Occurrence and concentrations of isothiazolinones in detergents and cosmetics in Switzerland

Current frequency of contact allergy to isothiazolinones (methyl-, benz- and octylisothiazolinone) across Europe

BACKGROUND

The use of methylisothiazolinone (MI) as a preservative in cosmetic products caused an alarming increase in MI contact allergy across Europe in the 2010s. This was followed by regulations of use with a total ban on leave-on (implemented in 2017) and reduced use concentrations in rinse-off cosmetics (2018).

OBJECTIVE

To follow-up on the prevalence of contact allergy to MI and the related benzisothiazolinone (BIT) and octylisothiazolinone (OIT) in consecutively patch-tested patients in Europe.

METHODS

A cross-sectional audit following the design of two previous audits on MI contact allergy from 1 May 2022 to 31 October 2022 included all patients patch tested with the European baseline series, including or supplemented with MI, BIT and OIT across 10 departments in eight European countries.

RESULTS

A total of 2554 patients were consecutively patch tested with the three isothiazolinones during the study period. The prevalence of MI and BIT contact allergy was 2.9% (95% confidence interval [CI]: 2.3%-3.7%; range 1.1%-5.8%) and 3.1% (95% CI: 2.4%-3.9%; range 0.0%-6.6%), respectively; that of OIT was 0.7% (95% CI: 0.4%-1.1%; range 0%-3.2%). Rinse-off cosmetic (73.3%) and leave-on cosmetic products (13.3%) were still associated with eliciting allergic contact dermatitis to MI.

CONCLUSION

We confirmed a positive impact of regulatory measures on the prevalence of MI contact allergy in Europe, which halved compared to 2015. However, our data suggest that consumers may still be exposed to older cosmetic products containing MI. BIT has superseded MI in causing contact allergy, despite not being allowed for use in cosmetic products.

Increasing non-cosmetic exposure and sensitization to isothiazolinones require action for prevention: Review

Frequent use of methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) and MI in cosmetic products has been the main cause of widespread sensitization and allergic contact dermatitis to these preservatives (biocides). Their use in non-cosmetic products is also an important source of sensitization. Less is known about sensitization rates and use of benzisothiazolinone (BIT), octylisothiazolinone (OIT), and dichlorooctylisothiazolinone (DCOIT), which have never been permitted in cosmetic products in Europe. BIT and OIT have occasionally been routinely patch-tested. These preservatives are often used together in chemical products and articles. In this study, we review the occurrence of contact allergy to MI, BIT, OIT, and DCOIT over time, based on concomitant patch testing in large studies, and case reports. We review EU legislations, and we discuss the role of industry, regulators, and dermatology in prevention of sensitization and protection of health. The frequency of contact allergy to MI, BIT, and OIT has increased. The frequency of contact allergy to DCOIT is not known because it has seldom been patch-tested. Label information on isothiazolinones in chemical products and articles, irrespective of concentration, is required for assessment of relevance, information to patients, and avoidance of exposure and allergic contact dermatitis.

Decoding Cosmetic Complexities: A Comprehensive Guide to Matrix Composition and Pretreatment Technology

Despite advancements in analytical technologies, the complex nature of cosmetic matrices, coupled with the presence of diverse and trace unauthorized additives, hinders the application of these technologies in cosmetics analysis. This not only impedes effective regulation of cosmetics but also leads to the continual infiltration of illegal products into the market, posing serious health risks to consumers. The establishment of cosmetic regulations is often based on extensive scientific experiments, resulting in a certain degree of latency. Therefore, timely advancement in laboratory research is crucial to ensure the timely update and adaptability of regulations. A comprehensive understanding of the composition of cosmetic matrices and their pretreatment technologies is vital for enhancing the efficiency and accuracy of cosmetic detection. Drawing upon the China National Medical Products Administration's 2021 Cosmetic Classification Rules and Classification Catalogue, we streamline the wide array of cosmetics into four principal categories based on the following compositions: emulsified, liquid, powdered, and wax-based cosmetics. In this review, the characteristics, compositional elements, and physicochemical properties inherent to each category, as well as an extensive overview of the evolution of pretreatment methods for different categories, will be explored. Our objective is to provide a clear and comprehensive guide, equipping researchers with profound insights into the core compositions and pretreatment methods of cosmetics, which will in turn advance cosmetic analysis and improve detection and regulatory approaches in the industry.

Physiological impact of personal care product constituents on non-target aquatic organisms

Personal care products (PCPs) are products used in cleaning, beautification, grooming, and personal hygiene. The rise in diversity, usage, and availability of PCPs has resulted in their higher accumulation in the environment. Thus, these constitute an emerging category of environmental contaminants due to the potential of its constituents (chemical and non-chemical) to induce various physiological effects even at lower concentrations (ng/L). For analyzing the impact of the PCPs constituents on the non-target organism about 300 article including research articles, review articles and guidelines were studied from 2000 to 2023. This review aims to firstly discuss the fate and accumulation of PCPs in the aquatic environment and organisms; secondly provides overview of environmental risks that are linked to PCPs; thirdly review the trends, current status of regulations and risks associated with PCPs and finally discuss the knowledge gaps and future perspectives for future research. The article discusses important constituents of PCPs such as antimicrobials, cleansing agents and disinfectants, fragrances, insect repellent, moisturizers, plasticizers, preservatives, surfactants, UV filters, and UV stabilizers. Each of them has been found to display certain toxic impact on the aquatic organisms especially the plasticizers and UV filters. These continuously and persistently release biologically active and inactive components which interferes with the physiological system of the non-target organism such as fish, corals, shrimps, bivalves, algae, etc. With a rise in the number of toxicity reports, concerns are being raised over the potential impacts of these contaminant on aquatic organism and humans. The rate of adoption of nanotechnology in PCPs is greater than the evaluation of the safety risk associated with the nano-additives. Hence, this review article presents the current state of knowledge on PCPs in aquatic ecosystems.

Potential for Allergic Contact Dermatitis in Popular Hair Care Practices and Ingredients

The incidence of allergic contact dermatitis (ACD) due to personal care products is rising in parallel with increasing product availability and consumer interest. Hair products specifically represent a significant source of potential allergens, including preservatives, surfactants, emulsifiers, fragrances, adhesives, and dyes. ACD due to hair care products can present as dermatitis in the distinctive "rinse-off" distribution, involving the neck, eyelids, and lateral face in addition to the scalp. Herein, the authors review ingredients in hair care products that can cause ACD and practical tips for allergen identification.

Acute Toxicity and Stress Behaviour of Heterobranchus bidorsalis Exposed to the Detergent Nittol® NTL

The acute toxicity of the detergent Nittol® 0.8, 1.0, 1.2, 1.4, 1.6, and 0.0 mg NTL/L of clean water on Heterobrunchus bidorsalis, 5.5 ± 0.3 g, 6.4 ± 0.5 cm were investigated, using semi-static bioassay, for 96 h in 50 L capacity plastic test bowls. The fingerlings of the same brood stock and age were collected from Onose Farms Limited, Ughelli, Delta State to the University Research Laboratory, Enugu Lat. 7.4 N; 8°7′5 and long 6°8′ E. 7°6′ W. The test fish were acclimatized for 14 days, and fed at 3% body weight once daily, on a 40% CP commercial diet. Feeding was suspended 24 h before and during the range finding and acute tests. The whole set-up was replicated three times, and no death was recorded during the acclimatization period and in the control. A total of 180 fingerlings were used, and 10 fingerlings were assigned to each replicate. The test set-up was monitored daily for water quality parameters, opercular ventilation, tail fin beat frequency, and mortality. Dose and time-dependent behavioural patterns exhibited by the test fish, during the exposure periods include rapid swimming, air gulping, loss of balance, and a period of convulsion before death. Significant elevation in pH and temperature, reduction of DO compared to the control (p < 0.05) in the water quality, and dose-dependent early elevation of the tail and fin movements declined towards the end of the experiment. The 96 h LC50 was determined to be 1.41 mg/L, indicating that the detergent NTL is toxic to the test fish. The haematological parameters were significantly (p < 0.05) reduced in the treated ranges of RBC 5.20 ± 0.07–8.00 ± 0.02 × 106 mm3, HB 7.53 ± 0.50–10.72 ± 0.14 g/dl, PCV 13.20 ± 0.8.50–18.00 ± 0.43 % below their elevated respective controls of 10.50 ± 0.01 × 10 6 mm3, 11.00 ± 0.01 g/dl, and 23.48 ± 0.2.6 %. The white blood cells (WBC) recorded a significant (p < 0.05) increase in ranges of 23.72 ± 0.14–51.80 ± 1.9 × 103 mm3 above the control value of 11.00 ± 0.01 × 103 mm3 Therefore, values greater than the safe amount of 0.014 mg/L should not be allowed in the receiving culture waters for Heterobrunchus bidorsalis fingerlings.

Analytical Method Development of Benzisothiazolinone, a Biocide, Using LC-MS/MS and a Pharmacokinetic Application in Rat Biological Matrices

Benzisothiazolinone (BIT), a biocide widely used as a preservative in household cleaning and personal care products, is cytotoxic to lung cells and a known skin allergen in humans, which highlights the importance of assessing its toxicity and pharmacokinetics. In this study, a simple, sensitive, and accurate LC−MS/MS method for the quantification of BIT in rat plasma, urine, or tissue homogenates (50 μL) using phenacetin as an internal standard was developed and validated. Samples were extracted with ethyl acetate and separated using a Kinetex phenyl−hexyl column (100 × 2.1 mm, 2.6 μm) with isocratic 0.1% formic acid in methanol and distilled water over a run time of 6 min. Positive electrospray ionization with multiple reaction monitoring transitions of m/z 152.2 > 134.1 for BIT and 180.2 > 110.1 for phenacetin was used for quantification. This assay achieved good linearity in the calibration ranges of 2−2000 ng/mL (plasma and urine) and 10−1000 ng/mL (tissue homogenates), with r ≥ 0.9929. All validation parameters met the acceptance criteria. BIT pharmacokinetics was evaluated via an intravenous and dermal application. This is the first study that evaluated BIT pharmacokinetics in rats, providing insights into the relationship between BIT exposure and toxicity and a basis for future risk assessment studies in humans.

Cosmetic Preservatives: Hazardous Micropollutants in Need of Greater Attention?

In recent years, personal care products (PCPs) have surfaced as a novel class of pollutants due to their release into wastewater treatment plants (WWTPs) and receiving environments by sewage effluent and biosolid-augmentation soil, which poses potential risks to non-target organisms. Among PCPs, there are preservatives that are added to cosmetics for protection against microbial spoilage. This paper presents a review of the occurrence in different environmental matrices, toxicological effects, and mechanisms of microbial degradation of four selected preservatives (triclocarban, chloroxylenol, methylisothiazolinone, and benzalkonium chloride). Due to the insufficient removal from WWTPs, cosmetic preservatives have been widely detected in aquatic environments and sewage sludge at concentrations mainly below tens of µg L^-1. These compounds are toxic to aquatic organisms, such as fish, algae, daphnids, and rotifers, as well as terrestrial organisms. A summary of the mechanisms of preservative biodegradation by micro-organisms and analysis of emerging intermediates is also provided. Formed metabolites are often characterized by lower toxicity compared to the parent compounds. Further studies are needed for an evaluation of environmental concentrations of preservatives in diverse matrices and toxicity to more species of aquatic and terrestrial organisms, and for an understanding of the mechanisms of microbial degradation. The research should focus on chloroxylenol and methylisothiazolinone because these compounds are the least understood.

Preservatives in non-cosmetic products: Increasing human exposure requires action for protection of health

The widespread use of skin sensitizing preservatives is well-known. Contact allergy to preservatives is often caused by their presence in cosmetic products. Preservative use in non-cosmetic products is less well-known. We have reviewed European Union (EU) legislations on classification and labelling, biocides and cosmetics, concerning conditions for use of the most used sensitizing preservatives (including formaldehyde-releasing substances, isothiazolinones and parabens). We have analysed temporal trends in their use in non-cosmetic products (tonnes, number of products, concentrations), based on annual reports to the Swedish Products Register 1995-2018; and we discuss implications for stakeholders. Major changes over time are that the use of most of the preservatives has increased by tonnes and/or by number of products, and that several use concentrations have declined following harmonized classification as a skin sensitizer with low concentration limits for this classification. We conclude that the massive increase in use of preservatives is alarming, and that urgent action is needed for protection of health. Their use in non-cosmetic products is broad, increasing and often undisclosed. In the EU, legislations concerning chemicals can provide relevant restrictions to reduce their use and associated health risks, monitored by efficient surveillance. Prevention would be benefited by better coordination between legislations.

Identification of combinations of endocrine disrupting chemicals in household chemical products that require mixture toxicity testing

People are exposed to various chemicals contained in consumer products for which the risks are poorly characterized. There is growing evidence that exposure to endocrine disrupting chemicals (EDCs) through product use potentially affects development, behavior, and reproduction. However, limited information is available about common combinations of chemicals based on their appearance and potential health effects. The present study listed the ingredients contained in 11064 household chemical products from a publicly available database, and identified EDCs related to estrogenicity, androgenicity, thyroid hormone disruption, and changes in steroidogenesis. Association rule mining was applied to the dataset to identify frequent combinations of chemicals or commonly occurring EDCs contained in a single product. Among the target products, ingredient names were matched with 1241 chemical identifiers. A total of 293 chemicals were related to endocrine disruption, and nearly two-thirds of the products contained more than one of these chemicals. Cleaning products, synthetic detergents, fabric softeners, air fresheners, and deodorants have several hotspots for fragrances, isothiazolinones, glycol ethers, and parabens. The three most prevalent EDCs in household chemical products were added to act as fragrances and preservatives. The present study demonstrated that commonly occurring chemical combinations can be derived using an association rule mining algorithm. The results of this study will be useful in prioritizing chemical combinations and developing management plans for EDC mixture in consumer products.

Functional and dynamic mitochondrial damage by chloromethylisothiazolinone/methylisothiazolinone (CMIT/MIT) mixture in brain endothelial cell lines and rat cerebrovascular endothelium

The mixture of 5-chloro-2-methyl-4-isothiazolin-3-one (CMIT, chloromethylisothiazolinone) and 2-methyl-4-isothiazolin-3-one (MIT, methylisothiazolinone) is a commonly used biocide in consumer products. Despite the health issues related to its usage in cosmetics and humidifier disinfectants (HD), understanding its adverse outcome is still limited. Using in vitro cell lines and ex vivo rat models, we examined the effects of CMIT/MIT on the cellular redox homeostasis and energy metabolism in the brain microvascular endothelium, a highly restrictive interface between the bloodstream and brain. In murine bEND.3 and human hCMEC/D3, CMIT/MIT significantly amplified the mitochondrial-derived oxidative stress causing disruption of the mitochondrial membrane potential and oxidative phosphorylation at a sub-lethal concentration (1 μg/mL) or treatment duration (1 h). In addition, CMIT/MIT significantly increased a dynamic imbalance between mitochondrial fission and fusion, and endogenous pathological stressors significantly potentiated the CMIT/MIT-induced endothelial dysfunction. Notably, in the brain endothelium isolated from intravenously CMIT/MIT-administered rats, we observed significant mitochondrial damage and decreased tight junction protein. Taken together, we report that CMIT/MIT significantly impaired mitochondrial function and dynamics resulting in endothelial barrier dysfunction, giving an insight into the role of mitochondrial damage in CMIT/MIT-associated systemic health effects.

Occurrence and Transport of Isothiazolinone-Type Biocides from Commercial Products to Aquatic Environment and Environmental Risk Assessment

This study investigated the occurrence and transport of four isothiazolinone-type biocides from commercial products to wastewater treatment plants (influents, sludges, and effluents) and to natural emissaries (upstream and downstream the wastewater treatment plants) in Romania. All four biocides were determined in personal care and household products, with the highest concentration of 76.4 µg/L OIT (2-octyl-4-isothiazolin-3-one). For environmental samples, three of the four isothiazolinones were determined, CMI (5-chloro-2-methyl-4-isothiazolin-3-one) being the prominent compound for water samples. The maximum concentration of 84.0 µg/L in influent, 122 µg/L upstream, and 144 µg/L downstream the wastewater treatment plants were obtained for CMI. Unlike water samples, in the sewage sludge samples, OIT proved to be the dominant compound, with concentration up to 5.80 µg/g d.w. The extremely high levels of isothiazolinone determined in different WWTPs from Romania may be due to the COVID-19 pandemic situation, during which a much larger amount of cleaning, hygiene, and personal care products was used. The isothiazolinone-type biocides were readily removed from the influents of the five WWTPs, with the mean removal rate up to 67.5%. The mean mass loading value for the targeted biocides based on influent was 20.4 μg/day/1000 people, while the average environmental emissions were 6.93 μg/day/1000 people for effluents. The results obtained for riverine water combine with statistical analysis showed that the anthropogenic activities are the major contamination sources of the surface waters. Preliminary ecological risk evaluation showed that BIT (1,2-benzisothiazol-3(2H)-one), OIT, and CMI could pose a very high risks to different aquatic species living in the receiving aquatic environments.

An Ecotoxicological Evaluation of Four Fungal Metabolites with Potential Application as Biocides for the Conservation of Cultural Heritage

Biocides based on chemical synthetic compounds have been commonly used to counteract damages caused by microorganisms on stone cultural heritage. However, in the last few years, the use of commercial and traditional biocides has been banned and/or limited due to their dangerous profile for the environment, as well as human and animal health. Natural products could be used as suitable alternatives for cultural heritage purposes, as they have low toxicity and stability compared with synthetic pesticides. Even if most of the investigated solutions have already shown promising results, their efficiency, ecotoxicological, and chemical features are poorly investigated. In this manuscript, we aimed to evaluate the ecotoxicological profile of four fungal metabolites-namely, cavoxin, epi-epoformin, seiridin, and sphaeropsidone-with potential antimicrobial properties for monumental artworks. A battery of ecotoxicological tests using Aliivibrio fischeri (bacterium), Raphidocelis subcapitata (alga), Raphanus sativus L. (macrophyte), Daphnia magna (crustacean), and Caenorhabditis elegans (nematode) revealed a relative lower toxicity of these compounds, especially when compared with Preventol^® and Rocima^®, commercial biocides mainly used for the conservation of cultural heritage.

Quantification of Preservatives in Tattoo And Pmu Inks in The Frame of The New Requirements Under Reach Regulation

BACKGROUND

According to the REACH restriction, tattoo and permanent make-up (PMU) inks placed on the EU market after 4th January 2022 shall not contain methylisothiazolinone (MI), benzisothiazolinone (BIT), octylisothiazolinone (OIT) or other skin sensitisers in concentrations ≥10 mg/kg and phenoxyethanol (PE) or other eye irritants or damaging substances in concentrations ≥100 mg/kg. In addition, preservatives and other substances enlisted in Annex II to Cosmetic Product Regulation shall not be present in concentrations ≥0.5 mg/kg.

OBJECTIVES

Quantification of 14 preservatives in 99 tattoo and 39 PMU inks from the Italian market and comparison with concentration limits set by REACH restriction.

MATERIALS AND METHODS

Inks were analysed by applying validated analytical methods based on liquid-chromatography techniques.

RESULTS

About 24.0% and 1.5% of the overall samples contained BIT and OIT respectively in concentrations ≥10 mg/kg; PE was detected at concentrations ≥100 mg/kg in 15.2% of samples. Number of non-compliant tattoo inks (49.5%) would be significantly greater than PMU samples (17.9%).

CONCLUSIONS

About 40.6% of the samples would be non-compliant with the restriction for the presence of preservatives above the permitted level. Additional concentration limits will apply to skin sensitising preservatives for proper labelling of inks under CLP Regulation. This article is protected by copyright. All rights reserved.

Effects of methylisothiazolinone and octylisothiazolinone on development and thyroid endocrine system in zebrafish larvae

Methylisothiazolinone (MIT) and octylisothiazolinone (OIT) are used as preservatives and biocides to prevent product decay or deterioration. In the present study, developmental toxicity and the effect on the thyroid endocrine system were investigated in zebrafish embryos exposed to MIT and OIT for 96 h. Coagulation was significantly increased when zebrafish embryos were exposed to a concentration of 300 μg/L MIT and ≥ 0.3 μg/L OIT, resulting in a significant decrease in hatchability and larvae survival. The body length in zebrafish larvae exposed to 30 μg/L OIT was significantly shorter than that of the control group. The whole-body levels of triiodothyronine and thyroxine were significantly decreased in larvae exposed to MIT and OIT. Significant upregulation of crh, trh, tshβ, and tshr genes and downregulation of trαa, tg, ttr, and deio2 genes were observed in fish exposed to two isothiazolinones. The expression of dre-miR-193b and dre-miR-499 was significantly increased in zebrafish larvae exposed to MIT and OIT, indicating that epigenetic deregulation of miRNAs modulated genes involved in thyroid hormone regulation. OIT has a higher magnitude of toxicity than MIT, corresponding to the observed changes in thyroid hormones and developmental toxicity.

Comparative study of two isothiazolinone biocides, 1,2-benzisothiazolin-3-one (BIT) and 4,5-dichloro-2-n-octyl-isothiazolin-3-one (DCOIT), on barrier function and mitochondrial bioenergetics using murine brain endothelial cell line (bEND.3)

Isothiazolinone (IT) biocides are potent antibacterial substances used as preservatives and disinfectants. These biocides exert differing biocidal effects and display environmental stability based upon chemical structure. In agreement with our recent study reporting that 2-n-octyl-4-isothiazolin-3-one (OIT) induced dysfunction of the blood-brain barrier (BBB), the potential adverse health effects of two IT biocides 1,2-benzisothiazolin-3-one (BIT) and 4,5-dichloro-2-n-octyl-isothiazolin-3-one (DCOIT) were compared using brain endothelial cells (ECs) derived from murine brain endothelial cell line (bEND.3). BIT possesses an unchlorinated IT ring structure and used as a preservative in cleaning products. DCOIT contains a chlorinated IT ring structure and employed as an antifouling agent in paints. Data demonstrated that DCOIT altered cellular metabolism at a lower concentration than BIT. Both BIT and DCOIT increased reactive oxygen species (ROS) generation at the mitochondrial and cellular levels. However, the effect of DCOIT on glutathione (GSH) levels appeared to be greater than BIT. While mitochondrial membrane potential (MMP) was decreased in both BIT- and DCOIT-exposed cells, direct disturbance in mitochondrial bioenergetic flux was only observed in BIT-treated ECs. Taken together, IT biocides produced toxicity in brain EC and barrier dysfunction, but at different concentration ranges suggesting distinct differing mechanisms related to chemical structure.

Development and validation of a UPLC-MS/MS method for the quantification of isothiazolinones in the composition and emissions from consumer products

Isothiazolinones, a family of biocides, are used as preservatives for their fungicidal, bactericidal, and algacidal properties. These compounds can be found in a wide range of consumer and building products, such as paints, varnishes, shampoos, and liquid detergents. A robust analytical UPLC-MS/MS method to identify and quantify seven isothiazolinones (MIT, CMI, BIT, MBIT, BBIT, OIT, and DCOIT) in consumer products and their emissions was developed and validated according to ISO/IEC 17025. The limits of detection (LODs) ranged from 0.14 μg L^-1 (BIT) to 0.54 μg L^-1 (CMI). The method was applied for the quantification of the seven isothiazolinones in four types of consumer products (i.e., cosmetics, air fresheners, cleaning products, and building products) and the indoor emissions from a paint. Matrix effects were observed for the shampoo (63-74%), the shower gel (67-84%), and the ceramic glass cleaner (53-57%). All isothiazolinones indicated by the manufacturer (i.e., MIT, CMI, BIT, OIT, and DCOIT) were detected in the products and successfully quantified by the UPLC-MS/MS method.

Probabilistic risk assessment of preservatives in dishwashing detergents and wet wipes for Korean consumers

Preservatives are essential additives in dishwashing detergents and wet wipes. Ensuring the safe use of preservatives in products is important for public health, as some preservatives are associated with health issues. In this study, the content of 12 preservatives in 105 dishwashing detergents and 105 wet wipes was determined, where these compounds are commonly found, among consumer products. A realistic exposure estimation was considered by using Korean consumer-specific exposure parameters for adults and babies. A probabilistic risk assessment was conducted by applying the Monte Carlo simulation method. Benzoic acid (41%) and cetylpyridinium chloride (30%) were the most commonly used preservatives in dishwashing detergents and wet wipes, respectively, although their content in different products (benzoic acid: 0.28-19.4 mg/g in dishwashing detergents; cetylpyridinium chloride: 0.003-0.64 mg/g in wet wipes) varied widely. The calculated median and upper-limit margin of safety (MOS) values related to systemic health effects and skin sensitization from exposure to preservatives largely exceeded the target MOS, which confirmed the safety of the products. Exposure to preservatives from wet wipes was several times higher in babies than in adults. Sensitivity analysis revealed that the amount of the product used, frequency of use, and weight fraction of the preservative were the major contributors to the exposure to preservatives from dishwashing detergents and wet wipes.

Evolution of methylisothiazolinone sensitization: a Belgian multicentric study from 2014 to 2019

BACKGROUND

In the 2010s an epidemic of allergic contact dermatitis to methylisothiazolinone occurred in Europe. European authorities banned the use of methylisothiazolinone in leave-on cosmetics in 2017 and limited its use in rinse-off products in 2018.

OBJECTIVES

To investigate the sensitization rate to methylisothiazolinone in Belgium between January 2014 and December 2019, and to assess co-sensitizations to octylisothiazolinone and benzisothiazolinone in methylisothiazolinone -sensitized patients.

METHODS

A retrospective study of patch test results with methylisothiazolinone, octylisothiazolinone and benzisothiazolinone observed in patients attending five Belgian hospitals.

RESULTS

Overall, 560 of 10.029 patients (5.58%) had a positive patch test reaction to methylisothiazolinone, and its sensitization rate decreased from 7.9% in 2014 to 3.1% in 2019. Rinse-off cosmetics, paints and detergents were the most prevalent sensitization sources in recent years. Simultaneous reactions readily occurred to octylisothiazolinone, and, surprisingly, and increasingly, also to benzisothiazolinone.

CONCLUSIONS

Contact allergy to methylisothiazolinone in Belgium has reached a pre-epidemic level, reflecting the impact of recent regulatory measures. Leave-on cosmetics, in contrast to rinse-off products, have almost disappeared as sensitization sources in Europe. Paints and detergents also remain problematic. The remarkably high number of patients (co-) sensitized to benzisothiazolinone should be a focus of future research. This article is protected by copyright. All rights reserved.

Controversy around parabens: Alternative strategies for preservative use in cosmetics and personal care products

Parabens usage as preservatives in cosmetics and personal care products have been debated among scientists and consumers. Parabens are easy to production, effective and cheap, but its safety status remains controversial. Other popular cosmetics preservatives are formaldehyde, triclosan, methylisothiazolinone, methylchloroisothiazolinone, phenoxyethanol, benzyl alcohol and sodium benzoate. Although their high antimicrobial effectiveness, they also exhibit some adverse health effects. Lately, scientists have shown that natural substances such as essential oils and plant extracts present antimicrobial potential. However, their use in cosmetic is a challenge. The present review article is a comprehensive summary of the available methods to prevent microbial contamination of cosmetics and personal care products, which can allow reducing the use of parabens in these products.

New data on the metabolism of chloromethylisothiazolinone and methylisothiazolinone in human volunteers after oral dosage: excretion kinetics of a urinary mercapturic acid metabolite ("M-12")

Methylisothiazolinone (MI) as well as the mixture of chloromethylisothiazolinone/methylisothiazolinone [MCI/MI (3:1)] are biocides that are used in a variety of products of every-day life. Due to the skin sensitizing properties of these biocides, their use has come under scrutiny. We have previously examined the human metabolism of MI and MCI after oral dosage of isotope-labelled analogues in human volunteers and confirmed N-methylmalonamic acid to be a major, but presumably unspecific human urinary metabolite. In the present study, we have investigated the urinary kinetics of a mercapturic acid metabolite of MI and MCI using the same set of samples. Four human volunteers received 2 mg of isotopically labelled MI and MCI separately and at least 2 weeks apart. Consecutive urine samples were collected over 48 h and were examined for the content of the (labelled) 3-mercapturic acid conjugate of 3-thiomethyl-N-methyl-propionamide (“M-12”), a known metabolite in rats. On a molar basis, M-12 represented 7.1% (3.0–10.1%) of the dose excreted in urine after dosage of MI. Excretion of this mercapturate was fast with a mean half-life of 3.6 h. Surprisingly, for MCI the mercapturate M-12 represented only 0.13% of the dose excreted in urine. Thus, this biomarker is highly specific for exposures to MI and might be used to distinguish between different exposure patterns of these biocides [use of MI or MCI/MI (3:1)] in the general population.

Quantification of a mercapturate metabolite of the biocides methylisothiazolinone and chloromethylisothiazolinone ("M-12") in human urine using online-SPE-LC/MS/MS

Methylisothiazolinone and the reaction mixture of chloromethylisothiazolinone/methylisothiazolinone (MCI/MI, 3 : 1) are broadly used biocides that are contained in many products of everyday life (e.g. cosmetics, wet wipes, etc.). As MI and MCI are able to sensitize (and penetrate) the skin, their application in cosmetic products is of concern. In previous work, we have revealed a background exposure of the general population to MI and/or MCI/MI (3 : 1) by the determination of urinary N-methylmalonamic acid (NMMA) as the main human metabolite. To corroborate these findings, we have now developed a two-dimensional LC/MS/MS method for the quantification of a mercapturic acid metabolite of MI and MCI ((acetylamino){[3-(methylamino)-1-(methylthio)-3-oxopropyl]thio}acetic acid or shortly "M-12") in human urine. This analyte is enriched online using a Strata-X-column and stripped from the urinary matrix. Then, the analyte is back flushed to the analytical column (Phenomenex C18(2), 150 × 4.6 mm) and finally quantified by tandem mass spectrometry with the use of isotopically labelled M-12 as the internal standard. The LOQ for M-12 was 0.2 ng mL-1 urine and sufficient to quantify urinary background levels. Precision within and between series for M-12 in urine at concentrations varying from 0.2 to 5 ng mL-1 ranged from 2.1 to 23.9% and accuracy ranged from 86.3 to 101.8%. Mean accuracy for M-12 in individual urine samples was 94.3% (range: 89.7-102.9%). We applied this method to previously collected 24 h urine samples of 60 persons with no specific exposure to MI and/or MCI/MI (3 : 1). The metabolite M-12 could be quantified in each urine sample. The median and 95th percentile levels for urinary M-12 were determined to be 0.62 and 2.26 ng mL-1, respectively. In these urine samples, the concentrations of the previously determined metabolite NMMA and M-12 correlated well. In the future, we will apply this method to urine samples of a previously conducted human exposure study to explore the additional value of M-12 as a biomarker of exposure to MI and MCI.

In vivo demonstration of immunologic cross-reactivity to octylisothiazolinone in patients primarily and strongly sensitized to methylisothiazolinone

BACKGROUND

Notwithstanding that concomitant exposure to different isothiazolinone derivatives may result in concomitant sensitization, clinical and animal studies have suggested cross-reactivity between these derivatives, notably between methylisothiazolinone (MI) and octylisothiazolinone (OIT).

OBJECTIVE

To investigate if patients sensitized to MI show cross-reactions to OIT and/or to benzisothiazolinone (BIT) by applying the concept of the re-test method.

PATIENTS AND METHODS

From March to October 2019 consecutive patients were patch tested with MI 0.2% aqueous in duplicate at the two lower corners of both shoulder blades. Patients sensitized to MI, but not to OIT 0.1% petrolatum (pet.) nor to BIT 0.1% pet., were re-tested, 2 months later, with the latter two derivatives at the skin sites where the MI reactions had fully disappeared.

RESULTS

Of 116 patients, 15 (13%) were sensitized to MI, eight of these not sensitized to BIT nor to OIT. Of these, seven patients, all (very) strongly sensitized to MI, were re-tested: five patients showed positive patch test reactions to OIT 0.1% pet.; one patient to OIT 0.1% pet. and BIT 0.1% pet.; and one other patient showed no reactions.

CONCLUSION

This study suggests that patients primarily and strongly sensitized to MI may show immunologic cross-reactions to OIT, and to a far lesser extent to BIT.

N-methylmalonamic acid (NMMA) as metabolite of methylisothiazolinone and methylchloroisothiazolinone in 24-h urine samples of the German Environmental Specimen Bank from 2000 to 2017 - exposure and time trends

Methylisothiazolinone (MI) and the mixture of methylchloroisothiazo¬linone/methylisothiazolinone (MCI/MI, 3:1) are widespread biocides used in cosmetics, household products, paints or as disinfectant in air-conditioning systems. Exposure to these compounds has raised concerns due to their sensitizing potential, as rates of skin sensitization were reported to increase in the last decade. We have analyzed N-methylmalonamic acid (NMMA), a common metabolite of MI and MCI in 24-h urine samples of the German Environmental Specimen Bank collected from 480 participants (240 male/240 female) between the years 2000 and 2017. Using these data, we were able to calculate the overall daily intake of MI and/or MCI/MI (3:1) of the study participants and point out time trends. NMMA was determined in all urine samples investigated above the LOQ of 0.5 μg/L urine. Median and 95th percentile level of NMMA in all 24-h urine samples was 4.1 μg/g creatinine and 8.5 μg/g creatinine, respectively. This would correspond to a median and 95th percentile daily intake of 0.35 μg/kg bw and 0.71 μg/kg bw for exclusive uptake of MI and 0.64 μg/kg bw and 1.28 μg/kg bw for exclusive uptake of MCI/MI (3:1). We noted only slight variations over time for median exposures, but an increasing time trend in the 95th percentile exposure between 2006 and 2011 with a decrease in recent years, probably reflecting regulatory measures on MI and MCI/MI (3:1) in cosmetic products. Increasing knowledge on determinants of exposure to MI and/or MCI/MI (3:1) would be necessary to further lower exposure to these sensitizing compounds.

Analysis of consumer behavior for the estimation of the exposure to chemicals in personal care products

In this study, the main objective was to implement an integrative modelling framework in order to support the prioritization and screening of chemicals present in personal care products (PCPs) regarding their potential to expose users across multiple possible pathways. Here, we implemented an exposure-based framework based on product intake fractions (PiFs) calculated using a two-compartment model reproducing the skin uptake and the competing volatilization of chemicals applied on skin during PCP use. The implemented framework enabled to simultaneously and comprehensively accommodate coupled chemical specific parameters (i.e. physical and chemical properties of the candidate chemicals), exposure information specific for product-chemical combinations, and survey data informing on consumer behavior. A case-study, based on the usage pattern data of 22 PCPs investigated among Swiss individuals (Garcia-Hidalgo et al., 2017a) and 113 candidate chemicals chosen for their suspected presence in the PCP categories of interest was defined to evaluate the applicability of the framework. Nonnegative matrix factorization (NMF) and hierarchical clustering were subsequently applied to identify chemicals with the highest exposure potential and to highlight most relevant mixtures of chemicals on the basis of the specific usage patterns of the considered survey individuals.

Isothiazolinone Biocides: Chemistry, Biological, and Toxicity Profiles

The importance of isothiazole and of compounds containing the isothiazole nucleus has been growing over the last few years. Isothiazolinones are used in cosmetic and as chemical additives for occupational and industrial usage due to their bacteriostatic and fungiostatic activity. Despite their effectiveness as biocides, isothiazolinones are strong sensitizers, producing skin irritations and allergies and may pose ecotoxicological hazards. Therefore, their use is restricted by EU legislation. Considering the relevance and importance of isothiazolinone biocides, the present review describes the state-of-the-art knowledge regarding their synthesis, antibacterial components, toxicity (including structure–activity–toxicity relationships) outlines, and (photo)chemical stability. Due to the increasing prevalence and impact of isothiazolinones in consumer’s health, analytical methods for the identification and determination of this type of biocides were also discussed.

Occurrence and Concentration of Chemical Additives in Consumer Products in Korea

As the variety of chemicals used in consumer products (CPs) has increased, concerns about human health risk have grown accordingly. Even though restrictive guidelines and regulations have taken place to minimize the risks, human exposure to these chemicals and their eco-compatibility has remained a matter of greater scientific concern over the years. A major challenge in understanding the reality of the exposure is the lack of available information on the increasing number of ingredients and additives in the products. Even when ingredients of CPs formulations are identified on the product containers, the concentrations of the chemicals are rarely known to consumers. In the present study, an integrated target/suspect/non-target screening procedure using liquid chromatography-high resolution mass spectrometry (LC-HRMS) with stepwise identification workflow was used for the identification of known, suspect, and unknown chemicals in CPs including cosmetics, personal care products, and washing agents. The target screening was applied to identify and quantify isothiazolinones and phthalates. Among analyzed CPs, isothiazolinones and phthalates were found in 47% and in 24% of the samples, respectively. The highest concentrations were 518 mg/kg for benzisothiazolone, 7.1 mg/kg for methylisothiazolinone, 2.0 mg/kg for diethyl phthalate, and 21 mg/kg for dimethyl phthalate. Suspect and non-target analyses yielded six tentatively identified chemicals across the products including benzophenone, ricinine, iodocarb (IPBC), galaxolidone, triethanolamine, and 2-(2H-Benzotriazol-2-yl)-4, 6-bis (1-methyl-1-phenylethyl) phenol. Our results revealed that selected CPs consistently contain chemicals from multiple classes. Excessive use of these chemicals in daily life can increase the risk for human health and the environment.

Simultaneous Quantitative Analysis of Six Isothiazolinones in Water-Based Adhesive Used for Food Contact Materials by High-Performance Liquid Chromatography-Tandem Mass Spectrometry (HPLC-MS/MS)

In this study, a target analytical approach using high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) was developed to simultaneously determine six isothiazolinones containing 2-Methylisothiazol-3(2H)-one (MI), 5-Chloro-2-methyl-4-isothiazolin-3-one (CMI), 1,2-benzisothiazolin-3-one (BIT), 2-Octyl-3(2H)-isothiazolinone (OIT), Dichlorooctylisothiazolinone (DCOIT), and 2-methyl-1,2-benzisothiazolin-3-one (MBIT) in water-based adhesive used for food contact materials. The main factors affecting extraction efficiency such as extraction method, extraction time, extraction solvent, and solid–liquid ratio have been evaluated by using real adhesive samples. Multiple-reaction monitoring (MRM) was used for the qualitative and quantitative analyses of targeted isothiazolinones. This method was demonstrated as an effective and reliable technique for detecting multiple isothiazolinones with satisfactory recoveries (81.5~107.3%), and the limits of detection (LOD) and quantification (LOQ) were obtained at a low level. This method was validated and applied to the determination of six isothiazolinones in commercial water-based adhesives. The present results revealed that these adhesives contained a combination of isothiazolinones (BIT, MI, CMI, and MBIT) with the concentration ranging from 2.27 to 123.5 mg/kg. To our knowledge, it is the first time it has been reported that MBIT was detected in water-based adhesives used for food contact materials, which requires a further investigation for its migration to food and the risk to human health.

Isothiazolinones in cleaning products: Analysis with liquid chromatography tandem mass spectrometry of samples from sensitized patients and market

BACKGROUND

Methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI) contact dermatitis is a severe problem. The high concentrations of these substances and other isothiazolinones such as benzisothiazolinone (BIT) and octylisothiazolinone (OIT) contained in cleaning products may cause allergic contact dermatitis in sensitized patients.

OBJECTIVES

To evaluate the exposure to isothiazolinones contained in cleaning products on the market and from sensitized patients, and to verify the accuracy of labeling.

METHODS

A total of 34 cleaning products were collected (17 supplied by sensitized patients and 17 bought randomly). Analysis was made of the concentrations of MI, MCI, BIT, and OIT using liquid chromatography tandem mass spectrometry (LC-MS/MS).

RESULTS

MI and BIT were the components most frequently detected. Of all the products analyzed, 76.5% contained at least one isothiazolinone. Twelve products had an MI concentration above the permitted level for rinse-off cosmetics. Most of them were coming into direct contact with the skin in daily use. Mislabeling occurred in eight products.

CONCLUSIONS

Some cleaning products with high concentrations of isothiazolinones may cause cutaneous symptoms in sensitized patients, especially in spray form. The labeling should be correct, also regarding the use of each article.

An insight into toxicity and human-health-related adverse consequences of cosmeceuticals - A review

In recent years, the use of cosmeceutical-based personal care and beauty products has ever increased, around the world. Currently, an increasing number of compounds are being assimilated in the formulation of cosmetic products as preservatives, fragrances, surfactants, etc. to intensify the performance, quality, value, and lifespan of cosmetics. Nevertheless, many of these chemical additives pose toxic effects to the human body, exhibiting health risks from a mild hypersensitivity to life-threatening anaphylaxis or lethal intoxication. Therefore, the indiscriminate application of cosmeceuticals has recently become a mounting issue confronting public health. The present review focuses on exposure to a large variety of toxic substances used in cosmetic formulations such as 1,4-dioxane formaldehyde, paraformaldehyde, benzalkonium chloride, imidazolidinyl urea, diazolidinyl urea, trace heavy metals, parabens derivatives, phthalates, isothiazolinone derivatives (methylchloroiso-thiazolinone, and methylisothiazolinone), methyldibromo glutaronitrile, and phenoxy-ethanol. The biological risks related to these substances that they can pose to human health in terms of cytotoxicity, genotoxicity, mutagenicity, neurotoxicity oestrogenicity or others are also discussed. Researchers from academia, consultancy firms, governmental organizations, and cosmetic companies should carry out further progress to keep updating the consumers regarding the dark-sides, and health-related harmful apprehensions of cosmetics. In addition, the industry-motivated initiatives to abate environmental impact through green, sustainable and eco-friendly product development grasp significant perspective.

Aggregate consumer exposure to isothiazolinones via household care and personal care products: Probabilistic modelling and benzisothiazolinone risk assessment

Consumers regularly use household care and personal care products (HC&PCPs). Isothiazolinones are included in HC&PCPs as preservatives and are being held responsible for an epidemic rise in allergic contact dermatitis (ACD). The objective of this study was to assess the origin and extent of dermal exposure in order to evaluate the risk of ACD from isothiazolinones in HC&PCP. Individual-based aggregate dermal exposure to four isothiazolinones was estimated using the newly proposed Probabilistic Aggregated Consumer Exposure Model-Kinetic, Dermal (PACEM-KD) by combining the reported individual use patterns for HC&PCP in Switzerland (N = 669 (558 adults), ages 0-91) with isothiazolinone concentrations measured in products used by the individual person. PACEM-KD extends the original PACEM by considering exposure duration, product dilution and skin permeability. PACEM-KD-based higher-tier exposure on palms (99th percentile) was 15.4 ng/cm², 1.3 ng/cm², 0.9 ng/cm², and 0.08 ng/cm² for the isothiazolinones 1,2‑Benzisothiazol‑3‑(2H)‑one (BIT), 2‑Octyl‑3(2H)‑isothiazolinone (OIT), 2‑Methylisothiazolin‑3(2H)‑one (MI), and 5‑Chloro‑2‑methyl‑4‑isothiazolin‑3‑one (CMI), respectively. Major sources of exposure to BIT included all-purpose cleaners, dishwashing detergent, and kitchen cleaner, while exposure to OIT mainly stems from a fungicide. For MI, the main contributors were dishwashing detergent and all-purpose wet wipes, and for CMI all-purpose cleaner. A Quantitative Risk Assessment (QRA) for BIT using Sensitization Assessment Factors (SAFs) indicates that around 1% of the Swiss population is at risk to be sensitized by BIT in cosmetics and household chemicals. For isothiazolinones in general the presented higher-tier modelling approach suggests that household cleaners are currently more important sources of exposure than cosmetics.

Not only biocidal products: Washing and cleaning agents and personal care products can act as further sources of biocidal active substances in wastewater

The emission sources of biocidal active substances in households have been under discussion since these substances have been detected frequently in municipal wastewater and receiving surface water bodies. Therefore, the goal of this study was to investigate the products responsible for the emission of these substances to wastewater. We analysed the wastewater of two streets for a set of biocidal active substances. Time-proportional sampling was conducted for one week of each season during one year in each street. The 14 substances analysed with liquid chromatography coupled with tandem mass spectrometry were 1,2-benzisothiazol-3(2H)-one (BIT), C₁₂-benzalkonium chloride, carbendazim, 5-chloro-2-methyl-2H-isothiazol-3-one (CMIT), dichlorooctylisothiazolinone (DCOIT), N,N-diethyl-meta-toluamide (DEET), diuron, icaridine, 2-octyl-2H-isothiazol-3-one (OIT), piperonyl butoxide (PBO), triclosan, tebuconazole, terbutryn and tetramethrin. Using data available from household product inventories of the two streets, we searched the lists of ingredients for the products possibly being responsible for the emissions. Except for four substances, all substances have been detected in at least 10% of the samples. Highest concentrations were measured for C₁₂-benzalkonium chloride with an average concentration in the daily samples of 7.7 μg/L in one of the streets. Next to C₁₂-benzalkonium chloride, BIT, DEET and icaridine were detected in all samples in average concentrations above 1 μg/L in at least one street. The results show that washing and cleaning agents were important sources for preservatives such as BIT and OIT, while triclosan was apparently mainly emitted through personal care products. The mosquito repelling substances DEET and icaridine were found throughout the year, with highest emissions in summer and autumn. In conclusion, the results demonstrate that the sources of biocidal active substances in municipal wastewater are complex and that measures for the prevention of the emission of biocidal active substances into the aquatic environment have to be carried out under different legislations. This has to be taken into account discussing emission reduction at the source.

Contact Allergy: A Review of Current Problems from a Clinical Perspective

Contact allergy is common, affecting 27% of the general population in Europe. Original publications, including case reports, published since 2016 (inclusive) were identified with the aim of collating a full review of current problems in the field. To this end, a literature search employing methods of systematic reviewing was performed in the Medline^® and Web of Science™ databases on 28 January 2018, using the search terms (“contact sensitization” or “contact allergy”). Of 446 non-duplicate publications identified by above search, 147 were excluded based on scrutiny of title, abstract and key words. Of the remaining 299 examined in full text, 291 were deemed appropriate for inclusion, and main findings were summarised in topic sections. In conclusion, diverse sources of exposures to chemicals of widely-differing types and structures, continue to induce sensitisation in man and may result in allergic contact dermatitis. Many of the chemicals are “evergreen” but others are “newcomers”. Vigilance and proper investigation (patch testing) are required to detect and inform of the presence of these haptens to which our populations remain exposed.

The Role of Cleaning Products in Epidemic Allergic Contact Dermatitis to Methylchloroisothiazolinone/Methylisothiazolinone

BACKGROUND

Sensitivity to methylchloroisothiazolinone (MCI)/methylisothiazolinone (MI) has increased rapidly over recent years. This increase is mainly related to the extensive use of high concentrations of MI in cosmetic products, although a growing number of cases of occupational allergic contact dermatitis are caused by MCI/MI.

OBJECTIVE

The aim of this study was to examine the association between the increase in MCI/MI sensitization and the work performed by the patients in our area.

METHODS

A retrospective study was undertaken of the records of a total of 1179 patients who had undergone contact skin patch tests for MCI/MI from January 2005 to December 2015. A multivariate logistic regression analysis was performed to identify the factors independently associated with sensitivity to MCI/MI.

RESULTS

A constant increase in MCI/MI sensitization was observed over the observation period. The only work associated with a significant increase in the prevalence of MCI/MI sensitization was cleaning, with 38.5% of the cleaning professionals with MCI/MI sensitization consulting for cosmetics-related dermatitis.

CONCLUSIONS

Occupational sensitization to MCI/MI in cleaning professionals is worryingly increasing. This, in turn, could possibly account for many cases of cosmetics-associated contact dermatitis. Our findings suggest that a review of the regulations with regard to isothiazolinone concentrations in industrial and household detergents is necessary.