I’m afraid I don’t have the faintest idea. It certainly fits in the general ‘pathogen, immune defense, recent environmental’ bag, and if it interferes with iodine chemistry then it sounds more likely than ‘randomly chosen thing in that bag’.
If it’s true, it should be a simple experiment to inflict the stuff on rats and cause thyroid problems. If it doesn’t sod up the rats (even in small amounts) then there doesn’t seem to be a strong reason to believe that it would do anything nasty to us. It all works pretty much the same way. Do you know of any relevant experiments?
The central problem seems to be to get medicine to pay attention to the existence of thyroid problems with ‘normal’ TSH. At the moment they seem to be being run ragged by witch-doctors, but I’m not sure I trust the witch-doctors to do the job properly either. They seem to have convinced themselves that it’s mercury fillings or PCBs or fluoride in the water, or anything else they can think of.
If medicine can be persuaded to find out whether there’s a real problem, rather than just a weird information cascade from Broda Barnes that’s somehow hoodwinking thousands of people into believing they’ve got better by trying things that should harm them, then I kind of semi-trust it to investigate the possible causes. But perhaps I am being naive.
Here’s a more or less randomly chosen talk on the subject of environmental perchlorate and iodide, for what it’s worth (from Seti Talks, of all places):
A study that saw statistically significant hormone effects
First, 10 mg/kg/day is a LOT (that’s mg, not mcg).
Second, while there were morphological changes (“significantly increased thyroid weights and thyroid histopathology”) and some changes in the TSH/T3/T4, the study notes that “No toxicologically meaningful differences were observed between the control and AP-treated groups” which means there were no clinical symptoms whatsoever.
10 mg was what showed thyroid enlargement, but they saw hormone changes without definitive toxicological effects at all doses down to the minimum they tried, ten micrograms per kg per day. Quote:
“Statistically significant changes in TSH and thyroid hormones were observed at all AP dosage levels tested; however, no thyroid organ weight or histopathological effects were observed at AP dosage levels < or = 1.0 mg/kg/day. In the absence of thyroid organ weight and histopathological effects, the toxicological significance of TSH and thyroid hormone changes at AP dosage levels < or = 1.0 mg/kg/day remains to be determined.”
I have little strong opinion here, just noting that they saw subtle hormone changes at very low doses and it’s hard to ask a mouse how they feel.
Is it normal in a study like this to report the results separately for males and females? At low intervention levels what’s significant for males is not significant for females and vice versa, so there’s some potential for statistical shenanigans.
Agree with this too. On the one hand, Simpson’s Paradox, on the other hand, Simpson’s Paradox. But if you don’t expect male/female confounder, it just gives you three goes at the magic p<0.05.
This is absolutely evidence that huge doses of this stuff knacker your thyroid. But huge doses of most nasty chemicals probably do that. There’s no particular reason to finger this as a significant cause unless it’s in the environment in huge doses.
I totally concur. 10mg/kg/day is a gram a day. If I took that amount of thyroid hormone, which I believe to be one of the safest drugs ever used, and of huge benefit to a large subset of the population, I would confidently expect to give myself an immediate heart attack. At the very least it would make me spectacularly ill.
No toxicologically meaningful differences were observed between the control and AP-treated groups with respect to survival, clinical observations, body weights, food consumption, water consumption, ophthalmology, hematology, clinical chemistry, estrous cycling, sperm parameters, or bone marrow micronucleus formation.
So it’s not buggered them up too badly.
For comparison, if you took the poor wee things’ thyroids out, then you’d expect them to display horrible symptoms and die off in droves.
Oh the effect is definitely small. They do however note observable differences in the hormones down to a thousandth the dose that caused histological changes, albeit without being able to see secondary effects on quantifiable health outcomes. No idea at all if that’s significant but figured I’d contribute it to the discussion of subtle thyroid dysfunction.
Well, I don’t want to sound like an endocrinologist, but there aren’t many chemicals which don’t have some sort of effect on thyroid hormones, and if this one screwed up the system in a way measurable by hormone blood tests, it would just cause ordinary hypothyroidism, and that would get treated.
As far as I can see, the evidence for it causing any sort of subtle dysfunction is non-existent. All I’ve seen is the one study, but it sounds from that as though it would be safe to ingest in small doses.
I’m afraid I don’t have the faintest idea. It certainly fits in the general ‘pathogen, immune defense, recent environmental’ bag, and if it interferes with iodine chemistry then it sounds more likely than ‘randomly chosen thing in that bag’.
If it’s true, it should be a simple experiment to inflict the stuff on rats and cause thyroid problems. If it doesn’t sod up the rats (even in small amounts) then there doesn’t seem to be a strong reason to believe that it would do anything nasty to us. It all works pretty much the same way. Do you know of any relevant experiments?
The central problem seems to be to get medicine to pay attention to the existence of thyroid problems with ‘normal’ TSH. At the moment they seem to be being run ragged by witch-doctors, but I’m not sure I trust the witch-doctors to do the job properly either. They seem to have convinced themselves that it’s mercury fillings or PCBs or fluoride in the water, or anything else they can think of.
If medicine can be persuaded to find out whether there’s a real problem, rather than just a weird information cascade from Broda Barnes that’s somehow hoodwinking thousands of people into believing they’ve got better by trying things that should harm them, then I kind of semi-trust it to investigate the possible causes. But perhaps I am being naive.
Here’s a more or less randomly chosen talk on the subject of environmental perchlorate and iodide, for what it’s worth (from Seti Talks, of all places):
https://m.youtube.com/watch?v=r-p55WLXAEI
A study that saw statistically significant hormone effects at 10 micrograms per kilogram per day: http://www.ncbi.nlm.nih.gov/pubmed/10966512
First, 10 mg/kg/day is a LOT (that’s mg, not mcg).
Second, while there were morphological changes (“significantly increased thyroid weights and thyroid histopathology”) and some changes in the TSH/T3/T4, the study notes that “No toxicologically meaningful differences were observed between the control and AP-treated groups” which means there were no clinical symptoms whatsoever.
10 mg was what showed thyroid enlargement, but they saw hormone changes without definitive toxicological effects at all doses down to the minimum they tried, ten micrograms per kg per day. Quote:
“Statistically significant changes in TSH and thyroid hormones were observed at all AP dosage levels tested; however, no thyroid organ weight or histopathological effects were observed at AP dosage levels < or = 1.0 mg/kg/day. In the absence of thyroid organ weight and histopathological effects, the toxicological significance of TSH and thyroid hormone changes at AP dosage levels < or = 1.0 mg/kg/day remains to be determined.”
I have little strong opinion here, just noting that they saw subtle hormone changes at very low doses and it’s hard to ask a mouse how they feel.
Is it normal in a study like this to report the results separately for males and females? At low intervention levels what’s significant for males is not significant for females and vice versa, so there’s some potential for statistical shenanigans.
Agree with this too. On the one hand, Simpson’s Paradox, on the other hand, Simpson’s Paradox. But if you don’t expect male/female confounder, it just gives you three goes at the magic p<0.05.
Frequentism. It’s just broken.
This is absolutely evidence that huge doses of this stuff knacker your thyroid. But huge doses of most nasty chemicals probably do that. There’s no particular reason to finger this as a significant cause unless it’s in the environment in huge doses.
I totally concur. 10mg/kg/day is a gram a day. If I took that amount of thyroid hormone, which I believe to be one of the safest drugs ever used, and of huge benefit to a large subset of the population, I would confidently expect to give myself an immediate heart attack. At the very least it would make me spectacularly ill.
So it’s not buggered them up too badly.
For comparison, if you took the poor wee things’ thyroids out, then you’d expect them to display horrible symptoms and die off in droves.
Oh the effect is definitely small. They do however note observable differences in the hormones down to a thousandth the dose that caused histological changes, albeit without being able to see secondary effects on quantifiable health outcomes. No idea at all if that’s significant but figured I’d contribute it to the discussion of subtle thyroid dysfunction.
Well, I don’t want to sound like an endocrinologist, but there aren’t many chemicals which don’t have some sort of effect on thyroid hormones, and if this one screwed up the system in a way measurable by hormone blood tests, it would just cause ordinary hypothyroidism, and that would get treated.
As far as I can see, the evidence for it causing any sort of subtle dysfunction is non-existent. All I’ve seen is the one study, but it sounds from that as though it would be safe to ingest in small doses.