from the world's big
Why synthetic chemicals seem more toxic than natural ones
Some pesticides are about as toxic as table salt.
Many people believe that chemicals, particularly the man-made ones, are highly dangerous.
After all, more than 80,000 chemicals have been synthesised for commercial use in the United States, and many have been released into the environment without proper safety testing. Should we be afraid of the synthetic chemicals that permeate our world?
While it is not possible to compare the toxicity of all natural and synthetic chemicals, it is worth noting that the five most toxic chemicals on Earth are all naturally found. When it comes to pesticides, some of the newer man-made versions are remarkably safe to humans; and at high doses, these pesticides are as toxic as table salt and aspirin. Rats continually exposed to low doses of these pesticides (ie, doses found in the environment) don't develop cancer or problems in growth and reproduction. There are many natural pesticides that are produced by plants, some of which are also carcinogenic, and although this does not make synthetic pesticides safe, it does remind us that simple oppositions between 'safe and natural' and 'deadly and synthetic' are not helpful ways to analyse risk.
I study toxicology: I look at the effects of substances on living organisms. All substances (natural and artificial) are harmful if the exposure is high enough. Even too much water consumed within a very short time can dilute the salts in the blood, and cause brain cells to swell. A number of marathon runners have collapsed and died because of consuming excessive amounts of water with no salt.
Toxicologists believe that nearly every substance is safe in certain amounts. Take the example of botulinum, the most poisonous substance on Earth. Just 50 grammes of the toxin spread evenly worldwide would kill everyone. But, in very minute amounts, it is safely used for cosmetic purposes in Botox. Thus the adage 'the dose makes the poison'.
Apart from understanding what doses make a substance 'safe' or 'unsafe', toxicologists also love figuring out how a substance causes a harmful effect. How exactly does smoking cause lung cancer? Once we find a mechanism through which chemicals in smoke cause cancer (and we have), we can be more confident about smoking's role in lung cancer. Merely showing that smokers have a higher rate of cancer isn't evidence, since it is easy to find two factors whose patterns correlate. Look at the graph below: it shows that higher rates of divorce in Maine correspond to a higher per-capita consumption of margarine:
Courtesy Tyler Vigen/Spurious Correlations
While we wouldn't think that this graph proves anything, we are less likely to question correlations that might seem more plausible. For example, the graph below shows that higher exposure to mercury through vaccinations corresponds to higher rates of autism:
Courtesy David Geier and Mark Geier, 2004
Causal link can be established in two ways: by showing how a chemical can cause a certain effect or by fulfilling a set of conditions called Hill's criteria. Hill's criteria requires that we consistently find a correlation between the chemical and effect in different populations, that the effect only shows up after chemical exposure and, if lab studies are conducted, we should obtain similar correlations between chemical and effect.
One can argue that, though there is no conclusive evidence presently to show that some chemicals cause health problems, it's better to be safe than sorry and so restrict the chemical before health problems emerge. Yet while this idea is tempting, it ignores a basic truth: risk exists in nearly everything. Walking outside (we could get mugged), travelling in cars and planes (we could crash), eating food (we could ingest plant oestrogens or the organic pesticide copper sulphate) or drinking water (parts of the US and Bangladesh have high levels of naturally occurring fluoride and arsenic, respectively). We therefore need to understand probability: is the chemical exposure high enough for a high probability of adverse effects? We also need to know the risks of using an alternative chemical – or no chemical at all.
Studies have shown that people vary widely at ranking risks. Below is a snapshot of how the general public and experts ranked risk in 1979 (where 1 is the riskiest, and 30 the least risky).
Courtesy Federal Emergency Management Agency, 2007. Adapted from Slovic et al, 1979
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 experts do.
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:
- 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?
- 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.
- 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.
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 not 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.
The EPA has been analysing the safety of chemical pesticides for many years, and it recently began analysing the safety of the other chemicals it regulates. 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 that 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 disruption 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 one glass of wine every three months. However, this is far from a comprehensive analysis.)
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.
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.
- Everything is Made of Chemicals - Big Think ›
- You'll Never Guess How Many Chemicals Are Inside Your Body ... ›
Join Pulitzer Prize-winning reporter and best-selling author Charles Duhigg as he interviews Victoria Montgomery Brown, co-founder and CEO of Big Think, live at 1pm EDT tomorrow.
Richard Feynman once asked a silly question. Two MIT students just answered it.
Here's a fun experiment to try. Go to your pantry and see if you have a box of spaghetti. If you do, take out a noodle. Grab both ends of it and bend it until it breaks in half. How many pieces did it break into? If you got two large pieces and at least one small piece you're not alone.
But science loves a good challenge<p>The mystery remained unsolved until 2005, when French scientists <a href="http://www.lmm.jussieu.fr/~audoly/" target="_blank">Basile Audoly</a> and <a href="http://www.lmm.jussieu.fr/~neukirch/" target="_blank">Sebastien Neukirch </a>won an <a href="https://www.improbable.com/ig/" target="_blank">Ig Nobel Prize</a>, an award given to scientists for real work which is of a less serious nature than the discoveries that win Nobel prizes, for finally determining why this happens. <a href="http://www.lmm.jussieu.fr/spaghetti/audoly_neukirch_fragmentation.pdf" target="_blank">Their paper describing the effect is wonderfully funny to read</a>, as it takes such a banal issue so seriously. </p><p>They demonstrated that when a rod is bent past a certain point, such as when spaghetti is snapped in half by bending it at the ends, a "snapback effect" is created. This causes energy to reverberate from the initial break to other parts of the rod, often leading to a second break elsewhere.</p><p>While this settled the issue of <em>why </em>spaghetti noodles break into three or more pieces, it didn't establish if they always had to break this way. The question of if the snapback could be regulated remained unsettled.</p>
Physicists, being themselves, immediately wanted to try and break pasta into two pieces using this info<p><a href="https://roheiss.wordpress.com/fun/" target="_blank">Ronald Heisser</a> and <a href="https://math.mit.edu/directory/profile.php?pid=1787" target="_blank">Vishal Patil</a>, two graduate students currently at Cornell and MIT respectively, read about Feynman's night of noodle snapping in class and were inspired to try and find what could be done to make sure the pasta always broke in two.</p><p><a href="http://news.mit.edu/2018/mit-mathematicians-solve-age-old-spaghetti-mystery-0813" target="_blank">By placing the noodles in a special machine</a> built for the task and recording the bending with a high-powered camera, the young scientists were able to observe in extreme detail exactly what each change in their snapping method did to the pasta. After breaking more than 500 noodles, they found the solution.</p>
The apparatus the MIT researchers built specifically for the task of snapping hundreds of spaghetti sticks.
(Courtesy of the researchers)
What possible application could this have?<p>The snapback effect is not limited to uncooked pasta noodles and can be applied to rods of all sorts. The discovery of how to cleanly break them in two could be applied to future engineering projects.</p><p>Likewise, knowing how things fragment and fail is always handy to know when you're trying to build things. Carbon Nanotubes, <a href="https://bigthink.com/ideafeed/carbon-nanotube-space-elevator" target="_self">super strong cylinders often hailed as the building material of the future</a>, are also rods which can be better understood thanks to this odd experiment.</p><p>Sometimes big discoveries can be inspired by silly questions. If it hadn't been for Richard Feynman bending noodles seventy years ago, we wouldn't know what we know now about how energy is dispersed through rods and how to control their fracturing. While not all silly questions will lead to such a significant discovery, they can all help us learn.</p>
A study looks at the performance benefits delivered by asthma drugs when they're taken by athletes who don't have asthma.
- One on hand, the most common health condition among Olympic athletes is asthma. On the other, asthmatic athletes regularly outperform their non-asthmatic counterparts.
- A new study assesses the performance-enhancement effects of asthma medication for non-asthmatics.
- The analysis looks at the effects of both allowed and banned asthma medications.
WADA uncertainty<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzUzNzU0OS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYxMDc4NjUwN30.fFTvRR0yJDLtFhaYiixh5Fa7NK1t1T4CzUM0Yh6KYiA/img.jpg?width=980" id="01b1b" class="rm-shortcode" data-rm-shortcode-id="2fd91a47d91e4d5083449b258a2fd63f" data-rm-shortcode-name="rebelmouse-image" alt="urine sample for drug test" />
Image source: joel bubble ben/Shutterstock<p>When inhaled β-agonists first came out just before the 1972 Olympics, they were immediately banned altogether by the WADA as possible doping substances. Over the years, the WADA has reexamined their use and refined the organization's stance, evidence of the thorniness of finding an equitable position regarding their use. As of January 2020, only three β-agonists are allowed — salbutamol, formoterol, and salmeterol —and only in inhaled form. Oral consumption appears to have a greater effect on performance.</p>
The study<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzUzNzU0Ny9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY1MTIzMDQyMX0.Gk4v-7PCA7NohvJjw12L15p7SumPCY0tLdsSlMrLlGs/img.jpg?width=980" id="d3141" class="rm-shortcode" data-rm-shortcode-id="ebe7b30a315aeffcb4fe739095cf0767" data-rm-shortcode-name="rebelmouse-image" alt="runner at starting position on track" />
Image source: MinDof/Shutterstock<p>Of primary interest to the authors of the study is confirming and measuring the performance improvement to be gained from β-agonists when they're ingested by athletes who don't have asthma.</p><p>The researchers performed a meta-analysis of 34 existing studies documenting 44 randomized trials reporting on 472 participants. The pool of individuals included was broad, encompassing both untrained and elite athletes. In addition, lab tests, as opposed to actual competitions, tracked performance. The authors of the study therefore recommend taking its conclusions with just a grain of salt.</p><p>The effects of both WADA-banned and approved β-agonists were assessed.</p>
Approved β-agonists and non-asthmatic athletes<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzUzNzU1MC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYxMzkxODk0M30.3RssFwk_tWkHRkEl_tIee02rdq2tLuAePifnngqcIr8/img.jpg?width=980" id="39a99" class="rm-shortcode" data-rm-shortcode-id="b1fe4a580c6d4f8a0fd021d7d6570e2a" data-rm-shortcode-name="rebelmouse-image" alt="vaulter clearing pole" />
Image source: Andrey Yurlov/Shutterstock<p>What the meta-analysis showed is that the currently approved β-agonists didn't significantly improve athletic performance among those without asthma — what very slight benefit they <em>may</em> produce is just enough to prompt the study's authors to write that "it is still uncertain whether approved doses improve anaerobic performance." They note that the tiny effect did increase slightly over multiple weeks of β-agonist intake.</p>
Banned β-agonist and non-asthmatic athletes<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzUzNzU1Mi9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYzNjI3ODU5Mn0.vyoxSE5EYjPGc2ZEbBN8d5F79nSEIiC6TUzTt0ycVqc/img.jpg?width=980" id="de095" class="rm-shortcode" data-rm-shortcode-id="02fdd42dfda8e3665a7b547bb88007ef" data-rm-shortcode-name="rebelmouse-image" alt="swimmer mid stroke" />
Image source: Nejron Photo/Shutterstock<p>The study found that for athletes without asthma, however, the use of currently banned β-agonists did indeed result in enhanced performance. The authors write, "Our meta-analysis shows that β2-agonists improve anaerobic performance by 5%, an improvement that would change the outcome of most athletic competitions."</p><p>That 5 percent is an average: 70-meter sprint performance was improved by 3 percent, while strength performance, MVC (maximal voluntary contraction), was improved by 6 percent.</p><p>The analysis also revealed that different results were produced by different methods of ingestion. The percentages cited above were seen when a β-agonist was ingested orally. The effect was less pronounced when the banned substances were inhaled.</p><p>Given the difference between the results for allowed and banned β-agonists, the study's conclusions suggest that the WADA has it about right, at least in terms of selection of allowable β-agonists, as well as the allowable dosage method.</p>
Takeaway<p>The study, say its authors, "should be of interest to WADA and anyone who is interested in equal opportunities in competitive sports." Its results clearly support vigilance, with the report concluding: "The use of β2-agonists in athletes should be regulated and limited to those with an asthma diagnosis documented with objective tests."</p>
Certain water beetles can escape from frogs after being consumed.
- A Japanese scientist shows that some beetles can wiggle out of frog's butts after being eaten whole.
- The research suggests the beetle can get out in as little as 7 minutes.
- Most of the beetles swallowed in the experiment survived with no complications after being excreted.