from the world's big
Study finds that a colony's exposure to pesticides impairs offspring.
- Pesticide contamination in bee hives damages the learning capabilities of offspring, according to a recently published study.
- A key area of the affected bees' brains never correctly develops after pesticide exposure.
- Early impairment appears to be irreversible and is likely a factor in falling bee populations.
Broken learning<p>The study involved introducing neonicotinoids to the nectar consumed by members of 22 <a href="https://en.wikipedia.org/wiki/Bombus_terrestris" target="_blank"><em>Bombus terrestris audax</em></a> (buff-tailed honeybee) colonies. The learning abilities of their offspring were then measured against a control group of young bees from colonies whose food supply had not been contaminated.</p><p>The test assessed the extent to which a bee could learn to associate a specific smell with a reward, which was a sucrose solution. The bees from the neonicotinoid colony consistently fared more poorly than the control population.</p><img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjg2ODE5Ny9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0MTAyMzQzMn0.zxOo04Cq-7q4ClAydA0kLAwFMpj84Nr25DIVtR3EzAE/img.jpg?width=980" id="4967e" class="rm-shortcode" data-rm-shortcode-id="ba7b1c09f2daa90d686e7ee93ad0138a" data-rm-shortcode-name="rebelmouse-image" alt="a bumblebee on a purple flower" />
Image source: Mr. Meijer/Shutterstock
Tiny computed micrography (CT) scans<p>In hopes of identifying a structural explanation, the researchers stained the brain cells of 100 bees from the exposed colonies and took non-invasive <a href="https://www.imperial.ac.uk/news/171050/bee-brains-have-never-seen-them/" target="_blank">micro-CT</a> scans in a machine similar — albeit smaller — to those in which humans are medically imaged.</p><p>The researchers discovered a clear difference in brains of the young bees from pesticide-exposed colonies. A key brain area, the <a href="https://en.wikipedia.org/wiki/Mushroom_bodies" target="_blank">mushroom body</a>, was found to be much smaller in these bees' brains than it was in those from control colonies. This makes sense, since this region is believed to be involved in olfactory learning and memory.</p><p>The tests and scans were performed three days after pupal hatching and again after 12 days. The substandard learning capabilities and mushroom body sizes had not been resolved by the second test, indicating to the researchers that the damage caused by the neonicotinoids was irreversible.</p><p>(A honeybee's <a href="https://sciencing.com/life-span-honey-bee-6573678.html" target="_blank">life expectancy</a> depends on its role. Drones live roughly 8 weeks, while sterile workers live for about 6 weeks in the summer or 5 months in the winter. A queen can live for a few years.)</p><img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjg2ODIwMC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYxODYyNDExNn0.oejYHpeBD1HdgT3ttnSOLyjBIMFcQ1GDYOv1UIl5s_Q/img.jpg?width=980" id="ace39" class="rm-shortcode" data-rm-shortcode-id="dfecbbebdef8988fd1c297e88ee1a7b5" data-rm-shortcode-name="rebelmouse-image" alt="Scans of the mushroom body area of the bees' brains" />
Several views of the mushroom body
Image source: Gill, et al
Why this matters<p>The study's conclusion does not say definitively that the mushroom area is the only brain region impacted by pesticides. However, a smaller mushroom area is significant, explaining, as it does, the mechanism by which a bee's learning abilities and behavior may be impaired over the course of its life.</p><p>Gill says in a <a href="https://www.imperial.ac.uk/news/195793/pesticides-impair-baby-brain-development/" target="_blank">press release</a>, "Worryingly in this case, when young bees are fed on pesticide-contaminated food, this caused parts of the brain to grow less, leading to older adult bees possessing smaller and functionally impaired brains; an effect that appeared to be permanent and irreversible."</p><p>In fact, after the young bees were returned to their colonies, researchers saw lower-than-expected colony growth two to three weeks after the subjects' reintroduction.</p><p style="margin-left: 20px;"><em>"If future generations of workers are predisposed to be inefficient functioning cohorts, this could lead to a density-dependent build-up of colony-level impairment increasing the risk of colony collapse." — Gill, et al </em></p><img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjg2ODIwNC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYzMTUxMDAyN30.jOBiSfYKhVGP0nYZf-oWGEFqeCqL7AFwirgMDGpnDzc/img.jpg?width=980" id="f916f" class="rm-shortcode" data-rm-shortcode-id="93579968ab98750c4a8b349ef692a14f" data-rm-shortcode-name="rebelmouse-image" alt="Illustration of Bombus terrestris audax bee" />
Illustration of *Bombus terrestris audax*
Image source: Duda Vasilii/Shutterstock
And then there’s the adult bees<p>In addition to the problems caused by the behavior of bees hatched with pesticide damage, it's not as if pesticide exposure necessarily abates later on. As lead author of the study <a href="https://www.researchgate.net/profile/Dylan_Smith8" target="_blank">Dylan Smith</a> explains, "There has been growing evidence that pesticides can build up inside bee colonies. Our study reveals the risks to individuals being reared in such an environment, and that a colony's future workforce can be affected weeks after they are first exposed."</p><p>The study concludes that simply looking at the damaging effect of pesticide on adult bee population misses a significant, and more far-reaching, part of the story:</p><p style="margin-left: 20px;"><em>"Bees' direct exposure to pesticides through residues on flowers should not be the only consideration when determining potential harm to the colony. The amount of pesticide residue present inside colonies following exposure appears to be an important measure for assessing the impact on a colony's health in the future. " — Gill, et al</em></p>
Audio recordings reveal cows have unique voices and share emotions with each other.
- New audio recordings of cows reveal rich communication and unique individual voices.
- Cows do more than vocalize to their calves — they share emotions with each other.
- A better understanding of what cows are saying and feeling can help in the formulation of humane cattle-care standards.
The herd is heard<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjU5OTUxMC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYwMjE1MTE1M30.O3hB84ExyqI8n3AY064BkBNpB2MjC46DU_xRIIcACb0/img.jpg?width=980" id="4fed6" class="rm-shortcode" data-rm-shortcode-id="4c549ef4657f21c290e1caad0a98e0e5" data-rm-shortcode-name="rebelmouse-image" />
Image source: The Feed<p>Alexandra Green, a PhD student, is lead author of the study published in <a href="https://www.nature.com/articles/s41598-019-54968-4#Abs1" target="_blank"><em>Scientific Reports</em></a>. For her research, she <a href="https://sydney.edu.au/content/dam/corporate/documents/sydney-institute-of-agriculture/outreach-engagement/launch-and-research-showcase/Alexandra%20Green.pdf" target="_blank">recorded</a> 333 vocalizations of 13 Holstein-Friesian heifers. She tells <a href="https://sydney.edu.au/news-opinion/news/2019/12/19/stand-out-from-herd-how-cows-communicate.html" target="_blank"><em>University of Sydney News</em></a>, "We hope that through gaining knowledge of these vocalizations, farmers will be able to tune into the emotional state of their cattle, improving animal welfare."</p><p style="margin-left: 20px;"><em>"This study shows that cattle vocal individuality of high-frequency calls is stable across different emotionally loaded farming contexts. Individual distinctiveness is likely to attract social support from conspecifics, and knowledge of these individuality cues could assist farmers in detecting individual cattle for welfare or production purposes." — Green, et al</em></p><p>The study's recordings were captured across five months at an Australian farm. They were captured by Green during cows' estrus, during feed anticipation — a presumably happy moment — and during feed frustration as cattle were denied expected food. Vocalizations were also recorded when these social animals were individually isolated from their herd.</p>
Analysis<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjU5OTUxOS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYxNDA5MTM2MH0.IPQsSO51gOqtN_CJxJ_V5pFho0cbcYBZs_SZTs2CW-w/img.jpg?width=980" id="1a91a" class="rm-shortcode" data-rm-shortcode-id="b3e6e29964effbc2ec1fbb17c1241c67" data-rm-shortcode-name="rebelmouse-image" />
Audio analysis of a moo: Yellow arrow shows blue indicator of voices' fundamental pitch. Red arrow is where cow begins to close her mouth post-moo.
Image source: The Feed<p>Green traveled to Saint-Etienne, France, where she worked with co-authors psychologist <a href="http://www.sussex.ac.uk/profiles/115148" target="_blank">David Reby</a> and bioacoustician and animal behaviorist <a href="https://unito.academia.edu/LivioFavaro" target="_blank">Livio Favaro</a>. Together, they analyzed her field recordings using <a href="http://www.fon.hum.uva.nl/praat/" target="_blank">Praat</a> phonetics software, which produced visual representations of the audio, including an indicator of each voice's fundamental pitch.</p><p>These analyses proved the uniqueness of each cow's voice. For cattle farmer Neville Catt, on whose grounds the research was conducted, there's no doubt who he's hearing when a cow begins vocalizing. "Not only do I talk to cattle, I think they talk to me," he says. One of the new insights Green's study contributes is that the sound of each heifer's voice is not limited to specific circumstances like parenting, but in fact remains constant for life. Says Green, "We found that cattle vocal individuality is relatively stable across different emotionally loaded farming contexts."</p><p>"Cows are gregarious, social animals," says Green. "In one sense it isn't surprising they assert their individual identity throughout their life and not just during mother-calf imprinting. But this is the first time we have been able to analyze voice to have conclusive evidence of this trait."</p>
Getting to know Catt’s cows<iframe width="560" height="315" src="https://www.youtube.com/embed/wDZEcCps6aw" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe><p>In terms of the mechanics, says Green, cows produce calls in either of two ways. For up-close, quieter communication, their mouths remain closed, with the sound coming through their nasal passages as an "mmmmmmmm." To call out to other cows not nearby, however, they pump up the volume by opening their mouths as they vocalize. </p><p>In the end, "They've all got their very distinct personalities You've got your chatty cows, you've got your shy cows. I've got one girl who won't shut up," Green says.</p><p>Green plans to incorporate the research into her doctorate that proposes utilizing her findings in dairy-farm welfare assessments. On a personal level, she hopes one day to feel qualified as a genuine "cow whisperer" specializing in — her word here — "cowmoonication."<span></span></p>
When these particles are eaten by earthworms, the results are not good.
- New research from Anglia Ruskin University states that microplastics in soil are causing earthworms to lose weight.
- Soil affected by microplastics produces less crop yield due to less productive earthworms and lower pH levels.
- If this trend continues, our entire agricultural system could be compromised.
Microplastics are everywhere | Sarah Dudas | TEDxBinghamtonUniversity<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="a0f0c0566b5d3f51fba4540d77bb3b5e"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/jjsrmFUmyh4?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p>We often mistake broad names for processes as "extra." For example, dark matter, which represents 85 percent of all matter in the universe, is believed to non-baryonic, yet physicists recognize that it could be comprised of subatomic particles we haven't yet discovered. The universe isn't know for creating filler; usually, our own ignorance is the culprit.</p><p>"Dirt" and "soil," to non-farmers at least, are often treated as an earth layer; referencing it is often in the negative, as when a parent scolds a child for "playing in the dirt." But soil is a process, living and organic, dependent on decaying and dead matter constantly being churned through (by earthworms, for example) and recycled. </p><p>Soil is one of the major reasons that America has become a global power. Our fields supply an incredible amount of food for the planet. By contrast, China, with its billion-plus population to feed, struggles to produce adequate amounts of nutrition due to less fertile soil. This is, in fact, one of the undiscussed underpinnings of the current "trade war."</p><p>Damaged soil destroys not only ecosystems, but societies as well. When famers try to increase crop yield by introducing plastic mulches and irrigation, they're unknowingly polluting the soil with tons of microplastic particles. These particles are then ingested by earthworms (among other animals), causing them to lose weight.<span></span></p><p>The research team chose the most important grass grown in temperate regions; in grassland ecosystems ryegrass is abundant. A variety of ecosystems were used, some with added microplastics, one control without. Earthworms were most affected by HDPE microplastics, though any of the added particles made life worse for the worms.</p>
A view of the Schiavonea beach with microplastics, transported by the Ionian sea during the last sea storm.
Photo by Alfonso Di Vincenzo/KONTROLAB /LightRocket via Getty Images<p>Soil is generally low in nutrient value, meaning that worms have to eat and pass a lot of it for their existence. The team compares the results to aquatic environments, in which the digestive tracts of fish, like worms, are obstructed and worn away. The consumption of microplastic particles stunts their growth while compromising the survival of the organism.<br></p><p>Beyond worms, the particles (especially HDPE) decrease soil pH. This directly affects the diversity of organisms living there. As with the human microbiome, in which a diverse population of bacteria is healthiest, soil pays a steep price when diversity drops. </p><p>These particles don't remain in the soil; they end up, in some cases, on your plate. The team writes, </p><p style="margin-left: 20px;">"In agricultural settings, such effects may have implications for the production and quality of crop plants, by directly affecting plant development and altering the soil environment in which they are produced as well as having potential implications for human health through the accumulation of microplastics and harmful compounds in the tissues of plants."</p><p>All plastics are biodegradable. The problem is, some take weeks to mineralize while others hang around for millions of years. Until we implement broad solutions that implement a shelf life for plastics, these particles aren't going anywhere—except inside of our digestive tracts, eventually. As with worms, such news doesn't look good for the health of our species. </p><p>--</p><p><em>Stay in touch with Derek on <a href="http://www.twitter.com/derekberes" target="_blank">Twitter</a> and <a href="https://www.facebook.com/DerekBeresdotcom" target="_blank">Facebook</a>.</em></p>
The FDA calls out creators of genetically tweaked hornless bulls.
- Hornless bull clones turn out to have questionable genomes.
- Scientists were so confident they didn't even look for transgenic DNA.
- No one's sure what to do with the offspring.
The arrival of Spotigen and Buri<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMTE2MTE1Ny9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYwMzUzNDgxOX0.FncQraghoKRg6Kz4tj6XS2osmzY_GroWyWTpz4jHYds/img.jpg?width=980" id="e8da5" class="rm-shortcode" data-rm-shortcode-id="b19d6c0ae8f91f802036bfab1c873ac9" data-rm-shortcode-name="rebelmouse-image" />
Image source: ANGHI/Shutterstock/Big Think<p>Recombinetics' bulls were heralded examples of gene modification's potential. Farmers regularly "poll" cows — that is, remove their horns— in a painful, difficult process aimed at preventing accidental injuries in herds and the humans that tend them.</p><p>The company used TALENs gene editing ("Transcription Activator-Like Effector Nucleases) to swap out a section of about 200 genes from a Holstein dairy bull for genes from a hornless one.</p><p>DNA editing involves cutting DNA with enzymes called nucleases targeted at the desired location in a cell's genome. Nucleases are proteins, which are hard to work with, so many researchers — including Recombinetics' — instead introduce plasmids, circular mini-chromosomes that code for the required "scissor." This causes the target cell to produce the nucleases itself, sparing the scientists the complexities of dealing with unstable protein.</p><p>In the case of Recombinetics' bulls, the plasmids also contained the replacement hornless DNA for insertion at the cut. Coming along for the ride — unknown to Recombinetics — was transgenic DNA, including the antibiotic-resistant genes and a handful of other things from a range of diverse microbes. This wouldn't necessarily have been a problem if the plasmids hadn't unexpectedly inserted themselves into the target cell's genome instead of simply delivering their payload and being done, as planned. Thus, adjacent to its edit site were <a href="https://www.independentsciencenews.org/health/gene-editing-unintentionally-adds-bovine-dna-goat-dna-and-bacterial-dna-mouse-researchers-find/" target="_blank">4,000 base pairs</a> of DNA that from the plasmid.</p>
Over-confident<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMTE2MTE2MS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYwNDM1MTE4MX0.dfyGyeHtjCpNogRkwv3-UZHBAQ3dpFnOKtXRd-STK50/img.jpg?width=980" id="0a22f" class="rm-shortcode" data-rm-shortcode-id="4af032e6384db1af6345d8d74d1b3331" data-rm-shortcode-name="rebelmouse-image" />
Image source: wikimedia/U.S. Food and Drug Administration<p>At the time the editing was first announced, Recombinetics was very confident that what they'd produced was "100% bovine." "We know exactly where the gene should go, and we put it in its exact location," claimed Recombinetics to <a href="https://www.bloomberg.com/news/articles/2017-10-12/this-genetics-company-is-editing-horns-off-milk-cows" target="_blank">Bloomberg</a> in 2017. "We have all the scientific data that proves that there are no off-target effects." In response to the latest findings, however, Tad Sontesgard of the Recombinetics subsidiary that owns the animals, admitted, "It was not something expected, and we didn't look for it." He acknowledges a more thorough examination of their work "should have been done."</p><p>Since genetically edited animals may be consumed, the FDA's position is that they likely require thorough testing and approvals. Recombinetics has publicly complained about such hurdles standing in the way of making animal genetic editing a routine occurrence. (They've also developed piglets that never hit puberty.) The company attempted to <a href="https://www.technologyreview.com/s/610027/farmland-gene-editors-want-cows-without-horns-pigs-without-tails-and-business-without/" target="_blank">convince the Trump Administration</a> to take genetically altered animals away from under the FDA.</p>
How the problem was found<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMTE2MTE2NC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyMDA3NzAyMX0.SBCvmAAsWaDYU7dkPQ7CgcrtQovHK-MWvOizZUCZqQg/img.jpg?width=980" id="43f50" class="rm-shortcode" data-rm-shortcode-id="6f28fb809a618ce4383b7cb4942805fb" data-rm-shortcode-name="rebelmouse-image" />
Image source: Moving Moment/Shutterstock<p>Not surprisingly, Recombinetics never applied for approval with the FDA, but Alison Van Eenennaam, their collaborator from University of California, Davis, did inform the FDA of their existence to facilitate exchanges of research insights and data.</p><p>Since the surviving edited cattle were being put up at Davis, Eenennaam started thinking about what to do with them. Incinerating experimental animals — and each of these weighs about a ton — costs 60 cents per pound. On the other hand, turning them into hamburger and steaks could reverse that cash flow. Her attempt to win the cows a food exemption from the FDA led to the discovery of the plasmids, though Sontesgard <a href="https://www.technologyreview.com/s/614235/recombinetics-gene-edited-hornless-cattle-major-dna-screwup" target="_blank">asserts</a> they'd be safe to eat in either case.</p><p>And then there's milk. Brazil agreed to raise the first herd of genetically modified hornless dairy cows. Regulators there had even determined no exceptional oversight was going to be required.</p><p>Soon a bioinformatician from the FDA stumbled across the plasmid in a bull's genome. It's estimated that about half of Buri's 17 offspring also have it in theirs. The cows are now absolutely classified as genetically modified organisms, GMOs, not pure cow. Brazil has backed out.</p>
Slowing their roll<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMTE2MTE2OC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYwNzcxMDgxMn0.VmwCM6ss3JJ0-imNVggLLjNviBpY5KhHIuz7CtxvaMs/img.jpg?width=980" id="22429" class="rm-shortcode" data-rm-shortcode-id="0ad6c70f0e27fe6d94516a01cb5fb35f" data-rm-shortcode-name="rebelmouse-image" />
Image source: Sergey Nivens/Shutterstock<p> As science moves forward a few steps, it often has to back up a step or two. Glimpsing a solution, especially to such a complex problem as genome editing, isn't the same as having one fully in hand, no matter how attractive the reward of getting there first may be, or how much money is to be made. We're on the edge of a new frontier here, and there are a growing number of similar tales. Scientists do need courage to stretch the boundaries of the known, yes, but humility is also a good idea.</p>
Some pesticides are about as toxic as table salt.
Many people believe that chemicals, particularly the man-made ones, are highly dangerous.
Courtesy Federal Emergency Management Agency, 2007. Adapted from Slovic et al, 1979<p>It seems that laypeople rank risks that receive more media attention or have more vivid imageries higher than the more commonplace risks. Today, the public perceives a higher health risk from genetically engineered crops than <a href="https://www.pewresearch.org/science/2016/12/01/public-opinion-about-genetically-modified-foods-and-trust-in-scientists-connected-with-these-foods/" target="_blank">experts</a> do.</p><p>So while it is good to strive for the lowest possible risk, it is important to also consider any benefits, and not disallow things merely because of the risk they pose. The following examples explain this reasoning:</p><ul><li>Wind turbines kill birds and bats, dams kill fish, and the manufacture of solar cells exposes workers to dangerous chemicals. But how do those risks compare with the risks of global warming and respiratory illness through continued use of fossil fuels? Do the benefits of replacing fossil fuels outweigh the risks of developing alternative energy sources?</li><li>Birth control pills are very effective in preventing unwanted pregnancies and thus lessen our burden on the planet's resources. But their use leads to increased hormone levels in streams and rivers, and the feminisation of male fish and decreases in fish populations.</li><li>The insecticide DDT (now banned in most countries worldwide) caused several bird populations to crash. Yet prior to its ban, when safer alternatives did not exist, it saved millions of human lives by preventing diseases such as malaria and typhus.</li></ul><p>Regulators partly decide whether to allow a certain chemical into the marketplace by tallying up its costs and benefits. This can seem crude. For example, the US Environmental Protection Agency (EPA) values a human life at nearly $10 million. Thus, if a pesticide has a one in a 100,000 chance of causing a neurodegenerative disorder in people who apply it, and 1 million agricultural workers could be exposed to it, then the benefit of <em>not</em> registering the pesticide is $100 million (as 10 people will be protected by this decision). Unless the cost of reducing pesticide exposure to the workers exceeds $100 million, it is unlikely to be registered.</p><p>The EPA has been <a href="https://www.epa.gov/laws-regulations/summary-federal-insecticide-fungicide-and-rodenticide-act" target="_blank">analysing</a> the safety of chemical pesticides for many years, and it recently began <a href="https://www.epa.gov/assessing-and-managing-chemicals-under-tsca/highlights-key-provisions-frank-r-lautenberg-chemical" target="_blank">analysing</a> the safety of the other chemicals it <a href="https://www.epa.gov/tsca-inventory/about-tsca-chemical-substance-inventory" target="_blank">regulates</a>. Nevertheless, there are several uncertainties when it comes to understanding the toxicity and risks of any chemical. Regulators try to deal with it by using margins of safety. This means <a href="https://www.epa.gov/iris/reference-dose-rfd-description-and-use-health-risk-assessments" target="_blank">that</a> if x dose of a chemical is found safe in rats, then only doses that are at least 100- or 1,000-fold lower are considered safe in humans. However, this doesn't guarantee that we are exposed only to safe levels of chemicals, and toxicologists don't always look for effects – such as <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3365860/" target="_blank">disruption</a> of hormonal functions – that manifest only at low doses. Also, concerns about long-term exposure to a mix of chemicals are valid as this is rarely tested in the lab. (One Danish study found that the average adult's risk from consuming different pesticides in food is similar to the risk of drinking <a href="https://www.sciencedirect.com/science/article/pii/S0278691518300437" target="_blank">one glass of wine</a> every three months. However, this is far from a comprehensive analysis.)</p><p>Ultimately, though risk and uncertainty exist on all sides, people seem to be averse only to certain kinds of risks. And while we should undoubtedly work to reduce harmful chemical exposure and come up with safer alternatives, we also need to realise that our excessive phobia of chemicals, particularly synthetic ones, can often be unwarranted. </p><p><em>Correction: this article originally claimed that toxins produced by plants cause cancer at the same rate as synthetic chemicals. This claim was not supported by current research and has been corrected. </em><img src="https://metrics.aeon.co/count/ebacd34c-35ab-468a-ba0e-de04dcb23ee5.gif" alt="Aeon counter – do not remove"></p><p>This article was originally published at <a href="https://aeon.co/?utm_campaign=republished-article" target="_blank">Aeon</a> and has been republished under Creative Commons. Read the <a href="https://aeon.co/ideas/why-synthetic-chemicals-seem-more-toxic-than-natural-ones" target="_blank">original article</a>.</p>