QUESTION: RE: References regarding cessation of lactation due to lead or mercury fume exposure 05/02/09 Arizona, USA - United States of America
My question regards whether lead pollutants, or possibly also mercury pollutants, can cause a lactating woman to stop milk production? I am conducting research of a time period in Spanish history in what was then known as New Spain, now known as Mexico. I have found very good evidence written by an individual in his journal that Indian women (more than one) at his remote location stopped lactating and could not feed their babies. Because of other indications in the written text, dating from the mid-1700s, I believe that operations were ongoing that reduced silver bearing ore to precious metal. I have researched the ore reduction methods of that time, and it is a virtual certainty that large amounts of lead was used to reduce the ore to metal, and that a second stage refining operation parted the lead from the silver. The ore reduction operation at that time used an open furnace into which the ore was introduced, along with large quantities of lead. The molten! lead and silver sank to the bottom of the cauldron where it was drawn off and the slag was drawn off from the top. The molten lead and silver constituted a crude amalgam, which then had to be processed to part the lead from the silver. The Spanish person, who wrote the text and incidental remark about the mothers' cessation of milk production, appears to have been concerned for a shortage of labor, more than a concern for the health of the mothers and babies. The Mint operated by the Spanish in Mexico City constructed their building over the silver bullion melting furnaces in such a way that the harmful pollution fumes moved up a chimney to blow away. However, I have not found any historical evidence that the silver and gold ore processors in the hinterlands knew about or took any precautions. Hence, an intriguing question has come to the fore regarding the cessation of milk production by Indian females, and whether it is probably related to exposure to lead and/or mercury. Can heavy metal contamination result in such a conditio! n in human beings? If so, is this level of contamination considered light, medium, heavy, life threatening, toxic, terminal, or some such descriptor? Thank you for your consideration of my question. I have put these questions to several medical doctors here in the U.S. but I have not received an answer beyond being referred to some other medical doctor.
Sent: Wednesday, June 24, 2009 3:45 AM
Dear Elizabeth O'Brien:
Thank you for writing. I am greatly surprised and encouraged to learn that you have shown an interest in this subject matter.
I shall respond to you with more information that probably will intrigue you. For now, because of on-going pressing matters here, I am simply acknowledging that I have received your reply.
It is interesting that Dr. McGuirk said in part: "I was also surprised to read in your description of the process that lead was ADDED to the process so I asked my favourite metallurgist (who happens to work at the largest lead smelter in the world at Port Pirie in South Australia), Graham Burgess, about it. He replied: "I had a quick look around the web and found a few
references to salt and mercury being used during silver smelting, but not lead. I wouldn't discount it though."
When I draft a proper reply to you, I shall address Dr. McGuirk's comments. Indeed, it would seem, he shall be greatly surprised by two books dating from the 1550s, or 200 years before the date of this subject matter.
Ms. O'Brien. I am a retired, former intelligence analyst. If you search my surname on the Internet, you will get the idea. I have an extensive background in analysis, and I am a lifelong amateur historian. The subject matter that I am working with is one that I do not have a venue in which to publish. I am not a medical doctor, although I have a number of medical books on my library shelves. I am not a metallurgist, although I have some experience with studying and analyzing the subject matter, and I have books on the subject. I am not a geologist, although I did study geology in the University, I have quite a number of geology books on my shelves, and I prospect for gold as a retirement hobby. I am not a lettered historian, although I have very many books on the shelves. I have done a lot of research, professional analysis, and writing during my intelligence career. I am 65 years old, with an unending interest in history. Parting fact from fiction, and solving analytical mysteries is what I enjoy. I do this for myself because I enjoy doing it, and I have the time to devote to it. Perhaps this subject matter could be the basis for a doctoral thesis, but at this stage in my life I have no desire to pursue that. I don't really know how or where I could ever publish whatever I conclude, but I do know that there has to be an epidemiological explanation for Indian mothers stopping lactation and not feeding their babies. Likewise the same epidemiological explanation should prevail in the cases of a number of Jesuit priests who died from apparent heavy metal poisoning at the ages of 27 and 32 years, one priest who became paralyzed, and a suspicious number of priests who were removed from service because they became deranged. I wish to have medical considerations well accounted for prior to ever publishing evidentiary information that implicates the Jesuit Order of the Roman Catholic Church in illegal mining activities in New Spain (now Mexico). Perhaps the best venue for such a publication would be a medical journal, although a history publication would also be a good venue. As I am not a medical doctor I would have no voice a medical publication, and as a unlettered and unrecognized amateur historian I really do not have a venue there either. What is more, I am certain that there are modern day vested interests who would not suffer gladly my published conclusions.
ANSWER: February 5 2009
Your inquiry to the NSW Lead Group has been passed to me for attention.
Lead is a multisystem toxicant and produces a range of effects.
I am assuming high exposures in the situations you describe, and at such exposures, the reproductive system is a target organ. However the main effects are on foetal development and effects on pregnancy generally and miscarriage. There are some reports on milk production, but these are few and not well documented (try searches for "lead and lactation" in PubMed).
From: The LEAD Group
To: Inquirer Sent: Tuesday, June 23, 2009 3:51 PM
Subject: Can lead or possibly also mercury cause a lactating woman to stop milk production?
we are just reviewing all the answers to inquiries for the second half of the financial year, in preparation for web-publishing them in our Q&A section. I noticed that Professor Winder's answer to your query in February 2009 directed you to search for "lead and lactation" in PubMed.
I decided to do that search myself just to be sure that your question was fully answered. I found nothing relevant and had already found (before asking Prof Winder) that none of the 10,200 articles in our lead library throws any light on this question so I asked Australia's Lactation Resource Centre (LRC) for their thoughts.
They replied in the following EMAIL FROM LRC:
We have a number of articles on breastmilk lead and mercury. I haven't read them all, but the titles give no indication that cessation of lactation is one of the ill effects of maternal exposure. They are largely concerned with measuring maternal and infant blood lead levels and milk levels. Some are studies carried out in Mexico City and the Andes.
As to any other cause of lactation failure- I don't know. If mothers were separated from their babies for extended periods it is likely to result in a diminution of supply, and ultimately weaning. But employers might have allowed very young babies to stay onsite with their mothers; hardly a healthy alternative in that environment. If mothers were separated from their babies, they may have left their babies with a wet nurse. I don't know whether the indigenous South Americans were used to wet nursing, but it would have been familiar in Europe.
Assuming high exposures (as Prof Winder does) would lead have affected some other organ system that in turn affected lactation? Your knowledge of lead effects would help out here. Hypothyroidism leads to decreased milk supply.
Would lead destroy the thyroid? Or the pituitary? I'm sorry I can't offer any clear answer for you.
The references below should help.
Joshi JV, Bhandarkar SD, Chadha M, Balaiah D, Shah R Menstrual irregularities and lactation failure may precede thyroid dysfunction or goitre J Postgrad Med. 1993. 39(3): 137-141.
Motil KJ, Thotathuchery M, Montandon CM, Hachey DL, Boutton TW, Klein PD, Garza C Insulin, cortisol and thyroid hormones modulate maternal protein status and milk production and composition in humans J Nutr. 1994. 124: 1248-1257. (Freely available online through PubMed)
Neville MC, McFadden TB, Forsyth I Hormonal regulation of mammary differentiation and milk secretion J Mamm Gland Biol Neoplasia. 2002. 7(1): 49-66.
Capuco AV, Kahl S, Jack LJ, Bishop JO, Wallace H.Prolactin and growth hormone stimulation of lactation in mice requires thyroid hormones. Proc Soc Exp Biol Med. 1999 Sep;221(4):345-51.
It's nice to be able to put pieces of the jigsaw together and start making sense of the story. So it looks like only high level exposure would account for lactation effects?
Thanks for this, it has been interesting
Liz McGuire BSc IBCLC
Lactation Resource Centre www.lrc.asn.au
Australian Breastfeeding Association www.breastfeeding.asn.au
PO Box 4000 Glen Iris VIC 3146
1818-1822 Malvern Road East Malvern VIC 3145
Tel: +61 (0)3 9885 0855 Fax: +61 (0)3 9885 0866
As you can see from the above response, LRC pointed out that thyroid dysfunction (possibly originating in the pituitary) can cause cessation of lactation and asked whether lead or mercury affects the function of the thyroid or the pituitary, to which the answer seems to be "yes, but only at extremely high levels of occupational exposure."
This is when I turned to references about cattle to discover the lactation outcome of any dairy cows that might have been exposed to the kind of high level lead fumes (and possibly mercury fumes) that the particular women in question were exposed to, by dint of working in process you describe: in New Spain (now Mexico) in the mid-1700s, operations were ongoing that reduced silver bearing ore to precious metal...[and by] the ore reduction methods of that time, it is a virtual certainty that large amounts of lead were used to reduce the ore to metal, and that a second stage refining operation parted the lead from the silver. The ore reduction operation at that time used an open furnace into which the ore was introduced, along with large quantities of lead. The molten lead and silver sank to the bottom of the cauldron where it was drawn off and the slag was drawn off from the top. The molten lead and silver constituted a crude amalgam, which then had to be processed to part the lead from the silver."
I guess it is possible that no cow has ever been exposed to that level of pollution - at least not one that was depended on for milk - but I noted from my web searching that in the online abstract for the article: "Sheila M. McGuirk, DVM, PhD Susan D. Semrad, VMD, PhD. Veterinary Clinics of North America: Food Animal Practice Volume 21, Issue 3, November 2005, Pages 729–749 Toxicologic Emergencies in Cattle ", in the section "Toxicity characterized by clinical presentation", no mention is made of effects on lactation. [see: http://www.sciencedirect.com/science/article/pii/S0749072005000605 ]
Our charity can't afford to buy the full article so I emailed one of the co-authors, Dr Sheila McGuirk from the Madison School of Veterinary Medicine, University of Wisconsin, to ask, "to your knowledge, are there any cases of cessation of lactation in cows caused by mercury or lead toxicity?
"I look forward to your reply, and your opinion as to whether it is even useful to look for evidence of this problem in cows to answer a question related to humans, so that I can forward your response to the researcher."
Dr McGuirk replied: "I'd like to help but I am not aware of any information on this subject."
I was also surprised to read in your description of the process that lead was ADDED to the process so I asked my favourite metallurgist (who happens to work at the largest lead smelter in the world at Port Pirie in South Australia), Graham Burgess, about it. He replied:
"I had a quick look around the web and found a few references to salt and mercury being used during silver smelting, but not lead. I wouldn't discount it though. Some of the Spanish controlled mines in Mexico were particularly rich in silver, and I can imagine it being possible for lead to be used as a reductant for silver, ie. if the silver is present as silver oxide in the concentrate, and mixed with lead at high temperature, the reaction AgO + Pb = Ag + PbO will occur - you will end up with metallic silver and a litharge slag which will float to the top and be easily separated. Lead in this form is itself fairly easily reduced back to lead metal and could have been re-used."
[END OF EMAIL FROM GRAHAM BURGESS]
My own conclusion is that lead or lead and mercury or lead and mercury plus any other toxics in the process, at very high levels, can possibly cause a lactating woman to stop milk production but thankfully, the high levels required to do so are not happening anywhere in the world today... at least not in places where it's likely to hit the news or become the subject of research.
I hope this helps and wonder how your research is going. Are you finished already? Will your work be web-published? Can we please have a copy for our library?
I look forward to hearing from you again.
From: The LEAD Group
To: Inquirer Sent: Monday, July 06, 2009 5:59 PM
Subject: Re: Can lead or possibly also mercury cause a lactating woman to stop milk production?
Thanks for your second email.
We would be glad to consider the web-publication of any history you write about lead or lead and mercury poisoning. I just need to correct your reading of my last email to you. It was me who made the remark that you have quoted as if it were made by Dr. McGuirk.
Sorry for the confusion and sorry to rush.
All the best
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