Is There a Safer Time to Fly? (Skeptical Inquirer)

7 minute read

Flying in an airplane is incredibly safe despite what our anxieties and fears might tell us. According to the International Civil Aviation Organization (ICAO), aviation has become the first ultra-safe transportation system in history. That means that for every ten million cycles (one cycle involves both a takeoff and landing), there is less than one catastrophic failure.

It may not feel intuitively true, but you’re much safer traveling in an airplane than in a motor vehicle. In the United States, there are around 1.13 fatalities per every 100 million vehicle miles traveled, compared to just 0.035 fatalities per every 100 million airplane miles traveled. Put another way, your chances of dying in a U.S. car crash are around one in 114. Your chances of dying in a U.S. plane crash are around one in 9,821.

And yet, aviation accidents and incidents do still happen. I recently became deeply interested in aviation safety and got to wondering: Are there monthly or seasonal trends in when aviation accidents occur? Essentially, is there a statistically safer time to fly?

To answer that, we need to define the difference between an accident and an incident. It’s a subtle but important differentiation, because incidents happen all the time, while accidents are quite rare.

The ICAO defines an accident as “an occurrence associated with the operation of an aircraft which takes place between the time any person boards the aircraft with the intention of flight until such time as all such persons have disembarked, in which a person is fatally or seriously injured” and/or “the aircraft sustains damage or structural failure … or the aircraft is missing or is completely inaccessible.” On the other hand, an incident is defined as “an occurrence, other than an accident, associated with the operation of an aircraft which affects or could affect the safety of operation.” In car terms, an accident would be something like a fender bender or crash, whereas an incident would be something like your check engine light coming on or your headlight burning out.

At the time of writing this article in late January 2023, globally, there have been seven accidents in 2023, only one involving fatalities (seventy-two people presumed dead after Yeti AT72 crashed in Pokhara, Nepal). Compare this with incidents, of which there are usually around three or four every single day. If that seems like a lot, remember that the strict reporting of nearly any deviation from perfect plane operation and function is a big part of what has made aviation “ultra-safe.” No piece of machinery as complex as planes will function perfectly 100 percent of the time. By strictly cataloging all incidents, we can continuously identify trends, issues, and ways to improve aviation safety even further.

If there are temporal trends in aviation safety, there are a few reasons those could exist. One potential would be due to weather. There are definite seasonal trends in weather considered hazardous. For example, winter in Canada and the northern United States sees more ice and snow. But the question is whether these weather trends translate into accident trends.

A 2018 study examined all reported worldwide weather-related aircraft accidents from 1967 until 2010. The absolute number of weather-related accidents has increased over that period but so has the annual number of flights, so that is expected. More interesting is the percentage of accidents that are weather-related, which has also increased from about 40 percent to about 50 percent.

This rise could be due to changing weather patterns. The potential effects of climate change on airline safety are rarely discussed, but as incidences of severe weather continue increasing, presumably, so will weather-related incidents and accidents.

The authors of that study, however, believe that this increase is primarily due to “the aviation safety improvements conducted between 1967 and 2010 hav[ing] had a smaller effect on weather-caused aircraft accidents compared with other accidents.” Essentially, while improvements in areas such as crew resource management, training, and maintenance have had positive effects on aviation safety, weather-related accidents have been less sensitive to these improvements.

To look for seasonal trends, the authors of the study divided the globe into four symmetric zones according to latitudes: Zone 1: Within 12 degrees of the equator; Zone 2: between 12 and 38 degrees (which is roughly the middle of the United States); Zone 3: between 38 and 64 degrees (which encompasses most of Canada) and Zone 4: the polar regions in the far north and south.

(Photo source: https://www.timeanddate.com/geography/longitude-latitude.html)

While each zone experiences different weather and climate trends in all but the polar regions, “weather-caused accidents can be considered as uniformly distributed in the various meteorological seasons.”

The U.S. Federal Aviation Administration (FAA) agreed with the study’s conclusions, telling me that they “have not identified any other broad, seasonal or monthly incident trends.” So basically, no, there are not seasonal trends in weather-related aviation accidents, even though there are definite seasonal trends in weather considered severe.

There are three other very interesting takeaways from this study. First, the two zones nearest the equator show a much larger proportion of weather-related accidents, but that isn’t necessarily due to experiencing more severe or dangerous weather. Instead, the authors state that this is due to these zones containing a greater proportion of developing countries that, while adherent to the ICAO safety standards, tend to operate with older planes and equipment.

Second, weather is much less relevant in accidents in developed nations. While the global percentage of weather-related accidents is approaching 50 percent, in the United States and the United Kingdom, it was only 23 percent (in 2012 and between 1977 and 1986, respectively).

Third, despite snow being a widespread occurrence in Zone 4, it has never been reported as the primary cause of any accident. On the other hand, snow accounts for 7 percent of accidents in Zone 2 despite being far less common. This highlights both the disparities in safety between “developed” and “developing” nations and the increased danger associated with unusual weather. It is far safer to land in a snowstorm at an airport that frequently experiences snowstorms because it has systems in place to handle it. Unfortunately, climate change will likely only increase the incidences of unusual weather.

What about non-weather-related temporal trends in airline safety?

Dr. Daniel Bubb, former airline pilot and currently an associate professor at the University of Nevada, Las Vegas, explained to me that we tend to see more accidents in the months of June to September simply because a lot more people are flying. A 2020 analysis of airplane crash data echoed this, as did the National Transportation Safety Board: “the more risk exposure tends to track closely with the actual number of accidents,” which makes a lot of sense.

Another potential trend in aviation safety could come from something analogous to the “July Effect,” as it’s called in North America, or “Black Wednesday,” as it’s known in the United Kingdom—the idea that the day/week/month when new student doctors and nurses start at hospitals is associated with a rise in mortality or morbidity.

Luckily, the aviation industries have safeguards in place to avoid an influx of new workers. For example, both the FAA and NAV CANADA told me they specifically stagger the starts of their new air traffic controllers. A representative of Republic Airways (a regional U.S. airline) told me the same for new pilots and other employees.

An important thing to remember is just how frequently pilots have their soundness evaluated. Dr. Bubb writes that pilots “undergo recurrent training each year” and “undergo physicals each year to maintain their licenses.” With so much oversight, intense training, and staggered starts, the potential for a “July Effect” in aviation is vanishingly small.

In fact, evidence is mounting against the existence of the July Effect in medicine. A 2022 comprehensive meta-analysis of 113 studies published between 1989 and 2019 demonstrates “no evidence of a July Effect on mortality, major morbidity, or readmission.” Studies comparing teaching versus nonteaching hospitals have found teaching hospitals safer year-round!

So, is there a time of the year you should avoid flying? No, not in terms of safety. And you likewise should not avoid heading to the hospital if you feel you need to. However, if you want to decrease how much you drive, that could help with both your safety and the environment.

This article was written for Skeptical Inquirer. View the entire original for free here: https://skepticalinquirer.org/exclusive/is-there-a-safer-time-to-fly/

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You can’t hear this music, but it could still make you dance (McGill OSS)

1 minute read

Provided by bass instruments, the low-frequency parts of music tend to contribute the beat we actually dance to. Songs with lower-frequency baselines tend to have higher perceived “groove” ratings, but what if the frequency is so low that it falls outside humans’ audible range?

Researchers from McMaster University, Fitchburg State University and the Rotman Research Institute set out to test just that. Utilizing so-called very-low frequency (VLF) sound, researchers fitted participants with motion capture headbands at a live concert for electronic music duo Orphx and had them fill in pre- and post-concert questionnaires. VLF speakers were turned on and off every 2.5 minutes throughout the 55-minute performance, and the recorded mo-cap data was used to calculate participants’ head movement speeds in the presence or absence of VLF.

The resulting data showed that audience participants moved an average of 11.8% more when the VLF sound was on versus off. The researchers also performed additional experiments to confirm that the VLF was inaudible.

If it can’t be heard, how can VLF sounds contribute to a sense of groove or make people dance more? The researchers suggest that VLF sounds lead to changes in behaviour through subconscious processes involving our brains’ vestibular, vibrotactile, motor and reward systems. Sounds are mainly processed through our auditory pathways; however, low-frequency sounds are additionally processed via the vibrotactile and vestibular pathways.

While known for controlling our balance and proprioception (sense of where our bodies are), the vestibular system has previously been implicated in perceptions of rhythm. In addition, both the vestibular and vibrotactile pathways have close links to our motor systems. The researchers believe that one, or more, of these pathways, are responsible for the dance-inducing effects of VLF sound.

This article was written for the McGill Office of Science and Society. View the original here: https://www.mcgill.ca/oss/article/did-you-know/you-cant-hear-music-it-could-still-make-you-dance

The Potential for Caffeine-Free Coffee via Crispr/CAS9 or Crossbreeding (McGill OSS)

5 minute read

Our current methods for decaffeinating coffee are far from ideal. There are a few different methods, all with their own nuanced details, but they all shake out to using some kind of solvent to dissolve and remove caffeine from green coffee beans before roasting. This extra processing means costs to produce decaf are higher, profit margins lower, and production times longer. An even bigger problem is that even the best methods for decaffeination take some aromatic compounds away along with the stimulant molecule, affecting the taste and smell of the resulting coffee.

What if, instead of removing the caffeine from coffee beans, we could grow naturally caffeine-free coffee? Doing just that might be closer on the horizon than we expected.

To know how to stop a coffee plant from producing caffeine, it’s important first to recognize why it’s making it in the first place. Caffeine is a very bitter compound (one of the reasons coffee is a bitter drink), and just as we don’t tend to enjoy overly bitter things, neither do bugs. Coffee plants are believed to produce caffeine in their leaves mainly as a pesticide to defend against being eaten by pests like the coffee berry borer, Hypothenemus hampei.

Interestingly, ancestors of the modern coffee species were probably much lower in caffeine or entirely caffeine-free. The caffeine defence is believed to have developed in central and west Africa, where the coffee berry borer is native. This is where the highest caffeine species of coffee, like Coffea arabica and Coffea canephora, are found. These two species account for nearly 100% of the world’s coffee production.

A fascinating potential method for developing caffeine-free coffee plants involves the subject of the 2021 Nobel Prize in Chemistry: CRISPR/Cas9. Often referred to as “molecular scissors,” the CRISPR/Cas9 tool is inspired by bacterial defence mechanisms against viruses and allows the very precise cutting of an organism’s DNA. In this way, a gene can be targeted and deactivated. A review paper from 2022 took a look at the feasibility of using these molecular scissors to disrupt the biosynthesis of caffeine in coffee plants.

As caffeine is a relatively complex molecule, it isn’t built in just one step. Several enzymes are responsible for precise chemical changes to the proto-caffeine molecule en route to its final form. This is good news for scientists looking to disrupt the synthesis process, as they have multiple enzymes to aim for. The authors of the 2022 review identified an enzyme called XMT as a prime target. XMT is responsible for converting xanthosine into 7-methylxanthosine during step 1 out of 4 in the caffeine synthesis pathway. By targeting the very first step in the process, the subsequent enzymes have no molecules to work on. Debilitating XMT would lead to a build-up of xanthosine, but a different enzyme that can degrade it exists, so it shouldn’t be a problem.

Another potential target is called DXMT. This enzyme is responsible for the penultimate step in caffeine synthesis, converting theobromine into caffeine. Theobromine is quite similar to caffeine structurally and shares some properties with it, like being bitter and toxic to cats and dogs. Importantly, however, theobromine does not have the stimulating effect of caffeine. Targeting and disabling DXMT would lead to a build-up of theobromine in coffee beans, which may actually be a good thing! The bitterness of caffeine is part of the flavour of coffee, meaning that a C. arabica bean without caffeine may still taste different than a C. arabica bean with caffeine, even if they’re otherwise the same. The authors of the study postulate that the increased theobromine content of a DMXT-disabled bean could compensate for the missing bitterness from caffeine.

Genetically engineered caffeine-free coffee could represent a better way of getting our java without the jolt of stimulation, but it will undoubtedly face societal hurdles. While backlash to genetically modified organisms has calmed down recently, anti-GMO sentiments are still present in consumers and regulators. The regulations for getting such a product approved in Europe are particularly stringent and pose a significant barrier.

Even if CRISPR/Cas9 coffee isn’t commercially viable, using these molecular scissors to disable specific genes can help us better understand the complex biosynthesis pathways in coffee plants. So-called knock-out mice, named for having a gene’s function stopped (knocked out), have been pivotal in our understanding of physiology and biology. Want to know what a particular gene does? Knock out its function and see what happens. Much of our understanding of complex diseases like Parkinson’s, cancer or addiction is built upon the findings from knock-out mice.

Another approach to making delicious coffee without the kick may lie with modern species of coffee that naturally produce little or no caffeine. For example, Coffea charrieriana is a caffeine-free variety endemic to Cameroon. C. pseudozanguebariae is native to Tanzania and Kenya, C. salvatrix and C. eugenioides to eastern Africa. Unfortunately, these species of coffee all produce beans that would make a cup of joe that tastes decidedly different from what we’re used to. Still, one potential way to make coffee the same as our usual beans, just without caffeine, is by crossbreeding them with C. arabica plants.

There’s one big problem, though—Where the vast majority of coffee plants are diploid, meaning they have two sets of chromosomes (like humans), C. arabica is tetraploid and has four. Unfortunately, breeding between organisms with different ploidy is typically not successful. Recently, however, several low-caffeine varieties of C. arabica have been discovered in Ethiopia. Crossbreeding between the low- or high-caffeine types of C. arabica may result in a caffeine-free bean that is otherwise the familiar morning starter we know and love.

For the caffeine-sensitive among us, there are interesting new caffeine-free coffee possibilities on the horizon. Even if the methods I’ve outlined here don’t pan out, CRISPR/Cas9 will hopefully enable discoveries regarding caffeine and coffee plants. And we never know what the future may hold.

Birds Seem To Be Scared of Googly Eyes, and That’s a Good Thing (McGill OSS)

3 minute read

Every year upwards of 25 million birds are killed in Canada due to collisions with buildings, communication towers, wind turbines, and as a result of being tangled into marine gillnets. From window decals to flashing lights, humans have tried numerous preventative measures to stop these deaths. Their degree of success depends on the method, the location, and the types of birds in that ecosystem—amongst many other factors—and results are highly variable.

What may seem like benign interventions that—at worst—just won’t work, actually have the capacity to do harm. As an example, In Peru, bycatch (i.e., accidental catch) of Guanay Cormorants was reduced more than 80% after researchers attached green lights to gillnets. At the same time, bycatch of Peruvian Boobies increased. Possibly due to the boobie’s attraction to the lights.

Similarly, when researchers set out to the Baltic sea to compare the effects of attaching light panels, constant green lights, or flashing white lights to gillnets on sea birds (in particular the Long-tailed duck, a vulnerable species) they found that the nets with flashing white lights caught more ducks than the normal, non-illuminated ones.

One approach that is so far quite promising involves using giant looming googly eyes.

To continue reading for free, click here- https://www.mcgill.ca/oss/article/did-you-know-general-science/birds-seem-be-scared-googly-eyes-and-thats-good-thing

Does size matter when it comes to needles? (McGill OSS)

5 minute read

Shots, jabs, pricks—whatever you call it, having a needle inserted into your body is not most people’s idea of a fun afternoon activity. Even if you don’t have a specific needle phobia, injection reactions typically range from neutral at best to quite negative at worst. But what if needles didn’t have to hurt? Or, at least, what if they hurt less? It seems intuitively true that decreasing the size of a needle would make it hurt less, but is it really that simple?

The diameter of a needle (how big it is across) is measured in a unit called a gauge. Because the concept of a gauge pre-dates the 18^th century and has been defined in many different, inconsistent ways, it’s worth specifying that needle width is measured in the Birmingham gauge. The bigger the gauge, the smaller the needle. For example, the width of a 7-gauge needle is roughly 4.6 mm (0.18 inch), while the width of a 30-gauge needle is about 0.31 mm (0.012 inch). To give you some context, a typical spaghetti noodle is roughly 14-gauge, and a regular stud earring is about 19-gauge.

There are a few factors that determine what size of needle a practitioner needs to use, including the body size of the patient and the body part being pricked, but a critical factor is the amount of fluid being injected or drawn out of the patient. If you try to inject a large amount of fluid through a very thin needle, it will both take longer and hurt more due to the high pressure.

Image source: https://www.nms.ac.uk/explore-our-collections/stories/science-and-technology/syringes/

For blood collection, which is typically a few millilitres of blood, clinicians use needles of 21-22 gauge. Vaccines are often <1 mL and accordingly use needles that are slightly smaller, around 22-25 gauge. Delivering insulin to diabetic patients requires even less fluid and can use needles as small as 29-31 gauge.

Even with the limitations imposed by volume, there is some wiggle room in the gauge of needle used for a certain procedure. Medical practitioners can often use their own judgment, experience, and clinical guidelines to change the size of needle they use. Much like how artists may favour a certain size brush, some clinicians have personal preferences in the tools of their trade.

Luckily, it is actually relatively simple to study whether decreasing needle diameter decreases pain. Just find some volunteers who are willing to be stabbed for science (or who are already being treated with a needle-involved method), stick them with at least 2 needles of different gauges without telling them which is which, and ask them how much it hurt on a numeric scale. There are dozens of studies that take this form.

Regarding simple injections in the body, this study compared a 30-gauge needle with a 26-gauge one and found no significant difference in the reported pain. As did this study, which compared 27-gauge vs 23-gauge vs 21-gauge. For injecting Botox around patients’ eyes, this study found no difference in pain scores between a 32-gauge and a 30-gauge needle. These are by no means all of the studies on needle size and pain, but they are representative of the scientific literature on this topic. Again and again, trial participants seem to find no significant difference in their pain when comparing needle gauges.

For many people, the anesthetic injection is the worst part of any dentist visit. While it would be lovely to tell you that a quick swap to a thinner needle is all you need to decrease the pain of dental injections, there is a wealth of evidence to the contrary. For anesthetic injections in the mouth, smaller-width needles were not only ineffective at reducing pain; in one study, they actually increased it!

To continue reading, for free, click here- https://www.mcgill.ca/oss/article/medical/does-size-matter-when-it-comes-needles

Light, Wavelengths and Inactivating SARS-CoV-2 (McGill OSS)

3 minute read

Read the article here: https://mcgill.ca/oss/article/covid-19-general-science/light-wavelengths-and-inactivating-covid-19

Static Shocks Are a Seasonal Occurrence, but Science Can Help Us Avoid Them

5 minute read
Originally posted here: https://mcgill.ca/oss/article/environment-general-science/how-can-i-stop-getting-static-shocks

If you live in Canada, you know what a nightmare winter can be for your hair. No, not because of hat hair, (or at least not entirely because of hat hair), but because of static electricity! All those big scarves and wool hats really do a number on the frizziness of our hair. But even if you’re bald you’ve probably noticed that the number of times you get shocked when reaching for everyday items, like keys, doorknobs and shopping carts, increases in the winter too. There’s some interesting science behind these seasonal shocking scenes, and how you can stop them. 

The number one factor influencing how many zaps you get is humidity. But to understand why we need to review a bit about electricity.  When two objects made of different materials come in contact with each other, like your hair and a hat, for example, electrons can transfer between them. The more prolonged contact, the more electrons move, creating an imbalance of charges between your hair and the hat.

Whether the electrons move from your hair to the hat, or vice-versa, depends on something called the triboelectric series. It’s basically a ranking of different materials based on their tendency to lose or gain electrons. Some things, like rubber or acrylic, are very likely to gain electrons and become negatively charged. Whereas other things, like hair, glass or wool, are more likely to lose electrons and become positively charged. In the case of your hair and a wool hat, since human hair is higher on the triboelectric series, the electrons flow from your hair to the toque.

source: http://soft-matter.seas.harvard.edu/index.php/Triboelectric_series

The problem is that same charges repel each other, so now that your hair is full of positive charge, it’s rather unstable. That’s why, when you get near something conductive, like a metal doorknob, electrons from the knob will “jump” to your hair to neutralize the charge, shocking you in the process. It’s also why your hair stands on end when statically charged. The strands are repelling each other!

Why do charges build up in our hair or clothes, but not in other materials? Because insulating materials, like plastic, fabric or glass, will hold charges quite well, while conducting materials, like metals, will not.

Water happens to be an excellent conductor, so in the spring, summer and fall, when the air in Canada holds a lot of moisture, any negative charges built up on your body can jump to the air (or from the air to your body, either way results in a shock) whenever they want. We don’t even notice these numerous small jumps. But in the winter the air is drier, so the charges simply sit on your skin, waiting for you to approach another conductor (like your car or your girlfriend) to leap to freedom.

Read this to hear about why winter air, especially indoors, is so dry!

When thinking of how wet or dry the air is, we tend to only consider humidity. But there’s another metric that’s important: dew point. The dew point is the temperature at which the air is totally saturated with water. When temperatures fall below the dew point, water condenses on solid surfaces, forming dew in the summer, or frost in the winter (hence why the dew point can also be called the frost point). Warmer air can hold more moisture, meaning that when temperatures are low, the dew point and the actual temperature are quite close. Conversely, when temperatures are high, the dew point and actual temperature are far apart.

Why does dew point matter? Because temperature, dew point, and relative humidity (that % you see on your weather app) are closely linked.

As an example, as I’m writing this, the temperature outside is -9 ˚C, and the relative humidity is 57%. Using the chart below, or less confusingly, this online calculator, we can find that the dew point is -16 ˚C. This tells us that if we go outside it won’t feel muggy because the temperature is significantly above the dew point and the air isn’t saturated with water.

However, our furnaces bring that air into our homes and heat it. This doesn’t change the dew point, but it does change the temperature and the relative humidity. What was a relative humidity of 57% at -16 ˚C becomes a relative humidity of only 7% at 20 ˚C. That’s some really dry air.

Now importantly, the only thing changing here is the relative humidity. The absolute humidity is the same since the furnace doesn’t add or remove any moisture when it heats the air. So even though the air inside and outside is equally dry, it feels much dryer inside due to the relative nature of relative humidity. 

Source: https://www.ncbi.nlm.nih.gov/books/NBK143947/

One of the easiest ways to counteract the shocks that come with these Saharan conditions is to run a humidifier. Increasing the relative humidity of your home will allow more charges to dissipate into the air and avoid the shocks that come with letting them build up.  Side note: If you think desert-like is a bit too harsh to describe the indoor conditions in the Canadian winter, think again. The average relative humidity of the Mojave Desert is 28%, a full 21% higher than my house right now. No wonder I have chapped lips. 

If a humidifier isn’t cutting it for you, you could also try swapping out your rubber-soled slippers for ones with leather soles. Since leather is a better conductor than rubber, this will prevent charges from building up to the same degree. Similarly, try to surround yourself with more cotton. As it falls in the middle of the triboelectric series, it doesn’t have much of a tendency to gain or lose electrons, so won’t build charges like wool or fur.  

Still really worried about static shocks? You could always purposefully discharge yourself every once in a while. If you carry a metal object like a coin, key or paper clip around with you, and touch it to something metal in your house, any electrons stuck to your body will flow through the metal and away, preventing the “jumping” effect that causes a shock. 

Last, but not least, you can always rely on anti-static products to take the charge out of your hair and clothes. Dryer sheets contain chemicals like dipalmitoylethyl hydroxyethylmonium methosulfate that release positively charged ions when heated to neutralize the negatively charged electrons on your clothes. You can even rub your hair gently with one to remove static! Anti-static sprays and anti-static guns can also be used to keep static to a minimum wherever you need to, from your favourite dress to your Rubber Soul vinyl. 

Source: http://www.saapedia.org/en/saa/?type=detail&id=4070

Why Mosquitos Bite You and How to Make Them Stop

Originally posted here: https://mcgill.ca/oss/article/health-technology/why-mosquitos-bite-you-and-how-make-them-stop
15 minute read

Summertime means hammocks, BBQs, fireworks, and mosquito bites.

At least it does for me. Those rotten little suckers seem to just love me. They’ll flock to me even when there are three other people sitting in my backyard. What is it about my blood that they seem to enjoy so much?!

Let’s take a look at the science behind mosquitos and try to answer two questions: Why do mosquitos bite certain people, and what should we do to make them stop?

Take-home message:
– Blood type may or may not play a role in attracting mosquitos
– Products using DEET, icaridin, PMD, metofluthrin, and some blends of essential oils are effective at repelling mosquitos
– Bug zappers, sonic devices, citrosa plants, B vitamins, and scent-baited traps are not effective at repelling mosquitos and should be avoided

Mosquito isn’t a Species, it’s a Group

Before discussing the nitty-gritty of mosquito attraction, we need to realize something. While we tend to think of all flying bugs with proboscises as mosquitos, in truth there are more than 3500 species categorized into 112 genera that fall under the moniker of mosquito.

With such variation in species comes a lot of variation in habitats, behaviours, and risks. For instance, malaria is transmitted to humans only by mosquitos of the genus Anopheles, while yellow and dengue fever are transmitted by those in the genus Aedes. Canada is home to roughly 82 species of mosquitos belonging to the genera Anopheles, Culex, Aedes, Mansonia, and Culiseta. Some mosquitos are anthropophilic, meaning that they preferentially feed on humans, while others are zoophilic and preferentially feed on animals.

We’re typically taught to remove standing water from our property and avoid boggy or marshy areas (good luck in Ontario) to avoid mosquitos, but some species of these bugs don’t exclusively lay their eggs in water. We tend to think of mosquitos being at their worst in the summer, at dusk and dawn, but different species are active at different times, and their behaviour can even change from season to season, making it hard to predict when we are at risk of getting bitten.

Something that is true of all mosquito species though is that only the females bite. They require a blood meal in order to produce their eggs. The nasty by-product of this reproductive cycle is that they transmit diseases, and actually kill more people per year than any other animal.

How Mosquitos Track You

Mosquitos home in on their dinner-to-be by following a few different signals. The first clue that something biteable is nearby is the detection of a CO₂ plume exhaled on the breath of mammals and birds alike.

The amount of CO₂, however, does not affect the attractiveness of a specific target, so even if you’re a human who produces more CO₂ than others (such as those who are larger or pregnant) that alone is not responsible for your irresistible-to-mosquitos aura. This makes sense since large animals like cows naturally produce much more CO₂ than humans, yet many mosquito species still prefer to bite us.

Mosquitos will track a CO­₂ plume until they encounter host-cues. These first of these clues that a target is close by is usually smells emanating from the skin, which we’ll discuss more in a second. As they get close to the source of a smell, mosquitos will then detect and head towards heat and moisture signals emanating from a body.

Source: https://www.sciencedirect.com/science/article/pii/S096098221500740X

We don’t know whether changes in body temperature affect how attractive you are to a mosquito, but we do know that sweating increases the volatile compounds on your skin that they love, and that anhidrotic people, or those who show decreased sweating, are less attractive to the pests.

The main mosquito-cues that can differ between humans are the olfactory ones. While it’s easy to swap your shampoo and soap for unscented varieties that won’t attract mosquitos like the sweet-scented ones do, a lot of the smells that mosquitos sense are innate to your physiology and sadly are not something that we can really change.

A few of these odorous chemicals include ammonia, lactic acid, sulcatone, and acetone. For many of these compounds, however, higher concentrations don’t equal greater mosquito attraction. Instead, they modulate the attractiveness of other substances. For instance, lactic acid has been shown to increase mosquitos attraction to ammonia and CO₂.

While an animal may produce similar-to-human levels of CO₂, humans tend to produce more lactic acid than primates or cows. This lactic acid synergistically increases the appeal of CO₂for anthropophilic mosquito species, while actively dissuading zoophilic species from landing on you. Conversely, ruminants like cows also exhale1-octen-3-ol, a substance that attracts zoophilic species of mosquitos. In a demonstration of this, skin rubbings taken from cows were made just as attractive to anthropophilic mosquitos as skin rubbings from humans via the addition of lactic acid.

The Role of Blood Type

There has been significant debate over the role blood type plays in attracting mosquitos. Initially, a 1972 study using Anopheles gambiae found that mosquitos preferred those with O type blood (O>B>A>AB). But a 1976 study using the same mosquito species did not confirm this.

A 1980 study examined 736 patients and found that while those with A type blood made up 17.6% of the control group, they made up 29% of the malaria cases. Conversely, those with type O blood made up 33% of the control group but only 22% of the malaria cases. While this alone does not tell us whether or not certain blood types are more likely to be bitten by mosquitos or contract malaria, it does point to blood type playing some role in mosquito attraction.

Some clarity came with a 2009 study done with Aedes albopictus that found a similar pattern to the original 1972 study: O>B>AB>A. The researchers also compared the mosquito-attracting ability of those who secrete substances corresponding to their blood type onto their skin, versus those who do not. Their theory was that these blood type-specific secretions could explain mosquito’s ability to find their preferred type O prey. Their results, however, showed an order of preference of O secretors>A nonsecretors>B secretors>O nonsecretors>A secretors>AB secretors>B nonsecretors, which do not correspond to the blood type preferences established.

Concerning blood type’s role in attracting mosquitos, we’re stuck with the often-written phrase more research needed. Given the conflicting results and relatively small sample sizes of these studies, we cannot make definitive conclusions. Not to mention that we have no idea how mosquitos are able to detect a target’s blood type from a distance.

If mosquitos do truly target those with type O blood, the authors of this study theorize that preference could have evolved due to the prevalence of type O blood in African nations. The three most populous African nations are Nigeria, Ethiopia, and Egypt, and the percentage of their populations with type O blood are 51.3%, 39.0%, and 52.0% respectively.

How to Avoid Getting Bitten

Anyways, even if we knew what blood types attract mosquitos, you can’t change your blood type. So, what can you do to get some relief from these minuscule menaces?

First, it’s important to remember that just because you’re not forming welts doesn’t mean you’re not getting bit. Not all bites will lead to the familiar welts, so even if you’re not covered in itchy bumps, if you’re near mosquitos you should be using repellant.

Things That Work

Physical barriers should be your first line of defence against mosquito bites. Install screens on your windows, doors, tents, and RVs, and cover children’s cribs, playpens, and strollers with fine mesh to keep mosquitos out.

You can get specialty meshes and clothing treated with permethrin, an insecticide, for adults in Canada. The anti-mosquito effects of the chemical will last through several wash cycles, but permethrin-treated objects should never be used for or around children, including screens or mosquito nets that they may interact with, as their safety has not been evaluated.

In general, you should strive to wear light coloured clothing, and cover as much of your skin as the heat will allow. Mosquitos are better able to orient themselves towards darker targets, so skip the Nirvana t-shirt and try on a white tee instead.

Flowery and fruity scents will attract mosquitos greatly since they feed on flower nectar (in addition to us) but even non-botanical scented products should be avoided whenever possible. This includes (amongst many others): shampoo, soap, conditioner, shaving cream, aftershave, perfume, deodorant, hand cream, makeup, and even laundry soap and softener.

In terms of repellants, the good news is that you have more options on the market than ever. The bad news is that only some of them work.

DEET

N,N-Diethyl-meta-toluamide, better known as DEET, has been the standard ingredient in commercial bug sprays since 1957 when it made the jump from military to civilian applications. While it used to be thought that DEET interfered with a mosquito’s ability to detect lactic acid, more recent research has found that mosquitos detect and avoid DEET directly. Much like I do with vinegar.

Misguided fears about DEET’s safety have spurred some to move towards other mosquito repellants, and while there are other effectual repellants, none work as well or for as long as DEET. In terms of its safety, DEET has been more thoroughly studied than any other repellant and when used according to guidelines is quite safe.

When utilizing DEET-based repellants it’s important to pay attention to the concentration of DEET in the product. The Government of Canada recommends that no concentration over 30% be used on anyone and that only formulations containing up to 10% be used on children aged two to twelve (up to three daily applications) and aged 6 months to 2 years (only one daily application). Babies under 6 months should be kept mosquito-bite free through the use of nets and screens rather than repellants of any type.

Icaridin 

Icaridin, also known as picaridin, is a safe alternative to DEET popular in Europe and recommended by the Government of Canada for use against mosquitos and ticks on anyone over the age of 6 months. This study showed that products with 9.3% icaridin can repel mosquitos for up to 3 hours, while this study showed that a 10% concentration repelled mosquitos for more than 7 hours. This is comparable to the 5 to 7+ hours of protection provided by 7-15% DEET products, although DEET has been more widely studied. Contrarily this study found a 10% icaridin repellant rather ineffective. If you find them effective, icaridin-based products could be particularly useful for small children who have exceeded their daily recommended applications of DEET-based products but still need to remain outside.

Citronella

Citronella has long been the standard of backyard BBQs and picnics in its candle form, but in addition to the coils and candles designed to keep mosquitos out of a particular area, there are also repellants that contain citronella oil.

Citronella oil is made mostly from 2 species: C. nardusand C. winterianus, and contains many different chemicals, the most notable in terms of their insect-repelling nature include camphor, eucalyptol, eugenol, linalool, geraniol and citronellal.

While it’s citronellal that provides the flowers with their characteristic lemony scent, a 2008 study’s findings suggest that it is actually linalool and geraniol that provide the bug-repelling effects. The researchers compared candles made of 5% citronella, linalool, and geraniol, and found the geraniol and linalool candles much more successful at repelling mosquitos than normal citronella (85% and 71% versus 29% repellency rates over 3 hours). This study likewise confirmed straight citronella candle’s inability to effectively repel mosquitos alone.

This study examined three mosquito repellants that contained citronella and found them all significantly less effective than formulas containing DEET or icaridin, and this study examined 3 wearable bracelets that claimed to emit geraniol and found them as effective as using no repellant at all.

So while it could be useful to burn a geraniol or linalool candle while you’re sitting outside, you should probably still backup your protection with an effective repellent.

P-Menthane-3,8-diol (PMD)

Products with p-Menthane-3,8-diol, a chemical found in small amounts in oil extracted from the lemon eucalyptus tree, have generally (studies 1,2,3) show it to be as effective as DEET and icaridin. The Canadian government recognizes PMD’s repellency effects on blackflies and mosquitos but recommends against using PMD-containing products on anyone younger than three.

Soybean and Essential Oils 

Soybean oil is perhaps the strangest bug-repelling ingredient on this list, but repellant formulations containing mixes of soybean oil and various essential oils have been rapidly making their way onto the Canadian market. While the soybean oil itself does not repel mosquitos, it works in tandem with the essential oils also included in the repellants to stabilize their volatility.

This study found that a formulation including soybean oil, coconut oil, geranium, and vanillin repelled mosquitos for more than 7.2 hours. However, the same study, and another, showed that other formulations also containing soybean oil, as well as other various essential oils (menthol, eucalyptus, lavender, rosemary, sage, etc.) worked very minimally.

This points to the particular essential oils and other ingredients in the repellant making the difference rather than the soybean oil itself. This makes sense when you consider that the geranium included in the effective soybean repellant was likely citronella, and that vanillin has been shown to increase the repellency effects of citronella.

The Government of Canada doesn’t place any age restrictions on formulas containing soybean oil but recommends not using essential oil formulations on those younger than 2. So, you’re free to experiment with different products using different ingredient blends and see which works, but make sure to turn to something a bit more reliable when actually venturing into the woods.

Metofluthrin 

If you’d rather wear a clip-on device than use a mosquito repelling lotion or spray, your only good option is those that emit metofluthrin. This 2017 study examined the efficacy of 5 wearable anti-mosquito devices and found that only the metofluthrin at a concentration of 31.2% effectively repelled mosquitos. Much like citronella candles, however, clip-on devices work by creating a fog of mosquito-repelling chemicals around you. This means that they will only be effective for times when you’re sitting still.

Things That Don’t Work

While components of citronella oils may be effective repellants, citrosa houseplants are not. Nor are the sonic mosquito repelling products that claim to play sound at frequencies that will drive mosquitos away. I’ll let the authors of this paper sum up the evidence for these products: “We are not aware of any scientific study showing that mosquitoes can be repelled by sound waves and therefore we consider these devices as the modern equivalent of snake oil”.

While synthetic mosquito lures that attract the bugs just as well, if not better, than humans have been developed, in practice mosquitos continue to be attracted to humans even when these devices are used. Thus, their use is not recommended by the Canadian Government. Likewise, handheld or mounted bug zappers certainly exist and can be quite satisfying to use for revenge on the bugs that stole your blood, relying on them for protection is not a good idea.

You may have heard that eating bananas can alternatively make mosquitos more or less attracted to you. The claims of banana’s repelling power stem from their high vitamin B6 content, but a 2005 study tested the effects of vitamin B consumption on mosquito attraction and found absolutely no effects. In terms of bananas attracting power, those claims come from octenol content, a chemical that does indeed attract mosquitos. But, octenol isn’t unique to bananas, it’s found in many foods, and no studies have been done that prove consuming bananas does make you a bug-target, so keep on munching.

A subtler mistake you may make when selecting your mosquito repellant is to use a product that combines sunscreen and bug spray. While certainly convenient, the problem lies in sunscreen’s need to be reapplied much more frequently than mosquito-repellants. If both products are needed for an outing, it’s recommended that you wait 20 minutes between applying sunblock and repellant.

Basically, to avoid being a mosquito-target you should stay as scent-free as possible, wear light clothes, avoid bogs and use an effective repellent (such as those containing DEET or icaridin). Or, you could always stay inside- I hear its quite nice this time of year.

Cell Phones and Wifi are Perfectly Safe

2 minute read

The idea that cell phones, routers, wireless heart rate monitors, alarm clocks or pretty much any other electronic device will give you cancer is one of the most persistent fears around. The good news is, it’s also one of the most baseless.

Read the entire article here: https://mcgill.ca/oss/article/general-science-health-and-nutrition-you-asked/cell-phones-and-wifi-are-perfectly-safe

Lead Bullets Can Harm in More Ways Than One

Bullet Copper Ammunition Lead Brass Shell Ammo

It’s probably not news to anyone reading this that lead exposure is dangerous, but when most of us think of routes to lead exposure we think of leaded gasoline, paints, drinking water or pencils (although pencils do not, and never did, actually contain lead). But there is another means of exposure that’s causing significant issues for certain populations: lead bullets.

Bullets have traditionally been made from lead for several reasons. The metal is cheap and melts at only 327˚C (621˚F) meaning that it can easily be formed into bullets. It is also very dense, so that lead bullets pack a big punch, so to speak. But lead is also toxic.

After an animal is hunted, even if care is taken to remove the bullet from the carcass, lead contamination of the meat can still occur. Part of the problem comes from the fact that lead bullets often fragment into many small pieces that can disperse throughout the tissue. These lead fragments can then be consumed by the humans or pets who eat this meat.

Several studies have shown that when game is hunted, killed, processed and cooked in standard ways, higher-than-normal levels of lead are found in the meals. This lead contamination especially influences those who rely on game meat as their primary source of food, such as those in Greenland, or Indigenous Canadians, or those using food banks for whom donations from hunters are fairly common.

Even occasional game meat eaters, however, can be affected by lead contamination. Health Canada states that blood lead levels below 5 μg/dL are associated with adverse health effects. One study found that those eating one or fewer meals of gamebird shot with lead bullets per week showed blood lead levels of 7.5 μg/dL, and those eating gamebird meat daily showed blood lead levels of 17 μg/dL. But the effects of lead bullets don’t stop with humans.

As it’s fairly common for hunters to eviscerate their quarry in the field and leave behind the unwanted viscera, scavenging animals can feed upon the discarded remains of humans’ prey and ingest lead in the process. This can lead to many of the same symptoms as human lead exposure.

Another route for exposure is found in birds’ gizzards. To help break down their food birds swallow small rocks and store them in their gizzards. The problem is that to a bird a bullet looks a lot like a small rock.

One Italian study found that those who engaged in hunting showed a blood lead level almost double those who didn’t. This could be from the lead fumes that are released when guns are fired or from handling lead ammunition. The same study did not find any relationship between blood lead levels and consuming game meat, which could point to some regional differences in ammunition manufacturing, hunting or cooking styles influencing the amount of lead that makes it into a final dish of cooked game meat.

Lead exposure can also occur in humans that are shot with lead-based bullets, especially since bullets are sometimes left in a victim’s body, either due to lack of medical attention or complications that would arise from trying to remove them. In some cases, symptoms can occur many years after the gunshot wound. To remedy this, a combination of drugs to help eliminate lead from the body, chelation therapy and surgery to remove the bullet are used.

The good news is that non-lead bullets are becoming more popular. Several places have enacted lead munition bans, and one study showed that non-lead bullets were just as effective for hunting animals as lead bullets. Those who handle bullets in their jobs (such as police or military personnel) would benefit from a switch to non-lead-based munitions, but beyond environmental and health benefits, switching away from lead bullets would also have an economic benefit, as this study shows. As for what could be used instead of lead, there are a few options, the most popular of which seems to be copper, but the most interesting of which is definitely depleted uranium.