, turnings or gritty powder	4.3	II
UN3129	Water-reactive liquid, corrosive, n.o.s.	4.3	I
UN3130	Water-reactive liquid, toxic, n.o.s	4.3	I
UN3131	Water-reactive solid, corrosive, n.o.s	4.3	I
UN3132	Water-reactive solid, flammable, n.o.s.	4.3	I
UN3133	Water-reactive, solid, oxidizing, n.o.s	4.3	II
UN3134	Water-reactive solid, toxic, n.o.s	4.3	I
UN3135	Water-reactive solid, self-heating, n.o.s.	4.3	I
UN3148	Water-reactive liquid, n.o.s.	4.3	I
UN3170	Aluminum smelting by-products or Aluminum remelting by-products	4.3	II
UN3208	Metallic substance, water-reactive, n.o.s	4.3	I
UN3209	Metallic substance, water-reactive, self-heating, n.o.s	4.3	I
UN3292	Batteries, containing sodium	4.3	—
UN3292	Cells, containing sodium	4.3	—
UN3395	Organometallic substance, solid, water-reactive	4.3	I
UN3396	Organometallic substance, solid, water-reactive, flammable	4.3	I
UN3397	Organometallic substance, solid, water-reactive, self-heating	4.3	I
UN3398	Organometallic substance, liquid, water-reactive	4.3	I
UN3399	Organometallic substance, liquid, water-reactive, flammable	4.3	I
UN3401	Alkali metal amalgam, solid	4.3	I
UN3402	Alkaline earth metal amalgams, solid	4.3	I
UN3403	Potassium, metal alloys, solid	4.3	I
UN3404	Potassium sodium alloys, solid	4.3	I
UN3476	Fuel cell cartridges or Fuel cell cartridges contained in equipment or Fuel cell cartridges packed with equipment, containing water-reactive substances	4.3	—
UN3482	Alkali metal dispersions, flammable or Alkaline earth metal dispersions, flammable	4.3	I
UN3543	Articles containing a substance which in contact with water emits flammable gases, n.o.s.	4.3	—

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Other hazard classes

Class 1 Class 2.1 Class 2.2 Class 2.3 Class 3 Class 4.1 Class 4.2 Class 5.1 Class 5.2 Class 6.1 Class 6.2 Class 7 Class 8 Class 9

Source: 49 CFR §172.101 via eCFR.gov, current as of Oct 23, 2026. Reference only.