The toxicity of a substance is to be measured by each of the four different toxicities. The toxicity which indicates the most severe PG will be the PG assigned to that substance. Although it may be a general statement, the most severe result will come from inhalation toxicity.
The next severe will be from oral toxicity. The weakest toxicity will be measured from dermal toxicity. Therefore, it is unlikely that a substance will show PG II for inhalation toxicity and will show PG I for the other oral or dermal toxicities. Therefore, when inhalation toxicity is PG I, SP A4 and USG-02 will apply. In case of air transport, SP A4 dictates that 5L is the maximum quantity per package. Even if it shows 30L in Column L, air transportation of PG I Inhalation Toxicity is limited to 5L. For additional information, in case of surface transport, Packing Instruction P001 is used and the quantity is unlimited.