Which metal is safest for hair/scalp? Bismuth, silver or zinc oxide?

AI Thread Summary
The discussion centers on the safety and effectiveness of using different metals in combination with henna for hair dyeing. The participant seeks to determine which of three options—bismuth, silver, or zinc oxide—would be the safest and most effective for achieving shine in hair. It is noted that while bismuth and silver are metals, zinc oxide is a metal oxide, and both bismuth oxide and silver oxide are deemed unsuitable for cosmetic use. Safety data sheets (MSDS) indicate that zinc oxide is the least toxic of the three, with low toxicity and no chronic health effects recorded. Bismuth has potential health risks, including irritation and other systemic effects, while silver can cause skin discoloration with prolonged exposure. The participant expresses confusion regarding the safety of bismuth, especially in powdered form, and shows interest in exploring zinc oxide as a safer alternative.
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Which metal would be safest to apply to the hair if the scalp were to absorb any of the metal? Would it be Bismuth, silver or zinc oxide? Thanks!
A little background on my experiment … "Henna" (Lawsonia plant hair dye going way back to ancient times) used to be combined with metallic salts to cause it to adhere to the hair and make it thicker with cumulative use. In foreign countries "compound henna" is still being sold but often w/ harmful metals like lead as well as less harmful metals like zinc oxide. But, I want to combine it with the safest metal. Also, I understand that some metals make the hair dull (like iron) while others make hair shiny. Anyone have any clue which of the three metals - bismuth, silver or zinc oxide might yield the most shine to a strand of hair? Thanks for any input.
 
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Torey said:
Summary: Which metal would be safest to apply to the hair if the scalp were to absorb any of the metal? Would it be Bismuth, silver or zinc oxide? Thanks!

A little background on my experiment … "Henna" (Lawsonia plant hair dye going way back to ancient times) used to be combined with metallic salts to cause it to adhere to the hair and make it thicker with cumulative use. In foreign countries "compound henna" is still being sold but often w/ harmful metals like lead as well as less harmful metals like zinc oxide. But, I want to combine it with the safest metal. Also, I understand that some metals make the hair dull (like iron) while others make hair shiny. Anyone have any clue which of the three metals - bismuth, silver or zinc oxide might yield the most shine to a strand of hair? Thanks for any input.
To be clear, you are comparing two metals (Bismuth and Silver) and one metal oxide (Zinc Oxide).
In case you were not, Bismuth Oxide and Silver Oxide and both unsuitable for cosmetics.

A quick check of the MSDS for each of these materials indicates that Zinc Oxide is the most innocuous.

From https://www.espimetals.com/index.php/msds/51-Bismuth
11 TOXICOLOGICAL INFORMATION

Likely Routes of Exposure: Inhalation, skin, eyes.

Symptoms of Exposure: May cause irritation.

Acute and Chronic Effects: Prolonged inhalation of bismuth dusts may cause mental changes, nervousness, blood changes, lymphocytosis and bone marrow depression. Ingestion of bismuth compounds may cause nausea, vomiting, diarrhea, and pigmentation of the skin and mucous membranes.

Acute Toxicity: No data

Carcinogenicity: NTP: Not identified as carcinogenic IARC: Not identified as carcinogenic

To the best of our knowledge the chemical, physical and toxicological characteristics of the substance are not fully known.
From https://www.espimetals.com/index.php/msds/274-Silver:
11 TOXICOLOGICAL INFORMATION

Likely Routes of Exposure: Inhalation, skin, eyes.

Symptoms of Exposure: May cause irritation.

Acute and Chronic Effects: Silver metal is relatively inert. Chronic exposure to soluble silver compounds may cause a permanent bluish-gray discoloration of the skin and eyes known as argyria.

Acute Toxicity: No data

Carcinogenicity: NTP: Not identified as carcinogenic IARC: Not identified as carcinogenic

To the best of our knowledge the chemical, physical and toxicological characteristics of the substance are not fully known.
From https://www.espimetals.com/index.php/msds/309-Zinc Oxide:
V. HEALTH HAZARD INFORMATION

Effects of Exposure:

Zinc compounds have variable toxicity, but generally are of low toxicity. Zinc is not inherently a toxic element. However, when heated it evolves a fume of zinc oxide which, when inhaled fresh, can cause a disease known as “brass founders” “ague,” or “brass chills”. Zinc oxide dust which is not freshly formed is virtually innocuous. There is no cumulative effect form the inhalation of zinc fumes (Sax, Dangerous Properties of Industrial Materials, eighth edition).

Acute Effects:

Inhalation: May cause respiratory tract irritation with nasopharyngitis and laryngitis.

Ingestion: Moderately toxic by ingestion.

Skin: May cause irritation.

Eye: May cause irritation

Chronic Effects:

Inhalation: May cause human systemic effects.

Ingestion: No chronic health effects recorded.

Skin: No chronic health effects recorded.

Eye: No chronic health effects recorded.

Target Organs: No target organs recorded.

Medical Conditions Generally Aggravated by Exposure: Pre-existing respiratory disorders.

Carcinogenicity: NTP: No IARC: No OSHA: No
 
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I get you, Borek. The way I found Physics Forums in the first place was I stumbled on a thread where another person was asking about the safety of bismuth. He had a number of answers, with almost everyone thinking it was safe, but I wondered how this compared to other metals. But, I realize that "Physics Forum" is not making any recommendations - I'm just finding out the opinions of different members. Thanks.
 
.Scott said:
To be clear, you are comparing two metals (Bismuth and Silver) and one metal oxide (Zinc Oxide).
In case you were not, Bismuth Oxide and Silver Oxide and both unsuitable for cosmetics.

A quick check of the MSDS for each of these materials indicates that Zinc Oxide is the most innocuous.

From httying ps://www.espimetals.com/index.php/msds/51-Bismuth

From https://www.espimetals.com/index.php/msds/274-Silver:

From https://www.espimetals.com/index.php/msds/309-Zinc Oxide:
Thanks for all the pasted info. As you can see, I am a total novice at this … I ordered some 99.9% powdered bismuth but wanted to learn a little more first. I've heard most people say (and toxicology reports) that it's relatively safe - especially considering Pepto Bismol - but I've also read a few things that make it sound harmful. So, it's been confusing. But, I'm now also interested in checking out zinc oxide. Thanks.
 
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There are additional problem in handling Bismuth in powdered form.
Read the MSDS thoroughly - especially with regard to inhaling the powder.

This material should only be handled under adult supervision. If you are not an adult, get one.
 
.Scott said:
If you are not an adult, get one.
Amazon is having a special this week... 😉
 
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You also have to consider that Silver Oxide is a dark brown almost black powder. So that rules out it use to provide "shine".

BoB

Edit: Be careful with metal powders as they tend to be flammable. Some of them spontaneously.
 
Do not fool with materials if you have insufficient training, insufficient education, or insufficient equipment to handle or use them.
 
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For detailed health information, I've found the US National Institutes of Health (NIH) to be very useful. Try a Google search of the material followed by "site:nih.gov" (without the quotes).

For example the Search field would be: zinc oxide site:nih.gov

https://www.google.com/search?&q=zinc+oxide+site:nih.gov
Cheers,
Tom
 

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