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Details of mercury toxicity
- Apr 24, 2009 at 5:16 AM
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- Comments (13) Total Views (1268) Everyone can see this journal post.
Mercury poisoning is a topic that comes up with some frequency on Cafemom. There are groups that discuss mercury poisoning itself, and how mercury relates to vaccines and autsim. I don't follow the vaccine-autism debate at all, so I knew very little about this topic. About 2 weeks ago a friend mentioned how fish we eat has more mercury in it than vaccines do, so it immediately brought out the skeptic in me, and opened my mind to a series of questions I set out to answer. Does food really have more mercury in it? Does it have the same effect on the human body? Is there mercury in my breastmilk? This post outlines my personl mercury study, and provides the answers I found after 2 weeks of pretty intensive study. Please note this is my original writing, and if you choose to repost it on Cafemom or elsewhere, I insist you credit me by both mentioning me by Cafemom name, and linking directly to this post, or to The Science Spot homepage. If you don't, it's plagerism, plain and simple.
I am not an expert on mercury posioning, and I know almost nothing about autism. This post is not an attempt to defeat or support the vaccine-mercury-autism link. This information provides some background about mercury and what we know about how it affects the human body, like a springboard for those who want to know and understand more about it. It's quite likely that some moms of autistic children know all this information (and more), in which case, I invite you to correct any errors I may have made, and fill in the gaps with your knowledge, if you are willing.
I'll admit previously I was quite skeptical of any link between autism and mercury. However, after this study, I am much LESS skeptical, and I can now CLEARLY see that additional research on ethylmercury is needed before we can attempt to really address the concerns regarding mercury content in vaccines, our food, our air and our water.
Summary
I understand many people won't read this entire lenghty post. In order to accomodate you, please enjoy this brief summary. There are four main types of mercury, and each has different properties in terms of routes of entry into the body , accumulation in the body, and effect on the body. It is known that thimerosal in vaccines is not like methylmercury in fish. Thimerosal metabolizes to ethylmercury, which is not the same as methylmercury. Unfortunately, since there isn't much data about ethylmercury, we rely on methylmercury information, whch we know is not a good indicator of accumulation or effects on the body. The main difference I have found in my study, is that monkeys receiving ethylmercury by injection had a MUCH higher inorganic mercury level in the brain than monkeys receiving methylmercury by mouth. This was research work performed on animals.
In my opinion, there will be indiviuals that are more sensitive to mercury poisoning, just like there are people more sensitive to certain drugs, more sensitive to sunlight, etc., based on their genes. Total mercury consumption is a complicated topic, due to the various routes of entry into the body, and differences in consumption among individuals. All of these issues need to be taken into consideration when determining toxicity of a substance. For example, a child could receive a fairly high dose of elemental mercury through the mother's blood during fetal development, which would accumulate in the brain and be cleared slowly. This child could then receive some elemental mercury in early breastmilk, and then high levels of methylmercury due to clearance from the mother through breastmilk, which would accumulate in the blood. The child could also acquire ethylmercury injected with vaccination, which could be converted to elemental mercury, accumulating in the brain. The child could then go on to eat fish and consume water, which would add to their total mercury intake over their (relatively) short lifetime. All of these exposures add up, and each needs to be minimized in order to reduce risk of mercury poisoning.
Notes on the Details below
In order for the reader to follow this detailed information more clearly, I have color coded the information pertaining to the 4 mercury types discussed here. If you have trouble with your eyesight and prefer a single color version, please let me know and I can send it to you. Also, due to its length, I had to split the post into two sections, so please also read the first reply to this post for part two.
Ethylmercury - black
Methymercury - red
Elemental mercury - green
Mercurial salts - purple
*note - my calculations are based on an adult body weight of 150 pounds (67kg).
*note 1ppm = 1ug/g
What is mercury? Mercury (Hg) is a heavy metal found throughout our environment. It IS a naturally occuring metal, found in many different forms. In the past it was used for many more applications than in the present, specifically due to our greater understanding of its dangers and toxicity. It is extremely important to first know the different types of mercury, and some basic information about each one. I made the chart below to outline the information in the text of this section.
There are two broad categories of mercury. Organic mercury has one or more carbon atoms attached and inorganic mercury does not have any. That doesn't mean alot to most people, but chemists make this distinction, and it happens to be VERY important in terms of how the body metabolizes mercury. It is one clue, when reading the news or papers, about which type of mercury they are really talking about. If no reference to the type of mercury is made, you should assume they mean total mercury, which is really vague and doesn't give much practical information about toxicity or risk.
Organic mercury comes in two main types (although there are others) - ethylmercury and methylmercury. Chemically speaking, the ethylmercury is slightly larger, as it contains two carbon atoms bound to the mercury. Methylmercury is mercury bound to a single carbon atom.
Inorganic mercury also comes in two main types (althought there are others). Elemental mercury is the heavy metal you often see in pictures - it is a shiny, silver-colored liquid at room temperature, and was often used in thermometers. Mercurial salts are mercury atoms bound to things such as sulfide, chloride, etc. These salts are still used in some medications such as nasal srays, and some topical creams.
Picture above from ramehart
A few notes about this chart - you may immediately notice that ethylmercury does not accumulate in the body, and the known effects are on the gastrointestinal tract. Don't make any conclusions based on that information. Read on, the story doesn't end there.
How does mercury get into the human body? The answer depends on the type of mercury. As you can see from the chart above, each of the four types has a different mode of entry.
Ethylmercury is only brought into the body through vaccine injection. In the past, vaccines routinely contained detectable thimerasol, which is a compound metabolized into ethylmercury.
Humans inhale methylmercury from the air we breathe and ingest it from various food sources, including "later" breastmilk. Consumption of food containing methylmercury is the primary route of exposure. Fish (certain types) is the food containing the highest amounts of methylmercury.
Elemental mercury can be absorbed through the skin, from exposures due to broken thermometers and some broken light bulbs. Pregnant women pass elemetal mercury through there blood to the fetus. The fetus is known to have blood concentrations of 1.5x that of the mother, some of which is going to acucmulate in the fetal brain. Early breastmilk continues to move elemental mercury from the mother to the infant. Very low levels of elemental mercury is inhaled in the air we breathe as well.
Mercurial salts are also inhaled from the air. Mercurial salts in medicines such as nasal sprays and topical creams also are absorbed by the skin.
CONTINUE TO THE REPLIES FOR THE REST OF MY POST.
Tonya
AKA sunmoonstars
Comments:
Where does this mercury go once in the body and what effect does mercury have?
I was not able to find any information regarding blood ethylmercury concentrations and effects on the body - this is due mostly to the fact that ethylmercury does not accumulate in the blood or brain due to its relatively short half life of 2.2 - 7 days (depending on the study) in the blood and approximately 24 days in the brain. This means in the blood, the amount of ethylmercury is reduced by half every 2.2 - 7 days. Ethylmercury was detectable in the liver but not the kidneys, (and also the stools but not the urine) of vaccinated infants, indicating the method of clearance is through the feces.
What is most interesting is that in Dr. Burbacher's study, they found that the total elemental mercury accumulated in the brain is significantly higher in monkeys receiving ethylmercury by injection than in those receiving oral methylmercury. They speculate this is due to conversion of ehtylmercury to elemental mercury, which then accumulates in the brain. This is not known to aoccur with methylmercury, which remains in the blood until it is cleared from the body. This is probablly the most important point I have found during my study. My references - Dr. Pichichero Dr. Burbacher
In contrast, methylmercury blood concentrations have been well documented due to past accidental poisonings (from incidents such as fish and grain contaminations). Methylmercury is cleared from the blood slowly (half life is 20 - 40.5 days, depending an the study). The chart below is a summary of blood methylmercury concentration and the observed effects on the body. (Too many references to list)
>200 ug/L developmental issues, deafness, blindness, ataxia, insomnia
100-200 ataxia, vision and hearing loss
10-99 non-specific symptons
<10 no symptoms (normal range)
It is interesting that a toxicity study I found shows that giving mice extremely high oral doses routinely kills all males but only a smaller percentage of females. The same is true with extremely high levels of chronic oral doses. My reference - Dr. Yasutake
Accidental elemental mercury poisonings gives some blood concentration information also. This type of mercury is known to accumulate in the brain and is detectable in the blood. The half life in blood is 35 - 90 days.
> 60 ug/L severe tremors and fever
40-59 some tremors and fever
21-39 no symptoms, but some possible symptoms in sensitive individuals
< 20 no symptoms (normal level)
Note that if the ethylmercury from thimerosal in vaccines is converted to elemental mercury that is accumulated in the brain (as indicated in the study I referenced above), this needs to be considered as elemental mercury (not ethylmercury), with the effects indicated above. However, the effects indicated here are for acute dose to an adult, so the effects on a developing child (or brain) could vary.
Mercurial salts are also accumulated in the brain and detected in the blood. The half life in blood is about 40 days.
What information is missing from this story?
The data on ethylmercury is sparse. One thing we need is to have is more information on ethylmercury metabolism in the human body (or monkeys) and its probable conversion to elemental mercury.
We do know, from multiple studies, that methylmercury toxicity information is not a good indicator of the effects of ethylmercury on the body. First, because the route of entry is different, and second, because its conversion within the body and elimination from the body are different.
Much of what we know about mercury poisoning is research work performed in animals, or from information acquired due to accidental human exposures such as workplace mishaps and consumption of contaminated fish or grain. Often the information we gain is based on adults who are no longing developing, or animal species (mice or rats) that may not be applicable to humans.
In recent studies, we are seeing more information about the effects of mercury on development, but much of this information is looking at total mercury, which may not be specific enough since we know there are big differences in how the different forms of mercury affect the body.
I hoped you enjoyed reading my post, and learned something from it too. I never intend to sway opinions about a given topic, but rather give each person the information they need to make their own informed decisions. Please let me know if you have any questions or feel there are inaccuracies in my information. I learned alot by doing this study, and I always learn from people who correct my errors.
Tonya
AKA sunmoonstars
I don't know a whole lot about mercury, but lead is the same. one child can have a fairly low level, and have it really be seen in their ability, while a child with a higher level may not show the effects as much. Both are very scary!
Ok, I am not awake yet this morning, but I'm going to go ahead and have a stab at this.
As the mother of a child with autism, I am tired of this debate, and bit disappointed in my beloved Science Spot. As a scientist who has used her work to study ASD, I will add a few comments.
The first question, that we, as practitioners of science, is: Is mercury poisoning the same as autism? Are they two distinct things that may sometimes look alike? Secondly, we need to consider a control group. If mercury poisoning causes autism, then how to we account for children who have insignificant traces of mercury in their bodies, but still have autism? Third, we need to review the literature pertaining to autism. (Con't)
Let's discuss what we presently understand about ASD. It's difficult to even touch on all of the information available, so, let's exclude some of the common, and easiest to debunk arguments that support a connection between mercury and asd, and focus on genetics.
Last year at MIT, mutations in two genes (PTEN and serotonin transporter) that are likely to produce autistic features. Interestingly, if only one of these mutations occur, the autism appears "less severe". As parent, this makes me laugh (grimly), as I can easily guess which mutation most influence's my son's behavior and mental health- and because I take issue with the way we frame severity. Perhaps this is why so many autistic children respond favorably to SSRIs. Anyway...
Likewise, last year a Harvard team published a paper in Science identifying recessive 6 genes that can account for autistic functioning, and that can be "repaired" (ie, "turned on") via tried and true interventions such as ABA. If autism were indeed caused by mercury poisoning, this would not be the case.
So there are two bits of information to think about. I am very sleepy right now, but I would like to continue this discussion later today. I look forward to seeing what others have to put in, and I hope, dear Science Spot, that your thread will continue on from here as a thoughtful and peaceful exchange. What I mean is that sometimes mothers of spectrum children can, in their exhaustion, be carried away by their emotions and put an end to fruitful conversation. I wouldn't like to see that happen on a Science Spot post.
Awesome food for thought! I'll have to check out Dr. Pichichero and Dr. Burbacher to see if there are any reviews of their studies. I don't know if this was mentioned, but what are the trace levels of ethylmercury in vaccines now? If it isn't listed on the ingredient list, I'm guessing that there is a law that states if it is below a certain amount, it doesn't have to be listed. I'm wondering what that level is...
Although the notion that trace amounts of ethylmercury could have a measurable effect on the brain is suspect. Considering the number of children being exposed to it, I would think that problems would be widespread and well known.
Oh my...you all will have to forgive my abundant "I was 90% asleep while writing my comments" typos. Ha. I should ban myself from typing before my second cup of coffee.
21stcenturymom. Thank you for your information! That really is interesting about the gene mutations. I have to say I am surprised by the number of genes you reference as having relations to autism. I have not followed this topic at all (as I said), but when I do see conversation of autism, I don't usually see genetics in the discussion. This is quite interesting.
Why are you disappointed in me? Oh no! I had no intention to discuss autism since I am not qualified. But I do understand the topics of autism and mercury could now be permanently linked. I hope everyone will see my study for what it is - a study on heavy metal poisoning.
MothertoIreland - the first reply gives the link to the CDC website. They define "trace of thimerosal" as:
*** The term "trace" has been taken in this context to mean 1 microgram of mercury per dose or less.
So I believe "free from thimerosal" would be either none detectable, or significantly below the "trace" definition.
Thank you again for such an informative journal!
Where are all the people?? Well, 52 views is ok, but it should be more...This is very interesting and more information that I have ever read about Hg.
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How MUCH mercury gets into the human body?
Ethylmercury is the mercurial compound with the least data. I had trouble findng how much thimerasol USED to be in vaccines, so maybe someone can help fill this in (I even had two people help me look, with no luck!). The information I used for this section is found in the tables on the CDC's website. According to my calculations, if you stick to the current AAP vaccination schedule, including the flu vaccines, the child would be injected with 25 micrograms (ug) ethylmercury each year. In addition, pregnant women currenlty receiving Rogam or Gamulin shots would be injected with NO mercury, but in the past (1993-1997), these shots would have given the pregnant woman 12.75 ug and 50 ug per shot, respectively, It is unkown how much of this ethylmercury would have been transferred to the fetus before the being cleared from the blood. There is currently no recommendation set for maximum ethylmercury intake, although most sources agree that exposure should be minimized, partcularly during fetal development and infancy. This fact is recognixed by the dramatic reduction of thimerosal use in the vaccine industry in recent years.
In contrast, there is ALOT of data and other information about methylmercury. It has been known for decades that methylmercury accumulates in the blood and brain of humans and the muscle of fish. In 1991 the WHO estimated the average adult ingests 2.4 ug per day from fish and other seafood, and another 0.008 ug per day inhaled from the air.
These levels are far below the maximum ingestion recommendations from the EPA (ingestion of 6.7 ug/day), FDA (20.1 ug/day), and WHO (31.5 ug/day). This is also far below the FDA's maximum inhalation recommendation (0.2 ug/cubic meter of air/day).
In order to keep the public below these recommended maximums, the FDA set some guidelines regarding how much fish should be consumed, recognizing the sensitivity of the fetus and child during development. I made the chart below to summarize the FDA's guideline for methylmercury in food as well as consumption recommendations. Based on this information, a child following the recommendations could ingest a maximum of approximately 6 ug methylmercury a month.
Methylmercury can also be found in grain, where it is used an a fungicide. The FDA limits its concentration in grain to <1 ppm, although in the USA the actual concentration is much lower (or zero).
The methylmercury content in breastmilk depends on the methylmercury content in the mother's blood, as well on how much methylmercury she continues to ingest during lactation. It is known the methylmercury content that moves from the mother to the child through breastmilk is minimal because the methylmercury is bound to the blood cells in the mother.
Elemental mercury is introduced to the body through air, some foods, and absorption through the skin (or gums). WHO estimates (from 1991) that the average adult inhales 0.03 ug/day from the air and absorbs through the gums (from fillings) 3.8 - 21 ug/day. There is currently no maximum recommended intake, although it is known it is adviseable to keep it as low as possible.
Elemental mercury found in some HFCS (high fructose corn syrup) samples is in the range of 0.005 - 0.570 ug/g; the average adult consumption is 50g HFCS per day, which could be a total consumption of about 28.5 ug/day.
Elemental mercury in breastmilk is highest in early breastmilk and gets lower over time. One study showed a concentration of 0.25 - 20.3 ug/L. Assuming one liter consumption a day, this yields a maximum consumption of approximately 20.3 ug/day early on, and later 11.7 ug/day.
In 1991, the WHO gave estimates of adult daily intakes of total mercurial salts - 0.002 ug/day inhaled from the air, 3.6 ug/day ingested from food (non-fish), and 0.05 ug/day ingested from water. The current maximum recommended intakes for adults are givenby a few authorities. The EPA recommendation for both bottled water and open water is 0.002 ug/L, and for streams is 0.144 ug/L. The WHO recommends a maximum of 0.001 ug/L in all water systems. OSHA recommends a maximum of 0.1 mg/cubic meter of air (occupational exposure).
I found many references to total mercury in other foods, such as steak, pork and lamb, as well as raisins, rice and grapes. However, as I said before, it doesn't tell us much about mercury toxicity or risk since we don't know what type of mercury is represented in that sample. As a general guideline, the FDA recommends a maximum total mercury intake of 5 ug/kg body weight per day from all source (for an adult about 150 pounds, this is 33.5 ug/day).
From this data, I have esitmated the total mercury intake for a fetus, 2 month old baby, and one year old child. In the interest of space, I won't post my calculations here, but if anyone is interested in them, let me know and I can post it.
According to my calculations, the maximum peak total mercury blood level in a fetus could be around 195 ug/L, which is going to vary widely based on the mother's fish consumption habits and if she needed shots due to being Rh negative.
For a 2 month old baby (breastfed), I calculate a range of 7.5 - 1200 ug/month total monthly mercury intake from all sources, again depending mostly on the mother's fish consumption. Based on their weight, the FDA's maximum recommended intake is 600 ug/month. The same calculations for a formula fed infant yields much lower results, based on the fact the water used to mix formula has a dramatically lower methylmercury content than breastmilk.
The same calculations for a one year old child, who is no longer breastfeeding, but is consuming some fish and water, shows an approximate total mercury intake of around 867 ug/month. Based on weight, the FDA's recommended maximum intake is 1500 ug/month.
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