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Jan. 30, 2024 - Skeptoid
18:49
Skeptoid #921: Reconsidering the Seveso Dioxin Disaster

Was this infamous 1976 dioxin disaster as bad as reported, or might it have been much worse than we thought? Learn about your ad choices: dovetail.prx.org/ad-choices

Transcriber: nvidia/parakeet-tdt-0.6b-v2, sat-12l-sm, and large-v3-turbo
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The Sevizo Dioxin Disaster 00:08:14
There are a few events you'll find on every list of the world's worst industrial or environmental disasters.
And among these few is the 1976 dioxin poisoning of thousands of people when an Italian chemical plant in Sevizzo exploded.
Just how bad was it, really?
Are we giving it too much or too little attention?
Well, that's coming up right now.
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Reconsidering the Sevizo dioxin disaster.
Welcome to the show that separates fact from fiction, science from pseudoscience, real history from fake history, and helps us all make better life decisions by knowing what's real and what's not.
Today we're going to point the skeptical eye at a 1976 industrial disaster at a chemical plant in Sevizzo, Italy, long considered one of the worst in history.
Thousands of local residents were exposed to dioxin, widely believed to be one of the most toxic chemicals there is.
We're going to see how bad it really was and whether those labels are really deserved.
Developing effective solutions depends on having an accurate understanding of a problem.
So if the way we regard Sevizo today is inaccurate, then we're setting ourselves up to fail when we respond to some future similar event.
So what is dioxin anyway?
Surprisingly, this is not a simple question.
There are hundreds of chemicals that are classified as dioxins, falling into three groups, PCDDs, PCDFs, and PCBs.
All dioxins are persistent organic pollutants, meaning they take a long time to break down in the environment.
But only some of these are toxic, those that have a chlorine atom in certain positions in the molecule.
Those that are are considered highly toxic.
They're produced as unwanted byproducts during some chemical production processes, including the manufacturing of some herbicides.
But they're also produced naturally by combustion, such as forest fires and volcanic eruptions.
Thus, they are and always will be found throughout the environment.
About 90% of human exposure is via the consumption of animal fats, basically meat and dairy.
Dioxin stays in the fat of the animals and of the people who eat them, where its half-life can be up to a decade.
Since much of this dioxin in the environment comes from natural sources, it's impossible for us to keep it out.
But industry and regulators have been working together to eliminate the human-caused sources for a long time.
The dioxin at Sevazo was a PCDD called TCDD.
I'll spare you the complete chemical name because I don't feel like pronouncing it, and it doesn't matter for our purposes today.
TCDD is what's usually meant when we colloquially use the word dioxin.
Going forward in this episode, when I say dioxin, I'm referring to TCDD.
Dioxin is not good.
It's listed as a carcinogen and a cause of birth defects and about everything else.
However, the evidence is strong only for two health effects.
Chloracne, a type of environmentally triggered skin lesion resembling acne, which can be severe, and transient mild hepatotoxicity.
temporary mild impairment to liver function.
It might and probably does do worse, but these are the only confirmed effects.
The fact is we just don't know.
But regardless, you want as little dioxin in your body as possible, beyond what the natural environment is going to give you as a baseline.
Dioxin is also the component of Agent Orange, believed to be responsible for negative health impacts associated with its use in Vietnam.
Agent Orange probably warrants its own episode for another time, but for now, all we're going to say is that dioxin has these two known effects, and possibly others.
Suspected effects include cancer, reproductive and developmental problems, damage to the immune system, and endocrine disruption.
So, on July 10th, 1976, a chemical manufacturing plant in Italy, owned by a company called ICMESA, had an incident.
A string of human errors led a chemical compound to increase in pressure and temperature over the weekend when operations were supposed to be closed.
A relief valve blew, releasing six tons of chemicals into the atmosphere, which settled over an area estimated at 18 square kilometers.
This cloud was mostly composed of sodium hydroxide, ethylene glycol, and sodium trichlorophenate, themselves not much of a danger in that form, but also it probably contained between 1 and 30 kilograms of dioxin.
As this was one of the most extensively studied industrial disasters in history, we have a lot of pretty detailed information on the effects of that dioxin.
Those 18 square kilometers were divided into three zones.
Zone A, with about 750 residents, is where soil concentration of dioxin was above 50 micrograms per square meter.
Zone B, with a bit less than 5,000 people, was less than 50 micrograms per square meter.
And zone R, with over 30,000 residents, had a negligible concentration.
Dioxin is known to be more toxic to many animals than it is to humans, and the cloud killed about a quarter of all animals in Zone A immediately.
Within a few weeks, 3,300 animals were dead.
Eventually, 80,000 animals were culled to prevent them entering the food chain.
As far as people go, only those in Zone A were evacuated.
Everyone in all three zones was cautioned not to eat any locally sourced food, and people in zones A and B were given medical testing.
Due to Italian officials' initial denials that anything much had happened, it was two weeks before the event was reported in the rest of the world.
Among the first was London's Daily Telegraph on July 23rd, with the headline, Poison gas cloud over town after blast.
Dogs, cats, rabbits, and fowl in the area began to die immediately after the blast.
Experts said later that just 10% of the chemical which escaped would be enough to kill the 11 million population of New York if mixed with the water supply.
The New York Times didn't report on it until July 29th with the headline, 20 more evacuated from area in Italy hit by poison.
The most significant substance that escaped from the chemical plant was said by an American expert to be dioxin, one of the deadliest chemicals known.
Remembering the Poison Cloud 00:10:32
A dose of less than a billionth of a gram is fatal to guinea pigs.
The amount believed to have escaped from the Italian factory is said to be about four and a half pounds.
No one knows what the lethal dose is for human beings, but no one doubts that four and a half pounds would kill many thousands of people.
With such shocking reports, no doubt the actual loss of life must have been enormous.
Let's find out.
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There's a particularly infamous case of dioxin poisoning that you may remember.
In September 2004, Ukrainian presidential candidate Viktor Yushchenko was poisoned with a massive dose of TCDD dioxin at a dinner event during Ukraine's Orange Revolution.
He became severely ill and was hospitalized with 50,000 times as much dioxin in his system as normal.
Afterward, his only lasting symptom was severe disfiguring chloracne, making him nearly unrecognizable.
The chloracne was so severe that his face scarred, making his altered appearance permanent.
Yushchenko's case, however, cannot really be compared to Sevizo because he actually ingested a huge amount, while the Sevizo victims had skin and inhalation exposure to a far, far lower concentration.
Yushchenko's case was so uniquely severe that scientific papers were written about him, and he provided tissue samples for years.
And his case was instrumental in guiding our knowledge of dioxin's long-term toxicokinetic effects in the body.
Incidentally, he won the election, bringing the Orange Revolution to an end, and was inaugurated just four months after he was poisoned.
In the end, the final adverse health effects to the Sevizo population was 193 cases of chloracne, mostly among children, all but one of whom were considered completely recovered by 1983.
Nobody was killed.
A number of papers have been published attempting to characterize the total impact.
None found sufficient evidence to definitively link anything else to the dioxin exposure.
Here's from one such paper.
Other reversible early effects noted were peripheral neuropathy and liver enzyme induction.
The ascertainment of other possibly severe sequelae of dioxin exposure, e.g. birth defects, was hampered by inadequate information.
However, generally, no increased risks were evident.
Mortality studies shed some light on the long-term effects.
An unusual cardiovascular mortality pattern was reported in the exposed population.
Cancer mortality findings after 10 years do not allow firm conclusions to be drawn, but are suggestive of a departure from expectations for certain types of cancer.
The ongoing cancer incidence study will further explore these hypotheses.
Yet, Savizo made number eight on Time magazine's 2010 article, And the Earth Cried, Top 10 Environmental Disasters.
Was it an environmental disaster as well as a public health disaster?
It doesn't really appear so.
The total environmental cleanup consisted of bulldozing tons of soil, debris from demolished homes that were considered the most contaminated, and animal remains into two piles covered with concrete, which now form hills in a public park.
In addition, 42 barrels containing waste chemicals from the plant and used protective clothing were taken away for incineration.
No other cleanup was deemed necessary.
We should note that Time's list also includes Three Mile Island, the supposed 1979 nuclear disaster in Pennsylvania.
In that, nobody was killed or injured.
No significant amount of radioactive material escaped.
The safety systems functioned as intended, and the plant resumed normal operations.
But rather than being showcased as a success story, Three Mile Island is almost always portrayed as a disaster.
Why?
Sometimes we tend to have a strange way of categorizing what's a disaster and what's not.
Three Mile Island, which hurt nobody, is usually considered a catastrophe, while the coal power industry, which directly kills hundreds of thousands of people around the world every year from lung cancer, is not.
The Texas City disaster of 1947 killed 581 people, yet it's not on the list either.
Perhaps we should recalibrate our scale of worst disasters.
Quite obviously, when I imply something like, hey, Savizo wasn't all that bad, all they got was acne, look at this list of things that were worse.
It sounds incredibly dismissive, almost like I'm speaking in support of the chemical company that caused it.
What I'm speaking against, in fact, is the common tendency to have a disproportionate reaction to events that involve scary words, like dioxin, or chemical, or nuclear, when far more harmful events don't have nearly as much cultural influence, simply because they lack the triggering buzzwords.
The result is that attention and resources get misallocated.
Just think how much better off the world would be if the amount of media and cultural attention given to the Fukushima nuclear meltdown, which produced minimal casualties, was directed instead at the coal power industry, with its ongoing death toll up to perhaps the tens of millions.
We are emotional animals, to be sure.
The challenge to all of us is to allow data to have the amount of influence on our behavior that it deserves as well.
We continue with more on Viktor Yushchenko's poisoning and why dioxin causes chloracne in the ad-free and extended premium feed.
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