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Background/Objectives: In the last 10 years methylisothiazolinone (MI) emerged as a global cause of preservative‐related ACD. New Zealand has liberal regulations for the MI concentration limit in cosmetic products compared to Europe and Australia. The aim of this study was to evaluate the prevalence of MI sensitisation in New Zealand, explore sources of MI exposure and make recommendations on New Zealand regulations for MI use. Methods: This retrospective study included data from patients who underwent patch testing with MI from 2008 to 2021 in a tertiary hospital dermatology clinic and a private dermatology clinic in Auckland, New Zealand. Patient baseline characteristics were recorded along with results of patch testing. Sources of MI exposure were identified from medical records. Results: Over the study period, 1049 patch tests were performed in 1044 patients. MI was only tested as a stand‐alone allergen from 2015; positive reactions to MI increased from 5.3% in 2015 to a peak of 11.9% in 2017 and then decreased to 6.4% in 2021. The most common source of MI exposure was shampoo or conditioner (27.7% of all relevant reactions) followed by occupational exposures to paints, biocides or glue (19.1%). Conclusion: Both sensitisation and ACD to MI appear to be decreasing, likely secondary to changes in product compounding due to stricter concentration limits internationally. We recommend New Zealand adopt lower MI concentration limits for cosmetics to match the limits of Australia and Europe. [ABSTRACT FROM AUTHOR]

Background Objective Methods Results Conclusion 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).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.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.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.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. [ABSTRACT FROM AUTHOR]

Isothiazolinones are a common cause of allergic contact dermatitis. To examine the prevalence of positive patch test reactions to isothiazolinones from 2017-2020 and characterize isothiazolinone-allergic (Is+) patients compared with isothiazolinone nonallergic (Is–) patients. Retrospective cross-sectional analysis of 9028 patients patch tested to methylchloroisothiazolinone (MCI)/methylisothiazolinone (MI) 0.02% aqueous, MI 0.2% aqueous, benzisothiazolinone (BIT) 0.1% petrolatum, and/or octylisothiazolinone (OIT) 0.025% petrolatum. Prevalence, reaction strength, concurrent reactions, clinical relevance, and source of allergens were tabulated. In total, 21.9% (1976/9028) of patients had a positive reaction to 1 or more isothiazolinones. Positivity to MI was 14.4% (1296/9012), MCI/MI was 10.0% (903/9017), BIT was 8.6% (777/9018), and OIT was 05% (49/9028). Compared with Is–, Is+ patients were more likely to have occupational skin disease (16.5% vs 10.3%, P <.001), primary hand dermatitis (30.2% vs 19.7%, P <.001), and be >40 years (73.1% vs 61.9%, P <.001). Positive patch test reactions to >1 isothiazolinone occurred in 44.1% (871/1976) of Is+ patients. Testing solely to MCI/MI would miss 47.3% (611/1292) of MI and 60.1% (466/776) of BIT allergic reactions. Retrospective cross-sectional study design and lack of follow-up data. Sensitization to isothiazolinones is high and concurrent sensitization to multiple isothiazolinone allergens is common. [ABSTRACT FROM AUTHOR]

Methylisothiazolinone (MIT) is a commonly used bactericide in wastewater treatment. Residual MIT in wastewater can lead to high environmental risks and toxicity. In this work, an emerging material MXenes has been introduced into the heterogeneous electro-Fenton catalysts to degrade MIT. Ti3C2Tx@Fe3O4, V2CTx@Fe3O4, and Mo2CTx@Fe3O4 were assessed as catalysts for MIT removal. The reasons for the differences among the three catalyst effects were analyzed according to different characterization results. Mo2CTx@Fe3O4 exhibited the best catalytic activity for MIT degradation. At pH = 3, the removal rate of MIT and corresponding chemical oxygen demand of catalyst Mo2CTx@Fe3O4 were 93.41% and 62.46% after 120 min. Among the three catalysts, Mo2CTx@Fe3O4 had larger surface area and porosity. Mo2CTx@Fe3O4 had the highest surface iron content, which meant that Fe3O4 was more easily loaded on the surface of Mo2CTX. What is more, Mo2CTX had the strongest ability to accelerate the regeneration of Fe2+. The durability of Mo2CTx@Fe3O4 was also evaluated. After four cycles, the removal efficiency of MIT only decreased from 92.51% to 89%. This work supports the development of heterogeneous electro-Fenton catalysts and the degradation of MIT. [ABSTRACT FROM AUTHOR]

BackgroundPreservatives are often necessary components of commercial products. Large-scale North American studies on preservative allergy are limited.ObjectiveTo evaluate demographics, positive patch test reactions (PPTRs), clinical relevance, and trends for preservatives tested by the North American Contact Dermatitis Group.MethodsWe conducted a retrospective cross-sectional analysis of North American Contact Dermatitis Group patch testing results of preservatives from 1994 through 2016.ResultsA total of 50,799 patients were tested; 11,338 (22.3%) had a PPTR to at least 1 preservative. The most frequent reactions were to methylisothiazolinone 0.2% aqueous (aq) (12.2%), formaldehyde 2% aq (7.8%), formaldehyde 1% aq (7.8%), quaternium-15 2% petrolatum (pet) (7.7%), and methyldibromo glutaronitrile/phenoxyethanol 2% pet (5.1%). Paraben mix 12% pet (1%), iodopropynyl butylcarbamate 0.1% pet (0.4%), benzyl alcohol 1% pet (0.3%), and phenoxyethanol 1% pet (0.2%) had the lowest PPTRs. Linear regression analysis of preservatives tested showed that only methylchloroisothiazolinone/methylisothiazolinone 0.01% aq (parameter estimate, 0.42; 95% CI, 0.17-0.66; P

Background: Most occupational skin disease (OSD) is caused by contact dermatitis which affects workplace productivity, quality of life (QoL) and is associated with a substantial economic burden. We report on whether there have been any emerging workplace allergens identified over the past six years. Methods: A retrospective study was performed using de-identified data obtained from patients assessed at our Occupational Dermatology Clinic in Melbourne, Victoria, Australia from 2017 to 2022. Patch-testing was performed to identify allergens causing allergic contact dermatitis (ACD). Results: Of a total of 657 patch-tested patients, ACD (151/298, 50.3%) was the most common diagnosis in those with significant work-related skin conditions,. The top occupational groups affected were healthcare workers (HCW) (29%; 45/151), trade workers (25.2%; 38/151) and health-and-beauty workers (13.2%; 20/151). The most common allergens were rubber chemicals, particularly thiurams. The next most common were the preservatives such as methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI). Conclusion: Rubber chemicals remain the most common occupational allergens followed by MCI and MI. HCW were the largest affected occupational group. Despite occasional case reports of new allergens, no major change in the causes of OCD was detected. Where possible, workplaces should provide allergen-free products to reduce the risk of developing ACD. [ABSTRACT FROM AUTHOR]

Components of fragrance mix 2 were declared in 28/143 (17.5%) and fragrance mix 1 in 19/143 (13.3%). Allergic contact dermatitis, fragrance, ingredient labelling, consort dermatitis, methylisothiazolinone, pets Keywords: allergic contact dermatitis; consort dermatitis; fragrance; ingredient labelling; methylisothiazolinone; pets EN allergic contact dermatitis consort dermatitis fragrance ingredient labelling methylisothiazolinone pets 496 499 4 05/09/23 20230601 NES 230601 Dog cosmetics can directly cause allergic contact dermatitis (ACD) in owners, groomers or veterinarians, and/or consort ACD from touching dogs, including in those aware of pre-existing sensitisations.[1] A detailed clinical history is essential to identify such exposure. [Extracted from the article]

Background: Current frequency and risk factors for sensitization to methylisothiazolinone (MI), methylchloroisothiazolinone/methylisothiazolinone (MCI/MI), benzisothiazolinone (BIT) and octylisothiazolinone (OIT) in Spain are not well known. Objectives: To study the frequency of sensitization, risk factors and simultaneous sensitization between the four isothiazolinones. Materials and Methods: We analysed all 2019–2021 consecutive patients patch‐tested with MI (0.2% aq.), MCI/MI (0.02% aq.), BIT (0.1% pet.) and OIT (0.1% pet) within the Spanish Contact Dermatitis Registry (REIDAC). Results: A total of 2511 patients were analysed. Frequencies of sensitization were: any isothiazolinone 15.7%, MI 6.8%, MCI/MI 4.8%, BIT 3.5% and OIT 0.5%. MI and MCI/MI sensitization was associated with being occupationally active, hand dermatitis, detergents and age over 40. BIT sensitization was associated with leg dermatitis and age over 40. About one in nine MI‐positive patients were positive to BIT, whereas one in five BIT‐positive patients were positive to MI. Conclusions: Sensitization to MI, MCI/MI and BIT is still common in Spain, while sensitization to OIT is rare. Currently, sensitization to MI and MCI/MI seems to be occupationally related. Although its origin is unknown, sensitization to BIT is more frequent in patients aged over 40 years. Simultaneous sensitization between MI and BIT is uncommon. [ABSTRACT FROM AUTHOR]

Isothiazolinone preservatives (methylisothiazolinone (MIT) and methylchloroisothiazolinone (CMIT) are commonly used in cosmetics, industrial and household products. However, these isothiazolinone derivatives are known to cause allergic contact dermatitis. Hence, a sensitive, accurate, and reliable method for the detection of these compounds is thus warranted. The study aims to analyze concentrations of MIT and CMIT by high performance liquid chromatography. The analytical method used for quantification of MIT and CMIT in cosmetic products (leave-on-baby wet wipes) complies with the validation acceptance criteria (international standards ISO 5725, EU25 European Union for cosmetic regulations). MIT and CMIT were extracted and analyzed in leave-on baby wet-wipes collected from different stores in Riyadh city. Extraction was performed by ultrasonication of the samples, solid-phase extraction, and liquid-liquid extraction. Ten (10) µL of the sample was injected into the HPLC system and samples were analyzed with a mixture of acetic acid and methanol (80:20 v/v) in an isocratic mode. The flow rate was maintained at 1 mL/min. UV detection was performed at 274 nm. The results demonstrated recoveries between 90 and 106%, measurement uncertainty of C +/− 0.4% for methylisothiazolinone and C +/− 0.03% for methylchloroisothiazolinone, repeatability limit (r = 0.2%) and intermediate precision limit; R = 2% and R2 of 0.9996. [ABSTRACT FROM AUTHOR]

The electrochemical properties of methylisothiazolinone (MIT), the most widely used preservative, were investigated by cyclic (CV) and differential pulse voltammetry (DPV) to develop a new method for its determination. To our knowledge, this is the first demonstration of a voltammetric procedure for the determination of MIT on a boron-doped diamond electrode (BDDE) in a citrate–phosphate buffer (C-PB) environment. The anodic oxidation process of methylisothiazolinone, which is the basis of this method, proved to be diffusion-controlled and proceeded with an irreversible two-electron exchange. The radical cations, as unstable primary products, were converted in subsequent chemical reactions to sulfoxides and sulfones, and finally to more stable final products. Performed determinations were based on the DPV technique. A linear calibration curve was obtained in the concentration range from 0.7 to 18.7 mg L−1, with a correlation coefficient of 0.9999. The proposed procedure was accurate and precise, allowing the detection of MIT at a concentration level of 0.24 mg L−1. It successfully demonstrated its suitability for the determination of methylisothiazolinone in household products without the need for any separation steps. The proposed method can serve as an alternative to the prevailing chromatographic determinations of MIT in real samples. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The degradation of various preservatives used in the cosmetics industry, including five parabens and their most employed substitute, methylisothiazolinone (MIT), was investigated. A mild photo-Fenton process was applied using low iron concentrations (5 mg/L) at a pH of five, instead of the traditional acidic value of three. At these conditions, the paraben degradation was very low after one hour of reaction and it was necessary to present humic-like substances (HLS) acting as iron chelators to improve the process. Values obtained when MIT was treated were very low, also in the presence of HLS, indicating that their complexing effect was not acting properly. When MIT was added to the mixture of parabens an inhibitory effect was found in the presence of HLS. A possible complex between iron and MIT was suggested and the studies of hydrogen peroxide consumption and Job's plot technique confirmed this hypothesis. Evidence of the formation of this inactive complex, so far never reported, will be essential in future work when dealing with this compound using Fenton processes. Furthermore, this fact points out the importance of using mixtures of model contaminants instead of a single one or a group of the same family, since their ability to form active or inactive complexes with iron can strongly change the behavior of the whole system. [ABSTRACT FROM AUTHOR]

Methylisothiazolinone (MIT) is a widely used preservative and biocide to prevent product degradation, yet its potential impact on plant growth remains poorly understood. In this study, we investigated MIT's toxic effects on Arabidopsis thaliana root growth. Exposure to MIT significantly inhibited Arabidopsis root growth, associated with reduced root meristem size and root meristem cell numbers. We explored the polar auxin transport pathway and stem cell regulation as key factors in root meristem function. Our findings demonstrated that MIT suppressed the expression of the auxin efflux carrier PIN1 and major root stem cell regulators (PLT1, PLT2, SHR, and SCR). Additionally, MIT hindered root regeneration by downregulating the quiescent center (QC) marker WOX5. Transcriptome analysis revealed MIT-induced alterations in gene expression related to oxidative stress, with physiological experiments confirming elevated reactive oxygen species (ROS) levels and increased cell death in root tips at concentrations exceeding 50 μM. In summary, this study provides critical insights into MIT's toxicity on plant root development and regeneration, primarily linked to modifications in polar auxin transport and downregulation of genes associated with root stem cell regulation. [Display omitted] • Arabidopsis root length, meristem length, and cortex cell number were inhibited by methylisothiazolinone (MIT). • PIN1 expression decreased in 50 μM MIT-treated roots, implying MIT inhbits auxin intercellular movement. • MIT increases the cell death of root tips and decrease the cell division in Arabidopsis roots. • MIT toxicity inhibits root regeneration by reducing SCR expression. [ABSTRACT FROM AUTHOR]

5-Chloro-2-methyl-4-isothiazolin-3-one (CMIT) and 2-methyl-4-isothiazolin-3-one (MIT) used as preservatives in various products, including humidifier disinfectants, presents substantial health hazards. This research delves into the toxicological assessments of CMIT/MIT in the respiratory system using animal models. Through the synthesis of radiolabeled [14C]CMIT and [14C]MIT, we investigated the biological uptake and in vivo behaviors of CMIT/MIT in the respiratory tissues following intratracheal exposure. Quantitative whole-body autoradiography (QWBA) revealed significant persistence of CMIT/MIT in lung tissue. In addition, radio high-performance liquid chromatography (radio-HPLC) with tandem mass spectrometry (LC-MS/MS) was employed for metabolite profiling and identification. Notably, around 28% of the radiolabel was retained in tissue after the extraction step, suggesting covalent binding of CMIT/MIT and their metabolites with pulmonary biomolecules. This observation demonstrates the propensity of the electrophilic isothiazolinone ring in CMIT/MIT to undergo chemical interactions with biothiols in proteins and enzymes, fostering irreversible alterations of biomolecules. Such accumulations of transformations could result in direct toxicity at both cellular and organ levels. Additionally, the detection of metabolites, including a MIT dimer conjugated with glutathione (GSH), as analyzed by mass spectrometry indicates the possible reduction of cellular GSH levels and subsequent oxidative stress. This investigation offers an in-depth insight into the toxic mechanisms of CMIT/MIT, underlying their capability to engage in complex formations with biomacromolecules and induce pronounced respiratory toxicity. These results highlight the imperative for stringent safety assessments of these chemicals, advocating for improved public health and safety measures in the use of chemicals. [Display omitted] • The radiolabeled CMIT and MIT were synthesized using radioactive carbon (14C). • The SUV of CMIT/MIT in lung was determined to be 6.01 after 0.083 h post exposure. • In the analysis of metabolites, the parent structures of CMIT/MIT were not observed. • Some metabolites were found to be conjugated with glutathione. • Approximately 28% of the radiolabel was bound to pulmonary biomolecules. [ABSTRACT FROM AUTHOR]

A variety of isothiazolinone-containing small molecules have been registered and used as chemical additives in many household products. However, their biodistribution and potential harmful effects on human health, especially respiratory effects, were not yet identified in sufficient detail. The purpose of this study was to investigate whether a biocide comprising a mixture of chloromethylisothiazolinone (CMIT) and methylisothiazolinone (MIT) could reach the lungs and induce lung injury when exposure occurs by two administration routes involving the respiratory tract: intratracheal and intranasal instillation. To investigate the biodistribution of CMIT/MIT, we quantified the uptake of 14C-labeled CMIT/MIT in experimental animals for up to seven days after intratracheal and intranasal instillation. In the toxicity study, lung injury was assessed in mice using total inflammatory cell count in bronchoalveolar lavage fluid (BALF) and lung histopathology. The results of the biodistribution study indicated that CMIT/MIT were rapidly distributed throughout the respiratory tract. Using quantitative whole-body autoradiogram analysis, we confirmed that following intranasal exposure, CMIT/MIT reached the lungs via the respiratory tract (nose–trachea–lung). After 5 min post intratracheal and intranasal instillation, the amount of radiotracer ([14C]CMIT/MIT) in the lungs was 2720 ng g−1 and 752 ng g−1 tissue, respectively, and lung damage was observed. A higher amount of the radiotracer resulted in higher toxicity. Both intratracheal and intranasal instillation of CMIT/MIT increased inflammatory cell counts in the BALF and induced injuries in the alveoli. The frequency and the severity scores of injuries caused by intratracheal instillation were approximately-four to five times higher than those induced by intranasal instillation. Therefore, we concluded that CMIT/MIT could reach the lungs following nasal and intratracheal exposure and cause lung injuries, and the extent of injury was dependent on the exposure dose.

Background: According to the REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) restriction, tattoo and permanent make‐up (PMU) inks placed on the European Union market after January 4, 2022, shall not contain methylisothiazolinone, benzisothiazolinone (BIT), octylisothiazolinone (OIT), or other skin sensitizers in concentrations of 10 mg/kg or higher and phenoxyethanol (PE) or other eye irritants or damaging substances in concentrations of 100 mg/kg or higher. In addition, preservatives and other substances enlisted in Annex II to Cosmetic Product Regulation shall not be present in concentrations of 0.5 mg/kg or higher. Objectives: This study aims to quantify 14 preservatives in 99 tattoo and 39 PMU inks from the Italian market and presents a comparison with concentration limits set by the REACH restriction. Methods: Inks were analysed by applying validated analytical methods based on liquid chromatography techniques. Results: About 24.0%, 15.2% and 1.5% of the overall samples contained BIT, PE and OIT, respectively, at concentrations exceeding REACH concentration limits. The number of noncompliant tattoo inks (49.5%) would be significantly greater than that of the PMU inks (17.9%). Conclusions: About 40.6% of the samples would be noncompliant with the restriction for the presence of preservatives above the permitted level. Additional concentration limits will apply to skin sensitizing preservatives for proper labelling of inks under CLP (Classification, Labelling and Packaging) Regulation. [ABSTRACT FROM AUTHOR]

Isothiazolinones, used as preservative, are known to be skin sensitizers. Although cosmetics represent their main source, occupational exposure may be a significant origin of eczema. While allergic eczema related to these derivates have been reported in a number of professional sectors, their presence in the same workplace was not common. Isothiazolinones are commonly known as skin sensitizers in both domestic and workplace areas. Rubber manufacturing should be considered as a possible occupational exposure to isothiazolinones. This consideration will facilitate further declaration and recognition of allergic dermatitis related to these substances in this specific workplace. [ABSTRACT FROM AUTHOR]

Abstract Isothiazolinones, used as preservative, are known to be skin sensitizers. Although cosmetics represent their main source, occupational exposure may be a significant origin of eczema. While allergic eczema related to these derivates have been reported in a number of professional sectors, their presence in the same workplace was not common.

Biocides, which are found in nature as persistent pollutants, pose a great danger to the ecosystem. Methylisothiazolinone (MIT), a widely used biocide, reaches plants by mixing with water and soil. Vermicompost tea (VCT), which strengthens the plant defence mechanism and increases its growth and development, is a liquid fertiliser consisting of the cooperation of worms with microbes. In the present study, after applying 0.4 g/L (EC50/2), 0.8 g/L (EC50), and 1.6 g/L (EC50 × 2) MIT concentrations without and with VCT on forage pea (Pisum sativum), root lengths, mitotic index data, chromosome and nuclei abnormalities, and DNA damage level were determined. When VCT applied and non-applied groups were compared, it was found that, especially in the VCT applied group, they cope with the stress conditions created by MIT. In addition, positive effects were observed in root lengths, mitotic index data, and amount of cell nuclei abnormalities. In line with other study results, VCT reduces cellular damage by regulating the normal life cycle disrupted in the cell due to mutagens using the curative-regulatory feature. [ABSTRACT FROM AUTHOR]

• Investigated the photodegradation process of MIT and BIT under simulated sunlight in natural waters. • Alkaline conditions significantly promoted the photodegradation of BIT in its deprotonated form (BIT- N −). • Estimated the half-life of photodegradation of MIT and BIT under natural sunlight in actual surface water environments. • Frontier electron density (FED) theory calculations confirmed the degradation pathways of MIT and BIT. • The biological toxicity of photodegradation products was reduced by one level. Methylisothiazolinone (MIT) and Benzisothiazolinone (BIT) are two widely used non-oxidizing biocides of isothiazolinones. Their production and usage volume have sharply increased since the pandemic of COVID-19, inevitably leading to more release into water environment. However, their photochemical behaviors in water environment are still unclear. Therefore, this study investigated photodegradation properties of MIT and BIT in natural water under simulated sunlight. The results demonstrated that direct photolysis was mainly responsible for their photodegradation which occurred through their excited singlet states rather than triplet states. The quantum yields of MIT and BIT photodegradation were 11 - 13.6 × 10−4 and 2.43 - 5.79 × 10−4, respectively. pH had almost no effect on the photodegradation of MIT, while the photodegradation of BIT was significantly promoted under alkaline condition due to abundance of BIT in its deprotonated form (BIT- N −). Cl−, NO 3 − and dissolved organic matter (DOM) in natural water inhibited the photodegradation of both MIT and BIT, with the light screening effect of DOM being the most significantly inhibitory factor. The addition of other isothiazolinones, which possibly coexisted with MIT and BIT in actual condition, slightly inhibited the photodegradation of MIT and BIT. The estimated half-life under natural sunlight at a 30°N latitude was estimated to be approximately 1.1 days. The photodegradation pathways of MIT and BIT are similar, primarily initiated from the ring-opening at the N-S bond, with Frontier electron densities (FED) calculations suggesting the likelihood of oxidation and ·OH addition reactions at the O, N, and S sites. While the photodegradation products exhibited significantly reduced acute toxicity compared to their parent compounds, they nonetheless posed substantial chronic toxicity. These insights are vital for assessing the ecological impacts of MIT and BIT in aquatic environments. [Display omitted] [ABSTRACT FROM AUTHOR]

Keywords: acrylates; allergic contact dermatitis; case report; construction worker; leukoderma; marble; methacrylates; methylisothiazolinone; occupational; resin EN acrylates allergic contact dermatitis case report construction worker leukoderma marble methacrylates methylisothiazolinone occupational resin 242 244 3 02/08/23 20230301 NES 230301 Plastics/resins have become an emerging cause of occupational allergic contact dermatitis (OACD) in construction workers, mainly related to exposure to epoxy resin systems. Allergic contact dermatitis, case report, construction worker, acrylates, marble, methacrylates, methylisothiazolinone, occupational, resin, leukoderma 5 d Toledo University Hospital Acrylate series: methyl methacrylate, butyl methacrylate, 2-HEMA, 2-HPMA, EGDMA, triethyleneglycol dimethacrylate, 1,4-butanediol dimethacrylate, urethane dimethacrylate, bisphenol-A-dimethacrylate, bisphenol A glycerolate dimethacrylate, 1,6 hexanediol diacrylate, tetrahydrofurfuryl methacrylate, tetraethyleneglycol dimethacrylate, dimethylaminoethyl methacrylate, ethyl cyanoacrylate, ethyl methacrylate, isobornyl acrylate, butyl acrylate, 2-hydroxyethyl acrylate, benzoyl peroxide, bisphenol A (Chemotechnique Diagnostics). [Extracted from the article]

Methylisothiazolinone (MI) is commonly used as a preservative in personal care products and is a frequent cause of allergic contact dermatitis. Wepresent a patient with allergic contact dermatitis caused by MI in hair care products and discuss this allergen to bring attention to this common cause ofcontact dermatitis, and to highlight its frequent use in hair care products. If allergy to MI is suspected, testing should be performed to this individual preservative, as testing solely for the combination preservative,methylisothiazolinone/methylchloroisothiazolinone (Kathon CG®), may miss many cases of MI allergy.

Isothiazolinone preservatives (methylisothiazolinone (MIT) and methylchloroisothiazolinone (CMIT) are commonly used in cosmetics, industrial and household products. However, these isothiazolinone derivatives are known to cause allergic contact dermatitis. Hence, a sensitive, accurate, and reliable method for the detection of these compounds is thus warranted. The study aims to analyze concentrations of MIT and CMIT by high performance liquid chromatography. The analytical method used for quantification of MIT and CMIT in cosmetic products (leave-on-baby wet wipes) complies with the validation acceptance criteria (international standards ISO 5725, EU25 European Union for cosmetic regulations). MIT and CMIT were extracted and analyzed in leave-on baby wet-wipes collected from different stores in Riyadh city. Extraction was performed by ultrasonication of the samples, solid-phase extraction, and liquid-liquid extraction. Ten (10) µL of the sample was injected into the HPLC system and samples were analyzed with a mixture of acetic acid and methanol (80:20 v/v) in an isocratic mode. The flow rate was maintained at 1 mL/min. UV detection was performed at 274 nm. The results demonstrated recoveries between 90 and 106%, measurement uncertainty of C +/− 0.4% for methylisothiazolinone and C +/− 0.03% for methylchloroisothiazolinone, repeatability limit (r = 0.2%) and intermediate precision limit; R = 2% and R2 of 0.9996.

Contact dermatitis is a common disease that is caused by repeated skin contact with contact allergens or irritants, resulting in allergic contact dermatitis (ACD) and/or irritant contact dermatitis. Attempts have been made to identify biomarkers to distinguish irritant and allergic patch test reactions, which could aid diagnosis. Some promising candidates have recently been identified, but verification and validation in clinical cases still need to be done. New causes of ACD are constantly being recognized. In this review, 10 new contact allergens from recent years, several relating to anti-aging products, have been identified. Frequent allergens causing considerable morbidity in the population, such as the preservative methylisothiazolinone, have been regulated in the European Union. A significant drop in the number of cases has been seen, whereas high rates are still occurring in other areas such as North America. Other frequent causes are fragrance allergens, especially the widely used terpenes and acrylates found in medical devices for control of diabetes. These represent unsolved problems. Recent advances in immunology have opened the way for a better understanding of the complexity of contact dermatitis, especially ACD—a disease that may be more heterogenous that previous understood, with several subtypes. With the rapidly evolving molecular understanding of ACD, the potential for development of new drugs for personalized treatment of contact dermatitis is considerable. [ABSTRACT FROM AUTHOR]

Background: Allergic contact dermatitis has considerable public health impact and causative haptens vary over time. Objectives: To report the prevalence of contact allergy to allergens in the Swedish baseline series 2010 to 2017, as registered in the Swedish Patch Test Register. Methods: Results and demographic information for patients tested with the Swedish baseline series in 2010 to 2017 were analysed. Results: Data for 21 663 individuals (females 69%) were included. Females had significantly more positive patch tests (54% vs 40%). The reaction prevalence rates were highest for nickel sulfate (20.7%), fragrance mix I (7.1%), Myroxylon pereirae (6.9%), potassium dichromate (6.9%), cobalt chloride (6.8%), methylchloroisothiazolinone/methylisothiazolinone (MCI/MI; 6.4%), MI (3.7%), colophonium (3.5%), fragrance mix II (3.2%), and formaldehyde (3.2%). Myroxylon pereirae reaction prevalence increased from 5% in 2010 to 9% in 2017 and that for methyldibromo glutaronitrile from 3.1% to 4.6%. MCI/MI and MI reactions decreased in prevalence after 2014. Nickel reaction prevalence decreased among females aged 10 to 19 years. Conclusions: Nickel remains the most common sensitizing agent, with reaction prevalence decreasing among females younger than 20 years. The changes in MCI/MI and MI reaction prevalence mirrored those in Europe. The register can reveal changes in contact allergy prevalence over time among patients patch tested in Sweden. [ABSTRACT FROM AUTHOR]

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Background: Methylisothiazolinone (MI) and Methylchloroisothiazolinone (MCI) are among the most common skin sensitizers, yet the immunological events that occur during MCI/MI allergic contact dermatitis (ACD) are still poorly understood. Objectives: To analyse dendrocytes, macrophage subtypes and T cells in skin during the elicitation phase of MCI/MI ACD. Methods: Thirteen patients with positive patch test reactions to MCI/MI (ACD group) and 11 individuals with negative patch test results were selected. Skin biopsies were only performed at 48 hours of patch testing. Immunohistochemistry was conducted to assess T cells, dendrocytes (Factor XIIIa), M1 (p‐Stat1, CD68) and M2 (c‐Maf, CD163) macrophages. Transcriptional analyses were performed for cytokines and related factors, and further compared to atopic dermatitis samples (n=4). Immunofluorescence assays addressed T cells location, along with IL‐4 or IL‐13, within the skin. Results: MCI/MI elicited dermal dendrocytes and macrophages, pronouncedly the M2 subtype. T cells, majorly CD4+ T cells, accumulated in the perivascular areas. Similarly, abundant IL‐4 protein was detected in these areas. There was an upregulation of IL‐4 and IL‐13 mRNA expression, a mild increase in IFNG mRNA levels and a down‐regulation of RORC in the ACD group. Immunofluorescence revealed dermal clusters of T cells co‐localized with IL‐4. Conclusions: M2 macrophages and Th2 cells participate in the immunopathogenesis of MCI/MI ACD. Dermal dendrocytes and M2 macrophages may assist the formation of CD4+ T cells perivascular clusters. These findings render a mechanistic insight into the MCI/MI reaction. Further analysis at different timepoints of patch testing is required to fully comprehend this ACD kinetics. [ABSTRACT FROM AUTHOR]

Keywords: allergic contact dermatitis; CAS no. 26530-20-1; leather; methylisothiazolinone; octylisothiazolinone; preservative EN allergic contact dermatitis CAS no. 26530-20-1 leather methylisothiazolinone octylisothiazolinone preservative 455 457 3 10/06/22 20221101 NES 221101 CASE REPORT A 69 years non-atopic man presented with a 6 months history of pruriginous lesions started on his back with subsequent extension to his arms. [Extracted from the article]

Background: Preservatives are used widely in cosmetic, household, and industrial products to prevent microbial growth and spoiling of the products. There has been a recent epidemic of contact allergy to methylisothiazolinone (MI). Objectives: To establish emerging trends in preservative contact allergy as MI is replaced. Methods: We performed a retrospective study on consecutively patch‐tested patients at our center from January 2011 to December 2019. Results: A total of 7846 consecutively patch‐tested patients were included who were patch tested between January 2011 and December 2019. The prevalence of allergy to MI fell from a peak of 9.39% in 2013 to 1.98% in 2019. MI/methylchloroisothiazolinone (MCI) followed a similar trend, with a peak prevalence of 7.85% in 2014 and falling to 1.39% in 2018. The prevalence of contact allergy to benzisothiazolinone (BIT) has increased steadily increased in 2014 from 0.26% (confidence interval [CI] 0.03‐0.93) to 3.42% (CI 2.43‐4.66) in 2019. Conclusions: Our data show a significant increase in the prevalence of contact allergy to BIT over the last 6 years, probably as a consequence of increased use in household products. It is essential to continue to look for emerging trends in contact allergy to enable prompt preventative measures to be taken. [ABSTRACT FROM AUTHOR]

Background: In the 2010s an epidemic of allergic contact dermatitis to methylisothiazolinone (MI) 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 MI in Belgium between January 2014 and December 2019, and to assess cosensitizations to octylisothiazolinone (OIT) and benzisothiazolinone (BIT) in MI‐sensitized patients. Methods: A retrospective study of patch test results with MI, OIT, and BIT observed in patients attending five Belgian hospitals. Results: Overall, 560 of 10 029 patients (5.58%) had a positive patch test reaction to MI, 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 OIT, and, surprisingly, and increasingly, also to BIT. Conclusions: Contact allergy to MI 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 BIT should be a focus of future research. [ABSTRACT FROM AUTHOR]

Background: Personal care products (PCPs) are commonly responsible for allergic contact dermatitis and irritant contact dermatitis. PCP use was historically associated with females, but male-targeted PCPs are increasingly being marketed.Objective: To characterize and compare males with PCP-related contact dermatitis (MPCPs) and females with PCP-related contact dermatitis (FPCPs).Methods: This was a retrospective cross-sectional analysis of North American Contact Dermatitis Group data (1996-2016).Results: Four thousand six hundred eighty of 16,233 men (28.8%) and 12,730 of 32,222 (39.5%) women had a PCP identified as a source of irritant contact dermatitis or a positive patch test reaction. The proportion of PCP-related dermatitis in both sexes significantly increased (>2.7-fold) over the decade of study. Compared with FPCPs, a larger proportion of MPCPs were older or had trunk or extremity dermatitis (P < .0001). MPCPs were twice as likely to have soaps as a source while FPCPs were twice as likely to have hair care products (P < .0001). The most common PCP-related North American Contact Dermatitis Group allergens for both sexes were methylisothiazolinone (MPCP 28.8% and FPCP 21.5%), fragrance mix I (MPCP 22.3% and FPCP 20.1%), balsam of Peru (MPCP 18.5% and FPCP 14.1%), quaternium-15 (MPCP 16.1% and FPCP 12.3%), and paraphenylenediamine (MPCP 11.5% and FPCP 11.1%).Limitations: Patient population referred for suspected contact dermatitis.Conclusions: PCP-related dermatitis is increasing. Sites of involvement and relevant PCP sources are distinct between sexes. Male and female variation in exposure history may explain differences in reactivity to some allergen groups. [ABSTRACT FROM AUTHOR]

Introduction: Painters and varnishers ("painters") are exposed to various contact allergens and skin irritants, and therefore, are at risk for developing occupational dermatitis (OD). Objective: To describe the spectrum of occupational sensitizations in painters and revise the corresponding current patch test recommendations. Patients and Methods: Retrospective analysis of Information Network of Departments of Dermatology (IVDK) data from 2000 to 2019 with focus on male painters with OD, ages 20‐59 years (n = 557) in comparison to age‐matched male painters without OD (n = 422) and male OD patients who have had never worked as painters (n = 13 862). Results: Male painters with OD have a significantly higher rate of allergic contact dermatitis and face dermatitis than male patients with OD who work in other professions. Positive patch tests to epoxy resin, methylisothiazolinone (MI), and methylchloroisothiazolinone (MCI)/MI were significantly more frequent in painters with OD than in the other groups. Epoxy resin sensitization was significantly associated with face dermatitis. Conclusions: Epoxy resin, MI, and MCI/MI represent the most important occupational sensitizers in painters. In addition to baseline, resins and glues, and industrial biocides series, the patients' own workplace materials should be tested in painters with suspected OD. [ABSTRACT FROM AUTHOR]

Background Isothiazolinones are preservatives which are present in cosmetics, household chemicals and many other industrial products. Initially, a mixture of methylchloroisothiazolinone and methylisothiazolinone (MCI/MI – Kathon CG) was used, and then, from the beginning of the 21st century, only methylisothiazolinone. Due to a significant increase in the number of contact dermatitis caused by allergy to this compound, it was withdrawn from leave-on cosmetics, and its concentration in rinse-off cosmetics was reduced. The aim of the study was to analyze the incidence of contact allergy to isothiazolinones among patients in the Nofer Institute of Occupational Medicine, Łódź, the intensification of patch test results and hypersensitivity depending on the occupation, and to assess the contribution of immediate allergy to the occurrence of that hypersensitivity. Material and Methods In a group of 1137 patients (832 females and 305 males) with suspected contact dermatitis, diagnosed in 2014–2018, patch tests series including methylchloroisothiazolinone/methylisothiazolinone (0.01%) and methylisothiazolinone (0.2%), produced by Chemotechnique Diagnostics, Sweden, were performed. In a group of 29 individuals with contact allergy to isothiazolinones, prick tests with methylisothiazolinone (0.001%, 0.01%, 0.1%, 1%) (Sigma-Aldrich, Germany) were conducted. Results Of the 1137 subjects, 95 (8.3%) were allergic to isothiazolinones, slightly more often females – 71 (8.5%) than males – 24 (7.9%). In total, 150 positive patch tests with isothiazolinones (13.2%) were obtained. The number of positive results with methylisothiazolinone alone (7.8%) was higher than the number with methylisothiazolinone from Kathon CG (5.4%). Among the subjects sensitized to methylisothiazolinone alone strongly positive patch tests (+++) concerned 60.7%. In the female group, office workers (42.3%) and medical staff (18.3%) predominated, and in the male group – locksmiths, turners, mechanics and similar ones (45.8%), and construction workers (25.0%). Prick tests with methylisothiazolinone were negative, and they became positive after 3–5 h. Conclusions Isothiazolinones, particularly methylisothiazolinone, are significant causal factors of contact allergy, including that of occupational origin. They have strongly allergenic properties, and in patch tests they often give very severe inflammatory reactions. The issue of the role of immediate allergy in the pathogenesis of isothiazolinones sensitization requires further research. Med Pr. 2020;71(5):603–11

The electrochemical properties of methylisothiazolinone (MIT), the most widely used preservative, were investigated by cyclic (CV) and differential pulse voltammetry (DPV) to develop a new method for its determination. To our knowledge, this is the first demonstration of a voltammetric procedure for the determination of MIT on a boron-doped diamond electrode (BDDE) in a citrate–phosphate buffer (C-PB) environment. The anodic oxidation process of methylisothiazolinone, which is the basis of this method, proved to be diffusion-controlled and proceeded with an irreversible two-electron exchange. The radical cations, as unstable primary products, were converted in subsequent chemical reactions to sulfoxides and sulfones, and finally to more stable final products. Performed determinations were based on the DPV technique. A linear calibration curve was obtained in the concentration range from 0.7 to 18.7 mg L−1, with a correlation coefficient of 0.9999. The proposed procedure was accurate and precise, allowing the detection of MIT at a concentration level of 0.24 mg L−1. It successfully demonstrated its suitability for the determination of methylisothiazolinone in household products without the need for any separation steps. The proposed method can serve as an alternative to the prevailing chromatographic determinations of MIT in real samples.

The degradation of various preservatives used in the cosmetics industry, including five parabens and their most employed substitute, methylisothiazolinone (MIT), was investigated. A mild photo-Fenton process was applied using low iron concentrations (5 mg/L) at a pH of five, instead of the traditional acidic value of three. At these conditions, the paraben degradation was very low after one hour of reaction and it was necessary to present humic-like substances (HLS) acting as iron chelators to improve the process. Values obtained when MIT was treated were very low, also in the presence of HLS, indicating that their complexing effect was not acting properly. When MIT was added to the mixture of parabens an inhibitory effect was found in the presence of HLS. A possible complex between iron and MIT was suggested and the studies of hydrogen peroxide consumption and Job’s plot technique confirmed this hypothesis. Evidence of the formation of this inactive complex, so far never reported, will be essential in future work when dealing with this compound using Fenton processes. Furthermore, this fact points out the importance of using mixtures of model contaminants instead of a single one or a group of the same family, since their ability to form active or inactive complexes with iron can strongly change the behavior of the whole system.

Most of the materials studied as catalysts in the electro-Fenton system are variants of iron oxide or iron hydroxide. However, iron-based catalysts often exhibit weak catalytic capabilities under neutral and alkaline conditions. In this work, we synthesized three cobalt based bimetallic oxides, Co 2 CuOx, Co 2 AlOx, and Co 2 NiOx, using hydrothermal method and evaluated them as catalysts for the heterogeneous electro-Fenton system to remove 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) and Methylisothiazolinone [2-methyl-4-isothiazolin-3-one] (MIT). Co 2 NiOx has the highest catalytic degradation activity for HEDP, and Co 2 CuOx has the best catalytic degradation effect for MIT. Based on characterization results of the catalysts, the reasons for the differences in the pollutant removal efficiency were analysed, and the optimal pH for the three cobalt based oxides to remove HEDP and MIT was investigated. The results showed that the optimal pH values of the three cobalt based bimetallic oxides are not only influenced by the second metal type, but also by the properties of pollutants. Therefore, suitable cobalt based catalysts can be selected based on the different properties of pollutants, or the composition of cobalt based catalysts can be adjusted to meet the different pH requirements of target wastewater. The three cobalt based bimetallic oxides exhibited good degradation of HEDP and MIT under neutral conditions, which to some extent solved the problem of narrow pH range in the practical application of the electro-Fenton process.

A myasthenic crisis denotes a severe exacerbation of myasthenia gravis, leading a patient to enter a life-threatening state due to progressing muscle weakness that ultimately results in respiratory failure. A crisis can require intubation, mechanical ventilation, and additional critical care to prevent further decompensation and potentially death. Numerous well-documented precipitating factors exist, such as infections, surgery, stress, and various medications. We present the case of a 43-year-old woman recently diagnosed with myasthenia gravis who has experienced two myasthenic crises since diagnosis without evident triggers such as surgery, changes in medication, or infection. Following an unremarkable initial diagnostic test and continued treatment for the crisis, we sought additional information from the patient's family member at the bedside. We were informed that two weeks prior to both times of crisis with intubation, the patient had dyed her hair blue. The common chemical component in the two different hair dyes used was methylisothiazolinone, which is suspected to have contributed to the exacerbation of the patient's myasthenia gravis. As more evidence for new precipitating factors of myasthenic crises develops, it is crucial for physicians to quickly identify signs and symptoms of a crisis so appropriate intervention can occur in a time-sensitive manner. In addition, myasthenia gravis patients should be made aware to be cautious of precipitating factors of a crisis, including but not limited to new beauty products., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2024, Gomez Rosado et al.)

The Expert Panel for Cosmetic Ingredient Safety (Panel) reassessed the safety of the mixture Methylchloroisothiazolinone (MCI)/Methylisothiazolinone (MI), which functions as a preservative in cosmetic products. The Panel reviewed relevant animal and human data provided in this safety assessment, and data from the previously published safety assessment of this mixture, and concluded that MCI/MI is safe in cosmetics when formulated to be nonsensitizing, based on the results of a quantitative risk assessment or similar methodology; however, at no point should concentrations exceed 7.5 ppm in leave-on products or 15 ppm in rinse-off products. [ABSTRACT FROM AUTHOR]

The Expert Panel for Cosmetic Ingredient Safety (Panel) reassessed the safety of Methylisothiazolinone, which functions as a preservative in cosmetics. The Panel reviewed relevant animal and human data provided in this safety assessment, and data from the previously published safety assessments of Methylisothiazolinone, and concluded that Methylisothiazolinone is safe for use in rinse-off cosmetic products at concentrations up to 100 ppm (ie, 0.01%) and safe in leave-on cosmetic products when they are formulated to be nonsensitizing, which may be determined based on a quantitative risk assessment or similar methodology. [ABSTRACT FROM AUTHOR]

Background: Preservatives are widely used in personal and industrial products. Frequent and sustained exposure to preservatives can cause contact allergy. Objective: We investigated the prevalence of contact allergic reactions to common preservatives in Taiwan over a 20-year period. Methods: A retrospective analysis was conducted among patients with allergic contact dermatitis who underwent patch testing at our clinic between 1996 and 2015. Patients who showed positive reactions to preservatives were enrolled. The location of the reaction, likely source of the allergen, and patient occupation, sex, and age were recorded. Thirteen common preservatives, including methylchloroisothiazolinone/methylisothiazolinone (MCI/MI), MI, formaldehyde (FA), paraben mix, and quaternium-15, were investigated. Results: Of 757 enrolled patients, 151 showed at least one positive reaction to preservatives. Allergy to MCI/MI (12.5%), the most frequent allergen in the standard series, showed a steeply increasing trend over time. FA (4.8%) and paraben mix (2.1%) were the next common allergens. Cosmetic products were the most common source of exposure (63.6%), while hairdressers and massage therapists were most commonly associated with occupational contact dermatitis. A sharp increase of sensitivity to MCI/MI was observed after 2006 and that of allergy to MI after 2013. Conclusions: In Taiwan, the prevalence of contact allergy to MCI/MI, MI, and parabens has increased in recent years. Individuals who are frequently exposed to cosmetic products should consider precautions against sensitization.

Background: In 2005, methylisothiazolinone (MI) was allowed as a stand‐alone preservative in cosmetics. This resulted in an epidemic of allergic contact dermatitis to MI, mainly affecting women exposed to leave‐on cosmetics. Consequently, a regulation of Annex V in the European Union in 2017 banned the use of MI in leave‐on cosmetics and reduced the allowed concentration in rinse‐off products. Objective: To analyze the temporal trends in contact allergy to MI in Danish patients in relation to key events including European regulations over time. Methods: A retrospective study of consecutive patients patch tested with methylisothiazolinone from 2005 to 2019. Demographics and clinical characteristics in terms of MOAHLFA (male, occupational, atopic dermatitis, hand dermatitis, leg dermatitis, facial dermatitis and age >40 years), sources of exposure, and clinical relevance were analyzed in relation to key historical events. Results: Three hundred eighty of 12 494 patients (3.0%, 95CI: 2.7–3.4%) tested from 2005 to 2019 were sensitized to MI. An increasing trend in the prevalence of MI contact allergy from 2005 to 2019 (P <.01) was observed, although a decline in the absolute number of patch‐test positive patients was seen from 2013 and onward. A reduction in leave‐on cosmetics as a source of exposure was observed following the legislative ban in 2017, from 24.8% from in 2010 to 2013 to 6.2% in 2017 to 2019 (P <.01). Conclusion: The epidemic of MI contact allergy is declining in absolute terms, although the prevalence in the patch‐tested population has not returned to its pre‐epidemic levels. The legislative regulation of MI in 2017 has been effective in terms of leave‐on cosmetics as a source of exposure in MI allergic patients. The process of post‐marketing risk assessment of contact allergens in the European Union needs improvement. [ABSTRACT FROM AUTHOR]

Background: The epidemiological surveillance of contact dermatitis is one of the objectives of the Spanish Registry of Research in Contact Dermatitis and Cutaneous Allergy. Knowing whether the prevalence of positive tests to the different allergens changes over time is important for this monitoring process., Objectives: To describe the various temporary trends in allergen positivity in the GEIDAC standard series from 2018 through December 31, 2022., Methods: This was a multicenter, observational trial of consecutive patients analyzed via patch tests as part of the study of possible allergic contact dermatitises collected prospectively within the Spanish Registry of Research in Contact Dermatitis and Cutaneous Allergy. The data was analyzed using 2 statistical tests: one homogeneity test (to describe the changes seen over time) and one trend test (to see whether the changes described followed a linear trend)., Results: A total of 11327 patients were included in the study. Overall, the allergens associated with a highest sensitization were nickel sulfate, methylisothiazolinone, cobalt chloride, methylchloroisothiazolinone/methylisothiazolinone, and fragrance mix i. A statistically significant decrease was found in the percentage of methylisothiazolinone positive tests across the study years with an orderly trend., Conclusions: Although various changes were seen in the sensitizations trends to several allergens of the standard testing, it became obvious that a high sensitization to nickel, methylchloroisothiazolinone/methylisothiazolinone and fragrances mix i remained. Only a significant downward trend was seen for methylisothiazolinone., (Copyright © 2023 AEDV. Publicado por Elsevier España, S.L.U. All rights reserved.)

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. [ABSTRACT FROM AUTHOR]

The disposal of reverse osmosis (RO) concentrate (ROC) is a critical challenge impeding the application of RO-based wastewater reclamation. Herein, we proposed an enhanced biotreatment approach for the simultaneous removal of nitrogen, phosphorous, hardness, and methylisothiazolinone (MIT) from ROC by suspended-solid phase cultivation of Scenedesmus sp. LX1. Repeated carrier addition, guided by the developed optimal carrier addition model, efficiently enhanced algal growth and contaminant removal through dynamically controlling the suspended algal density by cell attachment. The maximum algal growth rate (212.2 mg/(L∙d)) increased by 41% compared with the control, and the time needed for reaching the maximum algal biomass (906.7 mg/L) was shortened by 1 d, attributing to the mitigation of density restriction. 91.8% of nitrogen (30.2 mg/L) was removed with 5.5 mg/(L∙d) accelerating removal rate, and phosphate (3.7 mg/L) was completely removed within 1 d. Hardness precursors calcium and inorganic carbon were also removed in large amounts, 268.4 and 128.2 mg/L, respectively. Moreover, suspended-solid phase cultivation significantly mitigated the growth inhibition caused by MIT toxicity, enabled the algae to completely biodegrade MIT of extremely high concentrations (4.7 mg/L and 11.4 mg/L) in a short time. Our results demonstrate the feasibility of suspended-solid phase algal cultivation for simultaneously and effectively removing multiple main contaminants from ROC.