The 1950s were crazy times. Human experimentation in the US was normalized in a way that would make modern IRBs implode from shock. After the Soviets tested their first nuclear bomb in 1949, war planners in the US, both civilian and military, were interested in accelerating alternative and unorthodox methods of warfare, including and especially biological weapons.

White picket fences and Leave it to Beaver, indeed.

If you’re interested in this history, I’d recommend Nicholson Baker’s Baseless or Leonard Cole’s Clouds of Secrecy.

The latter describes various experiments that the army did starting in the 1950s that involved spraying tons of actual biological agents or proxies thereof on US cities in an attempt to measure the scale and dispersion of such agents were they to be unleashed on our enemies. Cities in the US were picked for physical and meteorological congruity to Soviet target cities; St. Louis was Leningrad, Minneapolis was Kiev, etc. Not exactly high school science projects.

Through a combination of investigative reporting, FOIAs, and declassification, this came to light decades after the experiments concluded. I was a wee lad in 1997 when this culminated in a congressional committee doing a thorough investigation and concluding that these experiments definitely, definitely did not cause any deleterious health outcomes for the unwitting subjects of these experiments.

When it comes to blue-ribbon commissions, let them cook.

But suppose that the blue-ribbon commission was not correct about this. Maybe the commission was stacked with people who didn’t want black folks getting too uppity and demand damages to be paid because the US military used their neighborhood as a testing range for biological weapons proxies. This happened 70 years ago. Can we actually tell if the committee was mistaken after all this time has passed?

Zinc Cadmium Sulfide

One of the materials sprayed on these cities was zinc cadmium sulfide, ZnCdS. The military apparently chose this material because its particulates are of a similar size to Anthrax, and moreover its fluorescent properties allow it to be tracked over long distances. By a certain measure this 1957 experiment was an astonishingly success. Particles were found nearly 1,200 miles away from where they were dropped in Minnesota. There’s some ambiguity about whether it was well-known in the 1950s whether cadmium, a heavy metal, was actually toxic. Nicholson Baker seems to think it was well-known, but others are not so sure.

Regardless of whether the danger of spraying cadmium on a city was well-understood, the NRC blue-ribbon commission mentioned above had to take the army’s word about how much they actually sprayed. We live in a dose-dependent world, and if the concentrations of any toxins are low enough, maybe everything will be fine.

Cadmium sulfide is a well-known carcinogen. Cancer is tricky. It’s idiosyncratic and can be idiopathic. It can takes years to develop and years to kill you. It’s not just a single syndrome but can develop in multiple tissues even when it has a well-known cause. 

If the experiments really did affect the health of people in Minnesota, all these things contribute to it being unusually difficult to establish causation of cancer in epidemiological terms. Even if spraying cities with large quantities of ZnCdS did broadly-speaking elevate cancer risk there, we’d probably not be able to see it looking at subsequent cancer rates.

Osteoporosis

Osteoporosis affects millions of post-menopausal women. It’s a dangerous weakening of bones that leads to high incidence of fractures in older women. One interesting feature of cadmium poisoning is its elevation of the risk of osteoporosis in post-menopausal women. This understanding began with an early and strange mass cadmium poisoning in Japan, and has since developed into a fairly well-established scientific consensus, though the mechanism of action is not yet clear. See meta-analyses here and here. The 2013 former study finds a pooled cadmium dose odds ratio of around 2 in postmenopausal women, and the latter 2022 study concurs with a pooled OR of 1.95. It states

This study indicates that environmental Cd exposure, even at low levels, may be a risk factor for osteoporosis in postmenopausal women.

So even if the 1997 NRC committee is correct and only comparatively “low” volumes of cadmium were ejected onto these urban populations, the women might still be at risk of increased rate of osteoporosis.

Cooper et al., 1992

I went digging to try to find data—any data—on osteoporosis or bone fractures going back to the 1950s. Finding any medical data going back to the 1950s isn’t the easiest thing in the world; you have to navigate terrible early-2000s era web portals and when you’re successful the data might go back to the early-2000s if you’re very lucky.

However, something astonishing happened here.

Minneapolis was ground zero of the first military spraying exercises in 1957. Minnesota is interesting because it’s the home state of the Mayo Clinic. As a result of this historical quirk, the Rochester Epidemiological Project was born; it maintains extensive health data going back decades on residents of Rochester, Minnesota, a mere 75 miles from Minneapolis. This was well within the spraying radius of Minneapolis! Who else had used this data before?

I found Cyrus Cooper, lead author of Cooper et al. 1992 published long before the NRC committee had been assembled, entitled “Secular trends in the incidence of postmenopausal vertebral fractures”. The opening paragraph is a banger.

Categorization of fractures according to the level of preceding trauma, however, revealed a significant increase in the incidence of fractures following moderate trauma among women aged 60–69 years. This increase occurred between 1950 and 1964, and leveled off thereafter.

…

An increase in the prevalence of osteoporosis, however, might account for the trend in both types of fractures.

Vertebral fractures and hip fractures are the most common types associated with osteoporosis, and he gives us this figure.

In Rochester, MN, within a long commuting distance of Minneapolis, the Kiev of America, there’s an extraordinary rise in fractures among women commonly associated with osteoporosis after the area had been sprayed down with an undetermined amount of a substance known to cause osteoporosis in women.

Cooper concludes that it’s unclear what precisely caused this rise in fracture incidence, but the word “cadmium” isn’t used. He states

A statistically significant increase for moderate trauma fractures in postmenopausal women occurred between 1950 and 1964, but rates stabilized thereafter. Although this increase may have resulted from an increased prevalence of osteoporosis, it could also have resulted from increased ascertainment. Further studies of the pattern of incidence of vertebral fractures in different populations are urgently needed.

Does the back-of-napkin math check out? In Rochester, the incidence of vertebral fractures among postmenopausal women almost doubled between the late 1950s and 1970 (maybe 1.6x?). The meta-analyses above think the cadmium exposure/osteoporosis odds ratio is around 2. Sources like this think the osteoporosis/vertebral fracture odds ratio is also around 2, which means incidents of vertebral fracture increase by a factor of 4 if a woman of the right age gets dosed by cadmium. It’s within an order of magnitude. There could be age-dosage effects here, and no one is saying that literally all the women in Rochester got dosed with cadmium.

Open Science

Cooper thinks we need more study of this, and I agree. I sent a request to the Rochester Epidemiological Project to request access to long term fracture data.

Almost immediately, I got a response from a very nice lady.

This is a heavy lift, especially if you're just a random person on the internet. I contacted Cooper himself to see if he had any more granular data (particularly by geography) he could share, but with no reply. It will be very hard to make a more persuasive case without the detailed information the REP has. 

Research bureaucracy and oversight is now blocking an investigation into experiments that 70 years ago resulted from an obvious lack of research bureaucracy and oversight.