How harmful is parquet glue to health when using underfloor heating?

Our living/dining area shall be excluded from tiling because we find tiles too cold in this 70 sqm large room and wood conveys a warmer feeling. That's why we decided on solid oak parquet which should be firmly glued down with a parquet elastic adhesive (80 kg). I know that parquet is not the best choice for underfloor heating but still feasible.

Right decision! :) Both in terms of parquet and gluing. However, you probably won’t get by with 80 kg. Most likely you will need 85 - 100 kg.

Wouldn’t the problem even get worse due to the heating up of the underfloor heating?

Nowadays the flow temperatures are up to 35 °C. So you can hardly speak of "heating up" anymore.

Will the adhesive evaporate and will "toxic gases" be released into the room? Or are modern parquet adhesives unproblematic? I read something about EC1 and EC1 Plus standards. Is one safe with such an adhesive?

I always say: No chemistry is healthy, and there is quite a lot of it in everything surrounding us. Furniture, paints, carpets, tile adhesive, etc. ;) Against that, you can try to keep possible emissions as low as possible, and from my point of view, you do exactly that by paying attention to the mentioned EC1 standards ... and by using as high-quality, solvent-free adhesive as possible. So use reasonable adhesive and don’t worry further about it.

By the way, so far I had always lived in apartments/houses with floating floors and ultimately decided on gluing in my own home. We had been debating back and forth the whole time but never regretted choosing the right method. Long plank oak.

Last week I attended a small webinar on the topic of harmful building materials, during which I asked the presenter if he could recommend parquet/floorboard adhesive because we would like to lay floorboards... he couldn't (it has something to do with boiling point and declaration requirements, etc.). He recommends nailed floorboards or linoleum (there are apparently water-based "good" adhesives for that...). I'm still undecided because nailed floorboards are not an option for us. I'm a fan of linoleum, but doing it myself? Hmm... You can't get the perfect healthy living house anyway. So maybe just pay attention to a good adhesive and still go for floorboards/parquet?

Then maybe just pay attention to a good adhesive and still use planks/parquet?

Exactly. You won't be able to completely exclude or reduce the possible pollutant emissions to zero. With a potentially existing controlled residential ventilation system in the house, I at least imagine that a possible problem is further mitigated.

Last week I attended a small webinar on harmful building materials, during which I also asked whether the speaker could recommend parquet/floorboard adhesive, because we would like to lay floorboards... he could not (it has something to do with boiling point and declaration requirements, etc.). He recommends nailed floorboards or linoleum (there are apparently water-based "good" adhesives for that...).

I am still undecided because nailed floorboards are out of the question for us. I am a fan of linoleum, but as a DIY project? Hmm...
You can't get a perfectly healthy house anyway. Maybe just pay attention to a good adhesive and still go for floorboards/parquet?

Or just lay them floating? We did that, I wouldn't glue parquet.

Or just lay it floating? We did that, I wouldn’t glue parquet.

Sensibly, parquet should always be glued down whenever possible.

Or simply lay it floating?

The manufacturer clearly advises against it "due to the extraordinary dimensions."