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posted by n1 on Tuesday June 13 2017, @01:46PM   Printer-friendly
from the also-works-on-children dept.

A chemical currently being used to ward off mosquitoes carrying the Zika virus and a commonly used insecticide that was threatened with a ban in the United States have been associated with reduced motor function in Chinese infants, a University of Michigan study found.

Researchers at the U-M School of Public Health and U-M Center for Human Growth and Development tested children in China and found exposure to the chemical naled via their mothers during pregnancy was associated with 3-4 percent lower fine motor skills scores at age 9 months for those in the top 25 percent of naled exposure, compared to those in the lowest 25 percent of exposure. Infants exposed to chlorpyrifos scored 2-7 percent lower on a range of key gross and fine motor skills.

Girls appeared to be more sensitive to the negative effects of the chemicals than boys.

Naled is one of the chemicals being used in several U.S. states to combat the mosquito that transmits Zika. Chlorpyrifos, around since the 1960s, is used on vegetables, fruit and other crops to control pests.

Both are insecticides called organophosphates, a class of chemicals that includes nerve agents like sarin gas. They inhibit an enzyme involved in the nerve signaling process, paralyzing insects and triggering respiratory failure. However, they may adversely impact health through other mechanisms at lower exposure levels that are commonly encountered in the environment.

In the children studied, naled affected fine motor skills or the small movements of hands, fingers, face, mouth and feet. Chlorpyrifos was associated with lower scores for both gross (large movements of arms and legs) and fine motor skills.

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  • (Score: 4, Informative) by JoeMerchant on Wednesday June 14 2017, @01:06AM (2 children)

    by JoeMerchant (3937) on Wednesday June 14 2017, @01:06AM (#525190)

    So, 100% of people who drink water die, but 100% of people who do not drink (or otherwise ingest) water die much more quickly.

    In this study, the higher exposure group demonstrated motor deficits as compared to the lower exposure group. This study, by itself, says little about organophosphates. However, there are a few hundred similar "questionable" studies that also point in the same direction, and virtually none that found a null or inverse result. These studies have been done all over the world, in animals, and deconstructed via biochemistry (the same wonderful science that enabled creation of these things in the first place).

    One might say that the bleeding heart academics only publish results that make evil industry look bad - this would be overlooking the fact that evil industry funds the majority of bleeding heart academics either directly or indirectly and studies that refuted these results would be widely heralded by the companies that make money producing these chemicals at industrial scale.

    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1867968/ [nih.gov]

    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4908699/ [nih.gov]

    https://www.researchgate.net/publication/259128837_A_systematic_review_of_neurodevelopmental_effects_of_prenatal_and_postnatal_organophosphate_pesticide_exposure [researchgate.net]

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  • (Score: 1) by pTamok on Wednesday June 14 2017, @07:35AM (1 child)

    by pTamok (3042) on Wednesday June 14 2017, @07:35AM (#525320)

    Thanks for your reply.

    My complaint was meant to be more about the lack of a link to the original publication, rather than the merits of the hypothesis - the point being, it hasn't been made easy to evaluate the article. You illustrate my point very well: you provided links to publications in your reply, demonstrating that it is not difficult. You'd expect the PR office of a university to be able to do the same.

    Regarding the issue of organophosphate pesticides.

    It is entirely reasonable to be suspicious of chemicals that are closely related to chemical warfare nerve agents, and you point to the lack of null results. Unfortunately, there is a huge publication bias generally in the scientific literature in that confirmations of the null hypothesis are not publication-worthy, and don't get recognised. There is huge pressure to find 'significant' results, which leads, sometimes, to the use of inappropriate methods. This is a general problem, not just confined to this particular subject field.

    A good example is here:

    http://steamtraen.blogspot.no/2017/04/the-final-maybe-two-articles-from-food.html [blogspot.no]

    Without the paper, you can't even begin to evaluate the methods. If the effect sizes are small, it is extraordinarily difficult to eliminate confounders, and you have to be very careful not to fall into statistical traps like the one illustrated by xkcd:

    https://www.xkcd.com/882/ [xkcd.com]

    There is a lot of good science being done out there. But there is also a great deal of mediocre science, and even bad science. Press releases that don't even link to the publication being publicised don't help. So we can't tell if this is a good paper or not. Yes, there could be an effect here, but then number of papers in a topic area doesn't necessarily correlate with the truth of the proposition - just look at the publications supporting homoeopathy or acupuncture.

    Science is great, but the current publish-or-perish approach is doing nobody any favours.

    • (Score: 2) by JoeMerchant on Wednesday June 14 2017, @12:00PM

      by JoeMerchant (3937) on Wednesday June 14 2017, @12:00PM (#525379)

      I agree about the "null hypothesis hole" in the published literature, although meta-analysis papers (such as the one I linked) do seem to frequently take pot-shots at the body of work (deserved? maybe) and attempt to nullify results with criticism when there is clear unidirectional bias in the papers being studied i.e. calls for standardized methods, increased sample sizes, etc. To me it often reads like: "I tried to analyze these 150 publications for my PhD, but it was hard because everybody used their own methods and I can't figure out how to lump the results together in a clean, defensible package."

      The XKCD882 phenomenon is well understood and exploited by industry (pharmaceutical I know from personal dealings, I'm sure pesticides are in on the game also) wherein they launch a number of "trade secret protected" clinical trials and/or studies and then shut down the ones that don't appear to be generating the desired results - then, if they are lucky enough, they get one or more "statistically significant" results which back up their billion dollar product, at least long enough for it to make back the development costs.

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