Recently, the Michigan Department of Environmental Quality (MDEQ) drew attention by issuing a toxicity assessment of petroleum coke dust, in conjunction with its permitting of a coke storage facility in Detroit. At least one news article mistakenly labeled the report as finding that “petcoke [is] not dangerous to health.” This headline gives me a chance apply my years of public health school, so let’s take a closer look.
First, the MDEQ most certainly did find that there are health threats from petroleum coke, stating that “Human exposure to fine particulate matter (PM) emissions from petcoke storage piles, at sufficiently high concentrations and durations of exposure, could cause respiratory and cardiovascular effects characteristic of PM inhalation exposures.” In other words, inhaling pet coke dust is bad for your lungs and heart. The animal study of pet coke relied upon by both the EPA and MDEQ in their analyses of petcoke found “irreversible respiratory effects,” specifically chronic inflammation of the lungs and increased lung weights, “at all concentrations tested” (emphasis added).
MDEQ also concluded that petcoke dust is no more toxic than dust generally in terms of other health impacts like cancer. But there are at least two good reasons to be particularly concerned about petroleum coke compared to other materials stored at industrial sites:
- Petroleum coke is more prone to becoming airborne than other materials because it contains a higher amount of fine silt than substances like gravel or sand – so people are more likely to be exposed to higher levels of it, increasing the chance of lung and heart impacts.This point was recently made in a study conducted by CDM Smith, a global consulting firm, for the City of Chicago. As summarized by the City, the study showed that "due to its high silt content, petcoke was found to have much higher overall emissions than other bulk materials and, therefore, greater air quality impacts from outdoor storage." (quoting the City’s Response to Comments for its public health regulations, emphasis added)
- Not all other forms of dust are piled 4 to 5 stories high next to residential neighborhoods like the pet coke in the Calumet and Detroit areas - this proximity again increases exposure and so the risk of lung and heart impacts.
Moreover, the animal study that MDEQ relied upon is from 1987 and was sponsored by the American Petroleum Institute. While I’m sure that the researchers followed proper protocols and their findings of lung impacts at all concentrations indicates a lack of bias, I personally would feel more reassured about their finding a lack of cancer impacts if current and non-industry funded research confirmed these results.
And typical estimates of dust impacts by companies and air agencies assume average weather conditions (e.g., 10 mph winds) and high effectiveness of controls. In the real world, neither of these assumptions plays out in the course of a year: as those of us who live in Chicago know, there are many days per year when winds blow upwards of 20 mph, and controls that require daily efforts by personnel don’t always get implemented as intended (and in the case of dust, some controls don’t even work when the winds are blowing).
In sum, we know enough now to conclude that uncovered piles of petcoke served by streams of trucks and barges don't mix with neighborhoods. And we need more robust and objective scientific research to understand the full health ramifications of blowing this dust into places where people live and play. Until then, I wouldn’t move to or let my children play in a neighborhood next to these piles – would you?