Ruling on disposing of samples after testing them
If the samples are to be returned after examining them, then they belong to them and it is not permissible to anyone to take any of them without their permission, because the Prophet (peace and blessings of Allaah be upon him) said: “The wealth of a man is not permissible unless he gives it willingly.” Narrated by Ahmad (20172); classed as saheeh by al-Albaani in Saheeh al-Jaami’ (7662).
But if these samples are not returned to the owners because they no longer want them, rather they may be consulted as to do with them, then if they allow those who take them to dispose of them, it is permissible for the employees to take them and dispose of them.
It is permissible – even obligatory – for them to take them if they have been told to get rid of them, because Islam forbids wasting wealth and enjoins being grateful for blessings, and wasting them is contrary to these two commands.
It seems – and Allaah knows best – that the owners of these samples are not asking for them and they regard them as no longer belonging to them; if that is the case then there is nothing wrong with anyone taking them, and it is like the wealth that a person leaves because he no longer wants it, so the one who takes it becomes its owner, as the scholars said.
See: al-Mughni (5/347).
And Allaah knows best.