Q & A: Lead in Aluminium Cookware

Original question sent in by George Chapman, USA. Answers prepared by Swetha Lingala (The LEAD Group's Researcher) & Elizabeth O'Brien

George: "Is the lead (Pb) content of the common US aluminium alloy 6061 responsible for the perceived aluminium - Alzheimer's link? Apparently aluminium is readily filtered out of the body where as lead (Pb) is retained in the body.

Lead (Pb) adds some beneficial material property to the 6061 aluminium alloy. Could the small amount of consumed lead (Pb), leached out from the 6061 aluminium alloy commonly used to manufacture soda cans, cooking ware, etc.. , accumulate over decades in the body and cause appreciable health problems? If so why do we not hear more about this lead (Pb) problem?"

Swetha: "Hi George,

Thank you for your fascinating email about 6061 Aluminium alloy containing lead(Pb). Even our lead expert, Elizabeth O'Brien was not aware of it.

I found the following confirmation that lead can be added to Aluminium Alloys:

''Lead (Pb) and Bismuth (Bi) – Lead and bismuth are added to aluminium to assist in chip formation and improve machinability. These free machining alloys are often not weldable because the lead and bismuth produce low melting constituents and can produce poor mechanical properties and/or high crack sensitivity on solidification."

[http://www.esabna.com/us/en/education/blog/how-and-why-alloying-elements-are-added-to-aluminum.cfm]

The following article implies that 6061 Aluminium Alloy contains lead:

"In 1990, the development efforts at ALCOA's Massena Operations began with the objective to create a free machining alloy that would be comparable to a lead bearing alloy, 6262, in strength, machinability, corrosion resistance, anodizing, brazing, and welding responses while eliminating the health and environmental concerns associated with lead. "

".....Proclaimed as the fastest growing new product in automotive and miscellaneous applications the full cold finished product line in T8, T9 and T651 tempers excel in markets where 6262, 6061, 2011 aluminium alloys and 12L14 steels are used today."

[http://papers.sae.org/980459/]

The Following article doesn't indicate that 6061 Aluminium Alloy contains lead but shows the presence of lead and bismuth in some Aluminium Alloys:

"Lead. Normally present only as a trace element in commercial-purity aluminium, lead is added at about the 0.5% level with the same amount as bismuth in some alloys (2011 and 6262) to improve machinability."

[ http://www.keytometals.com/Article55.htm]

The following table shows that Lead (and any other element not specified separately) is limited in 6061 Aluminium Alloy to 0.05%, but unfortunately the table is not referenced:

[ http://en.wikipedia.org/wiki/Aluminium_alloy]

The Following article shows that 6061 Aluminium Alloy does not contain lead (Pb):

In 1988, Luxfer switched to a "6061" alloy, which does not contain lead.

[http://www.scubadiving.com/gear/accessories/consumers-guide-scuba-tanks]

Could you please provide references which state the actual level of lead found in 6061 Aluminium Alloy?

George: "Yes my mistake it's not 6061. Here's the list of Aluminum alloys I found earlier on line (www.aluminum.org/sites/default/files/Teal_Sheets.pdf ).

In the past what alloy did they make cookware out of? You can see many alloys with Pb as a constituent.

I'm sure things have changed now, perhaps this generation of Alzheimer sufferers were exposed to decades of aluminium alloys containing lead.

Thanks for the response & articles,

George:

Elizabeth: "You raise some very important questions and sadly my volunteer researcher has been unable to come into work for several weeks due to lack of a baby sitter

And today when she (Swetha) did come in, she only had time to put together the following info, which doesn't go all the way to answering the question as to whether the aluminium/aluminium cookware we all used in decades gone by, and which is likely still being used widely in many countries, contains lead. There's possibly a different answer in every country. Well worth finding out though.

Cheers,

Elizabeth O'Brien"

Swetha:

http://is.gd/XYEcMd

"The conventional aluminium cookware is usually made from a single layer of aluminium alloy which may be anodized on the outside surface and given a non-stick surface on the inside, cooking surface. Oftentimes such cookware is made from 3003 Aluminium alloy or a like aluminium alloy which offers higher strength than purer aluminium such as 1100 aluminium."

http://www.azom.com/article.aspx?ArticleID=6618

"The Aluminium / Aluminium 3003 alloy is used in ductwork, chemical equipment, and general sheet metal work. It is also used in manufacturing the following items:

• Cooking utensils
• Builder's hardware
• Pressure vessels
• Ice cube trays"

George: "Hi Swetha,

Thank you so much for looking into this and providing interesting links. I'll have to look into the aluminium hydroxide formation and toxicity. It would be interesting to see if some of the detrimental effects blamed on aluminium can be linked to lead or other known toxic alloy additives. Perhaps we can find a healthy metal for cooking - so far it sounds like surgical stainless steel is the best.

Thanks again for following up on this.

George Chapman"

Swetha: "Hi George,

Regarding recommended cookware metals, in the book "Clean, Green and Lean: Get rid of the toxins that make you fat - Drop the weight in 30 days." Author Dr Walter Crinnion, ND, writes:

'Cookware. Get rid of chemical-spewing non-stick pans. Ceramic titanium and porcelain-enamelled cast iron are great alternatives.' (Page 141)

But because iron deficiency is associated with increased lead absorption from the gut, and because enamel glazes on cast iron eliminate the possibility of adding iron to the food during cooking, the following recommendation on the best cookware metal could actually be more lead-safe:

“Cast iron cookware. Cast iron is known for its durability and even heat distribution. Unglazed cast iron can transfer notable amounts of iron into food, but unlike the metals that come off other types of pots and pans, iron is considered a healthy food additive by the U.S. Food and Drug Administration.”

(http://www.mnn.com/food/healthy-eating/questions/whats-the-safest-cookware)

It is also apparent from the following that cast iron cookware (without any coating/glaze) is recommended whenever reducing lead exposure is the aim:

For vegetarians or vegans a good supplementation technique is through cooking acidic vegetables (such as tomatoes or cabbage) in non enamelled cast iron pots which has been consistently shown to significantly increase dietary iron (165,60,166,167); a technique that works equally well for non-vegetarians and which may be preferable to iron supplementation in pill form. For this purpose it should be noted that materials do not have to be naturally high in iron to improve iron status (168). Should there be difficulty in finding non-enamelled cast iron cookware Lodge Cast Iron Cookware of Tennessee provides a range that is widely distributed. Note that the iron in many vegetables is more bioavailable (capable of being absorbed) when cooked rather than raw (341).

Iron cooking vessels: The following items have their iron content more than doubled when cooked in iron container without a protective surface. Rear Row: red cabbage, tomato, rice, corn meal Front Row: tomatoes, capsicum (bell or banana peppers in USA), pureed vegetables, wild rice, apple sauce, scrambled egg, corn meal, Foreground: scrambled egg Not pictured: milk

(https://lead.org.au/lanv9n3/Iron_Nutrition_and_Lead_Toxicity_Short.pdf - page 6)

So, despite the comment made about the iron of cast iron cooking pots not being absorbed (in the article I previously sent you, at http://www.happycookingco.com/hidden-dangers.cfm ) I find the information above on our own website to be better-referenced.

Returning to my search for the answers to the questions your emails raise...

1. Which Aluminium Alloys were used in United States in the past to make cooking pots?

Below URL shows 3000 series and 8000 series Aluminium Alloys ARE used in making cookware:

http://www.meyer-mab.com/technical-information/

Specifically, the above URL states:

“3XXX Series - Due to its excellent formability, 3003 has a wide range of uses including cookware.The addition of Magnesium gives it [3004] strengths approaching 5052 along with great corrosion resistance and good formability. These properties make 3004 a good candidate for storage tanks, pressure vessels and cookware.“

“8XXX Series - This series comprises alloys that use less common elements, including Tin, Iron, Nickel and Lithium. The Lithium alloys are attractive for some aerospace applications due to their very light weight, high strength and increased ability to stretch without breaking. Other uses for 8XXX alloys include cookware, conductor material, and some high temperature applications.”

Next time I am in the office I’ll search for whether the above-mentioned 3003, 3004 and 8000 series aluminium alloys contain any lead.

Skipping ahead to Q. 5 (Are there any lead containing Aluminium Alloys still used anywhere in the world to make cooking pots?), I have found the following three related articles about scrap metal being used to make aluminium pots in Cameroon, which release hundreds of times the Californian daily lead limit from consumer products, into the food. I am wondering what inspired your original question? Was it any of these articles (or another article about this Cameroon study):

http://www.voanews.com/content/africa-aluminum-cookware-15aug14/2414509.html;

http://www.sciencedaily.com/releases/2014/08/140812122325.htm;

http://www.sciencedirect.com/science/article/pii/S0048969714010316
[please find this last one attached as Weidenhame et al Lead exposure from aluminium cookware in Cameroon 20141015 FULL.pdf]

I hope that aluminium alloys for cookware were never made so carelessly from lead-containing scrap metal in the developed world, as the above articles report is occurring now in Cameroon and probably the rest of Africa as well as in Bangladesh and Thailand and possibly the rest of Asia, but I’ll keep researching just in case... until next week....

Kind regards

Swetha Lingala (with help from Elizabeth O’Brien)"

Swetha: "Hi George,

2. Do those Aluminium Alloys (3003, 3004, 8000) contain Lead?

As per my research the URL shown below shows these is no presence of Lead (Pb) in the above mentioned Aluminium Alloys.

http://www.suppliersonline.com/propertypages/3003.asp

http://www.suppliersonline.com/propertypages/3004.asp

Next time I am in the office I’ll search for whether the 8000 series aluminium alloys contain any lead.

Thanks

Swetha Lingala"

Swetha: "Hi George,

I am still searching the internet to answer the following Questions:

Which Aluminium Alloys were used in United States in past to make cooking parts?

Do those Aluminium Alloys contain Lead?

If so, how much lead?"

Swetha: "Hi George,

As there is no presence of Lead in US cookware made of Aluminium Alloys (3003, 3004, 8000 series), it gives answers to the remaining 3rd and 4th Questions.

3) If so, how much lead?

4) Are there any lead containing Aluminium Alloys still used in US to make cooking pots?

Regarding Question 5:

5) Are there any lead containing Aluminium Alloys still used anywhere in the world to make cooking pots?

A) As per my research the African countries and probably other under-developed countries are still using and making aluminium cooking utensils using scrap metal and thus the cookware can contain Lead.

For your ref:

http://www.voanews.com/content/africa-aluminum-cookware-15aug14/2414509.html

http://www.sciencedaily.com/releases/2014/08/140812122325.htm"

I realise that the following quotes don't answer any of the above Questions, but I think you will find the information very interesting nevertheless.

Very soft metal. Extreme chemical reaction between food and pan. "All Vegetables cooked in Aluminium produce hydroxide poison which neutralizes digestive juices, producing stomach and gastrointestinal trouble, such as stomach ulcers and colitis." Dr. A. McGuigan's Report on Findings for the Federal Trade Comm. In Docet Case No. 540 Washington, D.C. Note: The sale of aluminium cookware is prohibited in Germany, France, Belgium, Gr. Britain, Switzerland, Hungary and Brazil.

Glass / Enamel Coated

Poor heat distribution. Foods stick and burn. Contains lead. Lead can cause reproductive harm and learning disabilities. [ http://www.happycookingco.com/hidden-dangers.cfm ]

Interestingly also, the following website lists stainless steel alloys, some of which contain lead:

http://www.yamco-yamashin.com/en/products/guide_stainless_steel.html 

So that might be more research for another day, to work out if stainless steel cookware contains lead.

In trying to answer the above questions, today I located the following information:-

1. "The 3000 series is made up of alloys of aluminium and manganese. These alloys are not as strong as the 2000 series, but they also have good machinability. Alloys in this series are used for cooking utensils; storage tanks; aluminium furniture; highway signs and roofing." [http://www.chemistryexplained.com/elements/A-C/Aluminum.html ]

I will be back next week to research some more."

George: "Swetha,

Thank you so much for looking into this! I guess lead alloys are not intentionally used in aluminium cookware, nor is lead from cookware responsible for the Alzheimer/aluminium link.

I'll have to look into what it would take to remove lead from scrap metal so it doesn't end up in cookware in Cameroon. I would think something like spark gap spectrometry would be able to identify lead in an aluminium alloy. The real key would be to sort it out before it gets mixed in with aluminium.

I'll have to look into how cookware is made in Cameroon. Are there a few large metal smelting facilities, or do people make there own cookware? If there are only a few smelters the lead would probably be easier to sort out. If individuals are making their own cookware, one would have to go door to door offering to test & replace cookware.

Thanks again,

George Chapman"

Swetha: "George,

Your thoughts are so interesting, I am CC'ing this to our colleagues who were responsible for the Research and News articles about Leaded Aluminium pots in Cameroon.

Perhaps Jeffrey, Gilbert or Perry can send us the original copy of the below URL as we have only the abstract of it.

http://www.sciencedirect.com/science/article/pii/S0048969714010316

Hopefully all the ideas in the article and maybe George’s below can be incorporated into a Health programme for the affected people, with articles in the media and social networks.

Thank you,

Yours Sincerely
Swetha Lingala
Researcher"

Jeff Weidenhamer, Ph. D.: "Swetha,

Thanks for your email. Our judgment is that the lead in these aluminium alloys (not large amounts -- maximum 637 ppm by X-ray fluorescence) is picked up from the scrap materials used to make them. Please let me know if there are any other questions.

The paper is available through the OK International website at this address:

http://www.okinternational.org/docs/Final%20pb%20pots%20STOTEN%202014.pdf

In case you missed it, along the right side of the science direct posting is a short video presentation about the research project:
http://www.sciencedirect.com/science/article/pii/S0048969714010316

Jeff Weidenhamer"