"The current study provides the first analysis of potential transgenerational impacts of glyphosate in mammals"

'Carefully' is a word that applies to any science in terms of 'meaning' and 'generalisation'. Don't get me wrong, I'm a big fan of science and scientific evidence when it comes to life, the universe and everything. But I also understand that science can be used/manipulated in many, many different ways, and rarely, if at all, do we see something that could be considered perfect science. Hence my use of the word 'carefully' in opening this blog post. With all that in mind, I bring the findings reported by Deepika Kubsad and colleagues [1] to the blogging table and the proposal that: "glyphosate can induce the transgenerational inheritance of disease and germline (e.g. sperm) epimutations."

Why am I talking about such a study on a blog primarily hosting autism research? Well, a few reasons (see here and see here), predominantly based around the observations that (a) herbicides and insecticides whilst very useful, are not seemingly without a risk-benefit profile, and (b) autism (and other related labels) have been 'talked about' in the context of risk and 'exposure' to such compounds. I emphasised the words 'talked about' to ensure that the current peer-reviewed science base is not contorted into something that it is currently not (i.e. cause-and-effect). I might also add that 'transgenerational inheritance' is something that has also been discussed in the peer-reviewed science literature in the context of autism too (see here).

The basics of the Kubsad paper: "There are an increasing number of conflicting reports regarding the direct exposure toxicity (risk) of glyphosate, but no rigorous investigations on the generational actions." So, using a rodent (rat) model of study, researchers exposed mummy rats (F0 'gestating female') to glyphosate - "daily intraperitoneal injections of glyphosate" - at doses that probably would be considered 'excessive', and then followed successive generations of rats (F1, F2, F3) looking for any "transgenerational pathologies observed... including prostate disease, obesity, kidney disease, ovarian disease, and parturition (birth) abnormalities." They also included a set of control animals - "F0 generation gestating females administered vehicle control dimethyl sulfoxide (DMSO) or phosphate buffered saline (PBS)" - and whilst they were at it, checked for any germline transmission issues/differences via the inspection of sperm; specifically looking for differential DNA methylation regions (DMRs). Those DMRs are important when it comes to whether specific genes are expressing or not ('switched on' or 'off').

Results: with that word 'carefully' in mind, we are told that there were: "negligible impacts of glyphosate on the directly exposed F0 generation, or F1 generation offspring pathology." That's important because it suggests that those directly exposed and their immediate offspring don't seemingly show adverse effects.

But... "In contrast, the F2 generation grand-offspring, derived from a direct exposure F1 generation germline, had significant increases in testis disease, kidney disease, obesity, and multiple diseases in males" and: "The F2 generation females had significant increases in ovary disease, obesity, mammary gland tumors, parturition abnormalities, and multiple disease susceptibility." Researchers also reported seeing a few things in their F3 generation too, as the words "generational toxicology" entered discussions.

As to the DMRs results, well, there were some interesting findings there too: "the glyphosate lineage sperm were found to have altered DNA methylation in direct exposure F1 and F2 generations, as well as the transgenerational F3 generation." This led Kubsad et al to conclude that glyphosate exposure could "promote germline epigenetic alterations in DNA methylation" but more needs to be done on what this actually means for gene expression and whether it tied into the disease risk(s) noted in their exposed cohort and subsequent generations.

The authors mention how their study had limitations including the use of "an environmentally relevant exposure of twice the allowed industry exposure" and the use of an animal model (bearing in mind the logical fallacies that can follow). Lots more investigation is indicated before any big headlines are generated.

But... the Kubsad results are not to brushed under the scientific carpet. They add to the range of other compounds that seemingly carry transgenerational biological correlates and imply further inspection of glyphosate in that same potential category. Whether also there may be additive or interactive effects with other compounds could also be part of the research agenda.

----------

[1] Kubsad D. et al. Assessment of Glyphosate Induced Epigenetic Transgenerational Inheritance of Pathologies and Sperm Epimutations: Generational Toxicology. Scientific Reports. 2019; 9: 6372.

----------

"To examine associations between early developmental exposure to ambient pesticides and autism spectrum disorder"

The quote heading this post - "To examine associations between early developmental exposure to ambient pesticides and autism spectrum disorder" - reflects the aim of the study published by Ondine von Ehrenstein and colleagues [1]. Said aim was accomplished by examining data from "California’s main agricultural region, Central Valley, using 1998-2010 birth data from the Office of Vital Statistics" with regards to autism diagnoses (see here) and pesticide use and exposure. The results: "Findings suggest that an offspring’s risk of autism spectrum disorder increases following prenatal exposure to ambient pesticides within 2000 m of their mother’s residence during pregnancy, compared with offspring of women from the same agricultural region without such exposure." Also: "Infant exposure could further increase risks for autism spectrum disorder with comorbid intellectual disability."

The von Ehrenstein findings also come with an accompanying editorial [2] both published in the British Medical Journal (BMJ). That editorial provides a good overview of the findings and, importantly, some of their limitations. The editorial notes for example, that: "the study included only children with a diagnosis of “autistic disorder” by the California Department of Developmental Services, based on criteria described in the Diagnostic and Statistical Manual of Mental Disorders version IV-R." It cautions that the von Ehrenstein findings might not generalise to "milder forms of autism spectrum disorder." This 'lack of generalisation to milder forms' is a real reversal of what is typically seen in the peer-reviewed autism research literature (see here).

I don't want to linger too much on the von Ehrenstein study but a few points are worth noting. The question of what specific pesticides *might* influence risk of offspring autism is a complicated one. The researchers reported that "small to moderately increased risks for the disorder in offspring with prenatal exposure to the organophosphates chlorpyrifos, diazinon, and malathion, the pyrethroids permethrin and bifenthrin, as well as to glyphosate, avermectin, and methyl bromide" were observed. They (and the editorial) talk about how further research is required to "examine the joint effects of multi-exposure mixtures to more effectively protect human health." This is important in the context of other research (see here and see here) and also to avoid any big media headlines (see here) about specific preparations 'causing' autism (which has not yet been authoritatively established). Given that various different classes of pesticides have somewhat slightly different biological actions, there is a lot of work to be done on the possible biological mechanisms/targets and any synergistic effects.

Also: "children with autism spectrum disorder and co-occurring intellectual disability were examined as a separate outcome." The fact that von Ehrenstein et al observed something like a 'stronger association' between pesticide exposure and those at the "more severe end of the autism spectrum" (the description according to one media source) is another important point requiring further study. I say this in the context that 'comorbidity' might not always be the best description for symptoms and diagnoses accompanying autism (see here).

The authors conclude that their findings - with appropriate caveats - have implications. Namely: "Exposure of pregnant women and infants to ambient pesticides with a potential neurodevelopmental toxicity mode of action should be avoided as a preventive measure against autism spectrum disorder." I don't think too many people would disagree with the sentiments of 'avoiding pesticide exposure' particularly for pregnant women and those who might also be more vulnerable to their potential effects. The questions now turn to genetics and biology and the question of why...

Music to close: Hostiles on the Hill (apparently)...

----------

[1] von Ehrenstein OS. et al. Prenatal and infant exposure to ambient pesticides and autism spectrum disorder in children: population based case-control study. BMJ. 2019; 364: I962.

[2] Bakian AV. & VanDerslice JA. Pesticides and autism. BMJ. 2019; 364: I1149.

----------

An excess of ADHD among children born to glyphosate appliers?

The job of pesticide applicator is one that has been discussed on this blog before (see here). Minus any scaremongering, the conclusion of that post was that under certain circumstances (e.g. a high pesticide exposure event - HPEE), the effects of that particular occupation might be pretty far-reaching for the 'cognitive' as well as physical health of the individual concerned.

Today I'm talking about other potential effects "needing confirmation by further studies" related to perhaps one of the most famous pesticides in recent times: glyphosate. The systematic review "of observational studies" by Jessica de Araujo and colleagues [1] (open-access) provides the starting material and the suggestion that whilst "exposures to GLY [glyphosate] before conception and/or during pregnancy did not increase the risk of adverse reproductive outcomes" there was perhaps more to see when it came to "an excess of risk of ADD/ADHD [attention-deficit disorder/attention-deficit hyperactivity disorder] among the offspring of GLY applicators." The de Araujo paper was a review paper and included the findings reported by Vincent Garry and colleagues [2] that: "Use of the herbicide glyphosate yielded an OR [odds ratio] of 3.6 (CI, 1.3-9.6) in the neurobehavioral category" including ADD/ADHD.

Glyphosate - N-(Phosphonomethyl)glycine or Roundup - has something of a love/hate relationship in many circles. As a herbicide (an organophosphonate), it does a pretty good job killing weeds by interfering with some important biochemistry linked to the aromatic amino acids, and has enjoyed significant commercial success for quite a few years. As with all pesticides however, there are cautions attached to its use, and this preparation seems to catch media attention on a pretty regular basis; more so when organisations such as the World Health Organisation (WHO) come out with statements like the one last year (2015).

Before going back to the de Araujo and Garry papers, I think it's worth mentioning that the idea of an 'association' between GLY and ADHD is not without some controversy. I note that at least one attempt has been made to talk about the possibility of a link between the two albeit retracted for various methodological reasons. I therefore tread carefully and note there are some important strengths and weaknesses attached to the idea that offspring ADD/ADHD might specifically be more frequently present in GLY pesticide applicators.

Weaknesses, well, Garry et al relied heavily on self-report and interviews with no detailed use of analytical measures in terms of biological load for GLY. Yes, they did survey registered pesticide applicators on the basis of their licencing and the data provided at interview was cross-referenced with other available "medical records examination" but theirs was still a study heavily reliant on recall and association. de Araujo also make the point that "the herbicide was analyzed as a dichotomous (exposed / not exposed) variable" which takes no account of variables such as "wearing protective clothes, the diet, the amount of the pesticide used" and thus, says nothing about any dose-response relationship. Strengths - the Garry paper did cover various different types of pesticides, the metabolites of some have also subsequently been linked to risk of a diagnosis of ADHD for example (see here). They also reported on quite a few other variables that might impact on risk of offspring ADHD and controlled for them. In short, an interesting association which again is: "needing confirmation by further studies."

Insofar as the possibility that there may 'associations' between glyphosate use and behavioural outcomes, some people with some knowledge of autism research might have come across some pretty stark warnings about glyphosate exposure and the quite staggering increase in cases of autism being diagnosed around the world (see here). I, myself, am not so convinced that one agent, and one agent alone, plays such an important role in autism rates but am willing to concede that there may be more research to do on the effects of exposure and offspring outcomes (see here). Indeed minus any sweeping generalisations or solely resting any 'blame' at the door of a specific preparation, science really needs to conduct some more detailed analysis on environmental components such as pesticides and behaviour and developmental outcomes (including biochemistry [3]), if anything else, just to rule out any relationship. And various lawmakers around the world might be aiding efforts to do so...

Music to close: Beyoncé plays the SoL tonight. No, I'm not going but I do like some of her music...

----------

[1] de Araujo JSA. et al. Glyphosate and adverse pregnancy outcomes, a systematic review of observational studies. BMC Public Health. 2016; 16: 472.

[2] Garry VF. et al. Birth defects, season of conception, and sex of children born to pesticide applicators living in the Red River Valley of Minnesota, USA. Environmental Health Perspectives. 2002;110(Suppl 3):441-449.

[3] De Felice A. et al. Prenatal exposure to the organophosphate insecticide chlorpyrifos enhances brain oxidative stress and prostaglandin E2 synthesis in a mouse model of idiopathic autism. Journal of Neuroinflammation. 2016; 13: 149.

----------

de Araujo, J., Delgado, I., & Paumgartten, F. (2016). Glyphosate and adverse pregnancy outcomes, a systematic review of observational studies BMC Public Health, 16 (1) DOI: 10.1186/s12889-016-3153-3

On glyphosate and autism (without scaremongering)

Glyphosate use and autism rates - should I blog about it?

Well, after some deliberation I decided it was a topic worthy of an entry. There is some peer-reviewed science discussions behind it and, as per other areas of controversy on the autism research landscape, the idea that 'science is about debate' (why else does everyone keep going on about open-access and transparency) should always prevail.

I'm assuming most people have heard of the organophosphonate (that's phosphonate not phosphate) herbicide glyphosate - N-phosphonomethylglycine - over the course of its discovery and use under the trade name Roundup. First patented as a chelating agent (another area of 'discussion' with autism in mind) glyphosate has been successfully killing weeds for quite a few years by interfering with some of the chemistry of the aromatic amino acids tryptophan, tyrosine and phenylalanine via its actions on the shikimate pathway. As per many other herbicides, such formulations always require a degree of care in their use given the possibility of side-effects following accidental over-exposure. Indeed, government agencies are cottoning on to this fact (see here).

The debate on glyphosate and its potential effects on human and animal health has been a hot one in recent times. Partly overlapping with the introduction of genetically modified (GM) crops that are glyphosate-tolerant (Roundup Ready) by the company who initially brought glyphosate to the market, the safety angle of glyphosate has been scrutinised and debated. Only this year (2015), an arm of the World Health Organisation (WHO) described glyphosate (and several organophosphate pesticides I might add) as "probably carcinogenic to humans". Following such an announcement, quite a few media column inches were produced as one might expect.

Set within that context, discussions have turned to whether there may be other 'effects' following the fairly widespread use of glyphosate. Perhaps inevitably, autism, and particularly the quite phenomenal increase in cases of autism, has been suggested to be 'linked' to the use of glyphosate. One might say that in this respect, glyphosate is a victim of its own success insofar as how widely it has been and is currently used.

The paper that seems to have started the ball rolling suggesting a link between glyphosate and autism is that from Anthony Samsel and Stephanie Seneff [1]. A review paper focussing specifically on the proposed inhibitory actions of glyphosate on CYP enzymes, mention of autism in the text and particularly that "glyphosate may be the most significant environmental toxin contributing to autism" was bound to stir up debate. With added soundbites about how half of children will be born with autism in the United States by 2025 and graphs correlating autism prevalence and glyphosate use, such observations were ripe for speculation and discussion.

Further papers from Samsel & Seneff [2] have continued the theme that autism may be one of many conditions/labels where glyphosate might be implicated. Drawing on animal and plant studies implicating glyphosate use with specific depletion of manganese (Mn), a whirlwind of research studies and references have been used to link such depletions to autism (and associated aspects such as anxiety) among various other conditions. To quote: "Many diseases and conditions are currently on the rise in step with glyphosate usage in agriculture, particularly on GM crops of corn and soy. These include autism, AD [Alzheimer's disease], PD [Parkinson's disease], anxiety disorder, osteoporosis, inflammatory bowel disease, renal lithiasis, osteomalacia, cholestasis, thyroid dysfunction, and infertility. All of these conditions can be substantially explained by the dysregulation of Mn utilization in the body due to glyphosate." Just in case you thought that Samsel / Seneff are the sole research team talking about glyphosate use and autism rates, I'll also refer you to the paper by Cynthia Nevison [3] that has been previously discussed on this blog (see here).

As other commentators have noted, there are a few considerations to mention about the discussions so far on any relationship between glyphosate use and autism. That 'correlation is not the same as causation' is perhaps the most important element to the data as they currently stand given that, to my knowledge, no-one has actually published any peer-reviewed results on levels of glyphosate and/or metabolites in people with autism and/or other family members compared to asymptomatic controls for example. It's not as if such a feat is too complicated given the various means and methods already published on this topic [4].

'Correlation is not the same as causation' is one of the themes also discussed in the review paper by Miguel Faria [5] who provides an important discussion to some of the points raised by Samsel & Seneff. I don't want to head too much into this quite long commentary on the Samsel / Seneff paper (complete with author replies) but it does strike me as providing something of a counter-balance to the very hypothesis-based writings of the original authors. That glyphosate is one of a multitude of herbicides and insecticides in use is an important point made in terms of the difficulties in disentangling it from the 'chemical soup' (not to demonise) that we live our lives in these days. The only other thing that I might mention is my much-used notion about the continued pluralisation of autism (see here) and its varied comorbidity as being something to bear in mind when it comes to any discussions about aetiology.

Where next, or is there even 'a next' for looking at any possible relationship between glyphosate use and autism rates? Well, I'd like to think that autism research can learn a lesson or two about not throwing out baby and bathwater when it comes to theories about [some] autism as per what seems to have happened to something like methylmalonic acid (MMA) and autism (see here) for example. It's not beyond the realms of possibility that certain chemicals or mixtures might be linked to autism risk and/or onset as per preliminary research talk about dioxin exposure being potentially linked to [some] autism or autistic traits (see here) albeit with a lot more follow-up research required.

But such research needs to be done with care and assiduity; mindful that this is a topic that will inevitably garner significant attention (as per the editorial sentence on the original Samsel / Seneff paper: "Note added by the Publisher: This paper attracts great attention.") and knowing what can happen sometimes when science and media mix (see here).

Perhaps a little less focus on soundbites and more on cold, objective science is the best way forward in this area?

Music: Fleetwood Mac- Dreams.

----------

[1] Samsel A. & Seneff S. Glyphosate’s Suppression of Cytochrome P450 Enzymes and Amino Acid Biosynthesis by the Gut Microbiome: Pathways to Modern Diseases. Entropy 2013. 15; 1416-1463.

[2] Samsel A. & Seneff S. Glyphosate, pathways to modern diseases III: Manganese, neurological diseases, and associated pathologies. Surgical Neurology International. 2015;6:45.

[3] Nevison CD. A comparison of temporal trends in United States autism prevalence to trends in suspected environmental factors. Environ Health. 2014 Sep 5;13:73.

[4] Yoshioka N. et al. Rapid determination of glyphosate, glufosinate, bialaphos, and their major metabolites in serum by liquid chromatography-tandem mass spectrometry using hydrophilic interaction chromatography. J Chromatogr A. 2011 Jun 10;1218(23):3675-80.

[5] Faria MA. Glyphosate, neurological diseases – and the scientific method. Surgical Neurology International. 2015;6:132. doi:10.4103/2152-7806.162550.

----------

Faria MA (2015). Glyphosate, neurological diseases - and the scientific method. Surgical neurology international, 6 PMID: 26322242