An update of the risk assessment for methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) with focus on rinse-off products

Risk management of skin sensitisers: A commentary

Historically, allergic contact dermatitis (ACD) to chemicals encouraged hazard identification improvements, more sophisticated risk assessment and implementation of regulatory strategies, including banning of specific sensitising substances. The validation process applied to hazard identification methods demonstrates their accuracy; their use to characterise sensitiser potency facilitates quantitative and transparent risk assessment. Diagnostic patch testing at dermatology clinics worldwide delivers feedback showing where risk assessment/management has been insufficient or did not target the exposure of concern, thereby facilitating improvements. When urgent action to protect human health was required, regulations limited/banned, specific skin sensitisers. This can be seen in practice with the fragrance industry, a known source of ACD, thus requiring risk management, usually restrictions to limit allergy induction, and very rarely specific bans on ingredients. Experience and development of more sophisticated tools, e.g. to assess aggregate exposure from multitude of consumer product types, has led to repeated adaptation of risk assessment and promulgation of updated fragrance use limits. Although targeted control may not always lead to rapid change in the overall clinical picture, it is preferable to a blanket undifferentiated regulatory control of all sensitisers, resulting in unwarranted restrictions for many uses of no health concern, with consequent substantial socio-economic impacts.

Equilibria of semi-volatile isothiazolinones between air and glass surfaces measured by gas chromatography and Raman spectroscopy

Trace amounts of semi-volatile organic compounds (SVOCs) of the two isothiazolinones of 2-methylisothiazol-3(2H)-one (MIT) and 2-octyl-4-isothiazolin-3-one (OIT) were detected both in the air and on glass surfaces. Equilibria of SVOCs between air and glass were examined by solid phase microextraction-gas chromatography/mass spectrometry (SPME-GC/MS). Surface to air distribution ratios of K_sa for MIT and OIT were determined to be 5.10 m and 281.74 m, respectively, suggesting more abundant MIT in the gas phase by a factor of ∼55. In addition, a facile method of silver nanocube (AgNC)-assisted surface-enhanced Raman scattering (SERS) has been developed for the rapid and sensitive detection of MIT and OIT on glass surfaces. According to MIT and OIT concentration-correlated SERS intensities of Raman peaks at ∼1585 cm^-1 and ∼1125 cm^-1, respectively. Their calibration curves have been obtained in the concentration ranges between 10^-3 to 10^-10 M and 10^-3 to 10^-11 M with their linearity of 0.9986 and 0.9989 for MIT and OIT, respectively. The limits of detection (LODs) of the two isothiazolinones were estimated at 10^-10 M, and 10^-11 M for MIT and OIT, respectively. Our results indicate that AgNC-assisted SERS spectra are a rapid and high-ultrasensitive method for the quantification of MIT and OIT in practical applications. The development of analytical methods and determination of the Ksa value obtained in this study can be applied to the prediction of the exposure to MIT and OIT from various chemical products and dynamic behaviors to assess human health risks in indoor environments.

Occurrence, effects, and ecological risks of chemicals in sanitizers and disinfectants: A review

In response to the novel coronavirus referred to as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) – a virus that causes COVID-19 disease has led to wide use of sanitizers and disinfectants. This, in turn, triggered concerns on their potential deleterious effects to human health and the environment due to numerous chemicals incorporated in both product categories. Here, the current state of science regarding the occurrence and ecological effects of different classes of chemicals in these products (e.g., ultraviolent filters, fragrances, etc.) are summarized in different natural (e.g., rivers) and engineered (e.g., wastewater treatment plants) systems. Data collected in the literature suggests chemicals incorporated in sanitizers and disinfectants are present in the environment, and a large portion are toxic to fish, algae, and daphnia. Using the risk quotient approach based on occurrence data, we found eight chemicals that posed the highest risk to aquatic organisms in freshwater systems were benzalkonium chloride, 4-chloro-m-cresol, sodium ortho phenyl phenate, hydrogen peroxide, 1, 2-propanediol, 4-Methyl-benzilidine-camphor, ethylhexyl methoxy cinnamate, and octocrylene. Considering limited occurrence and effects information for most chemicals, further studies on environmental monitoring and potential consequences of long-term exposure in aquatic ecosystems are recommended.

Decision making in next generation risk assessment for skin allergy: Using historical clinical experience to benchmark risk

Our aim is to develop and apply next generation approaches to skin allergy risk assessment that do not require new animal test data and better quantify uncertainties. Quantitative risk assessment for skin sensitisation uses safety assessment factors to extrapolate from the point-of-departure to an acceptable human exposure level. It is currently unclear whether these safety assessment factors are appropriate when using non-animal test data to derive a point-of departure. Our skin allergy risk assessment model Defined Approach uses Bayesian statistics to infer a human-relevant metric of sensitiser potency with explicit quantification of uncertainty, using any combination of human repeat insult patch test, local lymph node assay, direct peptide reactivity assay, KeratinoSens™, h-CLAT or U-SENS™ data. Here we describe the incorporation of benchmark exposures pertaining to use of consumer products with clinical data supporting a high/low risk categorisation for skin sensitisation. Margins-of-exposure (potency estimate to consumer exposure level ratio) are regressed against the benchmark risk classifications, enabling derivation of a risk metric defined as the probability that an exposure is low risk. This approach circumvents the use of safety assessment factors and provides a simple and transparent mechanism whereby clinical experience can directly feed-back into risk assessment decisions.

A Study on the Behavior Patterns of Liquid Aerosols Using Disinfectant Chloromethylisothiazolinone/Methylisothiazolinone Solution

This study evaluates the behavioral characteristics of components (methylisothiazolinone (MIT) and chloromethylisothiazolinone (CMIT)) contained in disinfectant solutions when they convert to liquid aerosols. The analytical method for MIT and CMIT quantitation was established and optimized using sorbent tube/thermal desorber-gas chromatography-mass spectrometry system; their behavioral characteristics are discussed using the quantitative results of these aerosols under different liquid aerosol generation conditions. MIT and CMIT showed different behavioral characteristics depending on the aerosol mass concentration and sampling time (sampling volume). When the disinfectant solution was initially aerosolized, MIT and CMIT were primarily collected on glass filter (MIT = 91.8 ± 10.6% and CMIT = 90.6 ± 5.18%), although when the generation and filter sampling volumes of the aerosols increased to 30 L, the relative proportions collected on the filter decreased (MIT = 79.0 ± 12.0% and CMIT = 39.7 ± 8.35%). Although MIT and CMIT had relatively high vapor pressure, in liquid aerosolized state, they primarily accumulated on the filter and exhibited particulate behavior. Their relative proportions in the aerosol were different from those in disinfectant solution. In the aerosol with mass concentration of ≤5 mg m^-3, the relative proportion deviations of MIT and CMIT were large; when the mass concentration of the aerosol increased, their relative proportions constantly converged at a lower level than those in the disinfectant solution. Hence, it can be concluded that the behavioral characteristics and relative proportions need to be considered to perform the quantitative analysis of the liquid aerosols and evaluate various toxic effects using the quantitative data.

In silico Prediction of Skin Sensitization: Quo vadis?

Skin direct contact with chemical or physical substances is predisposed to allergic contact dermatitis (ACD), producing various allergic reactions, namely rash, blister, or itchy, in the contacted skin area. ACD can be triggered by various extremely complicated adverse outcome pathways (AOPs) remains to be causal for biosafety warrant. As such, commercial products such as ointments or cosmetics can fulfill the topically safe requirements in animal and non-animal models including allergy. Europe, nevertheless, has banned animal tests for the safety evaluations of cosmetic ingredients since 2013, followed by other countries. A variety of non-animal in vitro tests addressing different key events of the AOP, the direct peptide reactivity assay (DPRA), KeratinoSens™, LuSens and human cell line activation test h-CLAT and U-SENS™ have been developed and were adopted in OECD test guideline to identify the skin sensitizers. Other methods, such as the SENS-IS are not yet fully validated and regulatorily accepted. A broad spectrum of in silico models, alternatively, to predict skin sensitization have emerged based on various animal and non-animal data using assorted modeling schemes. In this article, we extensively summarize a number of skin sensitization predictive models that can be used in the biopharmaceutics and cosmeceuticals industries as well as their future perspectives, and the underlined challenges are also discussed.

Occurrence of methylisothiazolinone in water and soil samples in Poland and its biodegradation by Phanerochaete chrysosporium

Methylisothiazolinone is a commonly used biocide that is released into natural environments. In this work, the ability of the fungal strain Phanerochaete chrysosporium DSM 1556 to biotransform this compound was evaluated. The tested strain was able to remove MIT (at concentrations 50 μg L^-1 and 30 mg L^-1) from the growth medium with the efficiency 90% after the first 6 h and 100% after 12 h of incubation. Moreover, for the first time, qualitative LC-MS/MS and GC-MS analysis showed monohydroxylated and dihydroxylated methylisothiazolinone and N-methylmalonamic acid as the main products of fungal biodegradation. The ecological toxicity of the tested biocide and its derivatives was also evaluated by using an acute toxicity test with Daphnia magna. An approximately 90% decrease in the toxicity of metabolites formed in the P. chrysosporium culture was noticed. The concentration of MIT in soil and water samples collected in Poland was assessed for the first time. The analysis showed that the selected locations in Poland are contaminated by MIT in the range from 1.04-10.08 μg L^-1.

Thermal Desorption Technique for Analysis of Aerosolized Methylchloroisothiazolinone/Methylisothiazolinone (CMIT/MIT) in Inhalation Toxicity Testing

When assessing the inhalation toxicity of diverse inhalable substances, a first step is accurate quantitative analysis. In this study, we developed a method for the quantitative analysis of methylisothiazolinone (MIT) and methylchloroisothiazolinone (CMIT), main components in humidifier disinfectants. A simple thermal desorption (TD) method was used to analyze the CMIT/MIT. Using this method, sample loss during aerosolization was minimized compared with other more complicated pretreatment methods, like solvent absorption and extraction (SV). The results of the TD and SV methods were compared to determine the optimal analytical system for CMIT/MIT analysis. In both methods, the concentration of MIT increased systematically with increasing the CMIT/MIT aerosol concentration (R2 > 0.98). The MIT contents in the aerosol given by the two analytical methods were somewhat similar (MIT content = 1.52% (sample solution), 1.43% (TD) and 1.18% (SV)). In contrast, the measured CMIT content in the aerosol was different depending on the type of pretreatment used. The CMIT content was 2.90% for the TD method, while that for the solvent method recorded 0.75% (CMIT content of the sample solution = 4.66%). We confirmed that the sample loss of the CMIT with high reactivity occurred in the complicated sampling and pretreatment steps of the SV method.

Methylchloroisothiazolinone and/or Methylisothiazolinone Contact Allergies in Thailand

BACKGROUND

Methylchloroisothiazolinone, in combination with methylisothiazolinone (MCI/MI), and MI alone are common preservatives. The incidences of MCI/MI and MI-alone contact allergies have risen markedly worldwide, leading to changes in their use in products.

OBJECTIVES

The aim of the study was to determine the incidences of positive patch test reactions and factors associated with MCI and/or MI contact allergies during the recent decade in Thailand.

METHODS

Medical records of patients who underwent patch testing at Siriraj Hospital from 2009 to 2018 were retrospectively reviewed. The incidences of positive reactions, histories, and clinical data of MCI/MI and MI-alone contact allergy patients were analyzed.

RESULTS

Of 2789 patients undergoing patch testing, most were female (76.1%). The mean ± SD age was 42.7 ± 15.7 years. Positive reactions to MCI/MI increased from 2009 to 2016 before declining. The MCI/MI contact allergy was most common in females, middle-aged patients, and those with metal allergy histories, with the hands and arms being the predominant sites. However, MI-alone contact allergy was more common in males and mainly at the trunk. Its incidence significantly declined for the last 5 years.

CONCLUSIONS

The incidences of MCI/MI and MI-alone contact allergies began to decline because the Food and Drug Administration Thailand regulations restricted their use. The risk factors for the allergies reported in this study provide important information for patient care.

Occupationally Induced Allergic Contact Dermatitis to Methylchloroisothiazolinone/Methylisothiazolinone Among Water Bottle Plant Workers

BACKGROUND

Methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) allergy has increased for the last decade, mostly not only because of high concentrations in cosmetics but also because of its use as a biocide in industrial settings.

OBJECTIVE

We report an outbreak of allergic contact dermatitis in 8 workers at a water bottling plant secondary to excess levels of MCI/MI in the cooling system, found to be at levels 5 times the manufacturer's recommendations.

METHODS

Of 15 workers in the plastic bottle manufacturing area, 8 developed dermatitis, and 4 were referred for patch testing using a 100-allergen panel applied and interpreted in the standardized method according to the North American Contact Dermatitis Group.

RESULTS

Four workers had a positive reaction to MCI/MI. An investigation at the plant revealed that the concentration of MCI/MI was 365 ppm. The manufacturer's recommended level was 48 ppm. The cooling system was subsequently flushed, and biocide levels decreased to recommended levels. Afterward, all the affected workers experienced clearance of their allergic contact dermatitis.

CONCLUSIONS

Occupational sensitization to MCI/MI is on the rise, in this instance, because of excess levels in the cooling system. Our findings demonstrate the continued need for awareness of the allergenicity of this preservative in the occupational setting.

Allergic Contact Dermatitis

Allergic contact dermatitis is common, resulting in considerable morbidity. Diagnosis is based on a thorough history, physical examination, and patch testing. Several commercially available panels of patch testing are currently used. Allergens are found in a wide variety of daily products, occupational exposures, and foods. The mainstay of treatment is avoidance of the allergen, and databases like Contact Allergen Management Program and Contact Allergen Replacement Database help patients to select products that do not contain allergens to which they are sensitized. Topical corticosteroids can be used to treat exacerbations, but should be avoided in long-term treatment.

Development and Validation of an HPLC Method for Simultaneous Assay of MCI and MI in Shampoos Containing Plant Extracts

A simple, easy-to-implement HPLC method was developed and validated for simultaneous determination of two isothiazolinone preservatives, methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI), in hair care shampoo containing plant extracts. In this method, shampoo samples were first dissolved in isopropyl myristate and then MCI and MI were extracted from isopropyl myristate layer by a mixture of methanol and 0.02 M phosphate buffer solution pH 3.0 (30: 70, v/v) and analyzed on an analytical biphenyl column maintained at 25°C with a mixture of methanol and water (10: 90, v/v) in isocratic elution mode as mobile phase. Total flow rate of mobile phase was maintained at 1.0 mL per minute. The UV detection was performed at 274 nm. Injection volume was 50 μl. The method was fully validated in terms of specificity, linearity, precision, accuracy, and robustness according to requirements of AOAC International and was proved as reliable and suitable for the intended application.

Allergic Contact Dermatitis Caused by Homemade Slime

Nowadays, allergic reactions in children are seen in dermatological practice on a daily basis. The most common reasons for allergic contact dermatitis (ACD) are piercings, temporary tattoos, a wide range of cosmetic products, substances related to the practice of a variety of hobbies and sports, etc. Slime is a new hobby and has become an obsession for some kids. There are many homemade slime recipes. The most common recipe for slime is glue, borax and food coloring for all kinds of rainbow effects. We present a case of an 11-year-old Caucasian girl with hand contact dermatitis caused by an allergic reaction to Slime.

Positive lists of cosmetic ingredients: Analytical methodology for regulatory and safety controls - A review

Cosmetic products placed on the market and their ingredients, must be safe under reasonable conditions of use, in accordance to the current legislation. Therefore, regulated and allowed chemical substances must meet the regulatory criteria to be used as ingredients in cosmetics and personal care products, and adequate analytical methodology is needed to evaluate the degree of compliance. This article reviews the most recent methods (2005-2015) used for the extraction and the analytical determination of the ingredients included in the positive lists of the European Regulation of Cosmetic Products (EC 1223/2009): comprising colorants, preservatives and UV filters. It summarizes the analytical properties of the most relevant analytical methods along with the possibilities of fulfilment of the current regulatory issues. The cosmetic legislation is frequently being updated; consequently, the analytical methodology must be constantly revised and improved to meet safety requirements. The article highlights the most important advances in analytical methodology for cosmetics control, both in relation to the sample pretreatment and extraction and the different instrumental approaches developed to solve this challenge. Cosmetics are complex samples, and most of them require a sample pretreatment before analysis. In the last times, the research conducted covering this aspect, tended to the use of green extraction and microextraction techniques. Analytical methods were generally based on liquid chromatography with UV detection, and gas and liquid chromatographic techniques hyphenated with single or tandem mass spectrometry; but some interesting proposals based on electrophoresis have also been reported, together with some electroanalytical approaches. Regarding the number of ingredients considered for analytical control, single analyte methods have been proposed, although the most useful ones in the real life cosmetic analysis are the multianalyte approaches.

Activated soil filters for removal of biocides from contaminated run-off and waste-waters

Building facades can be equipped with biocides to prevent formation of algal, fungal and bacterial films. Thus run-off waters may contain these highly active compounds. In this study, the removal of several groups of biocides from contaminated waters by means of an activated soil filter was studied. A technical scale activated vertical soil filter (biofilter) with different layers (peat, sand and gravel), was planted with reed (Phragmites australis) and used to study the removal rates and fate of hydrophilic to moderate hydrophobic (log K(ow) 1.8-4.4) biocides and biocide metabolites such as: Terbutryn, Cybutryn (Irgarol® 1051), Descyclopropyl-Cybutryn (Cybutryn and Terbutryn metabolite), Isoproturon, Diuron, and its metabolite Diuron-desmonomethyl, Benzo-isothiazolinone, n-Octyl-isothiazolinone, Dichloro-n-octylisothiazolinone and Iodocarbamate (Iodocarb). Three experiments were performed: the first one (36 d) under low flow conditions (61 L m(-2) d(-1)) reached removal rates between 82% and 100%. The second one was performed to study high flow conditions: During this experiment, water was added as a pulse to the filter system with a hydraulic load of 255 L m(-2) within 5 min (retention time <1 h). During this experiment the removal rates of the compounds decreased drastically. For five compounds (Cybutryn, Descyclopropyl-Cybutryn, Diuron, Isoproturon, and Iodocarb) the removal dropped temporarily below 60%, while it was always above 70% for the others (Terbutryn, Benzo-isothiazolinone, n-Octyl-isothiazolinone, Dichloro-n-octylisothiazolinone). However, this removal is a considerable improvement compared to direct discharge into surface waters or infiltration into soil without appropriate removal. In the last experiment the removal efficiencies of the different layers were studied. Though the peat layer was responsible for most of the removal, the sand and gravel layers also contributed significantly for some compounds. All compounds are rather removed by degradation than by sorption.

[Determination of 3 isothiazolinone preservatives in toys using liquid chromatography-tandem mass spectrometry]

A rapid analytical method for the determination of 3 isothiazolinone preservatives (2-methyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one and 1,2-benzylisothiazolin-3-one) in toys using liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed. After ultrasonic extraction with water, the analytes in the sample were separated and analyzed by LC-MS/MS under the isocratic elution of methanol and water (15:85, v/v) and in selected-reaction monitoring (SRM) mode. The linear ranges of calibration curves for the 3 analytes were 2.0 - 1 000 microg/L. The limit of quantification was 0.04 mg/kg for all the 3 analytes, which was lower than that of the method recommended by the European Toy Safety Directive in EN71-11-2005. The recoveries of the spiked standards in the two toy samples were 95.9% - 105.2% and 94.7% - 102.8% with the relative standard deviation ranges from 3.04% to 4.96% and from 2.36% to 4.79%, respectively. The method was applied in the determination of 10 toy samples, and the results can meet the requirements of the European Toy Safety Directive in EN71-9-2005 for the determination of isothiazolinones in toys.

Cosmeceutical vehicles

Consumers will pay a premium for high-performance skin and hair care products. The demand exists, and in return for the high cost, consumers expect the product to perform as claimed and to meet aesthetic standards beyond many products found in the mass market. To be successful in this highly competitive market, products must function as claimed or consumers will not repurchase. Effective contemporary high-end products must be properly formulated in nonirritating vehicles that consumers will perceive as elegant.

Analysis of isothiazolinones in environmental waters by gas chromatography-mass spectrometry

This paper describes an analytical method for the determination of five biocides of isothiazolinone type (2-methyl-3-isothiazolinone (MI), 5-chloro-2-methyl-3-isothiazolinone (CMI), 1,2-benzisothiazolinone (BIT), 2-octyl-3-isothiazolinone (OI), 4,5-dichloro-2-octyl-3-isothiazolinone (DCOI)) in environmental waters. The method is based on pre-concentration of the analytes by solid-phase extraction onto a mixture of a polymeric material and RP-C18 material and subsequent determination by gas chromatography-mass spectrometry (GC-MS). One of the target compounds (BIT) is derivatised with diazomethane after pre-concentration to improve its chromatographic performance. The method was optimised with respect to pre-concentration conditions (liquid-liquid extraction versus solid-phase extraction, solid-phase material, elution solvent and volume) and extensively validated. Applying the method to surface waters, groundwaters, and drinking waters, limits of detection between 0.01 and 0.1 microg/l could be achieved and the repeatability was below 10% for all compounds except for MI. Additional investigations showed that the stability of the isothiazolinones in environmental waters is limited and sample storage at 4 degrees C is mandatory to preserve the target biocides. First investigations of influents and effluents of a wastewater treatment plant showed that conventional wastewater treatment exhibits a high efficiency for removal of the isothiazolinones. In river waters, the target isothiazolinones could not be detected.