Preliminary dioxin results in East Palestine

And issues with transparency in reporting on "dioxin".

Correction 3/21/2023: As Pete Lincoln has noted in the comment the calculations used by The Guardian report were based on the toxic equivalence (TEQs) of dioxins. Because not all dioxins have similar toxicities they are all referenced based on the most toxic one 2,3,7,8-TCDD which gets a value of one. Essentially, TEQs weigh the assumed toxicities given the values of the total dioxin levels.

These values can be found at the bottom right of the Pace Analytical reports, and in converting them you should get 110, 700, and 150 ppt respectively. It would appear that the second sample ran extremely high, and thus was run again. There’s no explanation to why this sample ran high, but it seems as if the 700 ppt initial result was deserving of a second run.

I will expand upon this portion in the next post to add more context to these numbers. I apologize for overlooking these numbers as they change some of the interpretations.

Soil Sampling for Dioxin

Since the last series on East Palestine the state of Indiana, more specifically the Indiana Department of of Environmental Management, had conducted soil sampling for dioxin in East Palestine.

This sampling doesn’t appear to be on-the-grounds sampling, but rather sampling of the soil being moved from East Palestine for disposal in Indiana, which has been reported to be within acceptable limits for disposal.

Dioxins have been a hot-button issue since the derailment first occurred, with several independent reports on Substack being the first to raise concerns, followed by various mainstream outlets.

And recently, the report released on the soil sampling conducted by IDEM has made headlines in outlets such as The Guardian who report that levels of dioxin tested were “hundreds of times greater” than was considered acceptable risk of cancer:

From The Guardian

Upon first glance the mention of something from 2010 seems rather specific. The article notes the following with respect to this reference:

Newly released data shows soil in the Ohio town of East Palestine – scene of a recent catastrophic train crash and chemical spill – contains dioxin levels hundreds of times greater than the exposure threshold above which Environmental Protection Agency (EPA) scientists in 2010 found poses cancer risks.

[…]

Though the dioxin levels in East Palestine are below the federal action threshold and an EPA administrator last week told Congress the levels were “very low”, chemical experts, including former EPA officials, who reviewed the data for the Guardian called them “concerning”.

Unfortunately, like many mainstream outlets, The Guardian doesn’t provide any proof of evidence to the experts’ opinions, and only quoting their statements. Because what exactly would be considered “concerning?” here.

Well, we can take a look at the data and see what the report actually states. In doing so we’ll notice that there’s a lot of ambiguity with respect to what “dioxins” are.

Generally, when the term “dioxin” is used I am referring to the compound 2,3,7,8-tetrachlorodibenzodioxin, or TCDD for short.

Image from Wikipedia, with TCDD boxed above.

TCDD may be lumped into the broader category of polychlorinated dibenzo-para-dioxins, or they may be referred to as dioxin and dioxin-like compounds, or even just dioxins in general.

In any given case, what’s important to remember is that not all polychlorinated compounds with similar structures are toxic/carcinogenic to humans, so even though they all may be lumped together they all don’t exhibit the same levels of toxicity, with 2,3,7,8-TCDD being considered one of the most toxic forms.¹

Essentially, it’s important that these compounds don’t get lumped together as it may either overestimate or underestimate the actual levels of toxicity.

On that point, we can take a look at some of the results from the soil samples. Remember that only two samples were taken from the East Palestine soil with one being run twice. Therefore, the data here is extraordinarily limited—a running issue with many of the samples taken.

The Substack Planet Waves FM provided a memo detailing the results of the soil samples below:

The above results of dioxin testing were conducted to determine whether soil from Ohio was deemed safe for disposal in Indiana. Only two samples were taken, with one being duplicated.

Note that these results are in parts per billion. 2,3,7,8-TCDD is considered to be toxic in the parts per trillion levels, and in order to get that you just need to multiply the values above by 1,000.²

If we focus on the group for TCDD you’d get something such as 170, 230, and 200 ppt respectively for each sample.

Are these levels carcinogenic, and are they hundreds of times higher than should be expected?

The citation provided by The Guardian links to this notice from the EPA with respect to dioxin in the soil of CERCLA and RCRA sites.

CERCLA refers to the the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), which is a bill which taxes oil and petroleum companies and provides federal authority to respond to chemical spills. It also acts a method for holding these companies liable.

With respect to skin exposure and possible risks of cancer, the EPA notice provides the following remark (emphasis mine):

These draft recommended interim PRGs are informed by the best available peer-reviewed science, as well as the work of states and other agencies. Based on a consideration of oral and dermal exposures to dioxin, EPA has developed the following draft recommended interim PRGs for dioxin in soil: 72 ppt for residential soil and 950 ppt for commercial/industrial soil. EPA believes that these draft recommended interim PRGs would generally provide adequate protection against non-cancer effects, and generally should protect against cancer effects at approximately the 1E-05 risk level (1 in 100,000). These recommended interim PRGs are within EPA's protective risk range of 1E-04 to 1E-06 (see 40 CFR 300.430(e)(2)(i)(A)), and are more protective than the 1998 PRGs.

Note that this estimate is given based on a cancer risk level of 1 in 100,000. That is, at the thresholds noted above it may be estimated that 1 in 100,000 people exposed to these levels may develop cancer, with higher levels of course increasing the risk level.

If we compare the 72 ppt from the excerpt above it may seem like the exposure in East Palestine is much higher with one of the samples showing 170 ppt of dioxins. Is it in the hundreds? I’m not sure, and again The Guardian doesn’t provide evidence as to where they are getting their numbers from.

So does this mean that there’s a cancer risk from dioxin exposure in East Palestine?

Remember that the point of this exercise is to note that the term “dioxin” is being used very broadly, and in some sense this ambiguity provides leeway for more sensationalized headlines.

If we look at the EPA notice we’d have to wonder what the article refers to when speaking about dioxin.

In this case, it seems the EPA is referring to 2,3,7,8-TCDD in particular, with one citation linking to a post that seems to differentiate between dioxin and other compounds similar to dioxin. However, I also confess that dioxin here may still be used to refer to the class of compounds which would also change this interpretation.

So was that what was being measured in the East Palestine soil samples?

It appears that the memo provides an account of total dioxins and furans in the soil; not measures of 2,3,7,8-TCDD in particular:

Given that not all dioxin-like compounds show similar toxicities, it’s probably not a good idea to lump them all together to assume that the levels provided are carcinogenic.

If we take a look at the actual document from Pace Analytical for the first sample (WS-1) we can actually determine the levels of 2,3,7,8-TCDD:

So that’s about 0.0030 ug/Kg (ppb) of 2,3,7,8-TCDD in the soil sample provided, or about 3 ppt.

It’s important to remember that this level may not be representative of the actual levels in the soil- movement of the soil may mix any dioxin that may have settled at the top, and so the actual levels may differ substantially compared to what was present at the site.

But even with that being said, the reports here don’t appear to corroborate the cancer thresholds for 1 in 100,000 risk provided by the EPA, and it makes me curious where The Guardian is getting their “hundreds of times” greater evidence from.

Again, this depends on if dioxin is referring to the class or the compound 2,3,7,8-TCDD in particular.

The Guardian provides this remark with respect to dioxin levels in other regions of the country, with the levels in East Palestine appearing 14 times higher relative to other sites:

The levels found in two soil samples are also up to 14 times higher than dioxin soil limits in some states, and the numbers point to wider contamination, said Linda Birnbaum, a former head of the US National Toxicology Program and EPA scientist.

This may have come from this pilot program the EPA conducted to check for dioxins, furans, and mercury in various parts of the country, with the results in question likely being the following:

Or they may have come from another source. Again, the ambiguity makes it hard to determine where this information is coming from and whether it can be corroborated, or just an opinion stated as fact from a supposed expert.

The above values are in ppt, and the results from the Pace Analytical testing do appear much higher, although the above table again references total TCDDs and not 2,3,7,8-TCDD in particular (in which case, the values would be assumed to be much lower in this table).

Will the most toxic dioxin please stand up?

Given the limited information it’s likely that the fire released some dioxin into the local environment. However, to the extent that the levels are actually toxic are a different concern, and one that can’t be concretely answered given the limited testing.

The levels of total dioxins and furans appear to be elevated, but whether the levels of 2,3,7,8-TCDD provided are of concern with respect to cancer risk is, again, uncertain.

Remember that exposure to any chemical doesn’t inherently mean toxicity- the main principle of toxicology is based on the idea that it’s the dosage, not the compound, that makes for the poison.³

It’s also worth remembering that much of this discussion on dioxin has referred to 2,3,7,8-TCDD in particular, and not necessarily the other dioxins that are likely to have been produced as well even if they may be toxic in their own right.

This may be due to the fact that other chlorinated dioxins have not been studied as extensively, or because 2,3,7,8-TCDD in particular appears to be the most toxic out of the group.

Regardless, in looking at this information consistency of some sort should at least be required. Given that much of the discussion has focused on 2,3,7,8-TCDD it would seem a little disingenuous for outlets to then lump all dioxins together, especially if it is meant to overinflate the numbers and provide for a more worrying scenario.

But that also comes with the issue of determining what outlets are referring to specifically in their reporting when they use the term “dioxin”. For instance, in a prior post from The Guardian dioxin is used in reference to the class, but particular notice is provided towards 2,3,7,8-TCDD. This would probably argue that The Guardian is being consistent in their use of the term dioxin.

Whether the EPA’s notice refers to dioxin as a class or 2,3,7,8-TCDD in particular is somewhat uncertain as well.

In Summary…

If this article has provided too much confusion, the main takeaways are the following:

• Sampling for dioxin has been extremely minimal, with soil results only being provided in order to assess whether translocation of soil to other regions was considered “safe”. On-the-ground sampling of soil doesn’t appear to have been done, which would provide more relevant data on top soil dioxin levels.

  • Remember that this means the reported results may be much higher, or much lower than is actually present.

• The term “dioxin” is used rather ambiguously, with most outlets referring to dioxin as a class of compounds and yet referring in particular to the toxicity of 2,3,7,8-TCDD when describing dioxin toxicity.

• Inconsistencies in how the term “dioxin” is used makes it hard to corroborate reports- more transparency in what is being referenced should be used.

• Dioxin levels appear to be elevated in East Palestine with respect to other regions. Whether this elevation can infer toxic levels appear uncertain to me, including with respect to 2,3,7,8-TCDD levels. To that, more transparency is needed in explaining what the findings represent with respect to human exposure and possible toxicity rather than declarations that these levels are “safe”.

  • This also doesn’t take into account the background level of dioxin in that region. Keep in mind that if East Palestine is an industrial community levels of dioxin will be elevated relative to other regions. That also includes the fact that the railroad is in close proximity to residents, which itself may also elevate dioxin levels as well. Again, the context of these values is important, and in many cases

• There still doesn’t appear to be any toxicology reports. Instead of arguing over the level of possible dioxin exposure why not test people to see if they have been exposed to get an actual measure of possible toxicity?

• People are still experiencing symptoms with no clear explanation provided. Whether real or psychosomatic, again no robust assessment appears to be going on.

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1. This is corroborated in an article from the EPA which refers to dioxin as a class, but notes that many chlorinated dioxins may not have the same level of toxicity:

Although hundreds of PCDDs, PCDFs, and PCBs exist, only some are toxic, those with the chlorine atoms in specific positions. Counting around the carbon rings, those with chlorines at positions 2, 3, 7, and 8 are toxic (see figure 1). The dioxin-like PCBs have both biphenyl rings in the same plane (flat appearance), which allows them to act like dioxins in the body.

Although, this argument should be contextualized with the fact that 2,3,7,8-TCDD is the most extensively studied, so it’s possible that this remark is based on limited data on the other compounds.

2. Remember that “parts per x” is a ratio of one compound relative to the total amount of substance obtained whether it be air, soil, or water. We use “parts per x” all the time when we use percentages, which are “per cent” or “parts per 100”. These units of concentration are generally calculated by factors of 10, with parts per million being a factor of 10^6, ppb being 10^9, and ppt (trillion) being 10^12. Because these values are concentrations, there have been some criticism over the ambiguity of using these notations. For instance, 1 ppm is the equivalent of 1 mg/kg as well as 1 mg/L. Thus, one can covert from a concentration of mg/kg or mg/L into ppm, but you may not be able to convert in the opposite direction since the units used may be different. It’s important to remember these differences when comparing samples from different sources or that use different units.

3. This adage appears to come from Paracelsus, who supposedly stated it in the following manner:

“All things are poisons, for there is nothing without poisonous qualities. It is only the dose which makes a thing poison.”

There are inherent limits to this adage, as many things may show a variety of different toxicity mechanisms. Thus, a compound may be considered carcinogenic at higher doses than it would be considered a teratogen. Again, it’s the context that describes the toxicity and in what particular manner the toxicity may manifest. Remember that the above values provided by the EPA refer to a broad concern over cancer, but does not suggest anything related to acute toxicity, teratogenicity, or anything more nuanced.