HHCB [1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta(g)-2-benzopyran] and 4-tert-octylphenol [4-(1,1,3,3-tetramethylbutyl)phenol] are widely used emerging contaminants that have the potential to cause adverse effects in the environment. The purpose of this study was to observe if and how environmentally realistic concentrations of these contaminants alter growth in plant populations. It was hypothesized that within an exposed Gypsophila elegans Bieb (annual baby’s breath) population especially fast-growing seedlings are impaired even when the population mean is unaffected, and small doses can cause hormesis and, thus, an increase in shoot or root length. In a dose-response experiment, an experimental population of G. elegans was established (total 15.600 seeds, 50 seeds per replicate, 24 replicates per concentration, 5.2 seedlings/cm2) and exposed to 12 doses of HHCB or 4-tert-octylphenol. After five days, shoot and root length values were measured and population averages, as well as slow- and fast-growing subpopulations, were compared with unexposed controls. Growth responses were predominantly monophasic. HHCB seemed to selectively inhibit both root and shoot elongation among slow- and fast-growing individuals, while 4-tert-octylphenol selectively inhibited both root and shoot elongation of mainly fast-growing seedlings. The ED50 values (dose causing 50% inhibition) revealed that the slow-growing seedlings were more sensitive and fast-growing seedlings less sensitive than the average of all individuals. Although there was toxicant specific variation between the effects, selective toxicity was consistently found among both slow- and fast-growing plants starting already at concentrations of 0.0067 µM, that are usually considered to be harmless. This study indicates that these contaminants can change size distribution of a plant population at low concentrations in the nM/µM range.
This is a preview of subscription content, log in to check access.
This study was conducted as part of a student exchange between the University of Helsinki and the University of Hohenheim within the framework of a project funded by the German Research Foundation (DFG, individual grant number BE4189/1-2 and BE4189/1-3). The language editing by Jessica Lloyd and the statistical advice by Prof. Dr Hans-Peter Piepho is greatly acknowledged.
This study was funded by the German Research Foundation (DFG, individual grant number BE4189/1-2 and BE4189/1-3). AS was funded by Business Finland (Tekes grant 40333/14).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
Agathokleous E, Belz RG, Kitao M, Koike T, Calabrese EJ (2018) Does the root to shoot ratio show a hormetic response to stress? An ecological and environmental perspective. J For Res. https://doi.org/10.1007/s11676-018-0863-7
An J, Zhou Q, Sun Y, Xu Z (2009) Ecotoxicological effects of typical personal care products on seed germination and seedling development of wheat (Triticum aestivum L.). Chemosphere 76:1428–1434.Google Scholar
Hernando MD, Mezcua M, Gómez MJ, Malato O, Agüera A, Fernández-Alba AR (2004) Comparative study of analytical methods involving gas chromatography-mass spectrometry after derivatization and gas chromatography-tandem mass spectrometry for the determination of selected endocrine disrupting compounds in wastewaters. J Chromatogr A 1047:129–135CrossRefGoogle Scholar
Płociniczak T, Sinkkonen A, Romantschuk M, Sułowicz S, Piotrowska-Seget Z (2016) Rhizospheric bacterial strain Brevibacterium casei MH8a colonizes plant tissues and enhances Cd, Zn, Cu phytoextraction by white mustard. Front Plant Sci 7:1–10. https://doi.org/10.3389/fpls.2016.00101Google Scholar