10 Misconceptions on the Link Between Environmental Factors and Cancer
As a cancer epidemiologist, I’ve spent a lot of time researching the links between environmental contaminants and cancer. One of the pitfalls of the Digital Age is that people come across a lot of information that isn’t based on sound scientific evidence or is, at best, anecdotal. That’s dangerous, because conjecture and falsehoods that masquerade as fact can hamper efforts to prevent and treat cancer.
Here are some common misconceptions:
1. Getting cancer is almost completely out of your control.
While genetics and bad luck play a role, many cancers are caused by other factors, some of which you can control.
Smoking, poor diet and lack of exercise are major contributors to the development of cancer. Another 20 percent of cancers, according to the World Health Organization (WHO), are believed to be caused by environmental factors such as pollution, infections and radiation.
The bottom line: You certainly can’t avoid every potentially dangerous exposure, but as many as half of cancers may be preventable.
2. “Everything” causes cancer.
Almost every day, you may read a news story suggesting that items in your home or substances in your food are linked to cancer or otherwise bad for your health. Recent headlines trumpeted the risks of eating red and processed meats. The constant onslaught of warnings can be overwhelming. But not all chemicals, pollutants or guilty pleasures will lead to cancer. The International Agency for Research on Cancer, a research arm of the WHO, has looked into nearly a thousand suspected causes of cancer. Of those suspicious substances and activities, they have concluded that just about half are known or potentially carcinogenic (117 known, 74 probable and 287 possible carcinogens).
Keep in mind that dose plays a key role. Smoking one cigarette probably won’t hurt you, but smoking for years is a clear health hazard.
3. Exposure to a known carcinogen will give you cancer.
Government agencies and international health bodies classify a substance as a “known carcinogen” when strong evidence demonstrates that it can cause cancer. Officials at these institutions base their determinations on the strength of scientific evidence. But a person exposed to a known carcinogen is not 100 percent certain to develop cancer, not by a long shot.
Let’s compare asbestos and processed meats. Both are known carcinogens based on many scientific studies that consistently show they can cause cancer. In both cases, the strength of the evidence is consistently high. But there’s a difference. Asbestos is a potent carcinogen. Substantial exposure dramatically increases a person’s risk of getting mesothelioma, lung and other cancers. On the other hand, eating processed meats only modestly increases your chances of getting cancer.
4. Natural products are safe and synthetic products are harmful.
Arsenic, asbestos, formaldehyde, radiation and tobacco occur naturally and are known carcinogens. The word “natural” on a food label or consumer product is meaningless. The government does not issue standard guidelines for the term, in contrast to “organic,” which can be displayed only by certain foods meeting strict government standards. Arm yourself with information. Read labels, consult Environmental Working Group’s guides and resources, know what you’re buying and don’t assume everything that says “natural” is harmless.
5. Chemicals that the body absorbs and retains for a long time are more dangerous than those that are quickly excreted or metabolized.
The hazard of a substance is determined not just by the degree of exposure but also how it interacts with the body. Sometimes a chemical that isn’t dangerous can metabolize into a compound that is carcinogenic. Nitrates and nitrites in food and water can metabolize during digestion into carcinogenic N-nitroso compounds. Other chemicals such as benzene, pesticides and heavy metals are excreted quickly from the body, but they are still carcinogenic. The chemicals that persist in the body can act as a constant source of exposure and may even pass from mother to child, which are additional concerns.
6. The cancer risk you accumulate is irreversible.
Your ability to turn back the clock on cancer risk depends on the exposure. Certain harmful exposures, such as to radiation, damage cells so seriously that the body cannot recover fully. Other substances can accumulate in the body and act as a source of continuous exposure. However, damage from many environmental exposures can be partly reversed by eliminating or significantly reducing the exposure. The Surgeon General’s report on tobacco concluded that quitting smoking at any age reduces a smoker’s risk of cancer by up to 50 percent in just five to 10 years. That’s powerful evidence that it’s never too late to make healthy lifestyle changes.
7. Mammograms cause breast cancer.
The risk associated with the very small amount of radiation emitted during a mammogram is minuscule for most patients. It’s equivalent to a few weeks of the natural background radiation you experience from the elements in the earth, cosmic radiation and even your own body. A small percentage of the carbon that makes up the body is the isotope carbon-14, which is unstable and emits radiation. Women who are pregnant should avoid mammograms and X-rays that their doctors don’t consider necessary. Radiation could harm the developing fetus. Consult your health care professional to determine if a mammogram or any other medical screening is appropriate.
8. Cell phones, Wi-Fi, microwaves, power lines and airport X-ray machines will cause cancer.
Cell phones, Wi-Fi, microwaves and power lines emit non-ionizing radiation, which is less energetic and doesn’t penetrate the body to the same degree as cancer-causing ionizing radiation such as X-rays, sunlight and the radiation from uranium. The WHO considers cell phone radiation a possible carcinogen based on a suspected association between cell phone use and brain cancer. Holding the phone a few millimeters from your body can drastically reduce exposure. EWG recommends hands-free devices and texting. Although little or no evidence supports a conclusion that Wi-Fi signals, microwaves and power lines cause cancer, it’s a good idea to keep wireless routers a few feet from places where people spend long periods of time. Airport screening devices use either low-dose X-rays or non-ionizing radiation. It takes about 1,000 trips through an airport X-ray scanner to equal the radiation exposure from one medical chest X-ray.
9. Artificial turf sports fields cause cancer.
Scientists have detected several carcinogens in ground-up tire rubber, also known as crumb rubber, used as infill and cushioning in artificial turf. Heavy metals, PCBs and other volatile compounds have shown up in some turf. Air measurements over turf, especially in indoor facilities, have found excessive amounts of certain volatile chemicals. Researchers do not know whether worrisome chemicals in turf migrate into the body through contact with skin or breathing. No data exists at this time to say that artificial turf causes cancer, but scientists are just beginning to explore the question. In the meantime, you should play on artificial turf in well-ventilated areas, avoid hand-to-mouth contact while playing and limit direct contact between turf and skin.
10. Residential pesticides are safe.
Many of the pesticides suspected to cause cancer in farm workers are being sold for residential use. Some evidence exists that exposure to pesticides can increase the risk of cancer, even though people tend to apply pesticides less frequently and at lower doses around the home than would be done on farms. Children may be particularly susceptible to damage from pesticides. Scientific studies have shown that children exposed in the womb and in infancy to pesticides face increased risk of childhood cancers such as leukemia and brain tumors.
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By Shelly Miller
The vast majority of SARS-CoV-2 transmission occurs indoors, most of it from the inhalation of airborne particles that contain the coronavirus. The best way to prevent the virus from spreading in a home or business would be to simply keep infected people away. But this is hard to do when an estimated 40% of cases are asymptomatic and asymptomatic people can still spread the coronavirus to others.
It’s All About Fresh, Outside Air<p>The safest indoor space is one that constantly has lots of <a href="https://www.epa.gov/indoor-air-quality-iaq/how-does-outdoor-air-enter-building" target="_blank">outside air</a> replacing the stale air inside.</p><p>In commercial buildings, <a href="https://www.ncbi.nlm.nih.gov/books/NBK143277/" target="_blank">outside air is usually pumped in</a> through heating, ventilating and air-conditioning (HVAC) systems. In <a href="https://www.epa.gov/indoor-air-quality-iaq/how-does-outdoor-air-enter-building" target="_blank">homes, outside air gets in</a> through open windows and doors, in addition to seeping in through various nooks and crannies.</p><p>Simply put, the more fresh, outside air inside a building, the better. Bringing in this air dilutes any contaminant in a building, whether a virus or a something else, and <a href="https://doi.org/10.1111/j.1600-0668.2010.00703.x" target="_blank">reduces the exposure of anyone inside</a>. Environmental engineers like me quantify how much outside air is getting into a building using a measure called the <a href="https://doi.org/10.1038/jes.2013.30" target="_blank">air exchange rate</a>. This number quantifies the number of times the air inside a building gets replaced with air from outside in an hour.</p><p>While the exact rate depends on the number of people and size of the room, most experts consider roughly <a href="https://doi.org/10.1034/j.1600-0668.2002.01145.x" target="_blank">six air changes an hour</a> to be good for a 10-foot-by-10-foot room with three to four people in it. In a pandemic this should be higher, with one study from 2016 suggesting that an exchange rate of nine times per hour <a href="https://doi.org/10.1177%2F1420326X16631596" target="_blank">reduced the spread of SARS, MERS and H1N1</a> in a Hong Kong hospital.</p><p>Many buildings in the U.S., <a href="https://doi.org/10.1111/ina.12403" target="_blank">especially schools</a>, do not meet recommended ventilation rates. Thankfully, it can be pretty easy to get more outside air into a building. Keeping <a href="https://doi.org/10.1016/S0960-1481(99)00012-9" target="_blank">windows and doors open</a> is a good start. Putting a box fan in a window blowing out can greatly increase air exchange too. In buildings that don't have operable windows, you can change the mechanical ventilation system to increase how much air it is pumping. But in any room, the more people inside, the faster the air should be replaced.</p>
Using CO2 to Measure Air Circulation<p>So how do you know if the room you're in has enough air exchange? It's actually a pretty hard number to calculate. But there's an easy-to-measure proxy that can help. Every time you exhale, you <a href="https://doi.org/10.1111/ina.12383" target="_blank">release CO2</a> into the air. Since the coronavirus is most often spread by breathing, coughing or talking, you can use <a href="https://pdfs.semanticscholar.org/dd7e/b2870c38f70e5285e5118ed6f158c091f7cf.pdf" target="_blank">CO2 levels</a> to see if the room is filling up with potentially infectious exhalations. The CO2 level lets you estimate if enough fresh outside air is getting in.</p><p>Outdoors, CO2 levels are just above 400 parts per million (ppm). A well ventilated room will have around <a href="https://doi.org/10.1111/j.1600-0668.1999.00003.x" target="_blank">800 ppm of CO2</a>. Any higher than that and it is a sign the room might need more ventilation.</p><p>Last year, researchers in Taiwan reported on the <a href="https://doi.org/10.1111/ina.12639" target="_blank">effect of ventilation on a tuberculosis outbreak</a> at Taipei University. Many of the rooms in the school were underventilated and had CO2 levels above 3,000 ppm. When engineers improved air circulation and got CO2 levels under 600 ppm, <a href="https://doi.org/10.1111/ina.12639" target="_blank">the outbreak completely stopped</a>. According to the research, the increase in ventilation was responsible for 97% of the decrease in transmission.</p><p>Since the coronavirus is spread through the air, higher CO2 levels in a room likely mean there is a <a href="https://doi.org/10.1111/ina.12639" target="_blank">higher chance of transmission</a> if an infected person is inside. Based on the study above, I recommend trying to keep the CO2 levels below 600 ppm. You can buy <a href="https://doi.org/10.5194/amt-7-3325-2014" target="_blank">good CO2 meters</a> for around $100 online; just make sure that they are accurate to within 50 ppm.</p>
Air Cleaners<p>If you are in a room that can't get enough outside air for dilution, consider an air cleaner, also commonly called air purifiers. These machines remove particles from the air, usually using <a href="https://doi.org/10.1016/j.cap.2005.07.013" target="_blank">a filter</a> made of tightly woven fibers. They can <a href="https://shellym80304.files.wordpress.com/2020/06/miller-leiden-et-al-1996.pdf" target="_blank">capture particles containing bacteria and viruses</a> and can help reduce disease transmission.</p><p>The U.S. Environmental Protection Agency says that <a href="https://www.epa.gov/coronavirus/air-cleaners-hvac-filters-and-coronavirus-covid-19" target="_blank">air cleaners can do this for the coronavirus</a>, but not all air cleaners are equal. Before you go out and buy one, there are few things to keep in mind.</p><p>The first thing to consider is <a href="https://shellym80304.files.wordpress.com/2020/06/air-cleaner-report.pdf" target="_blank">how effective an air cleaner's filter is</a>. Your best option is a cleaner that uses a high-efficiency particulate air (<a href="https://doi.org/10.1016/S0021-8502(05)80214-9" target="_blank">HEPA</a>) filter, as these remove more than <a href="https://doi.org/10.1063/1.2771421" target="_blank">99.97% of all particle sizes</a>.</p><p>The second thing to consider is how powerful the cleaner is. The bigger the room – or the more people in it – the more air needs to be cleaned. I worked with some colleagues at Harvard to put together a tool to help teachers and schools determine <a href="https://docs.google.com/spreadsheets/d/1NEhk1IEdbEi_b3wa6gI_zNs8uBJjlSS-86d4b7bW098/edit#gid=1275403500" target="_blank">how powerful of an air cleaner you need for different classroom sizes</a>.</p><p>The last thing to consider is the validity of the claims made by the company producing the air cleaner.</p><p>The Association of Home Appliance Manufacturers certifies air cleaners, so the AHAM Verifide seal is a good place to start. Additionally, the California Air Resources Board has a <a href="https://ww2.arb.ca.gov/our-work/programs/air-cleaners-ozone-products/california-certified-air-cleaning-devices" target="_blank">list of air cleaners</a> that are certified as safe and effective, though not all of them use HEPA filters.</p>
Keep Air Fresh or Get Outside<p>Both the <a href="https://www.who.int/news-room/commentaries/detail/transmission-of-sars-cov-2-implications-for-infection-prevention-precautions" target="_blank">World Health Organization</a> and <a href="https://www.cdc.gov/coronavirus/2019-ncov/daily-life-coping/deciding-to-go-out.html" target="_blank">U.S. Centers for Disease Control and Prevention</a> say that poor ventilation increases the risk of transmitting the coronavirus.</p><p>If you are in control of your indoor environment, make sure you are getting enough fresh air from outside circulating into the building. A CO2 monitor can help give you a clue if there is enough ventilation, and if CO2 levels start going up, open some windows and <a href="https://www.advisory.com/daily-briefing/2020/07/17/outdoor-gathering" target="_blank">take a break outside</a>. If you can't get enough fresh air into a room, an air cleaner might be a good idea. If you do get an air cleaner, be aware that they don't remove CO2, so even though the air might be safer, CO2 levels could still be high in the room.</p><p>If you walk into a building and it feels hot, stuffy and crowded, chances are that there is not enough ventilation. Turn around and leave.</p><p>By paying attention to air circulation and filtration, improving them where you can and staying away from places where you can't, you can add another powerful tool to your anti-coronavirus toolkit.</p>
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The tiny island nation of Mauritius, known for its turquoise waters, vibrant corals and diverse ecosystem, is in the midst of an environmental catastrophe after a Japanese cargo ship struck a reef off the country's coast two weeks ago. That ship, which is still intact, has since leaked more than 1,000 metric tons of oil into the Indian Ocean. Now, a greater threat looms, as a growing crack in the ship's hull might cause the ship to split in two and release the rest of the ship's oil into the water, NPR reported.
On Friday, Prime Minister Pravind Jugnauth declared a state of environmental emergency.
France has sent a military aircraft carrying pollution control equipment from the nearby island of Reunion to help mitigate the disaster. Additionally, Japan has sent a six-member team to assist as well, the BBC reported.
The teams are working to pump out the remaining oil from the ship, which was believed to be carrying 4,000 metric tons of fuel.
"We are expecting the worst," Mauritian Wildlife Foundation manager Jean Hugues Gardenne said on Monday, The Weather Channel reported. "The ship is showing really big, big cracks. We believe it will break into two at any time, at the maximum within two days. So much oil remains in the ship, so the disaster could become much worse. It's important to remove as much oil as possible. Helicopters are taking out the fuel little by little, ton by ton."
Sunil Dowarkasing, a former strategist for Greenpeace International and former member of parliament in Mauritius, told CNN that the ship contains three oil tanks. The one that ruptured has stopped leaking oil, giving disaster crews time to use a tanker and salvage teams to remove oil from the other two tanks before the ship splits.
By the end of Tuesday, the crew had removed over 1,000 metric tons of oil from the ship, NPR reported, leaving about 1,800 metric tons of oil and diesel, according to the company that owns the ship. So far the frantic efforts are paying off. Earlier today, a local police chief told BBC that there were still 700 metric tons aboard the ship.
The oil spill has already killed marine animals and turned the turquoise water black. It's also threatening the long-term viability of the country's coral reefs, lagoons and shoreline, NBC News reported.
"We are starting to see dead fish. We are starting to see animals like crabs covered in oil, we are starting to see seabirds covered in oil, including some which could not be rescued," said Vikash Tatayah, conservation director at Mauritius Wildlife Foundation, according to The Weather Channel.
While the Mauritian authorities have asked residents to leave the clean-up to officials, locals have organized to help.
"People have realized that they need to take things into their hands. We are here to protect our fauna and flora," environmental activist Ashok Subron said in an AFP story.
Reuters reported that sugar cane leaves, plastic bottles and human hair donated by locals are being sewn into makeshift booms.
Human hair absorbs oil, but not water, so scientists have long suggested it as a material to contain oil spills, Gizmodo reported. Mauritians are currently collecting as much human hair as possible to contribute to the booms, which consist of tubes and nets that float on the water to trap the oil.
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By Elizabeth Claire Alberts
There are trillions of microplastics in the ocean — they bob on the surface, float through the water column, and accumulate in clusters on the seafloor. With plastic being so ubiquitous, it's inevitable that marine organisms, such as sharks, will ingest them.
Polyproylene fibers found in one of the sampled sharks. Kristian Parton
Spiny dogfish. NOAA / Wikimedia Commons<p>"There appear to be two routes for these particles to end up in the sharks," Parton said. "The first through their food source [such as] crustaceans. Their prey may already contain these fibers, and consequently it's passed to the shark through bioaccumulation up the food chain. The second pathway is direct ingestion from the sediment. As these sharks feed, they'll often suck up sediment into their mouths, some of this is expelled straight away, although some is swallowed, therefore fibers and particles that may have sunk down into the seabed may be directly ingested from the surrounding sediment as these sharks feed."</p><p>Some sharks only contained a few plastic particles, but others contained dozens. The larger the shark, the more plastic was in it, the findings suggested. The highest number of microplastics was found in an individual bull huss, which had 154 polypropylene fibers inside its stomach and intestines.</p><p>"It's perhaps likely this individual shark had swallowed a larger piece of fishing rope/netting and this has broken down during digestive processes within the shark, and also broken down into smaller pieces during our analysis," Parton said.</p>
Lesser-spotted dogfish caught as bycatch. Kristian Parton<p>While this study only examined the stomach and digestive tracts of demersal sharks, Parton says it's possible that plastic would be present in other parts of the sharks' bodies, such as the liver and muscle tissue. However, more research would be needed to prove this.</p><p>At the moment, there is also limited understanding of how microplastic ingestion would impact a shark's health, although microplastics are known to negatively influence feeding behavior, development, reproduction and life span of zooplankton and crustaceans.</p><p>"If we can show that these fibers contain inorganic pollutants attached to them, then that could have real consequences for these shark species at a cellular level, impacting various internal body systems," Parton said.</p>
Parton in the lab. Kristian Parton<p>This new study demonstrates how pervasive and destructive plastic pollution can be in the marine environment, according to Will McCallum, head of oceans for Greenpeace U.K.</p><p>"Our addiction to plastics combined with the lack of mechanisms to protect our oceans is suffocating marine life," McCallum said in a statement. "Sharks sit on top of the marine food web and play a vital role in ocean ecosystems. Yet, they are completely exposed to pollutants and other human impactful activities. We need to stop producing so much plastic and create a network of ocean sanctuaries to give wildlife space to recover. The ocean is not our dump, marine life deserves better than plastic."</p>
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By Loveday Wright and Stuart Braun
After a Japanese-owned oil tanker struck a reef off Mauritius on July 25, a prolonged period of inaction is threatening to become an ecological disaster.
<div id="bb0a7" class="rm-shortcode" data-rm-shortcode-id="e5aefc0fff61ab1aea2f4b03c5399864"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1291765757013983238" data-partner="rebelmouse"><div style="margin:1em 0">The #oilspill is devastating but I want to honour the community mobilisation at the Mahebourg waterfront today (to… https://t.co/UWFkZFdjdi</div> — Fabiola Monty (@Fabiola Monty)<a href="https://twitter.com/LFabiolaMonty/statuses/1291765757013983238">1596815930.0</a></blockquote></div><p>"Booms are made of nylon mesh filled with #sugarcane straws all hand-stitched by Mauritian volunteers, empty plastic bottles used as buoys," described Mauritian journalist Zeenat Hansrod in a tweet. </p>
How to Tackle Oil Spills<p>The method for tackling oil spills depends on several factors, including the type and amount of oil in question, location and weather conditions.</p><p>"Once the oil comes to shore, the more intensive the cleaning technique. You can risk causing further damage," said Nicky Cariglia, an independent consultant at Marittima, who specializes in marine pollution. </p><p>"If you wanted to remove all traces of oil, the techniques available become increasingly aggressive the less oil that remains. In mangroves, you would have the added risk of causing damage by trampling," Cariglia told DW. Highly sensitive mangrove ecosystems line the Mauritius east coast that is threatened by the current spill.</p><p>Because oil normally has a lower density than water, it floats on the surface of the ocean. This means that for clean-up action to be most effective, it should happen very quickly after a spill, before the oil disperses. </p>
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