In 1982, around 20% of the people who ate some of the roughly 7,400 bags of cashews sold as part of a Little League fundraiser in Pennsylvania broke out in rashes because of natural urushiol residue on the nuts that hadn't been removed and fully cooked off—the same allergy-inducing substance found in poison ivy.

Poison ivy is in the same family as mangoes, cashews, and pistachios—and they all produce oily urushiol in their raw unprocessed state, and chewing or touching mango skin can produce blister rashes.

Poison ivy's characteristic rash is caused by an allergic response to an oily compound in the plant called urushiol.

Poison ivy, which produces urushiol throughout the plant, not just in the leaves, can cause year-round rashes.

Urushiol, the oily toxin in poison ivy, can remain allergenic on clothing for up to 5 years—or even longer.

Between 10 million and 50 million people in the US develop rashes from poison ivy, poison sumac, and poison oak annually.

See if you know how to recognize poison ivy with this quiz.

More than 90% of America’s food allergies are triggered by 9 foods

Milk, egg, peanut, tree nuts, soy, wheat, fish, shellfish and most recently, sesame, are recognized as the most common food allergies in the US. Together, they are responsible for at least 90% of the serious food allergy responses in the country.

During the French Revolution, a botanist's letter asking about "dear Rhus" (poison ivy) was intercepted and led to authorities' suspicions he was conspiring with the Russians.

Researchers are investigating if nanoparticle treatments could combat allergies

In rodent work, Northwestern University’s Evan Scott (now at the University of Virginia) and his colleagues have been trying to attack allergies with specially designed nanoparticles—miniscule lab-made objects that can penetrate cells. They stud the nanoparticles with a tiny bit of the allergen specific to the allergy (i.e. cashew protein for cashew allergy) and antibodies that shut down allergic response processes.

One-third of kids with food allergies report being bullied because of it, surprising parents

Research published in 2021 surveyed how more than 100 kids with food allergies were treated by their peers. About one-third of the surveyed kids had their allergies used against them. Bullying tactics included that their allergens were sometimes intentionally put in their food or thrown at them. Parents usually had no idea this bullying was happening.

Allergies occur when our immune system mistakenly considers a substance a threat

Immunoglobulin E antibodies, or IgE antibodies, may bind to an allergen, effectively labeling it as a threat. That triggers a cascade of actions in the body, including the release of histamine, which causes the characteristic itching and hives of allergies. Sometimes a cooked version of an allergen—like a cooked carrot—may look different enough from its raw form to the immune system that antibodies ignore it, and no allergic response takes place.

Scientists testing how climate change affected plants found in a years-long simulation study that poison ivy grew 70% faster than it did without extra carbon dioxide.

Amish kids have far fewer allergies than the general population

Only about 7% of Amish children in a northern Indiana community have tested positive for common allergens in routine skin prick tests, whereas half of the general US population tests positive for them. Asthma is also extremely uncommon among the Amish, even when compared with other farming communities. Researchers are interested in exploring if approaches like exposing kids across the general population to Amish farm dust might stave off some allergies.

You can be allergic to grass—but there are other reasons it can make you itch

Modern conveniences may be contributing to allergy increases

A combination of genetics and how the environment changes our genes are likely contributing to the rise in allergies. But daily conveniences, such as dishwashers and packaged baby food, also change the level of bacterial exposures in early life, with potential implications for allergy development, experts from Mount Sinai Health System state in this video discussion.

The life of a pistachio

Pistachios—which are actually a seed, not a nut—are a superfood with lots of great fat, fiber, antioxidants, and more, and is listed as a complete protein. Originally from the Middle East, the seed was imported to the US where California has become the leading grower in the world. Harvested once a year around October, the flavor is having a bit of a moment both for its taste and nutrition. Watch more here.

Alpha-gal allergy is a problem for red meat lovers, and that same sugar is an issue for xenotransplants, too

In recent years, researchers have discovered ticks can induce spontaneous meat allergies in people they bite, a particularly problematic condition for previous meat lovers. This 18-minute podcast from RadioLab breaks down the cause.

Revelations that apples were sprayed with the chemical Alar led to its ban in the 1980s

Almost three decades after Rachel Carson’s “Silent Spring,” a “60 Minutes” segment on the use of Alar, a chemical sprayed on apples, drew national attention and inspired supermarkets and schools to remove apples from their shelves and cafeterias. That same year, the Environmental Protection Agency took action against the use of the chemical in food.

Zoo animals have developed allergies, too

Although scientists do not know if allergies manifest among wild animals—and if animals can survive with them—in a zoo setting, veterinarians have observed zoo animals with common allergy symptoms, including itchiness, crusty skin, and runny eyes. Veterinarians have identified Asian elephants with pollen allergies and at least one jaguar with an allergy to fleas.

People can—and have—contracted leprosy from armadillos

A 2011 study linked multiple human cases to the handling of armadillos or the consumption of their meat. The research couldn't document direct transmission, but did find that the animals and humans shared the same exact strain of the disease.

Mycotoxins are toxic compounds produced by fungi—some show up in food

About a quarter of the world’s agricultural products are contaminated with mycotoxins. Some of these compounds can cause serious health problems, including cancer, so the US government has set up monitoring programs to detect them in our food and in animal feed. Humans can become ill if they eat contaminated food, but also if they ingest products from animals that had previously consumed these toxic compounds, such as milk from a cow that ate contaminated corn.

Volatile chemical contamination can last in burn areas long after urban wildfires

Lead, arsenic, asbestos, and other chemicals have been found trapped in smoke-exposed rugs, couches, pillows, and other furniture that appeared otherwise undamaged from the 2025 LA wildfires. The gradual release of these substances has produced dangerous indoor air concentrations and contributed to increased emergency room visits and abnormal blood tests.

Who was behind the fatal 1982 Tylenol poisonings?

In 1982, an unknown suspect laced Tylenol packages with potassium cyanide in a Chicago pharmacy. Seven people were killed, and the case led to a nationwide panic, as well as the development of tamper-resistant packaging. No one was ever charged with the deaths, and the lead suspect died in 2023 after serving time in prison for trying to extort $1 million from a manufacturer to "stop the killing."

How scientists know invasive nutria were likely introduced to California by humans

Although native to South America, DNA testing of the semiaquatic rodents showed they are closely related to a population in Oregon, suggesting they were deliberately transported into the state. First identified in the San Joaquin Valley in 2017, the distance, terrain, and lack of nutria between the two regions has allowed researchers to rule out natural migration.

Wichita is the worst US city to live in if you suffer from seasonal allergies

More than 100 million people in the United States suffer from allergies each year. But Wichita, Kansas, tops the charts year after year as the worst city in America for those suffering from seasonal allergies. Longer and more intense pollen allergy seasons, however, are increasing the burden of living with seasonal allergies in numerous locations across the country.

Cantaloupe’s textured skin boosts the risk of food poisoning

Food safety expert Darin Wetwiler says he prefers to stay clear of this fruit altogether since it’s so hard to keep the textured skin pathogen-free. He advises trying to avoid pre-cut cantaloupe in particular, since consumers won’t know when the fruit was sliced and pathogens on the outside could have been spread to the part we consume during slicing and multiplied.

The first major norovirus outbreak, in 1968, sickened half an elementary school.

Are seed oils as bad as rumors say?

Some claim seed oils—oils extracted from seeds, such as sunflower or canola—increase inflammation and disease risk, advising consumers reach for saturated fats instead. Saturated fats, typically solid at room temperature, are found in animal products and some vegetable oils, including coconut. When adjusting for lifestyle risk factors, research shows seed oils are, on average, good for one's heart and considered healthy alternatives to saturated fat.

CDC does not require docs to report hand, foot, and mouth cases which makes tracking difficult

Mid-Atlantic states saw a surge of hand, foot, and mouth disease in 2025 for as-yet unknown reasons. Virginia, Maryland, and New Jersey, reported elevated outbreak numbers in 2025 as compared to other recent years, but since the US Centers for Disease Control and Prevention does not require mandatory reporting of positive HFMD cases—unlike strictly notifiable diseases like measles—it's hard to truly know the extent of the outbreaks and how significant the caseload is as compared to prior years across the region or country.

A delicious flavor used to be made from a beaver’s butt

Love vanilla-flavored foods? Well, it was once made from castoreum - a yellowish exudate from the castor sacs of mature beavers. And the FDA regards castoreum as “natural flavoring."

Two festival-goers were hospitalized after receiving peptide injections, raising questions

Investigative journalism shop ProPublica wrote about two people who became extremely ill following antiaging peptide injections. Authorities were examining whether the individuals were sickened by an infection, contamination related to the injections, or an issue with the medication itself, according to documents obtained by the journalists at ProPublica.

Multiple sugar substitutes were accidental discoveries when lab workers didn't wash their hands

Saccharin, aspartame, and cyclamate all have origin stories from lab workers tasting something sweet on their hands. A Johns Hopkins University worker in the late 1800s, for example, tasted something sweet on his (unwashed or poorly washed) hands during dinner, prompting him to then taste everything on his lab bench in order to identify that the sweetness was a compound derived from his overheated coal tar—a substance he later named saccharin. (Some users may encounter a paywall.)

Soybean oil fraud almost decimated American Express in 1963

A New York commodities trader who had defrauded the American government over uninspected meat for school lunches, Anthony "Tino" De Angelis, used American Express warehouses to sell soybean oil. However, Angelis had actually filled the tanks with water and placed just enough soybean oil on top of the tanks to pass inspection. American Express was liable for many of the tanks and its stock faced a huge downturn, opening the door for a then 33-year-old Warren Buffett to make his first purchase in the company.

Every MLB baseball needs to be rubbed with mud

When baseballs are done being hand-sewn and shipped to an MLB ballpark, they don't go straight to the field. Every ball that is put in play–an average of 100 per game–has to be rubbed with mud to give the ball a better grip. This video introduces the only family licensed to sell mud to MLB and shows what's special about this particular mud.

Erythema migrans rash is common in Lyme—but it often doesn't look like a bull's-eye

The US Centers for Disease Control and Prevention states that this rash occurs in roughly 70% or more of Lyme disease patients, and typically occurs at the site of a tick bite. The rash may expand slowly over several days and feel warm to the touch, but it's rarely itchy or painful. As it grows, areas of it may clear—creating a target or "bull's-eye" appearance.

Learn about the violent history of the nutmeg industry

From the 1600s to the 1860s, the Dutch East India Company enslaved thousands of people on the Banda Islands, the world's only nutmeg source, forcing them to work on plantations under a system unlike anything seen in the Caribbean or American South.

More than half of the 7,000 'kissing bugs' locals sent to Texas A&M University had parasites

Texas A&M University scientists began a community science program in 2012 asking people to send in kissing bugs (any of the 11 species of bugs potentially infected with Trypanosoma cruzi parasites). About 1,500 people sent in over 7,000 bugs for scientific research, and about 55% of the bugs were infected with the parasite that causes Chagas disease.

Random lasers can be created from biomaterials, such as peanuts and birch leaves

Rather than creating a narrow beam of light via amplification in an optical cavity, the random laser produces a red glow by scattering photons created in the natural pores of a peanut kernel after it has been injected with a solution of light-generating carbon dots derived from birch leaves.

Three Oklahoma athletes were penalized for eating too much pasta at a team banquet

In 2013, Oklahoma athletes lost NCAA eligibility after exceeding a pasta limit at a team banquet—regaining it only after repaying $3.83 each—highlighting how difficult it was to navigate the NCAA’s old amateurism rules.

A root lice infestation once destroyed over 80% of Napa's vines

In the late 1860s, an infestation of root lice nearly destroyed the global wine industry. European rootstock, now planted across multiple continents, had no natural defenses against the pests, which infected the vines (as seen below). As a result, more than 80% of Napa’s vines were destroyed by 1900. It took decades for the industry to recover.

Why there's a snack recession

Inflation and economic uncertainty have driven many Americans to make cuts to their snack budgets, according to reports from major food manufacturers like General Mills, JM Smucker, and Campbell's. Major retailers have also observed lower-income consumers cutting back on nonessentials due to the macroeconomic environment.

25 million pounds of beads are distributed every Mardi Gras, leading to environmental concerns

The necklaces—which are mostly made from cheap, often toxic, plastic—are believed to be harmful to New Orleans and its residents. Dr. Howard Mielke, an environmental scientist at Tulane University, found that the majority of lead in the city's soil can be found along Mardi Gras parade routes.

See examples of hyperaccumulators, the plants that can harvest heavy metals

These ideal species for phytoremediation possess biochemistry that allows them to absorb and store these elements without being poisoned by their accumulation. Pycnandra acuminata, one such plant, has blue-green sap due to an abundance of nickel, which it captures from the nickel-rich soil in which it grows.

More than 2 billion people across the globe include bugs in their diets

Entomophagy is the practice of eating insects. It has been around for millennia. Bugs are nutritious and, in some places, considered a delicacy.

The amount of plastic chemicals in 300 everyday Bay Area foods

Food production is more complicated than it appears, and manufacturing, packaging, and shipping processes can add significant substances to your food. This massive project compiled data on 300 samples of foods delivered to the San Francisco area, testing for the presence of 18 different kind of plastic. Learn how to read the data here with its helpful guides and then explore the table yourself.

The Zulu krewe's coconuts are highly coveted 'throws'

The long-running krewe is known for its finely decorated and highly sought-after coconuts, which it tosses from its floats. In 1987, the group faced lawsuits alleging injuries from its coconut tosses, but the state legislature responded with the "Coconut Bill," which freed the krewe from liability for such claims.

Conversation candy hearts were originally message-free medicinal lozenges

In 1847, a Boston pharmacist invented a machine that automated the production of his pharmacy's medicinal lozenges and then formed the New England Confectionery Company, which later became part of the company now known as NECCO. By the late 1800s, they were producing cookies with Valentine-themed messages and eventually brought the romantic messages to their smaller lozenges, which they later called Sweethearts.

Most people with East Asian ancestry are genetically predisposed to be less smelly

A gene variant found in 80%-95% of individuals with East Asian ancestry reduces armpit bacteria and related odors. People with this nonfunctioning ABCC11 gene variant lack a protein that transports molecules, including sweat, across cellular membranes, so their armpits are starved of sweat that bacteria may have metabolized to help them multiply.

The Chumash manufactured shell beads for thousands of years, eventually as money

The practice was unique to the Chumash among North American Indians. Some researchers have made the case theirs was the first use of money on the continent.

Korey Stringer, of the Minnesota Vikings, died of heat-related illness in 2001

In response, the NFL overhauled its heat approach and no other player has since died from heat-related illness. Even at the high school level, research suggests safety measures should include: mandating water breaks, keeping a cool tub available, and having athletes acclimate to high-temperature playing conditions for a week or longer before donning the full set of protective equipment.