How did a meteor make hundreds of people sick?

On the afternoon of Sept. 15, 2007, residents of a village near Lake Titicaca in southern Peru heard a loud roaring noise and looked up to see a ball of fire blazing through the sky. The object struck the earth, creating a loud noise, shaking the ground and launching debris as far as 250 meters away from the impact site [source: National Geographic News]. The event resulted in a crater measuring about 16 feet deep and 55 feet across [source: Living in Peru]. The impact of the object registered a 1.5 on the Richter scale [source: AP].

But before scientists could determine what happened, hundreds of local residents became sick. Up to 600 people in the area became ill, some of them after venturing to the site of the crater [source: Living in Peru]. Some of those who were ill said they felt nauseated, were vomiting and had headaches.

Besides the widespread illness, several other mysterious events occurred. Early reports included claims from residents that water in the crater boiled for several minutes after impact and that a smell of sulfur filled the air. All of these events generated worried speculation as to what exactly happened and why people were sick.

Many different ideas were put forth, several of them suggesting a meteorite impact. Some wondered whether a meteorite’s impact released harmful gases and possible radiation. Another proposed that there wasn’t a meteorite at all and that a natural geyser or small volcanic eruption might have expelled gases from underneath the soil. Other reports mentioned a “fireball” as a possible cause of the explosion. Finally, a sensational article syndicated in the Russian tabloid Pravda made its rounds on the Internet; the writer claimed that as part of an­ elaborate conspiracy, the U.S. government shot down its own spy satellite, which spilled its radioactive fuel upon crashing in the Andes.

The confusion was compounded by conflicting details in some reports, especially about symptoms of those who were sick, whether groundwater boiled, if a strange smell was present and even how large the crater was. Some scientists speculated that noxious gases were stirred up by the meteor impact, while others claimed that dust caused people to experience dizziness and nausea. But what really did happen near Lake Titicaca? Read on to find out.


Six days after the initial event, scientists from Peru’s Mining, Metallurgy and Geology Institute confirmed that a meteorite did crash in the area and that the impact stirred up arsenic fumes. Tests confirmed that groundwater in the area was contaminated with arsenic. The explosion sent up some of the arsenic in the form of gas, making people sick. (In some parts of Peru, the soil and groundwater contain natural arsenic deposits.)

Despite initial concerns, those who became sick improved after several days. Peruvian health workers reported that they treated about 200 residents for various symptoms, none especially severe [source: Living in Peru]. The hundreds of people who claimed they felt ill may have been suffering from a psychosomatic reaction. Some of the local residents said they thought that the loud roaring noise they heard and the subsequent explosion were the sounds of Chilean military forces launching an attack. The stress and mysterious nature of the event could have provoked physical symptoms, even without a physical cause.

As for the meteorite itself, Peruvian scientists recovered and analyzed several samples. One scientist who specializes in meteors estimated that prior to impact, the meteoroid measured 10 feet across, though it could have been far larger before breaking apart in the atmosphere [source: AP]. The meteorite was not radioactive or harmful. The samples did show that the meteorite was made entirely out of rock, which is considered unusual. Meteorites found on Earth usually contain metal because those meteorites are better at surviving the stress of entering the atmosphere, when friction can raise temperatures up to 3,000 degrees Fahrenheit. But the tests confirmed that it was indeed a meteorite that scientists found and that the explosion did not come from some other source. The meteorite samples also had magnetic properties, which scientists attributed to the rock’s high iron content.

The meteorite and arsenic discoveries put to rest questions of what caused the explosion and why people became sick, but questions remain about the reports of water boiling in the crater — if they are true at all. Was the meteorite so hot that, upon impact, it caused the groundwater to boil? Some commentators have claimed that meteorites, especially those of moderate size like scientists believe this one was, are cold when they hit the ground — not hot. However, there’s no conclusive proof about whether meteorites are hot or cold upon impact. Available evidence indicates that just after landing, meteorites are cold or only slightly warm [source: Cornell University Astronomy Department]. Meteorite impacts aren’t known to cause major fires or to scorch large areas.

So why did the water boil? One possible answer is that some sort of geothermal event took place, with venting gases boiling the water, or perhaps the local villagers misreported what they saw. In any case, it’s a question that may never be solved.

For more information about meteors and other related topics, please check out the links below.

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