In Wednesday’s newsletter, we asked you what kind of cookware you mostly use, and got the above-depicted, below-described, set of responses:

• About 45% said stainless steel
• About 21% said cast iron
• About 15% said non-stick (e.g. Teflon)
• About 9% said enamel
• About 6% said aluminum
• And 1 person selected “something else”, but then commented to the contrary, writing “I use all of the above”

So, what does the science say about these options?

Stainless steel cookware is safe: True or False?

True! Assuming good quality and normal use, anyway. There really isn’t a lot to say about this, because it’s very unexciting. So long as it is what it is labelled as: there’s nothing coating it, nothing comes out of it unless you go to extremes*, and it’s easy to clean.

*If you cook for long durations at very high temperatures, it can leach nickel and chromium into food. What this means in practical terms: if you are using stainless steel to do deep-frying, then maybe stop that, and also consider going easy on deep-frying in general anyway, because obviously deep-frying is unhealthy for other reasons.

Per normal use, however: pretty much the only way (good quality) stainless steel cookware will harm you is if you touch it while it’s hot, or if it falls off a shelf onto your head.

That said, do watch out for cheap stainless steel cookware that can contain a lot of impurities, including heavy metals. Since you probably don’t have a mass spectrometer and/or chemistry lab at home to check for those impurities, your best guard here is simply to buy from a reputable brand with credible certifications.

Ceramic cookware is safe: True or False?

True… Most of the time! Ceramic pans usually have metal parts and a ceramic cooking surface coated with a very thin layer of silicon. Those metal parts will be as safe as the metals used, so if that’s stainless steel, you’re just as safe as the above. As for the silicon, it is famously inert and body-safe (which is why it’s used in body implants).

However: ceramic cookware that doesn’t have an obvious metal part and is marketed as being pure ceramic, will generally be sealed with some kind of glaze that can leach heavy metals contaminants into the food; here’s an example:

Lead toxicity from glazed ceramic cookware

Copper cookware is safe: True or False?

False! This is one we forgot to mention in the poll, as one doesn’t see a lot of it nowadays. The copper from copper pans can leach into food. Now, of course copper is an important mineral that we must get from our diet, but the amount of copper that that can leach into food from copper pans is far too much, and can induce copper toxicity.

In addition, copper cookware has been found to be, on average, highly contaminated with lead:

Assessing Leaching of Potentially Hazardous Elements from Cookware during Cooking: A Serious Public Health Concern

Non-stick cookware contaminates the food with microplastics: True or False?

True! If we were to discuss all the common non-stick contaminants here, this email would no longer fit (there’s a size limit before it gets clipped by most email services).

Suffice it to say: the non-stick coating, polytetrafluoroethylene, is itself a PFAS, that is to say, part of the category of chemicals considered environmental pollutants, and associated with a long list of health issues in humans (wherein the level of PFAS in our bloodstream is associated with higher incidence of many illnesses):

Presence of Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) in Food Contact Materials (FCM) and Its Migration to Food

You may have noticed, of course, that the “non-stick” coating doesn’t stick very well to the pan, either, and will tend to come off over time, even if used carefully.

Also, any kind of wet cooking (e.g. saucepans, skillets, rice cooker inserts) will leach PFAS into the food. In contrast, a non-stick baking tray lined with baking paper (thus: a barrier between the tray and your food) is really not such an issue.

We wrote about PFAS before, so if you’d like a more readable pop-science article than the scientific paper above, then check out:

PFAS Exposure & Cancer: The Numbers Are High

Aluminum cookware contaminates the food with aluminum: True or False?

True! But not usually in sufficient quantities to induce aluminum toxicity, unless you are aluminum pans Georg who eats half a gram of aluminum per day, who is a statistical outlier and should not be counted.

That’s a silly example, but an actual number; the dose required for aluminum toxicity in blood is 100mg/L, and you have about 5 liters of blood.

Unless you are on kidney dialysis (because 95% of aluminum is excreted by the kidneys, and kidney dialysis solution can itself contain aluminum), you will excrete aluminum a lot faster than you can possibly absorb it from cookware. On the other hand, you can get too much of it from it being a permitted additive in foods and medications, for example if you are taking antacids they often have a lot of aluminum oxide in them—but that is outside the scope of today’s article.

However, aluminum may not be the real problem in aluminum pans:

❝In addition, aluminum (3.2 ± 0.25 to 4.64 ± 0.20 g/kg) and copper cookware (2.90 ± 0.12 g/kg) were highly contaminated with lead.

The time and pH-dependent study revealed that leaching of metals (Al, Pb, Ni, Cr, Cd, Cu, and Fe, etc.) into food was predominantly from anodized and non-anodized aluminum cookware.

More metal leaching was observed from new aluminum cookware compared to old. Acidic food was found to cause more metals to leach during cooking.❞

~ the same paper we cited when talking about copper

Cast iron cookware contaminates the food with iron: True or False?

True, but unlike with the other metals discussed, this is purely a positive, and indeed, it’s even recommended as a good way to fortify one’s diet with iron:

Effect of cooking food in iron-containing cookware on increase in blood hemoglobin level and iron content of the food: A systematic review

The only notable counterpoint we could find for this is if you have hemochromatosis, a disorder in which the body is too good at absorbing iron and holding onto it.

Thinking of getting some new cookware?

Here are some example products of high-quality safe materials on Amazon, but of course feel free to shop around:

Stainless Steel | Ceramic* | Cast Iron

*it says “non-stick” in the description, but don’t worry, it’s ceramic, not Teflon etc, and is safe

Bonus: rice cooker with stainless steel inner pot

Take care!

Mythbusting The Mask Debate

We asked you for your mask policy this respiratory virus season, and got the above-depicted, below-described, set of responses:

• A little under half of you said you will be masking when practical in indoor public places
• A little over a fifth of you said you will mask only if you have respiratory virus symptoms
• A little under a fifth of you said that you will not mask, because you don’t think it helps
• A much smaller minority of you (7%) said you will go with whatever people around you are doing
• An equally small minority of you said that you will not mask, because you’re not concerned about infections

So, what does the science say?

Wearing a mask reduces the transmission of respiratory viruses: True or False?

True…with limitations. The limitations include:

• The type of mask
  • A homemade polyester single-sheet is not the same as an N95 respirator, for instance
• How well it is fitted
  • It needs to be a physical barrier, so a loose-fitting “going through the motions” fit won’t help
• The condition of the mask
  • And if applicable, the replaceable filter in the mask
• What exactly it has to stop
  • What kind of virus, what kind of viral load, what kind of environment, is someone coughing/sneezing, etc

More details on these things can be found in the link at the end of today’s main feature, as it’s more than we could fit here!

Note: We’re talking about respiratory viruses in general in this main feature, but most extant up-to-date research is on COVID, so that’s going to appear quite a lot. Remember though, even COVID is not one beast, but many different variants, each with their own properties.

Nevertheless, the scientific consensus is “it does help, but is not a magical amulet”:

• 2021: Effectiveness of Face Masks in Reducing the Spread of COVID-19: A Model-Based Analysis
• 2022: Why Masks are Important during COVID‐19 Pandemic
• 2023: The mitigating effect of masks on the spread of COVID-19

Wearing a mask is actually unhygienic: True or False?

False, assuming your mask is clean when you put it on.

This (the fear of breathing more of one’s own germs in a cyclic fashion) was a point raised by some of those who expressed mask-unfavorable views in response to our poll.

There have been studies testing this, and they mostly say the same thing, “if it’s clean when you put it on, great, if not, then well yes, that can be a problem”:

❝A longer mask usage significantly increased the fungal colony numbers but not the bacterial colony numbers.

Although most identified microbes were non-pathogenic in humans; Staphylococcus epidermidis, Staphylococcus aureus, and Cladosporium, we found several pathogenic microbes; Bacillus cereus, Staphylococcus saprophyticus, Aspergillus, and Microsporum.

We also found no associations of mask-attached microbes with the transportation methods or gargling.

We propose that immunocompromised people should avoid repeated use of masks to prevent microbial infection.❞

Source: Bacterial and fungal isolation from face masks under the COVID-19 pandemic

Wearing a mask can mean we don’t get enough oxygen: True or False?

False, for any masks made-for-purpose (i.e., are by default “breathable”), under normal conditions:

• COVID‐19 pandemic: do surgical masks impact respiratory nasal functions?
• Performance Comparison of Single and Double Masks: Filtration Efficiencies, Breathing Resistance and CO2 Content

However, wearing a mask while engaging in strenuous best-effort cardiovascular exercise, will reduce VO₂max. To be clear, you will still have more than enough oxygen to function; it’s not considered a health hazard. However, it will reduce peak athletic performance:

Effects of wearing a cloth face mask on performance, physiological and perceptual responses during a graded treadmill running exercise test

…so if you are worrying about whether the mask will impede you breathing, ask yourself: am I engaging in an activity that requires my peak athletic performance?

Also: don’t let it get soaked with water, because…

Writer’s anecdote as an additional caveat: in the earliest days of the COVID pandemic, I had a simple cloth mask on, the one-piece polyester kind that we later learned quite useless. The fit wasn’t perfect either, but one day I was caught in heavy rain (I had left it on while going from one store to another while shopping), and suddenly, it fitted perfectly, as being soaked through caused it to cling beautifully to my face.

However, I was now effectively being waterboarded. I will say, it was not pleasant, but also I did not die. I did buy a new mask in the next store, though.

tl;dr = an exception to “no it won’t impede your breathing” is that a mask may indeed impede your breathing if it is made of cloth and literally soaked with water; that is how waterboarding works!

Want up-to-date information?

Most of the studies we cited today were from 2022 or 2023, but you can get up-to-date information and guidance from the World Health Organization, who really do not have any agenda besides actual world health, here:

Coronavirus disease (COVID-19): Masks | Frequently Asked Questions

At the time of writing this newsletter, the above information was last updated yesterday.

Take care!