SCIENCE

Ten Natural Products That Kill

November 9, 2010

I have to laugh anytime I see a product label claiming that something is "all natural," as if everything that is man-made is dangerous and all that is not is perfectly safe. Not that I'm claiming there are no synthetic evils, but there's plenty of deadly natural items out in the world. Let's start with this list:

1 ) Asbestos: A fibrous mineral once used for making fireproof materials. There were reports from as early as the first century A.D. that workers who came in contact with the material developed lung disease, but it wasn't until 1989 that the EPA banned its use. Inhalation of asbestos fibers causes a host of serious diseases, including a rare form of cancer called mesothelioma. Fear of the substance runs so high that the California State Senate passed a bill earlier this year that would defrock its state rock, serpentine, because it can harbor asbestos.

2 ) Arsenic: Atomic number 33, it sits just below phosphorus on the periodic table. It was once used to treat syphilis and applied topically to whiten skin. Symptoms of arsenic poisoning start with headaches and confusion and progress to vomiting, hair loss and convulsions, resulting in coma and/or death. Sadly, groundwater throughout Bangladesh is contaminated with arsenic, leading to widespread poisoning. It is estimated that up to 20 percent of deaths in the country are the result of drinking arsenic-laced water.

3 ) Snake venom: This modified saliva contains a host of chemicals that act to kill or disable prey. Snake bites kill 20,000 people in developing countries each year. And snakes aren't the only venomous species: there are hosts of insects, fish, reptiles and mammals (even a venomous shrew) that can kill with chemical warfare.

4 ) Botulism: The soil bacterium Clostridium botulinum produces neurotoxins that cause paralysis. Modern science has harnessed that feature to eliminate wrinkles on the faces of an aging population. The disease is relatively rare, but it kills 5 to 10 percent of those who become infected.

5 ) Plants: There are too many deadly plants to name here (if you want a good list, check out the book Wicked Plants). But there are good reasons why you shouldn't go through fields or forests eating anything you find.

6 ) Mercury: The pretty liquid metal fascinated for centuries until the mid-1800s, when it was found to be toxic. Now school principals freak out whenever someone drops a mercury thermometer and pregnant women are advised to limit fish consumption. The element can damage the central nervous and endocrine systems and kidneys and other organs.

7 ) Ionizing Radiation: Types include alpha- and beta-decay, X-rays and gamma rays. These subatomic particles and electromagnetic waves have enough energy to strip atoms of electrons, which causes damage to DNA (at high enough levels, it kills instantly). Natural sources include radon and uranium.

8 ) Cosmic Rays: These high-energy particles come mostly from faraway supernovas. They cause damage to DNA, similar to ionizing radiation, causing cancer, cataracts and other health problems. They're not a problem on Earth, because we have the atmosphere and magnetic field to shield us. But if we want to send anyone to Mars or beyond, we'll have to figure out how to protect them on the long journey.

9 ) Formaldehyde: This chemical—composed of carbon, hydrogen and oxygen—is formed during the burning of methane. Up to 90 percent of all the formaldehyde on Earth may originate in the atmosphere. It is used in the synthesis of many other chemicals, as a disinfectant and as a preservative. Though it is now known to be a human carcinogen, it is still widely used.

10 ) Anthrax: This illness, caused by the bacterium Bacillus anthracis, is lethal in most forms to humans, who usually contract it from livestock. This is just one more example of a microbe that can kill—the list is far too long to even attempt.