What item you use frequently would you be least surprised to learn is secretly bad for you?

Toothbrush. In one hand it scrubs food and gunk away and helps distribute fluoride toothpaste around. On the other it’s made of tiny plastic bristles that are probably disintegrating when in your mouth and growing a fun ecosystem when out of it.
- Ever since I heard of microplastic, this has been on my mind quite a bit. Although it might not be "ingested" if they are micro enough, it can probably still get absorbed every time you brush. Multiple that by every day of your life and, boom, now there's plastic in my balls and I'm 3D printing on my girl's face.
  
  boom, now there's plastic in my balls and I'm 3D printing on my girl's face.
  I’m stealing it
  
  Swirl necklace
- This is a clever answer and now I completely agree with you.
- the number of things growing on your toothbrush is definitely non zero but being frequently scrubbed in sodium fluoride probably inhibits a good portion of it\
  related though, electronic toothbrushes are way, way better in terms of tooth care, and my understanding the last time I read through marketing bullshit a few years ago was that the rotational/mechanical ones were better than the ones that just vibrate i.e. Oral B vs Sonicare, but the fucking Oral B toothbrush heads have fucking exposed bits of the mechanism, like, there's these holes in it, so like, guess what? mold grows in there
  I don't understand how that isn't like, you know, a massive design flaw that should be changed immediately, but I guess they want people to swap toothbrushes more often than mold would grow, idk
  
  A bit of advice from some dental organizations and my family member who is a dentist, you really shouldn't use the same toothbrush twice a day. The toothbrush should be left to completely dry out before reusing and that takes longer than 16 hours in most climates.
- I bought a uv tooth brush sterilizer. Not sure if it's doing anything useful but it's a colourful addition to the bathroom.
  
  UV is good at breaking down plastics ….
- In theory, your toothbrush is getting a clean twice a day. Its already covered in nice sudsy toothpaste foam and you'll (hopefully) be rubbing and rinsing that off.
  The plastic disintegrating in your mouth however, yeah, I can't dispute that!
- This is probably why dentists recommend replacing them frequently.

I work in hazardous materials handling and safety, and I studied chemistry. I've done a lot of soil remediation and I'm pretty up to date on how we (Europeans) handle the safety of our air, food and water.
So, good news: your air hasn't been cleaner since basically we started burning coal. Your drinking water hasn't been this safe since, oh, pre-agrarian times. Your food is probably less nutritious per gram thanks to faster growing food, but your diet is (potentially) better than any human has ever had (depending on your personal choices).
That said, there are some things I avoid like the plague:
Swimming in open water. It's (potentially) full of parasites, toxic algae, human and cattle feces and chemical runoff. Probably not all at once, but still. YMMV if you don't live near the sea, mountain streams are much cleaner then those at the river delta.
Home grown food from urban gardens. Your soil is probably completely untested, and the idea of "maybe I shouldn't just pour chemical waste out of the window" is barely 4 decades old. And that's counting the dubious quality of planter soil that is basically unregulated, and what people use as decoration. (Do NOT use wooden railroad ties or tires as planters for food). And of course what people use as pesticides isn't exactly closely monitored either.
Drinking water from wells, springs etc. see all the above.
Ordering anything with wish/aliexpress that comes in contact with food. You know that stuff is completely unregulated, why the hell would you lick it? Nobody knows what it's made of.
And there's one thing I don't avoid, but it's super unhealthy: wood fires. Yeah, a hearth or a campfire is awesome, but the smoke is super fucking bad for you. The carcinogens are stronger and last longer than in cigarettes, and its a hell of a lot more of them. I lie to myself and say it's worth it though, and that I don't do it every day, and other bad excuses.
- Wood fires are bad? Does this have to do with the wood? What about charcoal? No more bbqs then?
  
  Charcoal isn't as bad as wood, it creates less smoke and the most complex chemicals are already gone. Gas is better, since it burns much cleaner, and electric obviously doesn't create any gasses at all.
  On the other hand, grilling and smoking red meat means dripping fat, which means smoke, meaning you create a whole new set of PAHs (polycyclic aromatic hydrocarbons), which you breathe in and get stuck to the meat and those are carcinogens. On top of that, red meat is already not too great for you. Eating burned food (charring) is also really unhealthy.
  But assuming you don't spend every day breathing mostly bbq-smoke and gasses, I wouldn't worry about this too much. If your main diet is home grilled beef over self-made charcoal, you definitely need to reevaluate your lifestyle choices though.
- Home grown food from urban gardens. Your soil is probably completely untested, and the idea of “maybe I shouldn’t just pour chemical waste out of the window” is barely 4 decades old.
  And let's not forget that any soil near a road had a ton of lead released nearby throughout much of the last century, and that just stays there. As well as lead paint chips from buildings.

Plastic food containers. I mean, we already know it's pretty bad, but I would not be surprised if it ends up being way worse than we think. That, and most aerosols. Febreze, hairspray, spray tans, things of that nature
- I just saw an article the other day that black plastic utensils are toxic. I'm right there with you.
  A couple places near me still use styrofoam. I can't get past it.
  
  Because of those articles, I just got rid of my black plastic utensils, but I’ve been using them over a decade so if they were contaminated, it’s probably too late
- Yep, I never could get past the taste of plastic in my food.
  Only microwave in glass and ceramic!
- Febreze is air pressure driven.
  
  I think you're confusing volatile organic compounds like chlorofluorocarbons (CFCs) and HFCFs with general aerosols. CFCs destroy the ozone layer, and are banned worldwide.
  Aerosola are just droplets in a gas. Clouds are aerosols. They're perfectly safe to use in general, assuming the droplets and the gas are safe.
  
  I get where they're coming from! I was a kid when the aerosols were burning a hole in the ozone layer, and it taught me to distrust anything that can come out of a can too quickly.
  
  Clean air act banned cfcs, not aerosols. Aerosols are just pressurized gases.

Not really "secretly" bad for you, but all the plastic in our lives. I wonder how we'll ever replace it cause everything you buy at the supermarket (in developed countries) is wrapped in plastic.
- wrapped in plastic
- Everything you touch and use involves plastics and petrochemicals. Even stuff you wouldn’t think of like the coatings that allow street signs to reflect better and have massively improved safety. Lightbulbs? No more efficiency for you, most LEDs are on a plastic substrate. We will never get away from plastic, not at this point. You could make it so that food isn’t wrapped in plastic and that wouldn’t make a dent in our plastic use.
  
  You could make it so that food isn’t wrapped in plastic and that wouldn’t make a dent in our plastic use.
  Sure, but it might curb how much plastic ends up in our bodies. I have to assume that food wrapped in plastic has a greater impact in that regard than LEDs.
- I agree. I think it's worse than we already know.

Our phones are probably doing something to us
- We know that depending on your use it can ruin your attention span. But I agree, it's probably worse than we know.
- I read somewhere that the existence of the internet massively stifles our ability to reason. For every question I have, spending a few minutes to ponder what the most plausible answer is provides a small workout for my brain. If everything I'm curious about is answered within seconds, I don't get those mental workouts.
  
  I think that comes down to your desire to learn. One person might just repeat a google answer but another person might spend some time thinking about why it's the right answer.
  Google is how people get degrees after all, it's the modern day version of hunting down books in libraries

Probably my asbestos fake snow.
- But your snow is, at least, fireproof!
  Not all snow can make that promise. Some is quite flammable.
- I didn't even know such a thing existed!
  
  It was pretty common, even after the dangers of asbestos were well-known. The most famous example is probably the Wizard of Oz, but it was used all over the place.
- I'll stick to my anthrax lip balm.

Probably my vape tbh
- I figure we may see documetaries in yhr next decade on how Vape industry was complicit like the tabacco industry was
  
  There already are those documentaries? Jule or whatever it’s called has already been doing the exact same stuff that the tobacco industry did for literally a decade now.
  
  A majority of vape brands are already owned by tobacco companies.
  
  I mean, that's just how capitalism works. The health of your consumers isn't relevant, unless a law mandates it.
- I wouldn't be surprised. I wish there was a way to enjoy flavor without any horrific side effects.
  
  Tea, maybe?

Those water flavor squirts, mio or crystal light type stuff. I'll drink plain water over just about everything else (egg nog is the weakness and exception right now...), but the various lemonades or fruit flavors are always nice to have around. I wouldn't be surprised if something in their composition is not good for you.
A slightly more titillating answer would be lube. You're putting something on a mucous membrane, and it's almost guaranteed that some will be absorbed or ingested.
- I think if they find that these are a problem, any flavored drink will be found bad too. It's the same thing, just concentrated or not concentrated.
- The latter reason is why I use Yes WB which is an organic lube pH balanced for the... Mucous membrane.

Air fryers.
Most of them are designed so poorly that it’s also impossible to get all grease out of them. That can’t be healthy. My sister has a ninja air fryer, you can’t remove the top grate. There is grease build up in there. A friend of mine has one he brings it over during the Super Bowl party, the moment he opens up the lid on it you can smell the old grease come out of it. That’s not an exaggeration. There’s no way in hell that can be healthy. So it won’t surprise me if years from now people go we should never have used those.
It also won’t surprise me too much if there’s some health hazard with them other than just the buildup of grease.
Sidenote, what are these companies thinking to make a product where they know there’s going to be grease that is going to build up, and make it in a way that makes it almost impossible if not completely impossible to clean said grease?
Unless their thought process is: use it three times throw it away go buy a new one.
- It also won’t surprise me too much if there’s some health hazard with them other than just the buildup of grease.
  It’s an electric heating element and a fan, same as a convection oven except it exhausts rather than recirculates the air. Any issues beyond the grease buildup you mention would apply to any electric oven or toaster.
  
  I too have watched Technology Connection's video on the topic. :P
  
  Yes but with an oven you can get in there and clean it. The grate at the top of the air fryer is built in away, where you can’t really clean it.
- Huh we bought an expensive air fryer because my in-laws wouldn’t stop bragging about it. It was on super discount because bed bath and beyond was going out of business, but still super expensive. And I’ve never had any problem cleaning it, in fact it’s the easiest dish we own to clean, the grease just wipes out and the tray is removable.
- Oh my gosh, I never thought of that!
  I bought an air fryer, but honestly, I never use it because I hate cleaning the basket. I didn't even think about the top!
  Adding this one to my list. Definitely nothing good about blasting your food with old oils.
  
  Mine is one of my most non-stick surfaces and usually wipes clean with a paper towel
  …. Now that I’ve been trying to move away from teflon

Commercial yogurt. Yeah maybe it's just a tasty and healthy probiotic. Or maybe it's a way for food conglomerates to change our gut bacteria so that we crave even more foods with cheap sugar.

Bottled water. The plastic contaminates the fluid. Just drink straight from the sink if you live in an area that allows for it!
- I bet you're right. If you leave a plastic bottle in the sun, the water tastes god-awful.
  
  It doesn't even have to change temperature, it is enough that the water remains in the bottle for few days for plastic to start "decomposing" (probably not the correct word for it). And by the time you buy the bottle, it has been long since it was filled in the first place.
  Oh, and the expiration date on the water bottles? Obviously it's not the water getting stale. It's for the plastic.
- Tap water in super contaminated with PFAS in most areas, pick your poison
  (Or get a reverse osmosis filter)
- I switched over to have water delivered to my home in glass bottles (fortunately multi-use glass bottles are still a thing here in Germany). It tastes so much better than the same brand from PET bottles.
  (Why don't I drink tap water? Because I want my water sparkling with CO2 bubbles, and I don't like the simple carbonaton appliance)

The electric heating pad I sleep on. I wouldn't be surprised if some study finds that something about sleeping on wires would be kinda bad long-term. Maybe something about residual currents or the minimal magnetic field from the wires, idk
- The fireproofing chemicals are pretty bad for you.
  
  I guess, but fire isn't very healthy either I think
- I haven't been able to use one of these since I used a crummy one about 12 years ago and got burned, but it was so insanely nice to be so toasty.
  
  Yeah, that's very valid! I'd like to think that the technology got safer in the past years, but honestly I don't even wanna check and risk having to give up the coziness
- I’ve read articles with such claims, but not really reputable sources.
  However I like the idea of the timer ones where in theory you could have the bed preheated for you, but never be in it when it’s on.
  
  Most heated blankets have such a feature

Sugar
- That's not exactly secretly bad... It's just bad
  
  Yeah, the natural state of humans is ketosis. Glucose stinks and we don't need it!
- This is not really a secret. The sugar industry lobbied so hard to have sugar included in everything and well, we're seeing the damage.
- I think sugar by itself is not so bad. The fact it is in amost all types of prepared foods from the store is really bad. But I'm not a specialist.
- Ooh, excellent one.

Huel. I'm just waiting for some ~~random internet person~~ doctor to tell me how exactly I'm making my already shaky health significantly worse because I'm too ~~lazy~~ tired for anything more than powder in water.
Also, the decades-old radiator in my flat is probably just spewing all sorts of hazardous particles and nobody will know until they do an autopsy on me.
- I used to do Huel pretty regularly because one of my medicines makes me not want food and shakes are tolerable. But they kept selling out of my favorite flavor!
  Here's hoping it's not too toxic!
- Most radiators are just a big metal thing which a hot liquid slowly flows through to radiate the heat into the space. Kinda hard for that to be bad for you unless you burn yourself
- If it's any consolation I've been on at LEAST 80% Huel (and this is surely a low-ball; on the vast majority of days I'll go 100% Huel) since 2020 and my recent blood panel came back great.

The internet and all electronic equipment. I think they are doing something much more sinister than whatever is reported so far.
- Using it no... the trash yes. The amount of materials (toxic and rare) which goes to the bin is staggering.

- That's why I use a mini split ductless unit. A lot easier to clean.

Does it count if I already know whiskey is bad for me?
- It absolutely counts, if you wouldn't be surprised to learn that it's worse for you than you know.

Flavored soda water.

Warfarin blood thinners.
Wouldn't be surprised if we find later that after decades of use that someone's body can gain resistance to it. I'd be fucked since I'm on the blood thinner train for life*.
*or until we can start printing human cells to recreate human parts

My insulin.
- I can promise you it's not nearly as bad as not taking your insulin.
  
  Oh yeah, defiantly. Wife said, maybe it ends up like chemo, the benefits, out weigh the bad, but you still don't want to use it as a hair removal drug.

I'm so nervous I'm going to find out aquaphor is bad. I've been spreading it on my baby's diaper area since they were born. I know she's absorbing it right into her little body. There's been so many articles about how diapers and tampons and pads are all just awful for us and full of lead and who knows what else and we're putting them right against our mucus membranes and just poisoning ourselves.
- If you want to try something else, Burt's bees has a healing ointment for babies that is shea butter based instead of petroleum. Never actually used it on a baby myself lol but it worked wonders for me on my scalp (I have curly biracial hair and I'm picky about what goes in it) and scaly winter hands!

Cosmetic products containing carbomer - it's literally microplastic acryllic and it's in EVERYTHING

Methadone

UHT milk.
- I've been mad about UHT milk ever since I discovered I can't make clotted cream with the ultra high temperature stuff. I don't want unpastuerized milk but ffs, let me have some texture I can work with!
  
  You make clotted cream from milk? Doesn't that take like a week? Don't you usually start with some form of cream?
  I mean, I made it once from double cream, but they don't sell that here in the Netherlands, and it's so not worth the time compared to just buying a jar of clotted cream.
  More power to you though!

Beer
- That's been around for at least a couple millennia, though; you'd think we'd know by now, right?
- I mean frequent consumption is pretty well documented to be bad for your liver, and they don't call it a beer belly for nothing. Like any kind of indulgence, moderation is key
  Also worth noting beer historically was very very light on alcohol, so it was effectively a method of making water safe to drink rather than about having fun getting drunk

almond milk

I wouldn't expect shaving cream to do it; goo and foam and pretty normal

All of these Omega-3 and so-called healthy foods that have markup prices.
Like, an organic banana vs a original banana. What the fuck am I missing out on here?
- Like, an organic banana vs a original banana. What the fuck am I missing out on here?
  Mostly I've noticed the organic ones have more flavour. If there's nutritional differences, I'd mostly expect it to just be more of the same nutrients in the organic version.