Parent/Halogenated Polycyclic Aromatic Hydrocarbons in the Serum of Coal-Fired Power Plant Workers.

[NNadir]

Here's an interesting paper across which I came today: Parent and Halogenated Polycyclic Aromatic Hydrocarbons in the Serum of Coal-Fired Power Plant Workers: Levels, Sex Differences, Accumulation Trends, and Risks Chuxuan Zhao, An Li, Gaoxin Zhang, Yiyao Pan, Lingling Meng, Ruiqiang Yang, Yingming Li, Qinghua Zhang, and Guibin Jiang Environmental Science & Technology 2022 56 (17), 12431-12439.

I'm not going to spend a lot of time here with this paper, but will simply offer a few excerpts to make a point about selective attention.

From the introduction:

Coal burning generates precursors for the formation of polycyclic aromatic hydrocarbons (PAHs) and numerous other combustion byproducts, and coal-fired industrial boilers are one of the main contributors to PAH emissions. (1?3) Halogenated PAHs (HPAHs), which are emerging persistent organic pollutants and considered to be more toxic than PAHs, are also generated during coal burning. (4) Coal-fired power accounted for about 60% of electricity in China in 2021, (5) and about 2 billion tons of coal has been consumed annually for power generation since 2014. (6) HPAHs have been detected in the flue gas of coal burning, (7) and annual emissions of eight HPAHs from a coal-fired power plant in eastern China are reported to reach 90,000 tons. (4) With such high emissions and the discovery of a large accumulation of HPAHs in organisms at high nutritional levels, (8) concerns about the risk of human exposure to HPAHs have been raised.

Workers in coal-fired power plants are at a high risk of exposure to PAHs and HPAHs. In the working environment, HPAHs and PAHs are directly inhaled as gaseous pollutants or can attach to particles, thus entering the body through the respiratory tract or even entering blood circulation. (9,10) Due to their high lipophilicity, some HPAHs can distribute in the blood and organs at potentially higher rates than that of their corresponding parent PAHs (PPAHs). (11) Long-term exposure to HPAHs is highly likely to increase the risk of adverse health effects.

Exposure to HPAHs is of increasing public health concern because HPAHs are more toxic than their PPAHs and show different toxicological effects. (12,13) Although toxicological studies on HPAHs are still limited, their toxicity is thought to be mainly related to aromatic hydrocarbon receptor (AhR)-mediated toxicity, carcinogenicity, and DNA damage, (12,14?16) including their effect on the expression of cytochrome P-450 (CYP) genes. (17) They also stimulate the metabolic pathways of chemicals other than the AhR-mediated metabolism. (11) Just as PAHs can produce excessive reactive oxygen species and induce a significant increase in lipid peroxidation and a prominent decrease in antioxidant enzymes after being metabolized, (18,19) exposure to 6-chlorobenzo[a]pyrene at certain concentrations can cause strong oxidative stress and a strong inhibition effect on cell viability. (13) Other metabolic processes and potential health effects of HPAHs are still unclear. Since HPAHs and PAHs can be widely distributed in multiple organs and cause damage, (11,18) studies focused on the relationship between serum levels and various health indicators may provide critical insights into the internal processes and the mechanisms of causing toxicity.

To the best of our knowledge, there have been no systematic studies investigating HPAHs in humans, much less assessing occupational exposure to HPAHs.

I added the bold. It's too bad that the HPAH's aren't radioactive, because then the world could burn lots of coal to run computers for people pretending to care about the matter to comment illiterately on the subject with faux concern. There'd be all kinds of interest in the subject, and thousands of scientific papers to spectacularly misinterpret on the subject. (It's too bad these compounds weren't released by Fukushima, for instance; people would give a shit.)

The samples were collected from 172 coal plant workers in a Chinese coal plant and as these PAH's are volatile - they are constituents of air pollution which kills seven million people per year without a peep from energy "concern trolls" - the samples were analyzed by GC/MS/MS (Triple Quad GC).

A word on concentrations, the units are in ng/ml, nanograms/milliliter blood plasma. Most people do not have a sense of what these concentrations mean since bioanalysis is a somewhat esoteric subject. Most physiological active drugs are at concentrations roughly comparable to these; I have experience with concentrations as low as pg/ml (picograms/milliter) that have profound biological effects.

The concentration of ?8HPAHs in the serum was significantly higher in the exposure group (mean ± SD: 42 ± 24 ng/g lipid and range: 16–273 ng/g lipid) than in the control group (mean ± SD: 23 ± 11 ng/g lipid and range: 12–51 ng/g lipid, p < 0.001) (Figure 1a), suggesting that the operation of the coal-fired power plant may lead to a great accumulation of HPAHs in the serum of its workers. The ?8HPAH concentrations in the control group are consistent with that previously reported for the general population in Shandong, (20) which is the only report on HPAH levels in humans. The concentrations of 9-ClPhe, 9-ClAnt/2-ClAnt, 1,4-Cl2Ant, and 7-ClBaA increased significantly in the exposure group compared to that in the control group, as shown in Figure S1a,b. Although a large number of Br-PAHs (9-BrPhe, 7-BrBaA, etc.) have been detected in food (fish, pork, etc.) and the fly ash of coal-fired power plants, (4,8,41) almost no Br-PAHs were detected in the serum of this study.

It is notable that these toxic compounds are more or less endogenous; everybody in China is pretty much exposed to them, but unsurprisingly, the levels are higher in coal plant workers.

Some comments on the health risk assessments:

BaPeq describes potential toxicity relative to BaP. The results of BaPeq calculation suggest that while the eight HPAHs contributed only 2 ± 1% to the total concentration of all analytes involved in this work, their contribution to total BaPeq (i.e., toxicity contribution rate) was 21 ± 6% (Figure 5). The BaPeq ratio of ?8HPAHs to ?12PAHs was 0.3 ± 0.1, and the toxic REPs of most HPAHs are higher than that of their corresponding PPAHs (Tables S1 and S2), indicating that the health risks of serum HPAHs at low concentrations cannot be ignored...

...The BaPeq contribution order for HPAHs was 9-ClPhe > 7-ClBaA > 1-ClPyr (Figure S2), which together accounted for 74% of the HPAH BaPeq. In other studies, the major HPAHs contributing to health risks were 7-ClBaA (followed by 9-ClPhe and 6-ClBaP) in the air of Tokyo Bay, (52) 7-ClBaA and 6-ClBaP in PM2.5/PM10 of suburban Shanghai, (48) 7-ClBaA in e-waste recycling facility samples, (53) 9,10-Cl2Ant and 1-ClPyr in tap water, (54) and 7-BrBaA, 9,10-Cl2Ant, 9-ClPhe, and 2-ClAnt in South China seafood. (55) The reason for discrepancies is unclear, and the toxicological mechanisms underlying HPAHs based on the number and locations of substituted halogen atoms need further investigation. Previous studies on dietary exposure have also reported excess cancer risk (carcinogenic assessment model developed by the US EPA) through consumption of rice (49) and several types of seafood (55) at higher than acceptable risk levels (10^(–6)) but lower than priority risk levels (10^(–4)).

Some remarks on toxicological mechanisms:

...The controls were healthy male workers without any abnormal indicators. After adjusting for occupational exposure duration and BMI, logistic regression analyses showed an increase in ORs and p-values for half of the pollutants (Table S8). Specifically, the concentrations of 3-ClPhe, 9-ClPhe, 9,10-Cl2Phe, and 7-ClBaA were associated significantly with pulmonary hypofunction and those of 1,4-Cl2Ant, 9,10-Cl2Ant, and 1-ClPyr also showed positive correlations, while those of BaP and BaA were not. The difference between 7-ClBaA and BaA provides evidence that some HPAHs have different metabolic activation and biological effects and may be more toxic than their PPAHs.

Aggravation of lung function impairment also increased with average serum levels of PAHs and HPAHs (p < 0.05, Figure S3). A large body of evidence suggests that BaP triggers the occurrence and development of lung cancer; (56,57) however, the link between HPAHs and lung disease remains unclear. A recent study confirmed that BaP at the human blood equivalent level induces invasion and migration of lung epithelial cells via the AhR signaling pathway, (58) suggesting the possibility that HPAHs may also have similar effects through the AhR signaling pathway...

If any of this concerns you, don't worry; be happy:

The authors report that the levels of chlorinated polynuclear aromatic hydrocarbons in coal plant workers is lower than that found in children working in areas where e-waste is recycled in China. Don't worry; be happy about that too. Recycling is "green" for us, if not for the people who actually do the work.

Right now, after having spent hundreds upon hundred of billions of euros to Putin in order to be "green," Germany is burning coal, generally the worst form of it, lignite. The theory behind the decision to rely on coal when gas isn't available is that "nuclear power is 'too dangerous'" and "nuclear power is 'too expensive'" and climate change is not "too dangerous," nor is it "too expensive," and air pollution is not "too dangerous," nor is it "too expensive" and that funding a homicidal imperialistic dictator is not "too dangerous," nor is it "too expensive."

This paper of course, suggests that someone somewhere somehow might want to reconsider this calculation, but it's not like this scientific "screed" can be any more important than a flyer distributed by Greenpeace "activist" dressed in a monkey suit.

Germany recently saw its electricity prices soar to 1,000 Euros/MWh, which I believe may a world record for the price of electricity.

History will not forgive us; nor should it.

Have a pleasant afternoon.

[2naSalit]

1. We knew it wasn't good...

This is awful but not less than what I have anticipated seeing by now.