And furthermore, would you be willing to make the change if it meant making changes to the water supply?
Adding trace amounts of lithium to the drinking water could limit suicides. Two studies, a recent one in Japan and an older one in Texas, have shown that this naturally occurring substance, used as a psychotropic drug to combat bipolar disorder, could have beneficial effects for society: Communities with higher than average amounts of lithium in their drinking water had significantly lower suicide rates than communities with lower levels. Regions of Texas with lower lithium concentrations had an average suicide rate of 14.2 per 100,000 people, whereas those areas with naturally higher lithium levels had a dramatically lower suicide rate of 8.7 per 100,000.
A gated version of the study is available here. There are other benefits beyond a reduction in suicides. From the Texas study:
[T]he homicide rates during the decade studied were consistently lower (by 30-50%) in the high- than the medium- or low-Li counties. The incidences of robbery, burglary, theft and the total crime rates were also lower in the high-Li counties, but the respective differences involving assault were statistically significant.
Drug use was also lower in the area with the highest natural occurring lithium concentrations.
One question I've never seen answered is: How much would it cost a low-lithium city to artificially boost their concentrations to the highest level? We have experience adding trace elements to the water supply (fluoride), so it can certainly be done.
I decided to do a very rough back-of-the-envelope type calculation to see what the cost per person in lithium is.
I am not a chemist, but my understanding is that a city that wanted to increase the elemental lithium in the water supply would use lithium carbonate (if I'm mistaken here, please let me know). The largest bulk price I could find for lithium carbonate is 50kg for $3842.82 (Source), which works out to $76.86/kg or 7.686 cents per gram. This should only be used as a rough estimate - the price may be lower (because a city would be buying in far larger quantities) or higher (because the city would need a grade with less impurities than the one quoted). But for a rough back-of-the envelope calculation, it works.
A city with no-to-little elemental lithium would need to add 70 micrograms/L of elemental lithium to the water supply. Since we're adding lithium carbonate (not pure lithium), we would need roughly 200 micrograms/L. (For reference, there are a million micrograms in a gram).
The average Canadian domestic user uses just over 100,000 L of water a year (Source). At 200 micrograms/L, we would need to add roughly 20 grams per person of lithium carbonate for a total cost of $1.53 per person, or $153,000 per 100,000 people.
The city of Toronto has 3.3 murders/100,000 people (Source). A 30% reduction in this rate would lower it by 1 murder per year per 100,000 people. If our rough back-of-the-envelope calculations are correct and the lithium carbonate method works like the Texas study suggests, $153,000 buys us one less murder. That does not take into account the reductions in rapes, suicides, drug use or thefts.
Will it work? I don't know. It seems like it would be worthy a pilot study or two. Although those levels of elemental lithium are believed to be safe, there may be side-effects we are not considering. There are ethical considerations as well, but it is hard to make a case that adding fluoride to the water supply is ethical but lithium is not - and we've been adding fluoride to drinking water for over half a century.
Edited to add: The Texas study grouped counties into four groups: High lithium (70-160 micrograms), Medium (15-60), Low (0-12) and Low excluding big cities (0-12). If we compare the first group to the fourth, high lithium counties have, per 100,000 population:
- 5 fewer murders
- 5 fewer suicides
- 22 fewer rapes
- 310 fewer burglaries
- 751 fewer thefts
(all of which are statistically significant at the 5% level). There may be a multitude of other factors causing this than lithium levels. There is no guarantee that artificially raising lithium levels to get a county to go from low-lithium to high-lithium would provide these results. But given a (very rough) cost of $153,000 per year, isn't it worth investigating?