Should you worry about lone-wolf terrorists with Bio-Weapons? (No.)

David Manheim
4 min readNov 29, 2018


A recent story said that there was a terrorist “planning” to attack the Italian town of Macomer (pop. approx. 10,000) by putting Ricin and Anthrax in the water supply. That sounds scary, right?

First, he didn’t HAVE Anthrax or Ricin. He was planning on buying it online. Somehow. (No, no-one is selling biological weapons online. Not even on the dark web.) But let’s assume he managed to get it, somehow. Maybe ISIS or Al-Qaeda, which pursued biological weapons but couldn’t manage to buy or make them, nevertheless ended up finding some surplus bioweapons from the Russians, and gave them to this guy in Italy. And no, that’s not plausible, but we’re going well past the point of plausible in order to try to find a way to worry about this threat.

OK, so he’s got his materials, and wants to put them in the water. The water supply might be unguarded — I don’t know, but many places have fences and such around freshwater drinking sources, and might notice someone dumping in something. But maybe they don’t. Some places have water utilities that test the drinking water for various toxins somewhere along the line. Let’s assume there is no such program in place for the water delivered to this small Italian town. But how much Antrax and Ricin would he need to put in, exactly?

We can start with Ricin. It’s relatively easy to make. (Obviously much harder than a bomb, and most terrorists can’t manage to make those without a fair amount of help, but maybe the terrorist has a really good chemistry background.) The victims only need to ingest 1 ml of ricin per kilogram of body weight to have a 50% chance of dying. We’ll conservatively assume that the people of Macomer average 50kg. That’s only 50ml of ricin per person, or 500 liters of ricin toxin — or about 100 gallons, for Americans. That’s not an amount you can stick in a backpack — you need to back a truck up to the water supply to get that volume of toxin in.

But people aren’t ingesting all of that water. An approximate level of water usage per person is 450 liters per day. (That’s still about 100 gallons.) In California, with its droughts, they require about half that, and we’ll go with the lower number. People only need to drink about 2 liters of water (8 cups) a day. That doesn’t need to all be in the form of tap water — juices and soda works too. But again, let’s assume everyone is being healthy and environmentally conscious, and they drink only tap water. That’s about 1% of their daily water usage. So we need to multiply the amount in the water supply by 100 to get the same effect — that’s a large tanker truck worth of ricin. But a city isn’t only going to have a single day supply of water in the reservoir. For every day worth of water they have, we need to add another tanker truck.

OK, so maybe our would-be terrorist isn’t going to be able to order a couple dozen tanker trucks of Ricin on the dark web. (And don’t worry too much about a permanently contaminated water supply — boiling the water gets rid of ricin.)

But anthrax. Maybe that could work. And it is found naturally on the ground! Fortunately for us, and unfortunately for our would-be terrorist, culturing anthrax in large quantities is really, really hard. For an idea how hard, we can look at Aum Shinrikyo — the people who successfully made Sarin and used it to attack a subway in Japan. It turns out that before they did this, they spent years trying to isolate Anthrax. The eventually succeeded, but it turns out that the strain they ended up cultivating wasn’t a very good one for hurting people. Still, maybe our terrorist gets lucky, and finds someone on the internet who happens to be willing to sell the a dangerous strain of anthrax. All they need to do is cultivate it.

Unfortunately, the terrorist in question doesn’t have any lab experience in microbiology. He can try to buy a book, and some equipment, but he’s going to have a hard time figuring out something that the PhD bacteriologists need to use specially designed fermenters to culture.

And then he needs to add it to the water. And even though there doesn’t need to be a huge quantity of spores to cause fatal anthrax by ingestion in an individual, as with Ricin, the picture changes when the spores are dumped into a large body of water.

At the end of the day, biological threats exist, and it’s likely that we will see more in the future. But idiots claiming to have plans to poison water supplies with non-existent supplies of bio-weapons are just that — idiots that make ridiculous claims. Terrorist threats are serious, and I’m sure he’ll serve time in jail. That’s good, because there are lots of ways that people interested in committing terrorism can kill people. They just involve trucks and guns, not imaginary mail-order bioweapons.