Plastic. Its in your blood ffs

Social media. It wasn't until very recently that people started to realize just how harmful it actually is.

Sugar. People don't realize how bad it is for you and how addictive it is.

Perfluoroalkyls aka PFAS appear to screw with all manner of body functions.

Since you mention tobacco: It's worth noting that the smoking/cancer connection was noticed long before peak cigarette smoking in the population. Prior to WWII, lung cancer was considered a rare disease. That changed with the mass marketing of cigarettes.

PFAS, which are needed to produce teflon and other nonstick materials. It currently begins to attack attention, but wasn't really an issue a few years ago. It doesn't decay naturally so it will be forever in the environment. The EU is even planning to ban all PFAS.

Microplastics are the new lead, and screens are the new tobacco, in my opinion. Overuse of sugar in processed foods is the new version of how they'd cut food with inedible stuff like sawdust back in the day.

Social media

Vapes.

What will happen is one or another of the flavorings used will be safe to eat because of stomach acid and digestion, but inhaling it into delicate lungs will cause disease long term. Look up popcorn workers lung to see how a common butter flavoring in the past that was meant for eating on popcorn harmed factory workers breathing it in daily.

One of the existing vape flavors... or a new one... will eventually be shown to cause simular lung disease due to daily breathing it in never truly being studied. Someone with a favorite flavor will use it for years, like any smoker with a favorite brand of cigs, then probably get sick from constant long term exposure.

Tiktok.

You said product, and I mean this legitimately. Not because of meme hate or hating on what is trendy, but because it is and has been a tool of the CCP. This isn't really in question, and it was one of the first large platforms to entirely erase the idea of a timeline and fully devote itself only to a algorithm feed. One that bytedance has put their finger on the scales of many times.

The effect this has is hard to quantify, but the postmortem on it is going to be incredible as we unpack exactly how much this influenced the trends and politics among zoomers, and to what extent.

Social media.

Microplastics and plastic related byproducts, like phtalates (which are connected with a decreased fertility in mammals)
I'm positive that the long term effects of these substances, that can be found in every link of the food chain nowadays, will be discussed a lot in the future

Probably brake pads. Everyone's living in cities now, just breathing in brake pad and lead particles.

Oh and car tires. Just huffing those all day.

Microplastics

Teflon.

Microplastics and PFAS

No, seriously, these two will kill Earth, and us

Marketing. We put a person on the moon because we were scared of the space race, and then we spent the next 50 years figuring out how to make rich people richer by manipulating human behavior and gamifying everything so you buy into the buy more stuff you don't need and click more stuff you don't care about. We've gotten so good at it, we only need a 10 second short to advertise stuff to you.

This affects everything we do down to its core and will likely be the cause of astronomical ADHD rates in the future.

Resentment

Social Media

Fossil fuels.

Things have slowly drifted from "we might wanna consider doing something before this becomes a problem" to "we need an immediate and concrete plan" to "anything short of immediate and drastic action is killing and will continue to kill people" over the course of the last decade or two.

SOCIAL MEDIA