The dioxins created, among other things, are highly toxic in combustion processes, so their release is strictly regulated. But now a study shows that these long -lasting organic chlorine compounds can arise from widespread chemicals in the atmosphere. The solar radiation and with mineral dust particles as catalysts create high-toxic polychlorinated dibenzo-p dioxins and dibenzofurane (PCDD/FS) from fleeting chlorinated organic compounds (CVOC). Accordingly, the ubiquitous CVOCs are more dangerous than previously assumed. In view of these results, the environmental and health risk must now be re-evaluated by such chemicals, the chemists demand.
There are strict national and international rules for dangerous chemicals that determine how these substances have to be stored and disposed of. The security regulations are primarily based on the properties of the chemicals: whether they are poisonous for people and the environment and whether they are accumulated in nature or living beings. In contrast, the regulations, however, hardly or do not even take into account which conversions the substances in the atmosphere go through. In fact, however, other products can arise from many chemicals from chemical reactions in the air, some of which are even more poisonous and more environmentally harmful than the starting substances.
Chlorine chemicals on the test bench
A team around Xiaole Weng from the Zhejiang University in Chinese Hangzhou has now examined a certain group of chemicals in the atmosphere: fleeting chlorinated organic compounds (CVOC) such as Monochlorbenzene, dichlormethane and perchlorethylene. These chemicals are widespread in industry and agriculture. CVOCs are contained, for example, in colors and paints, chemical cleaning and pickling agents. These products and waste incineration plants and landfills reach the environment and are almost omnipresent. What is happening to them there and whether they are converted into other chemicals via natural processes has hardly been researched so far.
However, it is known for industrial combustion processes that dioxin compounds can arise from CVOCs. For example, under certain conditions, Chlorbenzole can be converted into polychlorinated Dibenzo-P dioxins and Dibenzofurane (PCDD/FS). Many of these substances are highly toxic-they damage organs, disturb the hormone system and are carcinogenic-as the scandalous accident in a chemical factory in Seveso, Italy impressively demonstrated in 1976. At that time, the dioxin TCDD was released, which is tens of thousands of poisonous times than cyankali and the residents poisoned.
Weng and his colleagues have therefore now checked whether conditions also prevail in the atmosphere that enable such a reaction of fleeting organic chlorine compounds to toxic dioxins and dibenzofurans. Your guess: the iron and aluminum minerals in the atmosphere could serve as the energy source as catalysts. The researchers checked this hypothesis in laboratory experiments and field tests with various mineral particles and determined possible reaction routes from them.
Source for toxic dioxin compounds
The experiments confirmed the assumption: In the atmosphere, CVOCs are photochemically converted into toxic dioxin compounds. Phenols form first, which are then chlorinated. Through iron oxides contained in the atmosphere in the atmosphere (α-FE
According to this, the ubiquitous chlorinated organic compounds are a previously overlooked source for dangerous PCDD/FS pollutants, the team closes around Weng. In view of the results, they advocate re-evaluating the health and environmental risk through CVOCs and numerous other commercial chemicals- and then also taking their conversion into account in the atmosphere. The risks could only be realistically assessed by such a comprehensive assessment.
Source: Society of German Chemist EV; Applied chemistry, DOI: 10.1002/attached 202500854
