{"id":39118,"date":"2026-06-09T10:01:59","date_gmt":"2026-06-09T09:01:59","guid":{"rendered":"https:\/\/www.vtei.cz\/2026\/06\/marketing-vs-realita-vyuziti-baterie-biotestu-pro-hodnoceni-akutni-toxicity-ekologicky-setrnych-detergentu\/"},"modified":"2026-06-10T09:56:10","modified_gmt":"2026-06-10T08:56:10","slug":"marketing-vs-reality-using-a-battery-of-bioassays-to-assess-the-acute-toxicity-of-environmentally-friendly-detergents","status":"publish","type":"post","link":"https:\/\/www.vtei.cz\/en\/2026\/06\/marketing-vs-reality-using-a-battery-of-bioassays-to-assess-the-acute-toxicity-of-environmentally-friendly-detergents\/","title":{"rendered":"Marketing vs. reality: using a battery of bioassays to assess the acute toxicity of environmentally friendly detergents"},"content":{"rendered":"

ABSTRACT<\/h2>\n

Household detergents are an\u00a0important source of\u00a0complex mixtures of\u00a0anthropogenic substances entering municipal wastewater systems and, subsequently, receiving waters. This study presents a\u00a0comparative assessment of\u00a0the\u00a0acute ecotoxicity of\u00a0conventional detergents and their environmentally certified counterparts (EU Ecolabel) using a\u00a0battery of\u00a0bioassays representing different trophic levels. The\u00a0tests included the\u00a0luminescent bacterium Vibrio fischeri<\/span>, the\u00a0water flea Daphnia magna<\/span>, the\u00a0green alga Desmodesmus subspicatus<\/span>, and seeds of\u00a0white mustard Sinapis alba<\/span><\/em>.<\/span><\/p>\n

The\u00a0determined EC50<\/span> values and inhibition levels at a\u00a0concentration of\u00a0100\u00a0mg\/L revealed substantial variability in\u00a0the\u00a0toxic effects of\u00a0the\u00a0final formulations, which often did not correlate with the\u00a0\u201ceco\u201d marketing label. The\u00a0most notable finding was the\u00a0high acute toxicity of\u00a0an\u00a0environmentally certified laundry gel to algae (72h EC50<\/span><\/sub> 3.93\u00a0mg\/L) and water flea (48h EC50<\/span><\/sub> 5.49\u00a0mg\/L), exceeding the\u00a0toxicity of\u00a0the\u00a0conventional product by an\u00a0order of\u00a0magnitude. This effect can\u00a0likely be explained by the\u00a0high total surfactant content in\u00a0the\u00a0environmentally certified product (up to 50\u00a0%) and potential synergistic interactions with additional additives such as enzymes. In\u00a0contrast, within\u00a0the\u00a0shampoo category, the\u00a0eco-variant (EC50<\/span><\/sub> > 100\u00a0mg\/L) showed lower toxicity due to the\u00a0replacement of\u00a0aggressive sulphate surfactants with non-ionic surfactants based on coco-glucoside.<\/span><\/p>\n

From a\u00a0methodological perspective, the\u00a0study confirmed that Daphnia magna<\/span><\/em> and Desmodesmus subspicatus<\/span><\/em> are the\u00a0most sensitive bioindicators of\u00a0detergent exposure, while Sinapis alba<\/span><\/em> seeds exhibited considerably higher tolerance to acute exposure. The\u00a0results highlight the\u00a0importance of\u00a0experimental testing of\u00a0complete product formulations, as the\u00a0regulatory criteria of\u00a0the\u00a0EU Ecolabel, primarily focused on biodegradability, do not necessarily guarantee lower acute toxicity of\u00a0the\u00a0mixture. Due to their widespread and continuous use, detergents may behave as pseudo-persistent pollutants in\u00a0aquatic environments, maintaining a\u00a0relatively constant toxic pressure on aquatic biota despite the\u00a0theoretical biodegradability of\u00a0their individual components.<\/span><\/p>\n

INTRODUCTION<\/h2>\n

The\u00a0use of\u00a0household detergents represents a\u00a0continuous source of\u00a0anthropogenic chemical substances entering municipal wastewater systems and subsequently aquatic receiving environments [1, 2]. These products, including, for example, hand dishwashing detergents, laundry gels, dishwasher tablets, and shampoos, are defined as complex mixtures of\u00a0intentionally added substances, by-products, and impurities [3, 4]. The\u00a0dominant components of\u00a0these formulations are surfactants, which account for approximately 15\u201340\u00a0% of\u00a0the\u00a0total mass of\u00a0the\u00a0detergent [2, 5]. In\u00a0addition to surfactants, detergents contain\u00a0a\u00a0range of\u00a0other additives, such as bleaching agents, enzymes, preservatives, and fragrances, which may exhibit their own toxic effects [6, 7].<\/span><\/p>\n

Although modern wastewater treatment plants (WWTPs) remove common surfactants with high efficiency, often exceeding 90\u00a0%, some of\u00a0these substances and their metabolites may still enter aquatic receiving environments [5,\u00a08, 9]. As a\u00a0result of\u00a0the\u00a0widespread and continuous use of\u00a0detergents, these substances behave as so-called pseudo-persistent pollutants in\u00a0the\u00a0hydrosphere. Although the\u00a0individual components are biodegradable, their concentrations in\u00a0the\u00a0environment remain\u00a0relatively stable due to the\u00a0continuous input from municipal wastewater. This phenomenon represents a\u00a0long-term toxic pressure on aquatic organisms [9]. Exposure to detergents may induce adverse biological responses, particularly through disruption of\u00a0cell membrane integrity and interference with the\u00a0metabolic processes of\u00a0organisms [5, 6, 8, 10].<\/span><\/p>\n

The\u00a0environmental risks associated with conventional detergents may be further increased by certain\u00a0additives. These include, for example, phosphates and phosphonates contributing to the\u00a0eutrophication of\u00a0aquatic ecosystems\u00a0[2,\u00a07], persistent chelating agents such as EDTA, and preservatives belonging to the\u00a0isothiazolinone group. Other potentially problematic components include enzymes such as subtilisin, which may exhibit high acute toxicity to aquatic organisms [3, 11\u201314].<\/span><\/p>\n

In\u00a0response to the\u00a0environmental impacts of\u00a0detergents, the\u00a0EU Ecolabel certification scheme was introduced in\u00a0the\u00a0European\u00a0Union (Regulation (EC) No 66\/2010) [15]. The\u00a0criteria of\u00a0this certification are based on scientific principles and focus primarily on the\u00a0biodegradability of\u00a0components (both aerobic and anaerobic) and on reducing the\u00a0overall toxic burden on the\u00a0aquatic environment through the\u00a0calculation of\u00a0the\u00a0Critical Dilution Volume (CDV). The\u00a0criteria also include restrictions on or bans of\u00a0substances of\u00a0very high concern (SVHCs) and substances with high persistence or bioaccumulative potential.<\/span><\/p>\n

Despite these regulatory requirements, which primarily focus on the environmental fate of individual components, the marketing label \u201cECO\u201d may not always directly correlate with low acute toxicity of the final formulation across all trophic levels [5]. Within the EU Ecolabel criteria, substances classified as highly toxic to the aquatic environment are permitted, provided that they comply with the established limits and requirements regarding performance\u00a0<\/span>and biodegradability. Moreover, in\u00a0the\u00a0complex matrix of\u00a0the\u00a0final product, synergistic interactions between surfactants and other additives may occur, potentially modifying the\u00a0resulting toxic effect beyond the\u00a0level predicted from the\u00a0properties of\u00a0the\u00a0individual components [5, 16, 17].<\/span><\/p>\n

To objectively assess the\u00a0actual impact of\u00a0detergents on biota, a\u00a0battery of\u00a0bioassays representing different trophic levels of\u00a0aquatic and terrestrial ecosystems was used in\u00a0this study. The\u00a0test battery included the\u00a0luminescent bacterium Vibrio fischeri<\/span><\/em>, which represents a\u00a0standard indicator of\u00a0microbial toxicity sensitive to a\u00a0broad spectrum of\u00a0pollutants. In\u00a0addition, bacteria fulfil an\u00a0important role as decomposers of\u00a0organic matter in\u00a0aquatic ecosystems. Another test organism used was the\u00a0green alga Desmodesmus subspicatus<\/span><\/em>, a\u00a0unicellular primary producer sensitive to the\u00a0lytic effects of\u00a0detergents and simultaneously susceptible to growth stimulation in\u00a0the\u00a0presence of\u00a0nutrients. Due to their position at the\u00a0base of\u00a0the\u00a0food chain, algae represent a\u00a0key trophic level in\u00a0aquatic ecosystems. To assess toxicity at the\u00a0consumer level, water fleas (Daphnia magna<\/span><\/em>) were used, as they are among the\u00a0most sensitive model organisms for surfactant testing. These planktonic crustaceans constitute an\u00a0important component of\u00a0zooplankton and form a\u00a0significant link in\u00a0the\u00a0food chain\u00a0of\u00a0freshwater ecosystems. The\u00a0test battery was complemented by a\u00a0phytotoxicity test using seeds of\u00a0white mustard (Sinapis alba<\/span><\/em>), which serves as a\u00a0model indicator of\u00a0potential risks to terrestrial organisms, for example in\u00a0the\u00a0agricultural use of\u00a0wastewater or sewage sludge.<\/span><\/p>\n

The\u00a0aim of\u00a0the\u00a0study was to verify to what extent the\u00a0marketing declaration of\u00a0environmental friendliness corresponds to the\u00a0actual impact on aquatic biota. The\u00a0study tests the\u00a0hypothesis that certified detergents exhibit lower acute hazard than\u00a0conventional products, taking into account the\u00a0synergistic effects of\u00a0all components present in\u00a0the\u00a0tested mixtures.<\/span><\/p>\n

MATERIALS AND METHODS<\/h2>\n

Tested substances and sample preparation<\/h3>\n

Eight commercially available household detergents were tested in\u00a0the\u00a0study across four categories (hand dishwashing detergents, laundry gels, dishwasher tablets, and shampoos), each represented by a\u00a0conventional and an\u00a0environmentally certified variant. The\u00a0characteristics of\u00a0the\u00a0samples, including pH and composition, are presented in\u00a0Tab.\u00a01<\/span><\/em>. Stock solutions at a concentration of 1 g\/L\u00a0<\/span>were prepared by dissolving an\u00a0accurately weighed amount of\u00a0the\u00a0product in\u00a0demineralised water and subsequently diluted to the\u00a0required concentration. For the\u00a0final tests, a\u00a0logarithmic concentration series starting at 100\u00a0mg\/L was used. In\u00a0this study, this value was established as the\u00a0upper testing limit, as products with EC50<\/span> values exceeding this threshold are no longer classified as acutely toxic to the\u00a0aquatic environment according to the\u00a0Globally Harmonized System (GHS) and the\u00a0European\u00a0CLP Regulation. Moreover, testing at higher concentrations lacks environmental relevance, since typical concentrations of\u00a0surfactants (i.e. the\u00a0active substances contained in\u00a0detergents) in\u00a0municipal wastewater generally reach only 1\u201310\u00a0mg\/L and, after passing through WWTPs with high removal efficiency, are further substantially diluted in\u00a0receiving waters [8, 18, 19].<\/span><\/p>\n

Tab. 1. Characteristics of tested detergents and their declared composition<\/h5>\n\"\"<\/a>\n

The\u00a0pH of\u00a0the\u00a0working solutions was adjusted as necessary using 0.1 M NaOH and HCl to a\u00a0value of\u00a07.5 \u00b1 0.5 in\u00a0accordance with the\u00a0validity criteria of\u00a0standardised test protocols. This step eliminated the\u00a0influence of\u00a0extreme acidity or alkalinity of\u00a0the\u00a0products, which could otherwise induce a\u00a0non-specific toxic response independent of\u00a0the\u00a0effects of\u00a0the\u00a0substances present.<\/span><\/p>\n

The\u00a0bioassays were conducted in\u00a0an\u00a0accredited laboratory with an\u00a0implemented quality control system, including regular determination of\u00a0the\u00a0toxicity of\u00a0a\u00a0reference substance (potassium dichromate) to verify the\u00a0condition of\u00a0the\u00a0test organisms. The\u00a0results of\u00a0the\u00a0reference tests confirmed that the\u00a0sensitivity of\u00a0the\u00a0cultures used complied with the\u00a0requirements of\u00a0the\u00a0relevant standards.<\/span><\/p>\n

Luminescence inhibition test using Vibrio fischeri<\/em><\/h3>\n

Acute toxicity to marine luminescent bacteria was determined according to ISO 11348-2 using the\u00a0strain\u00a0Vibrio fischeri [20]. The\u00a0test was performed using the\u00a0LumiStox 300\u00a0measuring system (Dr Lange), comprising an\u00a0incubation unit and a\u00a0luminometer. The\u00a0osmotic pressure of\u00a0the\u00a0samples was adjusted by the\u00a0addition of\u00a0NaCl to a\u00a0final concentration of\u00a02\u00a0%. Exposure was carried out at a\u00a0stable temperature of\u00a015 \u00b1 0.2 \u00b0C and pH 7.0 for 15 and 30\u00a0minutes. The\u00a0target parameter was the\u00a0EC50 value, representing the\u00a0concentration causing a\u00a050% reduction in\u00a0bacterial luminescence intensity compared with the\u00a0control, calculated from six concentration points within\u00a0the\u00a0range of\u00a01\u2013200\u00a0mg\/L.<\/p>\n

Acute toxicity test using Daphnia magna<\/em><\/h3>\n

Determination of\u00a0acute immobilisation of\u00a0the\u00a0freshwater crustacean\u00a0Daphnia magna (Straus) was carried out in\u00a0accordance with \u010cSN EN ISO 6341 [21]. A\u00a0total of\u00a020 individuals younger than\u00a024 hours were used for testing. The\u00a0tests were conducted under static conditions for 48 hours in\u00a0vessels containing 50\u00a0mL of\u00a0test solution without feeding or aeration. The\u00a0temperature was maintained within\u00a0the\u00a0range of\u00a018\u201320 \u00b0C under a\u00a0photoperiod of\u00a016 hours of\u00a0light and\u00a08\u00a0hours of\u00a0darkness. The\u00a0target parameters were the\u00a0EC50 values after 24\u00a0h and 48 h, defined as the\u00a0concentration of\u00a0the\u00a0product causing immobilisation in\u00a050\u00a0% of\u00a0exposed individuals. Five to six concentration levels ranging from 0.1\u00a0to 100\u00a0mg\/L were used for the\u00a0determination.<\/p>\n

Growth inhibition test using Desmodesmus subspicatus<\/em><\/h3>\n

To evaluate effects on primary producers, a\u00a0growth inhibition test using the\u00a0freshwater alga Desmodesmus subspicatus was performed according to \u010cSN\u00a0EN ISO\u00a08692 [22]. Exposure was carried out in\u00a0Erlenmeyer flasks with an\u00a0initial density of\u00a010,000 cells\/mL in\u00a0ISO culture medium for 72 hours. Cultivation was conducted at a\u00a0temperature of\u00a023 \u00b1 1 \u00b0C under continuous illumination with an\u00a0intensity of\u00a09,000 \u00b1 1,000\u00a0lux and constant stirring. The\u00a0density of\u00a0algal cells was measured after 72 hours using a\u00a0counting chamber. The\u00a0resulting parameter was the\u00a0EC50 value, expressing 50% inhibition of\u00a0the\u00a0specific growth rate of\u00a0the\u00a0algal culture, calculated from five concentration levels within\u00a0the\u00a0range of\u00a01\u2013100\u00a0mg\/L.<\/p>\n

Phytotoxicity test using Sinapis alba<\/em> seeds<\/h3>\n

The\u00a0test using white mustard seeds was performed according to the\u00a0Methodological Guideline of\u00a0the\u00a0Waste Department for the\u00a0Determination of\u00a0Waste Ecotoxicity [23]. Seeds (30 per concentration per Petri dish) were placed in\u00a0duplicate on filter paper in\u00a0Petri dishes and moistened with 5\u00a0mL of\u00a0the\u00a0tested solution at the\u00a0required concentration. Incubation was carried out in\u00a0a\u00a0thermostat without access to light for 72 \u00b1 2 hours at a\u00a0temperature of\u00a020\u00a0\u00b1\u00a02 \u00b0C. The\u00a0monitored test parameter was the\u00a0average root length of\u00a0white mustard seedlings after 72 hours, from which growth inhibition was calculated.<\/p>\n

Calculation of\u00a0surfactant concentration in\u00a0the\u00a0samples<\/h3>\n

As the\u00a0product compositions are reported in\u00a0percentage ranges, the\u00a0maximum theoretical surfactant load (i.e. a\u00a0worst-case scenario) was calculated for the\u00a0purposes of\u00a0the\u00a0discussion; however, this calculation represents only a\u00a0theoretical estimate based on the\u00a0declarations provided on the\u00a0product packaging rather than\u00a0an\u00a0analytically determined value (Tab.<\/span>\u00a01<\/span><\/em>).<\/span><\/p>\n

\u00a0<\/span><\/span>The\u00a0following equation was used to calculate the\u00a0surfactant concentration in\u00a0the\u00a0tested sample (Csurfactant<\/span><\/sub>):<\/span><\/p>\n\"\"<\/a>\n

Statistical data analysis<\/h3>\n

The\u00a0tests were performed in\u00a0three independent replicates. Statistical analysis included the\u00a0calculation of\u00a0mean\u00a0values and standard deviations. EC50<\/span><\/sub> values were calculated using GraphPad Prism (GraphPad Software) by means of\u00a0a\u00a0four-parameter logistic curve based on nonlinear regression. The\u00a0statistical significance of\u00a0differences between the\u00a0mean\u00a0inhibition values of\u00a0the\u00a0tested solutions and the\u00a0negative control was assessed at a\u00a0significance level of\u00a0\u03b1\u00a0=\u00a00.05 (p < 0.05) using Student\u2019s\u00a0t-test.<\/span><\/p>\n

RESULTS<\/h2>\n

Validity of\u00a0bioassays and overall ecotoxicological profile<\/h3>\n

The\u00a0results of\u00a0the\u00a0EC50<\/span> determinations (Tab.\u00a02<\/span>) and inhibition at the\u00a0limit concentration of\u00a0100\u00a0mg\/L (Tab.\u00a03<\/span><\/em>) indicate that the\u00a0sensitivity of\u00a0the\u00a0tested organisms to detergent exposure decreased in\u00a0the\u00a0following order: the\u00a0water flea Daphnia magna<\/span><\/em> > the\u00a0alga Desmodesmus subspicatus<\/span><\/em> > the\u00a0bacterium Vibrio fischeri<\/span><\/em> > white mustard Sinapis alba<\/span><\/em>.<\/span><\/p>\n

Within\u00a0the\u00a0applied battery of\u00a0bioassays, white mustard (Sinapis alba<\/span><\/em>) seeds exhibited the\u00a0highest degree of\u00a0tolerance to the\u00a0tested products. In\u00a0none of\u00a0the\u00a0eight evaluated samples was 50% root growth inhibition reached within\u00a0the\u00a0tested concentration range, and all EC50<\/span> values are therefore reported as > 100 mg\/L. According to the GHS and CLP classification standards, the tested\u00a0<\/span>products therefore do not meet the\u00a0criteria for classification as acutely hazardous to this indicator from the\u00a0perspective of\u00a0phytotoxicity.<\/span><\/p>\n

At the\u00a0highest tested concentration of\u00a0100\u00a0mg\/L, a\u00a0very low mean\u00a0response was recorded, not exceeding 13\u00a0%. Statistical evaluation using Student\u2019s\u00a0t-test demonstrated that the\u00a0measured values did not differ significantly from the\u00a0negative control (p > 0.05). This lack of\u00a0statistical significance was primarily due to the\u00a0higher variability of\u00a0the\u00a0measured data, as the\u00a0standard deviation (SD) values frequently exceeded the\u00a0mean\u00a0inhibitory effect.<\/span><\/p>\n

In\u00a0half of\u00a0the\u00a0tested samples, negative inhibition, i.e. slight stimulation of\u00a0root growth, was recorded at a\u00a0concentration of\u00a0100\u00a0mg\/L. The\u00a0most pronounced stimulatory effect was observed for environmentally certified dishwasher tablets (\u221212.8 \u00b1 18.3\u00a0%) and conventional dishwasher capsules (\u22126.17\u00a0\u00b1\u00a012.2\u00a0%). This response is probably related to the\u00a0nutrient effect of\u00a0certain\u00a0components (e.g.\u00a0phosphonates or plant proteins) at low concentrations, which, in\u00a0more resistant organisms such as S.<\/span> alba<\/span>, obscures the\u00a0difference compared with growth in\u00a0the\u00a0control medium.<\/span><\/p>\n

The\u00a0observed high tolerance and absence of\u00a0adverse effects on the\u00a0initial developmental stages are fully consistent with studies confirming that detergents at common concentrations do not affect seed germination [7,\u00a024,\u00a025]. A\u00a0study by Uzma et al. (2018) on maize demonstrated that detergents in\u00a0the\u00a0range of\u00a01\u2013500\u00a0mg\/L had no significant effect on germination. Similarly, Khan\u00a0et al. reported that surfactant concentrations up to 100\u00a0mg\/L did not affect the\u00a0germination of\u00a0lettuce or garden cress. According to the\u00a0scientific literature, this resistance is attributed to the\u00a0barrier function of\u00a0the\u00a0seed coat, which effectively protects the\u00a0plant embryo from the\u00a0penetration of\u00a0toxic substances from the\u00a0external environment [25].<\/span><\/p>\n

Tab. 2. Results of acute ecotoxicity tests expressed as EC50 [mg\/L] for selected bioindicators<\/h5>\n\"\"<\/a>\n
Tab. 3. Results of acute ecotoxicity tests expressed as inhibitory effect [%] at a concentration of 100 mg\/L (mean \u00b1 SD)<\/h5>\n\"\"<\/a>\n

Comparative evaluation of\u00a0products<\/h3>\n

Laundry gels<\/span><\/strong><\/p>\n

The\u00a0category of\u00a0laundry gels yielded the\u00a0most surprising results, with the\u00a0environmentally certified product (environmentally certified laundry gel) exhibiting significantly higher toxicity than\u00a0the\u00a0conventional variant (conventional laundry gel). The\u00a0environmentally certified laundry gel was classified as highly toxic to both algae (72h EC50<\/span> 3.93\u00a0mg\/L) and water fleas (48h EC50<\/span> 5.49\u00a0mg\/L), representing approximately a\u00a0fourfold higher toxic pressure compared with the\u00a0conventional gel, whose EC50 <\/span>values ranged from 20.1 to 25.3\u00a0mg\/L. At the\u00a0limit concentration of\u00a0100\u00a0mg\/L, the\u00a0environmentally certified laundry gel caused complete immobilisation of\u00a0water fleas (100\u00a0%) as well as inhibition of\u00a0algal growth (99\u00a0%), which, together with the\u00a0low EC50<\/span> values, demonstrates the\u00a0high degree of\u00a0acute hazard posed by this environmentally certified product.<\/span><\/p>\n

Shampoos<\/span><\/strong><\/span><\/p>\n

In\u00a0the\u00a0shampoo category, the\u00a0trend was reversed and confirmed the\u00a0environmental friendliness of\u00a0the\u00a0certified cosmetic product. The\u00a0environmentally certified shampoo exhibited low acute toxicity, with EC50<\/span><\/sub> values above 100\u00a0mg\/L for most organisms (except for water fleas, 48h EC50<\/span><\/sub> 59.5\u00a0mg\/L), whereas the\u00a0conventional shampoo was toxic to both algae (EC50<\/span><\/sub> 17.3\u00a0mg\/L) and water fleas (48h EC50<\/span><\/sub> 19.8\u00a0mg\/L).<\/span><\/p>\n

For the environmentally certified shampoo, growth stimulation of algae (-59.5 %) was observed at a concentration of 100 mg\/L, indicating a nutrient effect of the contained plant extracts and proteins (e.g. hydrolysed corn, wheat, and soy proteins). In contrast, the conventional variant contained sodium laureth\u00a0<\/span>sulphate (SLES), which contributes to the\u00a0high inhibition of\u00a0biota. The\u00a0literature reports EC50 <\/span><\/sub>values of\u00a0SLES for Daphnia magna<\/span> in\u00a0the\u00a0range of\u00a02\u201320\u00a0mg\/L [26,\u00a027]. The\u00a0SLES content in\u00a0the\u00a0shampoo is unknown, as the\u00a0legislation does not require the\u00a0declaration of\u00a0percentage ranges of\u00a0surfactants on product packaging and no safety data sheet is available for this type of\u00a0product (Tab.\u00a01<\/span><\/em>, Tab.<\/span>\u00a04<\/span><\/em>).<\/span><\/p>\n

Tab. 4. Calculation of theoretical maximum surfactant content in products and normalization of toxicity (EC50<\/sub>) to active ingredient for D. magna<\/em><\/h5>\n\"\"<\/a>\n

Dishwasher detergents<\/span><\/p>\n

Products intended for dishwashers exhibited a\u00a0moderate degree of\u00a0toxicity within\u00a0the\u00a0applied battery of\u00a0bioassays, while significant differences in\u00a0the\u00a0sensitivity of\u00a0individual organisms were identified. The\u00a0most sensitive indicator for this category was the\u00a0water flea Daphnia magna<\/span>, for which the\u00a048h EC50<\/span> values ranged from 52.3\u00a0mg\/L (conventional dishwasher capsules) to 76.5\u00a0mg\/L (environmentally certified dishwasher tablets). At the\u00a0limit concentration of\u00a0100\u00a0mg\/L, both products caused almost complete immobilisation of\u00a0water fleas (94\u00a0% for conventional capsules and 100\u00a0% for environmentally certified tablets), indicating a\u00a0high risk to aquatic invertebrates in\u00a0the\u00a0event of\u00a0local overloading of\u00a0the\u00a0receiving environment.<\/span><\/p>\n

A\u00a0pronounced difference was observed in\u00a0the\u00a0effects on the\u00a0alga Desmodesmus subspicatus<\/span><\/em>. While the\u00a0conventional capsules exhibited only mild inhibition at 100\u00a0mg\/L (14.7\u00a0%), the\u00a0environmentally certified variant caused strong growth suppression (89.6\u00a0%), corresponding to the\u00a0measured EC50<\/span><\/sub> value of\u00a073.3\u00a0mg\/L. This paradox is noteworthy, as the\u00a0conventional product theoretically contains a\u00a0higher load of\u00a0surfactants (15\u00a0%) as well as bleaching agents (15\u201330\u00a0%) than\u00a0the\u00a0environmentally certified tablets (5\u00a0% surfactants and 5\u201315\u00a0% bleaching agents). The\u00a0toxicity of\u00a0the\u00a0environmentally certified variant is probably influenced by other specific additives acting as stress factors for algae.<\/span><\/p>\n

For the\u00a0bacterium Vibrio fischeri<\/span><\/em>, acute toxicity was negligible in\u00a0both samples, with inhibition below 16\u00a0% at a\u00a0concentration of\u00a0100\u00a0mg\/L; consequently, the\u00a0EC50<\/span><\/sub> values were > 100\u00a0mg\/L.<\/span><\/p>\n

Hand dishwashing detergents<\/span><\/strong><\/span><\/p>\n

Hand dishwashing detergents were identified as the\u00a0most environmentally benign category within\u00a0the\u00a0entire study. For all tested trophic levels, the\u00a0determined EC50 <\/span>values were consistently higher than\u00a0100\u00a0mg\/L, which classifies these products, according to the\u00a0criteria of\u00a0the\u00a0CLP Regulation, as substances with\/lout acute hazard to the\u00a0aquatic environment.<\/span><\/p>\n

At the\u00a0highest tested concentration of\u00a0100\u00a0mg\/L, only low levels of\u00a0inhibition were recorded: the\u00a0conventional detergent caused only 13.3\u00a0% inhibition in\u00a0water fleas, whereas the\u00a0environmentally certified variant caused 46\u00a0% inhibition. The\u00a0stronger effect of\u00a0the\u00a0environmentally certified detergent may be attributed to the\u00a0higher declared content of\u00a0the\u00a0anionic surfactant SLES (up to 25\u00a0%) compared with the\u00a0conventional sample (< 5\u00a0%).<\/span><\/p>\n

The\u00a0results obtained for bacteria and algae showed that inhibition ranged from 4.6 to 24.6\u00a0% for both product types, with the\u00a0lowest response recorded for the\u00a0bacterium Vibrio fischeri<\/span> (9.1\u201311.6\u00a0%).<\/span><\/p>\n

Statistical evaluation using Student\u2019s\u00a0t-test confirmed that, for most organisms (with the\u00a0exception of\u00a0water fleas exposed to the\u00a0environmentally certified variant), the\u00a0measured effect at a\u00a0concentration of\u00a0100\u00a0mg\/L did not differ significantly from the\u00a0negative control (p > 0.05). The\u00a0results confirm that, despite the\u00a0presence of\u00a0substances such as SLES or preservatives (isothiazolinones), the\u00a0final toxicity of\u00a0these mixtures is very low owing to dilution in\u00a0the\u00a0working solutions.<\/span><\/p>\n

DISCUSSION<\/h2>\n

The results of this study demonstrated pronounced differences in acute toxicity among the individual detergent categories, with the most marked effect observed for laundry gels. The environmentally certified laundry gel exhibited\u00a0<\/span>an\u00a0order of\u00a0magnitude higher toxicity towards the\u00a0tested aquatic organisms than\u00a0its conventional counterpart. However, the\u00a0main\u00a0factor underlying this increased toxicity was probably not the\u00a0\u201cECO\u201d nature of\u00a0the\u00a0formulation itself, but rather the\u00a0high overall surfactant content, which in\u00a0the\u00a0environmentally certified variant reached a\u00a0theoretical maximum of\u00a0up to 50\u00a0%, compared with approximately 20\u00a0% in\u00a0the\u00a0conventional product (Tab.\u00a04<\/span><\/em>).<\/span><\/p>\n

After recalculation of\u00a0the\u00a0EC50 <\/span><\/sub>values to the\u00a0concentration of\u00a0pure surfactants, the\u00a0toxic profiles of\u00a0both products became considerably more similar. For Daphnia magna<\/span><\/em>, the\u00a0surfactant concentration at the\u00a0EC50<\/sub>\u00a0<\/span>level reached approximately 2.75\u00a0mg\/L for the\u00a0environmentally certified gel and 4.02\u00a0mg\/L for the\u00a0conventional variant. This result suggests that surfactants represent the\u00a0dominant factor determining the\u00a0acute toxicity of\u00a0the\u00a0mixture in\u00a0both types of\u00a0formulation. At the\u00a0same time, this finding confirms that even substances with relatively favourable biodegradability may exert significant toxic pressure on aquatic organisms when present at high concentrations in\u00a0the\u00a0final product. Moreover, the\u00a0measured EC50<\/span> values approached environmentally relevant surfactant concentrations, which at WWTP effluents generally remain\u00a0below 1\u00a0mg\/L [8, 18, 31], although concentrations of\u00a0anionic surfactants exceeding 8\u00a0mg\/L have also been reported [18]. According to the\u00a0literature, chronic toxic effects on aquatic biota may occur at surfactant concentrations as low as approximately 0.1\u00a0mg\/L, indicating a\u00a0realistic risk of\u00a0both acute and chronic toxic effects even under conditions of\u00a0moderate local overloading of\u00a0the\u00a0receiving environment.<\/span><\/p>\n

Nevertheless, the\u00a0results of\u00a0toxicity normalisation to pure surfactant concentrations must be interpreted with awareness of\u00a0the\u00a0considerable uncertainty arising from the\u00a0manufacturers\u2019 practice of\u00a0declaring composition only within\u00a0broad percentage ranges. The\u00a0applied estimate (worst-case scenario), based on the\u00a0maximum possible concentration, may lead to theoretical overestimation of\u00a0the\u00a0surfactant load. This lack of\u00a0transparency regarding the\u00a0composition of\u00a0commercial mixtures, combined with the\u00a0inability to quantify surfactant content in\u00a0shampoos, confirms that, for water management practice, direct testing of\u00a0final formulations as a\u00a0whole represents a\u00a0more valid approach, as it is the\u00a0only method capable of\u00a0capturing synergistic interactions among all additives.<\/span><\/p>\n

The\u00a0slightly higher toxicity of\u00a0the\u00a0environmentally certified gel, even after recalculation to surfactant content, can\u00a0probably be attributed to the\u00a0synergistic effects of\u00a0additional additives, particularly enzymes. For example, the\u00a0proteolytic enzyme subtilisin\u00a0is classified as a\u00a0substance highly toxic to aquatic organisms (H400), and the\u00a0literature reports its ability to damage cellular structures even at relatively low concentrations [6]. These results support the\u00a0assumption that the\u00a0resulting toxicity of\u00a0detergent formulations is determined not only by surfactant concentration, but also by complex interactions among the\u00a0individual components of\u00a0the\u00a0mixture.<\/span><\/p>\n

The\u00a0necessity of\u00a0testing final products as complete formulations, rather than\u00a0only their isolated components, is further confirmed by the\u00a0paradox observed in\u00a0dishwasher detergents. In\u00a0this case, the\u00a0environmentally certified variant caused strong inhibition of\u00a0algae (89.6\u00a0%), whereas the\u00a0conventional capsules induced only mild inhibition (14.7\u00a0%), despite the\u00a0fact that the\u00a0conventional product contained a\u00a0threefold higher surfactant load (15\u00a0% vs. 5\u00a0%). This demonstrates that synergistic interactions occur within\u00a0complex mixtures and may amplify the\u00a0resulting toxic effect beyond the\u00a0level predicted from the\u00a0properties of\u00a0the\u00a0individual components.<\/span><\/p>\n

In\u00a0the\u00a0context of\u00a0discussions on the\u00a0environmental impacts of\u00a0detergents, interpretation of\u00a0the\u00a0\u201cECO\u201d label plays a\u00a0crucial role, as consumers perceive it as a\u00a0promise of\u00a0lower toxicity and high biodegradability [5, 27]. Market surveys indicate that more than\u00a050\u00a0% of\u00a0customers are willing to pay extra for such products. Nevertheless, the\u00a0literature expresses justified scepticism towards marketing claims not supported by independent certification, as the\u00a0proprietary composition of\u00a0products often prevents public scrutiny of\u00a0all contained substances [5].<\/span><\/p>\n

Despite the\u00a0stringent regulatory requirements for the\u00a0award of\u00a0the\u00a0EU Ecolabel, which primarily focus on the\u00a0biodegradability and environmental fate of\u00a0individual components, the\u00a0results of\u00a0this study confirm that environmental certification does not necessarily represent an\u00a0absolute guarantee of\u00a0lower acute toxicity of\u00a0the\u00a0final formulation across all trophic levels. This finding is fully consistent with the\u00a0conclusions of\u00a0Gray (2022), who also documented cases in\u00a0which \u201cECO\u201d products were more toxic to aquatic invertebrates than\u00a0their conventional alternatives [5]. Similar conclusions were reported by Igos (2014), who stated that dishwasher tablets bearing an\u00a0ecolabel did not exhibit a\u00a0significant advantage over standard phosphate-free products, with their ecotoxic potential being nearly identical [28].<\/span><\/p>\n

These findings underline the\u00a0necessity of\u00a0testing complete mixtures, as synergistic interactions among permitted additives (e.g. enzymes, fragrances, or preservatives) may modify the\u00a0resulting toxicity beyond the\u00a0level predicted from the\u00a0individual components [6, 16].<\/span><\/p>\n

The\u00a0present study primarily focused on the\u00a0acute ecotoxicity of\u00a0final formulations, which represents an\u00a0essential first step in\u00a0the\u00a0assessment of\u00a0environmental risks, although with certain\u00a0methodological limitations. The\u00a0main\u00a0limitation lies in\u00a0the\u00a0absence of\u00a0data on chronic toxicity, which is particularly important for detergents as pseudo-persistent pollutants; long-term exposure to sublethal concentrations in\u00a0receiving environments may affect the\u00a0reproduction, growth, and physiological functions of\u00a0biota in\u00a0ways that short-term tests are unable to capture [9, 29]. Furthermore, the\u00a0study did not address the\u00a0assessment of\u00a0genotoxicity and mutagenicity, although the\u00a0scientific literature confirms that complex mixtures of\u00a0surfactants and specific additives may induce DNA damage or increase micronucleus frequency even at concentrations that do not cause immediate mortality [6, 16, 30]. Additional limiting factors include the\u00a0insufficiently explored potential for endocrine disruption [31,\u00a032] and the\u00a0absence of\u00a0monitoring of\u00a0the\u00a0toxicity of\u00a0biodegradation intermediates, which in\u00a0some cases may exhibit greater hazard than\u00a0the\u00a0parent substances [11,\u00a016]. It should also be noted that only a\u00a0limited number of\u00a0products within\u00a0each category were tested, which may to some extent restrict the\u00a0generalisability of\u00a0the\u00a0obtained results; the\u00a0observed differences therefore cannot be unequivocally interpreted as a\u00a0universally applicable trend. Expansion of\u00a0the\u00a0test battery to include the\u00a0above-mentioned aspects will be the\u00a0subject of\u00a0a\u00a0follow-up study, enabling a\u00a0more comprehensive understanding of\u00a0the\u00a0long-term environmental impacts of\u00a0modern detergents.<\/span><\/p>\n

CONCLUSION<\/h2>\n

The\u00a0results of\u00a0this study indicate that, for water management practice and environmental risk assessment, it is essential to test final products as complete formulations rather than\u00a0relying solely on theoretical calculations (e.g. Critical Dilution Volume \u2013 CDV) or marketing labels [16]. Experimental data confirm that the\u00a0\u201cECO\u201d label cannot automatically be equated with low acute toxicity, which is consistent with the\u00a0findings of\u00a0previous studies that also documented cases of\u00a0higher toxicity of\u00a0\u201cgreen\u201d products to aquatic organisms [5]. Although the\u00a0EU Ecolabel certification guarantees improved biodegradability and restrictions on persistent substances, this benefit does not necessarily imply lower risk to biota in\u00a0the\u00a0event of\u00a0accidental discharge of\u00a0undiluted products into receiving waters. The\u00a0main\u00a0factor influencing toxicity remains the\u00a0presence of\u00a0highly concentrated formulations, in\u00a0which the\u00a0intrinsic hazard of\u00a0the\u00a0mixture is determined by the\u00a0extreme surfactant load (up to 50\u00a0%) and the\u00a0presence of\u00a0specific additives that, through synergistic interactions, may damage cell membranes even at low concentrations. The\u00a0study therefore underlines the\u00a0critical necessity of\u00a0using a\u00a0battery of\u00a0bioassays to validate manufacturers\u2019 environmental claims within\u00a0regulatory processes, as only direct testing of\u00a0complex mixtures can\u00a0capture the\u00a0actual toxic pressure exerted on aquatic ecosystems [16].<\/span><\/p>\n

Acknowledgements<\/h3>\n

This article was prepared within\u00a0the\u00a0framework of\u00a0the\u00a0long-term research activities of\u00a0TGM WRI, supported by institutional funding from the\u00a0Ministry of\u00a0the\u00a0Environment of\u00a0the\u00a0Czech Republic for the\u00a0long-term conceptual development of\u00a0the\u00a0research organisation.<\/span><\/span><\/em><\/p>\n

The\u00a0Czech version of\u00a0this article was peer-reviewed, the\u00a0English version was translated from the\u00a0Czech original by Environmental Translation Ltd.<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

Household detergents are an important source of complex mixtures of anthropogenic substances entering municipal wastewater systems and, subsequently, receiving waters. This study presents a comparative assessment of the acute ecotoxicity of conventional detergents and their environmentally certified counterparts (EU Ecolabel) using a battery of bioassays representing different trophic levels. The tests included the luminescent bacterium Vibrio fischeri, the water flea Daphnia magna, the green alga Desmodesmus subspicatus, and seeds of white mustard Sinapis alba.<\/p>\n","protected":false},"author":8,"featured_media":39116,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[94,87],"tags":[4156,4160,4162,4157,4163,4161,4158,4159],"coauthors":[1901],"class_list":["post-39118","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-current-issue","category-hydrochemistry-radioecology-microbiology","tag-acute-toxicity","tag-bacterium-vibrio-fischeri","tag-battery-of-bioassays","tag-detergents","tag-environmental-risk","tag-green-alga-desmodesmus-subspicatus","tag-surfactants","tag-water-flea-daphnia-magna"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/39118","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/users\/8"}],"replies":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/comments?post=39118"}],"version-history":[{"count":5,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/39118\/revisions"}],"predecessor-version":[{"id":39202,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/39118\/revisions\/39202"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/media\/39116"}],"wp:attachment":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/media?parent=39118"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/categories?post=39118"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/tags?post=39118"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/coauthors?post=39118"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}