CHLORPHENESIN

Chlorphenesin is a legitimate preservative commonly used in cosmetics. It shares one urinary metabolite of 4-chlorophenoxyacetic acid with meclofenoxate, a prohibited stimulant in sports. Recently, there have been cases where athletes using chlorphenesin-containing products were falsely identified as users of meclofenoxate. This study developed and validated a liquid chromatography method with diode-array detection to determine the chlorphenesin content in 61 selected personal care products with various functions (e.g., facial care, body cleansing, sun protection, make-up, hairstyling, perfume, and oral cleaning). The analytical method demonstrated fit-for-purpose quantitation and provided good linearity, precision, accuracy, and recovery for analyzing different cosmetic matrices. Among the 27 cosmetics labeled with chlorphenesin, the chlorphenesin concentrations ranged from 0.10 to 2.67 mg/g, with three products showing no detection. None of the products exceeded the maximum limit of 3 mg/g (0.3%) set by regulatory authorities. Among the 34 cosmetics not labeled with chlorphenesin, none of them contained chlorphenesin. This study confirmed the absence of undeclared chlorphenesin in the selected cosmetics, supporting the correctness of chlorphenesin labeling in cosmetics sold in Taiwan. Further investigations studying urinary excretion patterns after different types, doses, frequencies, and sites of cosmetics applications could contribute to strengthen current testing approaches in anti-doping.

Photolysis experiments of chlorphenesin, used as a preservative in cosmetic products, were performed in aqueous solution and on a cream used in cosmetics. Three by-products resulting from the direct UV-visible photodegradation of chlorphenesin were characterized by chromatography (gas and liquid) coupled with tandem mass spectrometry (GC-MS/MS and LC-HR MS/MS) and found in both solutions. In vitro tests on Vibrio fischeri bacteria showed that the overall ecotoxicity of chlorphenesin increased with increasing irradiation time in both samples. In silico QSAR (Quantitative Structure Activity Relationship) tests were performed using T.E.S.T. (Toxicity Estimation Software Tool). Among the degradation compounds identified, 4-chlorophenol must contribute to the increased ecotoxicity of the photolyzed solution since the in silico LC50 estimated for all tests performed are always lower than those obtained for chlorphenesin. Les expériences de photolyse de la chlorphénésine, qui s’utilise comme conservateur dans les produits cosmétiques, ont été réalisées en solution aqueuse et sur une crème utilisée dans les cosmétiques. Trois sous-produits résultant de la photodégradation directe UV-visible de la chlorphénésine ont été caractérisés par chromatographie (gaz et liquide) couplée à une spectrométrie de masse en tandem (GC-MS/MS et LC-HR MS/MS) et trouvés dans les deux solutions. Les tests in vitro sur les bactéries Vibrio fischeri ont montré que l’écotoxicité globale de la chlorphénésine augmentait avec l’augmentation du temps d’irradiation dans les deux échantillons. Des tests QSAR (Quantitative Structure Activity Relationship, relation d’activité de structure quantitative) in silico ont été réalisés à l’aide du logiciel T.E.S.T. (Toxicity Estimation Software Tool, outil logiciel d’estimation de la toxicité). Parmi les composés de dégradation identifiés, le 4-chlorophénol doit contribuer à l’augmentation de l’écotoxicité de la solution photolysée puisque la LC50 in silico estimée pour l’ensemble des essais réalisés est toujours inférieure à celle obtenue pour la chlorphénésine.

Chlorphenesin is an approved biocide frequently used in cosmetics, and its carbamate ester is an approved skeletal muscle relaxant in certain countries for the treatment of discomfort related to skeletal muscle trauma and inflammation. A major urinary metabolite is 4-chlorophenoxy acetic acid (4-CPA), also known as para-chlorophenoxyacetate, which is also employed as a target analyte in sports drug testing to detect the use of the prohibited nootropic stimulant meclofenoxate. To distinguish between 4-CPA resulting from chlorphenesin, chlorphenesin carbamate, and meclofenoxate, urinary metabolite profiles of chlorphenesin after legitimate use were investigated. Human administration studies with commercially available sunscreen containing 0.25% by weight of chlorphenesin were conducted. Six study participants dermally applied 8 g of sunscreen and collected urine samples before and up to 7 days after application. Another set of six study participants applied 8 g of sunscreen on three consecutive days, and urine samples were also taken for up to 5 days after the last dosing. Urine specimens were analyzed using liquid chromatography-high resolution (tandem) mass spectrometry, and urinary metabolites were identified in accordance with literature data by accurate mass analysis of respective precursor and characteristic product ions. In accordance with literature data, chlorphenesin yielded the characteristic urinary metabolites, chlorphenesin glucuronide, chlorphenesin sulfate, and 3-(4-chlorophenoxy)-2-hydroxypropanoic acid (4-CPP), as well as the common metabolite 4-CPA. 4-CPA and 4-CPP were observed at similar abundances, with urinary concentrations of 4-CPA reaching up to ~1500 and 2300 ng/mL after single and multiple sunscreen applications, respectively. 4-CPA is a common metabolite of meclofenoxate, chlorphenesin, and chlorphenesin carbamate. Monitoring the diagnostic urinary metabolites of chlorphenesin provides conclusive supporting evidence of whether chlorphenesin or the prohibited nootropic meclofenoxate was administered.

We evaluated the activity of the preservative chlorphenesin and of four antimicrobial cosmetic multifunctional ingredients against various strains of gram-negative and gram-positive human opportunistic pathogens. Growth kinetics, modelling growth parameters and statistical analyses enabled comparing bacterial behaviour in the presence and in the absence of the compound. Whatever compound tested (i.e. chlorphenesin, phenylpropanol, hexanediol, ethylhexylglycerin, hydroxyacetophenone) and strain origin (i.e. clinical versus industrial), the growth of 42 strains belonging to Acinetobacter spp., Burkholderia cepacia complex and Stenotrophomonas maltophilia, was totally inhibited. On the opposite all of the P. aeruginosa strains (n = 13) as well as 4 and 6 out of 10 strains of Pluralibacter gergoviae grew in the presence of chlorphenesin and ethylhexylglycerin, respectively. Some P. gergoviae and Staphylococcus hominis strains withstand hydroxyacetophenone. Within a species, the different strains show variable latency phase, growth rate (r) and carrying capacity (K). They can be similar, lower or higher than those measured in control conditions. Data showed differences in the antimicrobial activity of compounds. Upon exposure, strains differed in their behaviour between and within species. Whatever species and strains, compound sensitivity could not be related to antibiotic resistance. Most multifunctional ingredients showed significant antimicrobial properties against the wide panel of species and strains evaluated. This will help adjusting preservation strategies in the cosmetic industry.

Recently, we discovered that the cosmetic preservatives, benzalkonium chloride and formaldehyde, are especially toxic to human meibomian gland epithelial cells (HMGECs). Exposure to these agents, at concentrations approved for human use, leads within hours to cellular atrophy and death. We hypothesize that these effects are not unique, and that other cosmetic preservatives also exert adverse effects on HMGECs. Such compounds include parabens, phenoxyethanol and chlorphenesin, which have been reported to be toxic to corneal and conjunctival epithelial cells, the liver and kidney, as well as to irritate the eye. To test our hypothesis, we examined the influence of parabens, phenoxyethanol and chlorphenesin on the morphology, signaling, survival, proliferation and lipid expression of immortalized (I) HMGECs. These cells were cultured under proliferating or differentiating conditions with varying concentrations of methylparaben, ethylparaben, phenoxyethanol and chlorphenesin for up to 5 days. We monitored the signaling ability, appearance, number and neutral lipid content of the IHMGECs, as well as their lysosome accumulation. Our findings show that a 30-min exposure of IHMGECs to these preservatives results in a significant reduction in the activity of the Akt pathway. This effect is dose-dependent and occurs at concentrations equal to (chlorphenesin) and less than (all others) those dosages approved for human use. Further, a 24-h treatment of the IHMGECs with concentrations of methylparaben, ethylparaben, phenoxyethanol and chlorphenesin close to, or at, the approved human dose induces cellular atrophy and death. At all concentrations tested, no preservative stimulated IHMGEC proliferation. Of particular interest, it was not possible to evaluate the influence of these preservatives, at close to human approved dosages, on IHMGEC differentiation, because the cells did not survive the treatment. In summary, our results support our hypothesis and show that methylparaben, ethylparaben, phenoxyethanol and chlorphenesin are toxic to IHMGECs.

Doping with meclofenoxate, a nootropic stimulant prohibited in-competition by the World Anti-Doping Agency (WADA), is identified through the primary marker of urinary 4-chlorophenoxyacetic acid (4-CPA). However, the presence of 4-CPA can also arise from permissible sources. This study ventured into comparing urinary excretion patterns among exposures to permitted chemicals (chlorphenesin and 4-CPA) and the banned stimulant (meclofenoxate) and interpreting the analytical findings according to the reporting requirements. A validated method, utilising direct injection and ultra-performance liquid chromatography-tandem mass spectrometry, was employed for urine analysis. In the first experiment, participants applied chlorphenesin-containing cosmetics with varied functions, dosages, frequencies, and application sites. Sunscreen usage led to significantly higher urinary 4-CPA concentrations (up to 1049 ng/mL) as compared to others, highlighting the impact of cosmetic formulation composition for chlorphenesin delivery. The diagnostic marker for preservative exposure included 3-(4-chlorophenoxy)-2-hydroxypropanoic acid (4-CPP) and chlorphenesin and its conjugated metabolites, with 4-CPP reaching higher concentrations (C max of 903-7629 ng/mL) and for a longer period, up to 7-14 days. In the second experiment involving meclofenoxate supplement administration, urinary C max levels of 4-CPA were observed between 36,287 and 39,769 ng/mL at 3-10 h post-dosing, with the parent meclofenoxate undetected in all participants' samples. The third experiment, focused on occupational herbicide exposure in agricultural environments, detected minimal 4-CPA (< 10 ng/mL) in urine. WADA's current guidance for meclofenoxate aligns with reporting correct analytical results. Investigations, such as the experimental approach herein, offer valuable evidence addressing accuracy concerns in anti-doping tests, contributing insights for future amendments.

The safety assessment of cosmetic products is based on the safety of the ingredients, which requires information on chemical structures, toxicological profiles, and exposure data. Approximately 6% of the population is sensitized to cosmetic ingredients, especially preservatives and fragrances. In this context, the aim of this study was to perform a hazard assessment and risk characterization of benzalkonium chloride (BAC), benzyl alcohol (BA), caprylyl glycol (CG), ethylhexylglycerin (EG), chlorphenesin (CP), dehydroacetic acid (DHA), sodium dehydroacetate (SDH), iodopropynyl butylcarbamate (IPBC), methylchloroisothiazolinone and methylisothiazolinone (MCI/MIT), methylisothiazolinone (MIT), phenoxyethanol (PE), potassium sorbate (PS), and sodium benzoate (SB). Considering the integrated approaches to testing and assessment (IATA) and weight of evidence (WoE) as a decision tree, based on published safety reports. The hazard assessment was composed of a toxicological matrix correlating the toxicity level, defined as low (L), moderate (M), or high (H) and local or systemic exposure, considering the endpoints of skin sensitization, skin irritation, eye irritation, phototoxicity, acute oral toxicity, carcinogenicity, mutagenicity/genotoxicity, and endocrine activity. In a risk assessment approach, most preservatives had a margin of safety (MoS) above 100, except for DHA, SDH, and EG, considering the worst-case scenario (100% dermal absorption). However, isolated data do not set up a safety assessment. It is necessary to carry out a rational risk characterization considering hazard and exposure assessment to estimate the level of risk of an adverse health outcome, based on the concentration in a product, frequency of use, type of product, route of exposure, body surface location, and target population.

Most cosmetic products are susceptible to microbiological spoilage due to contaminations that could happen during fabrication or by consumer's repetitive manipulation. The composition of cosmetic products must guarantee efficient bacterial inactivation all along with the product shelf life, which is usually assessed by challenge-tests. A challenge-test consists in inoculating specific bacteria, i.e. Staphylococcus aureus, in the formula and then investigating the bacterial log reduction over time. The main limitation of this method is relative to the time-consuming protocol, where 30 days are needed to obtain results. In this study, we have proposed a rapid alternative method coupling High Content Screening-Confocal Laser Scanning Microscopy (HCS-CLSM), image analysis and modeling. It consists in acquiring real-time S. aureus inactivation kinetics on short-time periods (typically 4h) and in predicting the efficiency of preservatives on longer scale periods (up to 7 days). The action of two preservatives, chlorphenesin and benzyl alcohol, was evaluated against S. aureus at several concentrations in a cosmetic matrix. From these datasets, we compared two secondary models to determine the logarithm reduction time (Dc) for each preservative concentration. Afterwards, we used two primary inactivation models to predict log reductions for up to 7 days and we compared them to observed log reductions. The IQ model better fits datasets and the Q value gives information about the matrix level of interference.

A method was developed for the simultaneous determination of benzoic acid and its esters, parabens, phenoxyisopropanol, chlorphenesin, dehydroacetic acid, 2,6-di- tert -butyl-4-methylphenol, methylchloroisothiazolone, methylisothiazolone and other preservatives in cosmetics by gas chromatography-tandem mass spectrometry (GC-MS/MS). The samples were extracted ultrasonically with a 0.1 mg/mL L(+)-ascorbic acid menthol solution after being spiked with a mixture solution of 2-octanol, phenol and heptachlor as internal standards and anhydrous sodium sulfate as a dehydrating reagent. Finally, the extract was centrifuged, filtered, and then analyzed by GC-MS/MS. The analytes were separated using an HP-5MS capillary column (30 m×0.25 mm×0.25 μm) with a temperature-programming program. The inlet, transfer line and ion source temperatures were set to 260, 250 and 230℃, respectively. Helium (99.999%) was used as the carrier gas at a flow rate of 1 mL/min. The final extract (1 μL) was injected in split mode (10:1). Analysis was performed in the multiple reaction monitoring (MRM) mode. Three types of cosmetics, as well as water, milk and cream as samples were selected to verify the accuracy of the method at four levels. The average spiked recoveries ranged from 82.3% to 119.4% with relative standard deviations ( n =6) of less than 14.3%. The limits of detection were lower than 0.99 μg/kg for all the preservatives. The method is sensitive, and reliable for the simultaneous determination of the 25 preservatives in cosmetics. Nonetheless, complementary methods need to be developed for the determination of some other preservatives that cannot be detected by GC-MS/MS.

Hydrosols are hydrodistillation products used in food and cosmetic industries, perfumery, pharmacy and aromatherapy. The ability of preservatives to control previously reported bacterial proliferation and spoilage was evaluated. All tested preservatives were authorized for food and cosmetic application. Major pathogens of concern for foods and cosmetics were poorly able to grow in rose and orange blossom hydrosols when inoculated and incubated at 30°C. Commercial antimicrobials, such as isothiazolinone, chlorphenesin and paraben solutions, benzyl alcohol and sodium benzoate at pH = 5·0, controlled the growth of Pseudomonas and Burkholderia sp. strains representative of the natural microbiota of both hydrosols for >90 days at 30°C, only at concentrations close to the authorized limits. Concentrations of some of the tested preservatives that controlled growth at 5°C were lower than at 30°C. Pathogenic micro-organisms likely represent a low risk in rose flower and orange blossom hydrosol. However, the oligotrophic character of hydrosols and the antimicrobial properties of their essential oils do not prevent microbiological spoilage by the naturally present microbiota. In the absence of aseptic conditions and microbial inactivation process, only preservatives can stabilize hydrosols for a several-month storage. Several effective preservatives have been identified.