Even Low Level Exposure To Organophosphate Pesticides Bad For Your Brain, Says Systematic Review
    By News Staff | December 3rd 2012 10:10 AM | 6 comments | Print | E-mail | Track Comments

    Organophosphate pesticides were once commonly used in roach control and other applications but organiphosphates were originally developed as nerve-gas agents for chemical warfare. The human body converts organophosphate pesticides into altered forms called metabolites, and  organophosphates are toxic to the nervous system, known to cause memory and vision problems.

    Organophosphates are also vital biochemicals that include DNA and RNA. However, there are safer ways to get rid of household pests and the EPA bans organophosphate pesticides for home use, but when studies showed health effects, somewhat sketchy papers began to link organophosphates to things like ADHD and if a child does not do well in school, though organophosphates were in common use decades ago. Organophosphates became widely employed both in natural and synthetic applications because organic groups can be linked together easily.

    A new review reaffirms that low-level exposure to organophosphates (OPs) produces lasting decrements in neurological and cognitive function and that memory and information processing speed are affected to a greater degree than other cognitive functions such as language.  The toxic effects of high-level poisoning are well established but the possibility that long-term low-level exposure to organophosphates in doses below acute toxicity can cause ill health is controversial.

    A systematic review did a quantitative evaluation of the data assimilated from 14 studies and more than 1,600 participants. The researchers then used meta-analysis to obtain an overview of the literature about the question they asked in their systematic review.

    "Meta-analysis combines the results of several studies and moves the discussion away from individual pieces of research, towards an overview of a body of literature," saids Dr. Sarah Mackenzie Ross, psychologist at University College London and lead author of the paper.  A systematic review involves examining the literature to ask an answerable question and a 
     meta-analysis is the statistical approach to combining the data from a systematic review.

    "This is considered to be the method of choice in situations where research findings may be used to inform public policy," explains Professor Chris McManus, also a psychologist at University College London and  co-author of the study. 

    They say this is the first time anyone has analyzed the literature concerning the neurotoxicity of organophosphate pesticides using meta-analysis, though that is hard to believe. The EPA banned organophosphate pesticides for home use 11 years ago. 

    Pesticides prevent millions of people from starvation and disease, but all pesticides, be they synthetic or natural,  can be harmful to humans. Organophosphate pesticides as a class remain the most widely used insecticides in the world. 

    "In the UK a number of occupational groups have expressed concern that their health has been affected by exposure to organophosphates," explains Dr Virginia Harrison of Open University, co-author of the study. This includes sheep farmers, who between 1988 and 1991 were required to dip sheep yearly in pesticide formulations containing OPs. Between 1985 and 1998 more than 600 reports of ill health following exposure to sheep dip were received by a government adverse reaction surveillance scheme.

     Published in Critical Reviews in Toxicology.


    Gerhard Adam
    So, what does this mean with respect to Round-up resistant GM crops?  Since Round-up's active ingredient is an organophosphate [Glyphosate], and this is still present in the crops that are resistant, then how does this play into concerns about food safety?
    Mundus vult decipi
    Roundup (Glyphosate) is not at all related to the organophosphate insecticides. Those (along with some carbamates) are inhibitors of Choline Esterase. Glyphosate is an inhibitor of EPSPS and is essentially non-toxic to mammals.

    Organophosphates may still be widely used in some parts of the world, but their use in the US has been dramatically declining for some time. See (Where Have All the Nasty Pesticides Gone? They are also not persistent (like DDT or other organochlorines which they replaced).

    My main concern for exposure today would be in things like fruit juice concentrated imported from places like China. I don't mean to be alarmist, but that seems to me like the most likely scenario for why we still find traces of organophosphate metabolites in samples of blood or urine from Americans.

    Gerhard Adam
    Thanks for the update, Steve
    Mundus vult decipi
    We're even importing fruit juice from China?! Economists have predicted that US imports from China will decline in the next decade while those from Mexico increase. Are organophosphates used south of the American border?
    Most of the produce we get from Mexico is from good companies and often from divisions or partners of US grower/shippers.  I'm far less concerned about that, but China is where most OPs are still manufactured and they don't really have much in the way of oversight.
    Steve Savage
    Yes, if 25% of organic food from China is just regular food certified under some shell they created to sell to dopey Westerners, who knows what shoddy conventional growers are spraying.  

    Obviously we survived organophosphate pesticides and they were widely used here before ADHD even existed as a diagnosis, but the lingering prevalence shows you have to wash your food. Pyrethrum is dangerous when used improperly, just like organophosphate, so organic food is not going to keep anyone toxin free, despite their marketing. Lime sulfur and nicotine sulfate are not on my health-based Christmas list either, but I could get it on produce at Whole Foods.