Соответствующая норма
Practice Relating to Rule 72. Poison and Poisoned Weapons
Iraq’s Law of the Supreme Iraqi Criminal Tribunal (2005) identifies “[u]sing poisons or poisoned weapons” as a serious violation of the laws and customs of war applicable in international armed conflicts. 
Iraq, Law of the Supreme Iraqi Criminal Tribunal, 2005, Article 13(2)(R).
In 1991, during a debate in the UN Security Council concerning the aftermath of the Gulf War, Iraq implied that the use of shells made of depleted uranium was against international law, since they had poisonous effects. 
Iraq, Statement before the UN Security Council, UN Doc. S/PV.2981, 3 April 1991, pp. 29–30.
The Report on the Practice of Iraq states: “The banning is absolute in using poisonous materials in itself due to its harmful effects to the individuals and the environment.” 
Report on the Practice of Iraq, 1998, Chapter 3.2.