Developmental neurotoxicity of industrial chemicals (320kb).
CBS news (amongst plenty of others) recently reported on a new study published in The Lancet
Exposure to industrial chemicals may be responsible for a “silent pandemic” of brain development disorders affecting millions of children worldwide, and not enough is being done to identify the risks.
In an essay published online in the journal The Lancet, the researchers identified 202 potentially harmful industrial chemicals that may be contributing to dramatic increases in autism, attention deficit hyperactivity disorder (ADHD), and other brain disorders among children.
Roughly half of the chemicals are in common use, but very few have been tested to determine their impact on brain development.
Right. So ‘very few’ of the chemicals’ have been tested to determine their impact on brain development but they are being touted as the cause of a ‘silent pandemic’? How does that work exactly?
Don’t get me wrong – these things should be looked at to determine their safety but really, this is an example of hysterical journalism. Lets take a look at what the paper itself actually says.
This is from the abstract:
Neurodevelopmental disorders such as autism, attention deficit disorder, mental retardation, and cerebral palsy….causes are mostly unknown.
And what about this ‘silent pandemic’? Well, firstly, lets make sure we’re on the same page. This essay ups the ante from ‘epidemic’ to ‘pandemic’ meaning that the ‘epidemic’ is on a large international scale. OK, so –
The underlying idea is that there is a dose-dependent continuum of toxic effects, in which clinically obvious effects have subclinical counterparts. A pandemic of subclinical neurotoxicity is therefore likely to be silent—ie, not apparent from standard health statistics.
The authors draw comparisons between this and the pioneering work which identified the issues of Lead toxicity in kids. However, they fail to note that these studies had actual data to back up their hypothesis. This is in direct contrast to this essay which has no such data. In fact, in relation to the idea of an ‘epidemic’ of autism, the authors admit that:
Some experts have reported that the prevalence of certain neurodevelopmental disorders—autism and attention deficit and hyperactivity disorder, in particular—might be increasing, but there are few data to sustain that position.
So, its clear that this ‘silent pandemic’, far from being a threat is totally hypothetical. Much as the authors might like to think it has happened, it is not apparent from any data that it has. The authors of this paper certainly failed to present _any_ supporting data.
Indeed, they even (inadvertently?) seem to exonerate thiomersal as a causative agent from their own investigation:
Substantial reductions have already been achieved in mercury use and release from hospitals and incinerators. A related substance, > ethylmercury, has been widely used as a preservative in vaccines, but neurotoxic risk has not been documented.
Very true.
Altogether this is an odd paper, which claims to support the idea that chemicals might play a role in causing neurodevelopmental disorders but fails to provide any evidence for that stance whatsoever.
If I was a more cynical person, I’d say somebody was trying to add to the ‘scientific’ knowledge being accumulated for the Autism Omnibus hearings next year as well as place the idea of poisoning in the public conciousness as well.
There’s a ‘Conflict of Interest’ statement on page 10:
P Grandjean has testified on behalf of the Natural Resources Defense Council in a court case in regard to mercury pollution from a chemical plant in Maine, USA. PJ Landrigan has testified on behalf of the State of Rhode Island, USA, in a lawsuit against the manufacturers of lead-based paint.
Very laudable. However, it fails to mention something else Grandjean is involved with. He’s an expert witness in the Autism Omnibus proceedings. That puts a slightly different slant on this weird essay.
Left Brain Right Brain 
I was disappointed at Phil Landrigan for getting involved in the Rhode Island suit. In this case he clearly crossed the line from dispassionate pursuit of truth into legal/political advocacy. I wish we folks didn’t do that.
best,
Flea
Thanks for walking me through it. [the ‘insert'[?] was tough on the old bifocals though. Best wishes
I think Grandjean is in general a reliable scientist and am surprised he would get into bed with the mercury militia. I wonder if it wasn’t made clear to him what he was agreeing to do.
And “pandemic” would mean that it’s something we all have—-don’t know about that.
http://neurodevelopment.com/en/neurotoxins.htm
The leader of the Faroe Islands study, Philippe Grandjean, an adjunct professor of environmental health at the Harvard School of Public Health, and his colleagues reported in the November 1997 issue of Neurotoxicology and Teratology that 7-year-old Faroese children had significant cognitive deficits and neurological changes after prenatal exposure to methylmercury.
http://www.springerlink.com/content/b758767u364g5255/
The prevalence of autism in the Faroe Islands was very similar to that reported from many western countries
I didn’t understand the fuss over that paper. It’s basically nothing more than an opinion piece.
this report in the Guardian offers a more balanced take on the story. While I share your concerns about this particular research paper I have witnessed at first hand the cavalier disregard for health and safety in industry. They may not cause autism but some of these chemicals are a potential health hazard.
Hi Kev
Beyond any problem/controversy I consider that there are several published clues about strong effect o chemicals, mainly as endocrine disruptors in general.
I have (strong) problems with the words like pandemia (for sure, as an aseveration) or cause – or the presentation of the press of these issues many times in sensacionalistic ways.
All the above is a different world in terms of what is the true importance of environment/epigenetics at an individual level -in terms of health hazards-and I do think that there are enough data to take seriously all the approach and , in fact, the impact of all these should be studied carefully.
A few of them:
“Developmental neurotoxicology of endocrine disruptors and pesticides: identification of information gaps and research needs”:http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=9646041
“Neurodevelopment and Endocrine Disruption”:http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=15198913
“The need for developmental neurotoxicity studies in risk assessment for developmental toxicity”:http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=16777374&query_hl=4&itool=pubmed_docsum
“Motor inhibition and learning impairments in school-aged children following exposure to organophosphate pesticides in infancy”:http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?itool=abstractplus&db=pubmed&cmd=Retrieve&dopt=abstractplus&list_uids=16788088
“A Case for Revisiting the Safety of Pesticides: A Closer Look at Neurodevelopment”:http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=16393651
“Quantitative risk assessment for developmental neurotoxic effects”:http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=15660620&query_hl=13&itool=pubmed_DocSum
“Metals and women’s health”:http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=12051792&query_hl=13&itool=pubmed_DocSum
“Longitudinal Associations Between Blood Lead Concentrations Lower Than 10 µg/dL and Neurobehavioral Development in Environmentally Exposed Children in Mexico City”:http://pediatrics.aappublications.org/cgi/content/full/118/2/e323
“Does inadequate maternal iron or DHA status have a negative impact on an infant’s functional outcomes?”:http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=16449018&query_hl=19&itool=pubmed_docsum
In fact, there are several studies concerned about environmental effect in ASD actually being done:
1-Autism Birth Cohort (Norway) 2004-2008
2-California Autism twin Study 2004-2009
3-Centers for Autism and Developmental Disabilities Research and Epidemiology 2000-2011 (CADDRE)
4-Early Markers for Autism 2004-2006
5-Markers for Autism Risk in Babies-.Learning Early signs 2006-2011 (planned)
6-“CHARGE Study MIND”:http://beincharge.ucdavis.edu/
The way that the “potentially real†problem is presented many times is against or decrease the credibility of the overall approach but this is different than a true problem can be present that deserves a deep analysis and study, with all the care and prudence of the case in terms of terminology/conclussions.
Hysterical journalism indeed! That’s the way news is broadcasted in our world. They do not care of revealing the truth about things, their real nature, but to get attention and to sell the newspaper or the entire info. That’s the way they consider themselves professionals.
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