Seems appropriate since controversial topics like vaccines are on the agenda this week.
A study published in EHP finds that high fluoride (mean of 8.3 mg/L) or arsenic in water decreases IQ (it’s very rare to have a fluoride level this high in the US, artificial fluoridation is supposed to be 0.7-1.2 mg/L and usually is). This isn’t anything new really, it’s been published multiple times before, just not in a major English language journal (and a couple of the previous studies had some control issues – controlling for Arsenic for one). This comes on the heels of a couple other interesting things about fluoride:
1) A study of US children (seems to be the most rigorous so far on the topic) showing increases in osteosarcoma (a bone cancer) only in boys only if exposed to fluoridated drinking water during periods of fast bone growth. The males only finding is also found in an other epi study done in NJ and in rats – it’s curious, I can’t think of why this would be. Naturally boys are predisposed to osteosarcoma from looking at the incident rates. Any oncologists know the biological basis for this sex difference?
2) The National Research Council (part of the National Academies) saying the EPA’s MCL for fluoride in water is too high (The MCL is currently 4 mg/L; most systems that fluoridate are at ~1 mg/L) due to skeletal fluorosis, I believe (brittle but very dense bones – accompanied by bone pain if I’m not mistaken). As an interesting aside, fluoride was tried as a treatment for osteoporosis a while back (80s-90s) becuase of the more dense bones thing. Unfortunately, it only makes them dense, not stronger, in fact more brittle (a density scan will tell you that things are getting better but a look at the bones show that the osteoporatic structure has not been changed – there is still loss of connectivity). Epi studies of the relationship between hip fracture and fluoride are all over the place (positive, negative, or no association).
3) The American Dental Association recommended (based on some info in the NRC report) that baby formula not be made up with fluoridated water.
I find all this a lot more credible than any of the anti-vaccine stuff. The Bassin et al. study is particularly good. They went back and verified the water fluoride levels of the cases and controls at the times of their early childhood in the towns they lived in (children usually are diagnosed with osteosarcoma in their mid to late teens I believe). Can you imagine the work (and mind-numbing at that)? Whew, I’m glad that wasn’t my thesis project back in the day.