Is PU foam carcinogenic?


Again and again you hear and read that PU foam should be carcinogenic. Which ingredients that means, what the risk actually is, and how to best protect yourself when working with construction foam, is covered in detail in this post.

Processing PU foam

The risk involved in processing PU foam comes from the isocyanates it contains. The group of substances used here is mainly MDI (methyldiphenylisocyanate).

In animal studies MDI has been shown to be carcinogenic when inhaled. Similar things are suspected in humans. MDI is in free form only during the foamy state. Once the mounting foam has cured, the MDI is firmly bound to the silane groups of the foam and can no longer be inhaled.

A high risk exists above all with improper processing and with improper use. Cans must always be well shaken and kept as far away as possible. Rooms should definitely be well ventilated to avoid contact with MDI as much as possible.

Isocyanate-free foams

In commerce, one finds more and more isocyanate-free foams. MDI are no longer released during curing, but completely free from isocyanates but no construction foam. Whether the higher price justifies the lower risk, everyone has to judge for themselves.

PU foam in the cured state

Once PU foam has cured, no more isocyanates are released. However, there is another potential risk here: Contact with moisture from the air could also produce carcinogenic diamines.

However, this is scientifically not considered secure, but is only a guess. Contact with atmospheric moisture can only be avoided by airtight covering of all foamed joints and areas.

To what extent there is actually a burden in living rooms, can not say in concrete terms. Today, construction foam is almost indispensable in many areas - especially when installing windows and doors you can hardly get out without assembly foam. Alternatives are hardly possible here and only very expensive to process (for example, stuffing with cellulose or the like).

Tips & Tricks

Those who do not work professionally with PU foam on a daily basis usually have little to worry about, as the possible dose of MDI is relaitv low. Of course, the prerequisite is that you really work properly with it. Protective gloves are mandatory in any case, even the eyes and skin (long-sleeved, skin completely covering clothing) should always protect you.


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