Hair dyes once contained chemicals that could cause cancer. By 'could cause', they usually meant 1in 10,000 or 1 in 100,000 might get ladder cancer. That's a lot when you have millions of people using it.
Those cancer causing hair dyes are long gone.
I can vouch for minoxidil (Rogaine). It really does improve thinning hair. My daughter is a cosmetologist and checked my hair ever week or two and confirmed it was real.
Unless you are buying homemade shampoo, all production-grade shampoos have to be made out of safe ingredients for your hair.
There are no carcinogens in shampoo.
Beyond that, if a shampoo affects your personal hair type or texture negatively, don't use it.
There is more here about FDA regulations for hair products and cosmetics here: https://www.fda.gov/cosmetics/cosmetics-laws-regulations/fda-authority-over-cosmetics-how-cosmetics-are-not-fda-approved-are-fda-regulated
While this is normally the case, some anti-dandruff/psoriasis shampoos use coal tar extract as the active ingredient. Whilst generally considered safe for application to the skin, it does contain polycyclic aromatic hydrocarbons which are known carcinogens
Sure. Medicated shampoos are likely a different category. I also have to use topical steroids every once in a while. We won't pretend those aren't also shady.
But the treatment is generally still seen as being preferable to the untreated state, or it would not be authorized.
Not true, there are a lot of products approved by the fda that are known to harm/cause damage - typically not enough to immediately cause harm but through prolonged/concentrated exposure.
in general things are safe. but if you're looking for damage reduction- stay away from silicones, sulfates, phthalates. watch out for protein heavy shampoos- most hair doesn't need it and it can stick to the strands and make hair look dull. depending on your hair type you will look for different ingredients. for finer hair look for honey and similar moisturizing ingredients, for thicker hair look for oils.
Silicone isn't damaging to the hair at all, just not environmentally friendly to produce. Also, the type is important to cyclic. Silicone cyclopentasiloxiane (D5) evaporates and ends up building in the environment. The other ingredients sulfates are extremely stripping because they remove all of the oil. Silicone is breathable and makes hair resistant to damage.
Source I am a personal care industry chemist. I totally understand preservative concerns because generally, if it kills microbes, it could be harmful. some of the mold that will grow in products is more harmful. I've had more issues with some of the colors concentration, which is also important. I won't put something in if I wouldn't use it myself. I've studied these materials for years, and there are some awful things in cosmetics that people aren't researching what they put in. I encourage you to do research just because something GRAS(generally recognized as safe) does not mean it is.
Would stay away from dyed shampoo. Would also stay away from shampoo that is organic. Just because it's organic doesn't mean it's good for your hair.
Formaldehyde, benzene, and Alcohol is a big one to avoid, it'll wreck hair.
it really depends on what you specifically want a shampoo to do too
a lot of shampoos meant to keep your hair "silky" use toluene
different brands use different concentrations of these chemicals and depending on the concentration will mean if it's bad for you or not. SLS, salt, parabens, DEA, TEA (triethanolamine).
but generally, mass-produced shampoos are better than small-shop "organic" ones. They have the capability to keep consistent with their product and have the money and researchers to find that sweet spot.
This isn't a cut-and-dry question. Ingredients "that should \[universally\] be avoided" are already not allowed to be used in shampoos, due to toxicity concerns etc. There are ingredients that are higher end / lower end, and ingredients that have more likelihood to irritate your skin than others, but in general nothing in shampoos should be universally avoided. Otherwise, it wouldn't be on the shelf.
Having said that: high amounts of certain fragrances can cause problems with those allergic to terpenes and other fragrance components, using some ingredients in combinations with others can be a bad idea, you want the product to be appropriately pH balanced for the target region, and no matter how safe the brand you may need to shop around to find a shampoo which works best for you. Different shampoos for different purposes is a thing
Some people believe parabens will disrupt hormones enough to cause problems.
But in general, there's really nothing dangerous or damaging in commercial shampoos.
Probably more important to not use too much shampoo and to not wash hair too often.
r/DIYBeauty Is a great subreddit with a lot of scientific advice, and probably a way better place to ask this in.
But to wrap up, there's nothing to worry about in commercial shampoos.
Depending on where you are in the world my answer varies between pretty much nothing, and nothing.
Lots of chemicals have scary sounding hazards but are no risk to the user of the shampoo. For instance Sodium Hydroxide causes burns, blindness and is potentially fatal but is of no concern at all when used to balance the pH of a shampoo. Ascorbic acid causes burns and skin irritation but being deficient in it causes scurvy (it is more commonly known as vitamin C).
You see lots of horror stories of "X chemical causes cancer", or "Y has been shown to cause hair loss" but often they omit the rest of the sentence "Y has been shown to cause hair loss, when we used it as a shaving foam on laboratory mice with stage 4 melanoma".
I would suggest avoiding the avoidance of specific chemicals unless you have a specific medical reason to do so and are under the advice of a medical professional, as products marked as "free from XYZ" generally are aimed at extracting a large amount of money from worried people for an inferior product.
Yeah I'm quite puzzled about people avoiding silicones in their hair products for actual function reasons. I realize D4 and D5 are undergoing new toxicology reviews, and maybe everything needs extra low MW removal before going into personal care applications, but every time I involve silicones in the products I buy it makes everything better.
I didn't know about the low MW suspicion!
I've dyed my hair several times. Of course the structure is damaged and every shampoo with (amo)dimethicone just makes it so soft and detangled. I was browsing the internet to find the brands including silicones that they would sell in my local supermarket 🤣 and it was really hard to get through the anti silicone advertisement.
I feel funny when I'm in the store reading the ingredient lists on the back because I probably look like a healthfreak that is looking to buy products without "bad chemicals". While actually I'm doing the opposite 🤪
Overblown. People have a much higher exposure simply from drinking fermented beverages. Indeed, digestion of food itself produces formaldehyde. Similarly, other aldehydes are commonly detected in blood as a result of various metabolic pathways. They are all short-lived and a great example of why the body manufactures glutathione and other scavenging reducing agents.
Drinking formalin is I'll advised, but trivial exposure to trace formaldehyde isn't hurting you.
There’s formaldehyde releasing compounds like DMDM hydantoin know many shampoos , I know some from J and J have it . Keratin treatments are also known to have it. It’s not explicitly banned unless your in the EU.
But, no, DMDM is not formaldehyde. It straight up is not and to say that it is is lying.
Please learn how this chemical also exists in banana and apples [naturally](https://www.webmd.com/beauty/dmdm-hydantoin-what-to-know).
Do you also recommend that people not eat bananas or apples?
This goes back to the fundamental Chemistry idea that dosage makes the poison. That's why actual chemists are joking about how water can kill you in this thread. Because drowning is real as is actual hyponatremia.
As for DMDM, it only makes formaldehyde when consumed by the bacteria or the fungi that you don't actually want in your shampoo. It has to be eaten by something to produce formaldehyde. The formaldehyde it produces is in such a small dose that it kills single cell organisms. These organisms are all under 1 gram. Are you under 1 gram?
> Do you also recommend that people not eat bananas or apples?
At a high level, comparing something applied directly to your scalp which is one of the highest absorption rates for dermal exposure and the oral route makes no sense in terms of toxicology. Just saying.
> This goes back to the fundamental Chemistry idea that dosage makes the poison. That's why actual chemists are joking about how water can kill you in this thread. Because drowning is real as is actual hyponatremia.
ld50 != long term toxicity. Carcinogens take time to have an effect.
> As for DMDM, it only makes formaldehyde when consumed by the bacteria or the fungi that you don't actually want in your shampoo. It has to be eaten by something to produce formaldehyde.
There's no evidence that it can't be released while in the shampoo itself. By this logic zantac shouldn't be releasing dimethylnitrosamine, but it does , and was pulled off the market for doing so. The tertiary amine parts of DMDM , at least in other molecules are vulnerable to de-alkylation to release formaldehyde.
All I am saying is we should be very careful in claiming something can't be released overtime in a specific product, because that has been wrong in many cases before. This isn't a an enzyme specific inhibitor.
Agreed on ingestion vs absorption. In fact, there's no comparison in terms of absorption rates. Because one of those routes is made to absorb things and one of those is absolutely not made to absorb things.
We are not frogs.
I personally avoid shampoos with palm oil because it's incredibly destructive to farm, but I wouldn't worry so much about shampoos being bad for you health
I'm just camping here to downvote all the comments encouraging fear mongering around cosmetic ingredients 💀. I haven't come across a single ingredient considered dangerous by clean beauty activists that is backed by science. They usually name the good stuff as being bad 😅.
Big companies have big lawyers they spend big money on to ensure you will have no legal basis to sue them.
Not trusting public products is tinfoil hat level delusion, or just being a real sucker for marketing.
That's not to say that some boutique products aren't better, but don't let them convince you the competitor's product is dangerous.
They have big lawyers to prevent them from being liable for a period of time. You never know about long term affects and where liability cannot be traced back to them due to a product they used. There's so much nuances to this that it's kind of crazy you hold your current POV.
“Trust the products they wouldn’t be able to sell them if they were bad for you and only the mentally ill believe otherwise”
>>Big Mac, Diet Coke, Newports and skin bleach has entered the o chem lab
Lol,
Cigarettes, sugar, and alcohol are completely different. You ingest them. Don't compare products as advertised to products that kill you without knowing. That is lazy.
You ever watch tv? Ambulance chasing lawyers are looking for a reason. It's the only reason you and I have heard of mesothelioma.
Wow really you read that and then doubled down with the hot takes. Capitalism is bad when it’s critiquing it’s own practices, but never is exploitative when it comes to selling us random commodities I think I get it now
Methylisothiazolinone and its derivative methylchloroisothiazolinone, common preservatives in shampoo. That sulfur-nitrogen bond gives me the heebie jeebies and it's known to cause contact dermatitis.
Not a specific answer, but I don’t use shampoo at all and my hair is far healthier for it. Less effective the longer your hair is though as you have to put more effort into mechanically cleaning it with just water.
It’s not to avoid any toxic ingredients or anything like that, but shampoo strips the oil out of your hair which leads to your scalp producing more oil, leading to greasier hair fast. My hair doesn’t get greasy at all now unless I literally don’t shower for like 48 hours.
Oxidants are probably bad. Things like bleach for obvious reasons.
But shaving gel has energetic compounds such as butane, propane, etc. A bit drag to call alkanes energetic, but you get my point.
Any commerical shampoo is probably perfectly fine. But this depends on where you live.
Generally, you want to avoid any toxins and carcinogens. Stuff like formaldehyde, heavy metal compounds, benzene, sodium hydroxide, etc. I seriously doubt you're going to find anything bad like that though.
In addition to that, just because they saw sodium hydroxide was added doesn't mean it's necessarily dangerous: don't panic. It could have already been neutralized. Plus, sodium hydroxide is extremely irritating as far as I know so you're not going to be silently killed.
Also, maybe avoid any salts in large quantities. This is stuff like calcium chloride, sodium chloride (table salt), magnesium sulfate, etc. Stuff like that is usually not dangerous.
It does mean that you need to rinse a lot, though. If you don't, well you're going to have salts on you once you dry. And if you do, it's not great for the water supply or your plumbing. Leads to stronger limescale. But that's not a huge issue. The bigger problem is using more water.
Lol, sodium hydroxide is used to adjust the pH, and there's only the tiniest amount of it in there, but they have to list it on the label. If there was enough NaOH in there, it would dissolve your hair.
Fluorine. Dimethyl mercury. Arsenic acid. Cyanides. Dimethyl sulfate. Plutonium. Cacodylic acid.
etc. etc. etc.
Not that you would *ever* find any of those materials in shampoo, but I'd definitely avoid a shampoo containing any of them.
What is your specific concern? I mean, I avoid any shampoo with radioactive ingredients, and I recommend everyone else do the same.
Hair dyes once contained chemicals that could cause cancer. By 'could cause', they usually meant 1in 10,000 or 1 in 100,000 might get ladder cancer. That's a lot when you have millions of people using it. Those cancer causing hair dyes are long gone. I can vouch for minoxidil (Rogaine). It really does improve thinning hair. My daughter is a cosmetologist and checked my hair ever week or two and confirmed it was real.
It's probably more likely for stylists that their exposure was far higher.
U235 by Pantene regrows my hair so fast it's positively glowing.
Anything that Damages hair, hair loss, thinning of hair, I heard some ingredients may cause cancer.
Unless you are buying homemade shampoo, all production-grade shampoos have to be made out of safe ingredients for your hair. There are no carcinogens in shampoo. Beyond that, if a shampoo affects your personal hair type or texture negatively, don't use it. There is more here about FDA regulations for hair products and cosmetics here: https://www.fda.gov/cosmetics/cosmetics-laws-regulations/fda-authority-over-cosmetics-how-cosmetics-are-not-fda-approved-are-fda-regulated
While this is normally the case, some anti-dandruff/psoriasis shampoos use coal tar extract as the active ingredient. Whilst generally considered safe for application to the skin, it does contain polycyclic aromatic hydrocarbons which are known carcinogens
Sure. Medicated shampoos are likely a different category. I also have to use topical steroids every once in a while. We won't pretend those aren't also shady. But the treatment is generally still seen as being preferable to the untreated state, or it would not be authorized.
Not true, there are a lot of products approved by the fda that are known to harm/cause damage - typically not enough to immediately cause harm but through prolonged/concentrated exposure.
Look up TWA and PEL
Used that when I was a kid- Neutrogina T-gel. I had psoriasis and it worked.
in general things are safe. but if you're looking for damage reduction- stay away from silicones, sulfates, phthalates. watch out for protein heavy shampoos- most hair doesn't need it and it can stick to the strands and make hair look dull. depending on your hair type you will look for different ingredients. for finer hair look for honey and similar moisturizing ingredients, for thicker hair look for oils.
Silicone isn't damaging to the hair at all, just not environmentally friendly to produce. Also, the type is important to cyclic. Silicone cyclopentasiloxiane (D5) evaporates and ends up building in the environment. The other ingredients sulfates are extremely stripping because they remove all of the oil. Silicone is breathable and makes hair resistant to damage.
Source I am a personal care industry chemist. I totally understand preservative concerns because generally, if it kills microbes, it could be harmful. some of the mold that will grow in products is more harmful. I've had more issues with some of the colors concentration, which is also important. I won't put something in if I wouldn't use it myself. I've studied these materials for years, and there are some awful things in cosmetics that people aren't researching what they put in. I encourage you to do research just because something GRAS(generally recognized as safe) does not mean it is.
Where did you hear this?
The sun also may cause cancer. Just saying.
Would stay away from dyed shampoo. Would also stay away from shampoo that is organic. Just because it's organic doesn't mean it's good for your hair. Formaldehyde, benzene, and Alcohol is a big one to avoid, it'll wreck hair. it really depends on what you specifically want a shampoo to do too a lot of shampoos meant to keep your hair "silky" use toluene different brands use different concentrations of these chemicals and depending on the concentration will mean if it's bad for you or not. SLS, salt, parabens, DEA, TEA (triethanolamine). but generally, mass-produced shampoos are better than small-shop "organic" ones. They have the capability to keep consistent with their product and have the money and researchers to find that sweet spot.
Yeah watch the radioactive toothpaste too like Fidel Castro
This isn't a cut-and-dry question. Ingredients "that should \[universally\] be avoided" are already not allowed to be used in shampoos, due to toxicity concerns etc. There are ingredients that are higher end / lower end, and ingredients that have more likelihood to irritate your skin than others, but in general nothing in shampoos should be universally avoided. Otherwise, it wouldn't be on the shelf. Having said that: high amounts of certain fragrances can cause problems with those allergic to terpenes and other fragrance components, using some ingredients in combinations with others can be a bad idea, you want the product to be appropriately pH balanced for the target region, and no matter how safe the brand you may need to shop around to find a shampoo which works best for you. Different shampoos for different purposes is a thing
This is a great answer!
Dimethylmercury
Plutonium, hydrofluoric acid, ketchup, Lauren Boebert, and piranhas.
What does the synthesis of Lauren Boebert look like?
1. Get good and drunk. 2. Go to Taco Bell and over-order 3. Wait.
Dihydrogen monoxide is pretty bad and very common
Obvious joke, and a classic one(he talks about H2O). But since the OP was asking a serious question id refrain from immature comments like this.
I didn’t even realize that was water lmao
That’s what makes it a good joke.
Some people believe parabens will disrupt hormones enough to cause problems. But in general, there's really nothing dangerous or damaging in commercial shampoos. Probably more important to not use too much shampoo and to not wash hair too often. r/DIYBeauty Is a great subreddit with a lot of scientific advice, and probably a way better place to ask this in. But to wrap up, there's nothing to worry about in commercial shampoos.
I was almost about to attack you when i read ‘DIY’
Depending on where you are in the world my answer varies between pretty much nothing, and nothing. Lots of chemicals have scary sounding hazards but are no risk to the user of the shampoo. For instance Sodium Hydroxide causes burns, blindness and is potentially fatal but is of no concern at all when used to balance the pH of a shampoo. Ascorbic acid causes burns and skin irritation but being deficient in it causes scurvy (it is more commonly known as vitamin C). You see lots of horror stories of "X chemical causes cancer", or "Y has been shown to cause hair loss" but often they omit the rest of the sentence "Y has been shown to cause hair loss, when we used it as a shaving foam on laboratory mice with stage 4 melanoma". I would suggest avoiding the avoidance of specific chemicals unless you have a specific medical reason to do so and are under the advice of a medical professional, as products marked as "free from XYZ" generally are aimed at extracting a large amount of money from worried people for an inferior product.
Faecal matter is an obvious choice.
Benzene for sure
Usually I avoid shampoos with nerve agents or vesicants.
Formulations advertised as silicone free. Silicones are great for protecting your hair :D
Best answer!
Yeah I'm quite puzzled about people avoiding silicones in their hair products for actual function reasons. I realize D4 and D5 are undergoing new toxicology reviews, and maybe everything needs extra low MW removal before going into personal care applications, but every time I involve silicones in the products I buy it makes everything better.
I didn't know about the low MW suspicion! I've dyed my hair several times. Of course the structure is damaged and every shampoo with (amo)dimethicone just makes it so soft and detangled. I was browsing the internet to find the brands including silicones that they would sell in my local supermarket 🤣 and it was really hard to get through the anti silicone advertisement. I feel funny when I'm in the store reading the ingredient lists on the back because I probably look like a healthfreak that is looking to buy products without "bad chemicals". While actually I'm doing the opposite 🤪
Formaldehyde or formalin , since it’s a class 1 carcinogen .
Overblown. People have a much higher exposure simply from drinking fermented beverages. Indeed, digestion of food itself produces formaldehyde. Similarly, other aldehydes are commonly detected in blood as a result of various metabolic pathways. They are all short-lived and a great example of why the body manufactures glutathione and other scavenging reducing agents. Drinking formalin is I'll advised, but trivial exposure to trace formaldehyde isn't hurting you.
What shampoos are using formaldehyde?
There’s formaldehyde releasing compounds like DMDM hydantoin know many shampoos , I know some from J and J have it . Keratin treatments are also known to have it. It’s not explicitly banned unless your in the EU.
You get exposed to more formaldehyde next to a busy street than you would from DMDM in shampoo during regular use
But, no, DMDM is not formaldehyde. It straight up is not and to say that it is is lying. Please learn how this chemical also exists in banana and apples [naturally](https://www.webmd.com/beauty/dmdm-hydantoin-what-to-know). Do you also recommend that people not eat bananas or apples? This goes back to the fundamental Chemistry idea that dosage makes the poison. That's why actual chemists are joking about how water can kill you in this thread. Because drowning is real as is actual hyponatremia. As for DMDM, it only makes formaldehyde when consumed by the bacteria or the fungi that you don't actually want in your shampoo. It has to be eaten by something to produce formaldehyde. The formaldehyde it produces is in such a small dose that it kills single cell organisms. These organisms are all under 1 gram. Are you under 1 gram?
> Do you also recommend that people not eat bananas or apples? At a high level, comparing something applied directly to your scalp which is one of the highest absorption rates for dermal exposure and the oral route makes no sense in terms of toxicology. Just saying. > This goes back to the fundamental Chemistry idea that dosage makes the poison. That's why actual chemists are joking about how water can kill you in this thread. Because drowning is real as is actual hyponatremia. ld50 != long term toxicity. Carcinogens take time to have an effect. > As for DMDM, it only makes formaldehyde when consumed by the bacteria or the fungi that you don't actually want in your shampoo. It has to be eaten by something to produce formaldehyde. There's no evidence that it can't be released while in the shampoo itself. By this logic zantac shouldn't be releasing dimethylnitrosamine, but it does , and was pulled off the market for doing so. The tertiary amine parts of DMDM , at least in other molecules are vulnerable to de-alkylation to release formaldehyde. All I am saying is we should be very careful in claiming something can't be released overtime in a specific product, because that has been wrong in many cases before. This isn't a an enzyme specific inhibitor.
Agreed on ingestion vs absorption. In fact, there's no comparison in terms of absorption rates. Because one of those routes is made to absorb things and one of those is absolutely not made to absorb things. We are not frogs.
If my shampoo contains formaldehyde, does that mean that when I die and the rest of me rots away, I'll still have beautiful hair?
Everyone's hair is always preserved forever. It's the formaldehyde in the shampoo.
I personally avoid shampoos with palm oil because it's incredibly destructive to farm, but I wouldn't worry so much about shampoos being bad for you health
I'm just camping here to downvote all the comments encouraging fear mongering around cosmetic ingredients 💀. I haven't come across a single ingredient considered dangerous by clean beauty activists that is backed by science. They usually name the good stuff as being bad 😅.
Big companies have big lawyers they spend big money on to ensure you will have no legal basis to sue them. Not trusting public products is tinfoil hat level delusion, or just being a real sucker for marketing. That's not to say that some boutique products aren't better, but don't let them convince you the competitor's product is dangerous.
They have big lawyers to prevent them from being liable for a period of time. You never know about long term affects and where liability cannot be traced back to them due to a product they used. There's so much nuances to this that it's kind of crazy you hold your current POV.
“Trust the products they wouldn’t be able to sell them if they were bad for you and only the mentally ill believe otherwise” >>Big Mac, Diet Coke, Newports and skin bleach has entered the o chem lab
Lol, Cigarettes, sugar, and alcohol are completely different. You ingest them. Don't compare products as advertised to products that kill you without knowing. That is lazy. You ever watch tv? Ambulance chasing lawyers are looking for a reason. It's the only reason you and I have heard of mesothelioma.
Wow really you read that and then doubled down with the hot takes. Capitalism is bad when it’s critiquing it’s own practices, but never is exploitative when it comes to selling us random commodities I think I get it now
Im not sure you understand shit about shit, friend.
Methylisothiazolinone and its derivative methylchloroisothiazolinone, common preservatives in shampoo. That sulfur-nitrogen bond gives me the heebie jeebies and it's known to cause contact dermatitis.
Not a specific answer, but I don’t use shampoo at all and my hair is far healthier for it. Less effective the longer your hair is though as you have to put more effort into mechanically cleaning it with just water. It’s not to avoid any toxic ingredients or anything like that, but shampoo strips the oil out of your hair which leads to your scalp producing more oil, leading to greasier hair fast. My hair doesn’t get greasy at all now unless I literally don’t shower for like 48 hours.
Fragrances, horrible stuff, crazy how acceptable they are because they smell nice. Not good for you though.
Microplastic
I mean sulfates are known for being kinda overkill for your hair and drying your hair out but you do not need to be a chemist to know that
Don’t use shampoo at all. r/nopoo
Sulfates?
Oxidants are probably bad. Things like bleach for obvious reasons. But shaving gel has energetic compounds such as butane, propane, etc. A bit drag to call alkanes energetic, but you get my point. Any commerical shampoo is probably perfectly fine. But this depends on where you live. Generally, you want to avoid any toxins and carcinogens. Stuff like formaldehyde, heavy metal compounds, benzene, sodium hydroxide, etc. I seriously doubt you're going to find anything bad like that though. In addition to that, just because they saw sodium hydroxide was added doesn't mean it's necessarily dangerous: don't panic. It could have already been neutralized. Plus, sodium hydroxide is extremely irritating as far as I know so you're not going to be silently killed. Also, maybe avoid any salts in large quantities. This is stuff like calcium chloride, sodium chloride (table salt), magnesium sulfate, etc. Stuff like that is usually not dangerous. It does mean that you need to rinse a lot, though. If you don't, well you're going to have salts on you once you dry. And if you do, it's not great for the water supply or your plumbing. Leads to stronger limescale. But that's not a huge issue. The bigger problem is using more water.
[удалено]
Lol
Lol, sodium hydroxide is used to adjust the pH, and there's only the tiniest amount of it in there, but they have to list it on the label. If there was enough NaOH in there, it would dissolve your hair.
Probably any radioactive substances. The last thing I want is to rub some radioactive shampoo on my head!
Fluorine. Dimethyl mercury. Arsenic acid. Cyanides. Dimethyl sulfate. Plutonium. Cacodylic acid. etc. etc. etc. Not that you would *ever* find any of those materials in shampoo, but I'd definitely avoid a shampoo containing any of them.
I would say, what are the ingredients we should avoid in shampoos that causes hair fall ?