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Comment by timw4mail | Hacker News Reader

Everytime I've seen something about plastics being a health risk, it's not the main polymer (eg. PET, LDPE, HDPE, etc.) that's pointed out, it's the plasticizers. Because plasticizers are not chemically bound to the polymer, it does make sense that they are more likely to have a biological effect than the polymers, as the polymer is generally a fairly stable molecule chain.

The polymers themselves can degrade, though. Especially with plastic items that have been exposed to the sun for long periods of time, the polymers can break down. I wonder if this degradation could also be a health risk, as many polymers are hydrocarbons, which do have known health risks.

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Rubber is similar to plastic in many regards. Here's how chemicals in rubber car tires find their way into water supplies and kill salmon. Lots of salmon. Most of this stuff we don't find out about for like 50 years, and usually on a fluke discovery. We trusted the science at the time.

https://www.science.org/content/article/common-tire-chemical...

FYI - Tires use synthetic rubber, which is just more plastic. Natural rubber would be way too expensive and difficult to extract at mass scale.

LDPE/HDPE don't need plasticisers.

I wonder if this degradation could also be a health risk, as many polymers are hydrocarbons, which do have known health risks.

Would you consider wax and vaseline as "health risks? Or mineral oil? Those are basically polyethylene but at much lower molecular weights. The hydrocarbons you're probably thinking of (octane and below) are even lower, but e.g. propane and butane aren't actually particularly toxic.

> Would you consider wax and vaseline as "health risks? Or mineral oil?

I would consider anything we didn't have in our environment until very recently a health risk, simply because it's a form of "testing previously untested inputs in production"

Edit: To be clear, in the context of evolution, I would eyeball "very recently" at about 100,000 years.

Over a century is "very recently"?

Relative to the 200,000 to 6 million years we have been in this shape? Yes.

It certainly is if we're looking at the rise in obesity and cvd.

If it takes a long time to have an effect and is linked to many other comorbidities (as will be the case for obesity at least).

And some epigenetic changes take effect on the subsequent generations and not the current one.

From the point of view of evolution and natural selection, yes, it is not even the blink of an eye.

Mineral oil does have some health risks (potential endocrine disruption and carcinogen).

Waxes are a huge category. I would guess some do and some don't. Beeswax for example has 300 chemicals in it, some may be beneficial and some could be harmful.

Vaseline is supposed to be largely safe. There are various grades of petroleum jelly, some of which could be carcinogenic.

Beeswax has been in our environment for millions of years. Not so for the other substances you mentioned.

But not in the quantities or frequency that it is available today through agriculture.

Exactly. A person today could eat honey and use beeswax in food every day if they wanted to. This would not have been available to anyone 10k years ago.

Many substances have been in our environment for millions of years. Lead has been around for ages. A substance being "natural" or having been around for 100,000+ years does not necessarily correlate to safe.

I would far more trust a new substance that has been tested thoughtfully.

Technically, it wouldn't be a new substance if thoroughly tested. It would need to be tested for at least a generation to study epigenetic effects.

I would prefer older substances that have a large battery of testing. This time also allows some group-think or other new product bias to dissipate.

This sounds an awful lot like asking job candidates for 10 years of experience in a technology that is only 2 years old. Nothing new will ever be created again.

I'm just saying, if it's new then it's basically being tested in prod.

Reminds me of my "Uranium is 100% all-natural!" quip.

People have burned peat or used lead for centuries, which is horrible for your health. Just because humans have had something in the environment historically doesn't mean it's safe.

I had a different scale in mind. I'm not talking about "historically", but "evolutionarily", so on the order of millions of years, not hundreds.

I don't think centuries is long enough. We don't seem to have finished evolving our coping strategies for alcohol and lactose and it is probably 20,000 years since those were added to our environment. And in both cases, we already had a head start - there has been trace amounts of alcohol in overripe fruit and lactose in breast milk, basically forever.

Evolution only corrects as much as is required for reproduction; and as far as reproduction is concerned, avoidance is just as good of a response as tolerance.

Humans have evolved to cope with lactose and alcohol. Getting sick is that response. This is the same in how we've evolved to live with fire. Not because evolution can magically make us invincible to chemical combustion -- instead we have pain receptors and learn to avoid it.

A minor quibble, though I agree with your point overall: lactose intolerance is not an adaptive response to something harmful in lactose (the way getting sick from alcohol is), it's more of an efficiency hack: since mammals normally only consume lactose as babies, our bodies stop producing the lactase enzyme around the time we stop breast-feeding, so we stop being able to digest this type of sugar, which we would normally never encounter again (or no more than trace amounts).

Some 20k years ago, some of our ancestors started consuming milk even in adulthood, and it turned out a few of them had a mutation that allowed them to continue producing lactase even in adulthood. Since milk is actually a very nutritious substance if you can farm it, these people thrived and passed on their genes, in some areas.

That's a good point.

I was thinking more generally: "someone drinks milk, they get sick, they don't drink it, don't die".

Yes, but it's interesting to contrast with alcohol sickness. The reason people without lactase get sick from lactose is because the lactose passes most of their digestive tract intact, and is then broken down by bacteria in their intestines, releasing gas, causing mechanical pressures on their intestines that are perceived as pain and other symptoms.

In the case of alcohol, our body detects the alck of balance and other neural impacts, classifies this as a poisoning, and it tries to provoke vomiting to eliminate as much as possible of the poison. It's explicitly an adaptive response that we developed to survive consumption of poisonous substances.

It's a different biological means to the same evolutionary ends. Maybe the additional involuntary processes associated with alcohol were evolutionarily necessary because humans also experience other feelings which induce the consumption of alcohol. I mean, milk is fine, but we don't call it happy-hour when we drink milk. :)

Havent rotten fruits been around since forever?

Our evolutionary ancestors could’ve involuntarily consumed alcohol way before 20k BC.

Involuntarily on 1 Jan 20,000 BC, but voluntarily ever since 2 Jan 20,000 BC.

I think it’s aromatic hydrocarbons, rings like cyclohexane and hybridized rings like benzene, that tend to be greater risk with chronic exposure.

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