So, Dr. Zoomie – I live outside of St. Louis and I just saw an article saying that there’s nuclear waste in the groundwater. I’ve got well water at my home, should I be worried?
I think I found the story you’re talking about; give me a chance to read it and let me see what it says.
(several minutes pass)
So…there are a couple of things going on here:
- A lot of work for the Manhattan Project occurred near St. Louis in the 1940s
- Some of this work involved processing uranium (most likely from processing uranium ore into uranium oxide or uranium metal)
- Waste from this processing was radioactive, containing radium and other radioactive elements in the U-238, U-235, and Th-232 decay series
- Some of this waste spilled along the road as it was being transported for disposal
- Other waste was put into a landfill
- Some of this waste made its way into the groundwater
- And the question is how much danger this poses to people – including you – who live in the area.
Here’s thing – when it comes to the health effects from radiation, the only meaningful question is “How much dose was there?” The higher the dose, the greater the likelihood that it will (or did) cause harm; the lower the dose, the lower the risk that it caused harm. So we need to find enough information to figure out what that risk might be – we need some numbers..
There are a few places where the documents mention that radionuclide concentrations are several times higher than levels normally found in nature – but this really doesn’t tell us much. For example – say I’ve upset an unsavory sort of person who cements my feet into two 5-gallon pails and sets me into a pool of water, shallow enough that my head isn’t covered. Then the depth of the water is increased by 500%…am I at risk?
Unless you know how deep the original water was or what the new depth is – unless you have some numbers – you have no way to answer this question. If the water was originally 18 inches (a foot and a half) deep then I’m in serious trouble because my head is now under water and I’m going to drown; if the water was only an inch deep then I’m perfectly safe. In fact, the depth could increase fifty-fold (5000%) and I’d still be safe (I’m over six feet tall).
Radioactivity in the groundwater is like that – unless there’s enough information provided to be able to figure out the dose to those exposed it’s simply not possible to tell if drinking the water, bathing or swimming in it, using it to water the garden, or anything else might or might not be harmful. Luckily, the EPA has posted some numbers on their website in an annual report about one of the sites. Here are the radium concentrations it reports:
And you may be asking yourself “What’s this mean?” And you’re right – if you ask me how fast I’m going and I say “Five” – what’s that mean? Five miles per hour? Five miles per second? The first is very slow and a collision isn’t going to hurt anyone (well, unless you run over someone); the second is blazingly fast and will not only take your car airborne, but is close to putting you in orbit – run into a tree or a cliff at this speed and you’re likely to simply vaporize. In other words, units are important!
“PCi” means picocurie – that’s a millionth of a millionth of a curie (the US unit for radioactivity). Since 1 Ci of any radionuclide will undergo 37 billion decays every second, 1 pCi will undergo 0.37 decays per second, or 1332 decays in 22 decays every minute. In other units, 1 pCi of radium in 1 liter of water will have a chemical concentration of 1 part per trillion (ppt) – a millionth as much as the more-familiar unit of parts per million (ppm). In other words, 1 pCi/l is about 1 ppt or 0.001 ppb of radium in water. So we’ve got a number and a unit – now let’s find out how much dose that will produce and how risky it might be.
First, this table also gives the natural levels of radium in groundwater in this part of the country (an average of 0.3 pCi/l with a maximum of 8.4 pCi/l in the soils and sediments; 5.9 pCi/l and 11.3 pCi/l – average and maximum respectively – in water in and in contact with the bedrock. In comparison, water in one of the areas sampled had an average radium concentration of slightly more than 3.8 pCi/l and a maximum of about 12 pCi/l in the water flowing through the soil and sediments with the water in and in contact with the bedrock showing average and maximum radium concentrations of about 5 and 38 pCi/l respectively. Or, put another way, the maximum radium concentrations are about 2.5 times as high as the average concentrations in the alluvial materials and about 5-6 times as high as background levels in the bedrock. That sounds pretty bad – but let’s see how much radiation dose that’ll cause before we jump to conclusions.
According to a study by the National Academies of Science, drinking water with 1 pCi/l of radium-226 plus its decay chain will give an annual radiation exposure of about 0.27 mrem each year to a person drinking two liters of water every day. This means that someone drinking two liters daily of the “hottest” well water would receive a dose of about 10 mrem annually. This is a low dose of radiation – it’s similar to what we receive from a single chest x-ray or from flying NYC to Los Angeles and back. The risk of developing cancer from this level of exposure is amazingly low.
Of course, we drink water our entire lives, not for only one year. But if I were to drink two liters of this water every day for 80 years I’d receive about 800 mrem over my lifetime – less than the 5000 mrem that radiation workers are allowed to receive in a single year. The risk of developing a dangerous cancer from this level of exposure is lower than the risk of dying in a traffic accident. That’s about 1/3 the dose I received during my time in the Navy and less than a quarter of my occupational radiation exposure over my career. It’s not a dose, or a risk, that would concern me – but that’s me; everyone has to decide for themselves what they’re comfortable with.
So getting back to this site….
Is there radioactivity in the groundwater from the work that was done here in decades past? Well, yes. Is that dose dangerous? To me, it isn’t because the risk is so much lower than the risk from driving. But for you – that’s for you to decide.