Arsenic and fish products
Food chemist at the University of Muenster studied toxicity of different compounds
Lace it does not bear, but of arsenic she understands a lot, because the food chemist Prof. Dr. Tanja Schwerdtle examined different arsenic compounds to determine their toxicity to humans. has been teaching this winter semester and researching the 33-year-old at the Institute of Food Chemistry of the University of Muenster. Previously, she was a research assistant at the Institute of Food Technology and Food Chemistry at the Technical University of Berlin.
Arsenic has a number of interesting properties. So the poison occurs in many different forms, both organic and inorganic. Although it has been established that arsenic is carcinogenic to humans, it is completely unclear why. "After oral ingestion in drinking water or food, arsenic does not have a carcinogenic effect in animal experiments," explains Schwerdtle. It is all the more urgent to research how arsenic compounds work, because around 200 million people around the world are exposed to arsenic-contaminated water. Skin and lung cancer can result from an increased intake of arsenic.
Arsenic is a component of our environment that is mainly from natural sources and is subject to a perpetual biogeochemical cycle. The largest deposits of arsenic on earth are bound in sulphide form in the earth's crust. However, in the past arsenic was also used for fertilization, so that many soils are still contaminated. Arsenic is particularly a problem in Asian countries. "One of the main foods there is rice, which grows in water. If it contains a lot of arsenic, the plant accumulates the toxin," says Schwerdtle, explaining the mechanisms. In addition, the rice is also prepared in water, which also increases the arsenic content. While in Europe, where the arsenic content in drinking water is limited to ten micrograms per liter, an average of only 25 grams of rice is eaten per serving, in Asia it is 300 grams. Concentrations of 800 micrograms of arsenic per kilo have already been found in rice.
Inorganic arsenic, which is considered to be particularly hazardous to health, does not necessarily pose a threat in Germany. However, around ten years ago a belief in food chemistry was shaken: organic arsenic can also have a toxic effect. "Until now, it was assumed that inorganic arsenic was metabolized into organic and therefore harmless. But organic arsenic metabolic compounds have been found that are more dangerous than inorganic ones," warns the 33-year-old. Each product class must be examined individually. In algae, for example, arsenic accumulates by a factor of 100000 compared to seawater. 180 milligrams of organic arsenic per kilogram of algae (dry weight) have already been found. The plants, praised as health miracle cures from the sea, can also contain up to 40 milligrams of inorganic arsenic per kilo of dry algae weight. Unlike drinking water, there is no limit value for food in Germany, so these algae can be freely sold. "We're always finding new product classes for which arsenic could be a problem," says Schwerdtle with concern. "We have to find out which compounds are present, how dangerous they are and whether a limit should be set."
As an example, she names the popular fish oil capsules, which with their high content of omega-3 fatty acids are said to be particularly good for the cholesterol level. "In Austria, up to ten milligrams of organic arsenic per kilo have been found in these capsules. It is not known whether these fat-soluble arsenic compounds pose a health risk. However, it is alarming that these compounds can lead to metabolic products that also occur with inorganic arsenic. " But isn't Asian cuisine praised as particularly healthy with a particularly large number of seafood? "It may be that the present organic arsenic is actually harmful to health, but that the Asians have developed a kind of genetic protection against it, for example in the context of a changed metabolism, which we Europeans lack", warns Schwerdtle.
Your working group is trying to find out what the carcinogenic effects of arsenic are based on. This is particularly difficult because rodents, which are often used to study the carcinogenic effects of toxins, do not metabolize arsenic in the same way as humans do. In addition, arsenic shows its carcinogenic effect especially after years of chronic ingestion of small amounts, a scenario that is difficult to reproduce in rodents due to their short lifespan.
Schwerdtle is therefore also looking for suitable biomarkers that can confirm the researched mechanisms of action of arsenic compounds on model organisms in the laboratory, in cell material from people exposed to arsenic. The identification of a suitable biomarker for exposure to a pollutant can provide important information about a later cancer. This can make a significant contribution to the assessment of potential hazards and the establishment of health-based limit values.
"Among other things, we examine the DNA damage in the white blood cells that is caused by the so-called oxidative stress. It is particularly important for us to find out whether this damage results from a disturbed DNA repair. The various DNA repair mechanisms contribute our bodies play a key role in maintaining the stability of our genetic make-up and thus reduce the risk of cancer developing, "said Schwerdtle. Münster is exactly the right place for this exciting task, as the analytical and toxicological research competencies can be combined in the chemistry and pharmacy department in order to be able to make a risk assessment for arsenic in food.
Source: Münster [WWU]
