###### Abstract  
The article presents a review of studies on the chemical diversity of essential oils and extracts from _Tanacetum vulgar_ L. under the influence of environmental factors and the bioaccumulation of heavy metals in the plant. These issues are crucial for consumer safety, especially when they concern plants widely used in alternative medicine. Stress factors to which plants are subjected may result in a decrease in their biological activity or toxic effects (as in the case of _Tanacetum vulgar_ L.). The issue is particularly important in the context of increasing environmental pollution, e.g., with heavy metals, and climate change, which is also a stress factor. The presented review clearly shows that detailed research is required both to identify the components of _T. vulgar_ with specific therapeutic potential and to assess their quantitative changes under the influence of a specific stressor. It was found that there is a need to standardize analytical procedures used in research on the bioaccumulation of metals by medicinal plants. The importance of environmental monitoring in herb-growing areas, as an important element of health policy, is also emphasized. T +
Footnote †: journal: Applied sciences  
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In order to survive in a polluted environment, plants had to develop appropriate defense mechanisms against stress, e.g., consisting of pollutant absorption and their detoxification and accumulation in specialized organs. Considering the great importance of herbs, the chemical purity of the raw material is very important [7]. The high content of some substances in plant raw materials may reduce their medicinal properties and even pose a threat to human and animal health. In the case of plants with a high variability of composition (e.g., _Tanacetin vulgare_ L.), the location of the site from which the raw material is collected is of great importance. Therefore, in order to reduce the risk for consumers, systematic control of the chemical composition of plants and soil is necessary [8]. The family _Asteraceae_ (formerly known as _Composite_) belongs to the order of _Asterales_. It has about 25,000 species and is one of the largest families among angiosperms. Representatives of the _Asteraceae_ family are mainly herbaceous plants [9; 10]. Based on the diversity of flowers, two subfamilies can be distinguished among the _Asteraceae_: _Asteridae_ (_Composite_--_Tubuliforae_) and _Cichorioideae_ (_Liguilforae_) [11]. The genus _Tanacetin_ includes over 200 species of plants, some of which have a long history of use in folk medicine [12; 13]. One of the species is _Tanacetin vulgare_ L., commonly known as tansy. The presented paper discusses studies on the chemical variability of _T. vulgare_ under the influence of environmental factors. This work concerns the composition of essential oils, extracts, and the content of heavy metals that are potentially toxic to consumers. Stress factors, both chemical and environmental (e.g., climate change) can cause a decrease in the biological activity of plants or the synthesis of toxic metabolites. This issue is of particular importance when the plants studied are commonly used not only in professional medical practice, which is associated with more restrictive cultivation methods and quality control but also in alternative medicine. The study of the accumulation capacity of plants may also have application potential, providing a basis for the development of methods for the phytoremediation of soils contaminated with metals. However, this requires a wider range of studies in various experimental conditions and using a uniform methodology both in the preparation of plant and soil samples for analysis, as well as the analytical procedures themselves. The aim of the article was to (i) summarize the current state of knowledge on the influence of environmental factors on the composition of _T.