Latest news with #toxicologists
CNN
a day ago
- Health
- CNN
A toxicologist's guide to poison ivy's itch and bee stings' burning pain – 2 examples of nature's chemical warfare
Enjoying the outdoors carries the danger of running into nature's less-friendly side: toxic plants and animals. As toxicologists at the University of Virginia's Blue Ridge Poison Center, we see many patients each year suffering from itchy rashes from poison ivy and stings from wasps or bees. Plants and animals deploy toxins most often in order to defend themselves. Learning how they do that and what happens when the human body is exposed to these substances can offer insights on how to prevent or manage these encounters with nature. The goal is not to scare people away from the outdoors, but to equip them with the knowledge to appreciate these organisms' intricate self-preservation strategies and to protect themselves in return. Whether in a remote state park or on a city playground, most people have encountered poison ivy. This plant is recognizable by its characteristic arrangement of leaves growing in groups of three with edges that vary from smooth to jagged. It can take many forms: a single small plant, a mass of ground cover, a small bush, or a climbing vine reaching many feet up a tree or building. READ: The molecule that makes you itch also stops inflammation Poison ivy – its scientific name is Toxicodendron radicans – and its close relatives poison oak and poison sumac contain an oily substance called urushiol. This chemical is found in every part of the plant: the leaves, roots, stems and even the small white berries it produces in late summer. About 75% of people will develop an allergic reaction on contact with urushiol. Urushiol has antimicrobial properties, and scientists think its job in the poison ivy plant is to protect it from diseases. Because it is so oily, urushiol spreads easily. It can transfer from the plant to your skin, clothes, garden tools or even your pets. Direct plant contact isn't the only risk: If urushiol is on your clothing or a pet's fur and your skin later brushes against it, you can develop the same rash as you'd get from directly touching the plant. Urushiol triggers a delayed allergic reaction. When the oil touches your skin, it binds to skin cells, changing their shape. A molecule called CD1a then clocks urushiol as a foreign substance, prompting the immune system to mount an attack on the cells – hence the rash. READ: Are twins allergic to the same things? The symptoms do not appear instantly; the rash usually appears 12 to 48 hours after exposure. It often starts as redness and itching, then develops into small bumps or fluid-filled blisters. The reaction can be mild or severe, depending on how sensitive you are and how much urushiol got on your skin. The rash itself isn't contagious. Fluid from the blisters doesn't spread it. What spreads the rash to other areas of your body or to others is the urushiol lingering on your skin, clothing, tools or pets. Once the oil is adequately washed away, the rash can't spread to other people or to other areas of your body. If you have touched poison ivy, wash the area as soon as you can with soap and water and change your clothes if possible. After that, the rash will eventually resolve on its own. You can help alleviate symptoms by using a topical steroid or anti-itch cream on the rash. In severe cases, or if the face is affected, patients may require oral steroids to treat the symptoms. Bees and wasps are most active in the late summer. Because of this, we receive more frequent poison center calls about them during this season. Bees and wasps generally sting to defend their hives or nests or to protect themselves from perceived threats. They store venom in their abdominal sacs. When they sting, the venom flows through their stinger and is injected into their target's skin. This venom is a clear, slightly acidic liquid loaded with various active ingredients. For example, it contains enzymes such as phospholipase A2 that break down cell membranes, and peptides such as melittin that cause pain. The venom also contains natural chemicals such as histamine and epinephrine that affect blood vessels and the immune system. Unlike with poison ivy, where the immune system's reaction to the substance causes irritation, with bee and wasp stings it's primarily the substance itself that causes pain – although immune response can still play a role. As soon as the venom enters a person's skin, their body reacts. READ: Are you really allergic to penicillin? A sharp, burning pain comes first as the components of the venom begin to inflict damage, followed by redness and then swelling of the area. Symptoms commonly peak within a few hours and fade within a day. However, some people have stronger reactions with larger areas of swelling that can last for several days. This is because everyone's immune system is slightly different, and some people tend to have stronger reactions than others to foreign substances. In rare cases, the immune system overreacts, releasing large amounts of histamine and other chemicals all at once. Histamine is most often released in response to a foreign substance, causing symptoms of an allergic reaction. This can lead to anaphylaxis, a severe allergic reaction that can make breathing difficult, lower blood pressure and cause airway swelling, and which can quickly become life-threatening. READ: How to manage hay fever in your pets Getting stung multiple times at once can also be life-threatening due to the sheer amount of venom injected, even in people without a bee venom allergy. If you're stung and the stinger is stuck in the skin, it should be removed immediately by the quickest means available. Bee stingers are barbed and can continue to deliver venom for up to a minute. Most bee or wasp stings require only symptomatic treatment, such as an over-the-counter steroid cream or oral antihistamine to reduce itching and swelling. However, people who begin to develop more severe symptoms such as full body hives, vomiting or difficulty breathing should immediately seek emergency care. Anaphylactic reactions require rapid treatment with a medication called epinephrine and close monitoring in the hospital. Christopher P. Holstege is a professor of emergency medicine and pediatrics at University of Virginia. Sandra H. Nixon is a fellow in the Division of Medical Toxicology at University of Virginia.
CBC
31-07-2025
- Health
- CBC
Do you know about the forever chemicals in your drinking water?
The overall average concentrations in the Great Lakes don't currently exceed federally recommended limits but toxicologists say there may be no safe level of exposure.
New York Times
19-05-2025
- Health
- New York Times
Is ‘Reef Safe' Sunscreen Really Better?
Some of the sunscreen you slather on this summer will end up in lakes, streams or the ocean, even if you don't go swimming. And a growing body of evidence suggests that ultraviolet filters, the active ingredients in sunscreens, can harm creatures that live in the water. Some products are marketed as 'reef safe' or friendly to aquatic life. But has that been proved? We talked to a dermatologist, several ecologists and toxicologists, and a chemical engineer to find out the best way to protect your skin and the environment, too. Your sunscreen options There are two kinds of UV filters in sunscreens on the market today. Mineral sunscreens create a physical barrier on your skin that reflects UV rays like a mirror, while chemical sunscreens are absorbed into the skin and convert the UV radiation into harmless heat. (Chemical sunscreens are also sometimes labeled 'organic,' but that's a chemistry term, not a claim of environmental friendliness.) Any sunscreen you apply will eventually end up in water. Researchers estimate that between 25 and 50 percent of sunscreen comes off during a dip. The rest goes down the drain when you shower or enters the wastewater system through the laundry when you wash your beach towels. Most standard treatment plants aren't effective at removing trace levels of UV filters from wastewater, said Dunia Santiago, a chemical engineer at the University of Las Palmas de Gran Canaria in Spain who studies how treatment plants process contaminants. That means the chemicals are still in the water that flows out of the plant and into the world. And, since many UV filters don't biodegrade well, levels can build up over time in the environment, floating around, settling into sediment and being eaten by animals, especially in shallow areas popular with swimmers. What we know and don't know There's a growing body of evidence that both chemical and mineral UV filters have the potential to harm wildlife, including coral reefs, at high concentrations. A 2016 study on the potential for a chemical UV filter called oxybenzone to make coral more vulnerable to bleaching made a particularly big splash in the public consciousness, increasing demand for gentler alternatives and leading some places to ban the sale of some chemical sunscreens. In response, some manufacturers started marketing mineral sunscreens as 'reef safe.' But researchers generally agree you shouldn't put too much stock in these labels, which aren't regulated. Calling one UV filter safer than another 'implies that we have information to make a comparison, which we do not have,' said Sandy Raimondo, an ecologist at the Environmental Protection Agency who studies chemical contaminants. The science on UV-filter toxicity isn't rock-solid because the laboratory methods used to test them haven't been standardized, according to ecologists and toxicologists we interviewed. One important issue is the 'stickiness' of chemical UV filters. They cling to the surface of the water, the sides of tanks and the inside of tools designed to measure their concentrations. When researchers can't be certain of the concentration of a chemical in water, Dr. Raimondo said, the resulting data isn't reliable. While the data on mineral UV filters is more reliable, new formulations designed to minimize that ghostly white cast on the skin cause their own problems. Some manufacturers use so-called nano versions of zinc oxide and titanium dioxide. These even-tinier particles can get embedded in the tissues of plants and animals in ways that scientists are only beginning to understand, Dr. Raimondo said. Trying to fill in the blanks The E.P.A. is currently funding studies to fill the gaps in our understanding of UV-filter toxicity. Top priorities include resolving measurement issues and developing standardized methods to make comparisons easier. But President Trump's plans for deep cuts at the agency have put the future of many environmental studies in doubt. Even if those studies continue, they will probably take years to complete, and the agency could take several more years to conduct an official ecological risk assessment for any particular UV filter. Some researchers say that, even with our incomplete knowledge of the impacts of UV filters, the existing evidence on certain chemical UV filters is damning enough for us to switch to alternatives that use non-nano mineral UV filters. Indeed, the stickiness of chemical UV filters may mean that existing research underestimates their environmental toxicity. What you can do right now Thankfully, you don't have to broil to help the environment. Dermatologists and toxicologists agree on the best form of sun protection. But it's not mineral or chemical sunscreen. It's clothing. Sunscreen is an important component of protection, 'but it's not the only component,' said Dr. Henry Lim, a dermatologist at Henry Ford Health in Detroit and a former president of the American Academy of Dermatology. 'Staying in the shade, wearing photoprotective clothing, a wide-brimmed hat and sunglasses are very, very important.' Cover as much real estate as you can with UPF rated clothing (that's the SPF equivalent for fabric). 'Sunscreen should be applied only in the areas that cannot be covered,' Dr. Lim said.
