Ruling on selling perfumes that contain harmful substances

If it is not proven (and it is not thought most likely) that these
perfumes are harmful, then there is nothing wrong with buying and selling
them, or using them, because the basic principle is that this is
permissible, and there is no evidence or reason to make us shift from this
basic principle. 

But if it is proven that these perfumes are harmful, then it is prohibited
to use them and perfume oneself with them. 

Based on what is well-known from the texts and basic aims of Islam, anything
that causes harm to one’s religious commitment or physical well-being,
whether it is food, drink, oil, perfume or the like, it is prohibited for
the individual to use it or deal in it. Allah, may He be exalted, says
(interpretation of the meaning): “and
make not your own hands contribute to (your) destruction”
[al-Baqarah 2:195]. 

It
is not permissible for the Muslim to sell these harmful perfumes, because
that is causing harm to others, which is haraam, because the Prophet
(blessings and peace of Allah be upon him) said: “There should be neither
harm nor reciprocating harm.” Narrated by al-Haakim (2/57-58). He said: Its
isnaad is saheeh according to the conditions of Muslim. It was also classed
as saheeh by al-Albaani in Silsilat al-Ahaadeeth as-Saheehah
(1/498). 

If
the purchaser is happy to buy these perfumes because he wants to imitate
women, then it is not permissible to sell it to him in this case either,
because that is helping him to imitate women, which is a major sin. The
Messenger of Allah (blessings and peace of Allah be upon him) cursed men who
imitate women and women who imitate men. Narrated by al-Bukhaari (5435). 

Secondly: 

With regard to finding out from the supplier about the ingredients of these
perfumes, if there is certainty that these perfumes are harmful, then there
is no need to ask about that in that case, because what you must do is
refrain from using them, and asking about it will not change the facts of
the matter at all. But if there is some doubt about the harmful effects of
these perfumes and the matter has not reached the degree of certainty, then
you should ask to find out the facts in this case. The stronger the
suspicions and doubts, the more important it is to ask. 

This applies if the supplier is going to the tell the truth. But if he is
going to lie in order to promote his own product, then asking this question
will not benefit the questioner at all. 

And Allah knows best.