Health safety of parabens evaluated by selected in vitro methods

Seven selected parabens (4 allowed, 3 banned in cosmetics) were tested in order to confirm and expand historical data on their toxicological properties and safety. The aim was to apply novel in vitro methods, which have been sufficiently technically and scientifically validated for the purposes of toxicological testing of chemicals. The study included several toxicological endpoints such as skin/eye irritation, skin sensitization, endocrine disruption and genotoxicity. The battery of selected methods comprised regulatory accepted EpiDerm™ skin model (OECD TG 439); EpiOcular™ corneal model (OECD TG 492) and scientifically valid test method HET-CAM (DB-ALM Protocol No. 47); in chemico test DPRA (OECD TG 442C); in vitro test LuSens (OECD TG 442D) and in vitro test h-CLAT (OECD TG 442E); Ames MPF™ (Xenometrix) and XenoScreen YES/YAS (Xenometrix). Overall, none of the 4 allowed parabens exhibited skin/eye irritation or genotoxicity. However, all allowed parabens in cosmetics were predicted as samples with potentially sensitizing properties in the LuSens and h-CLAT test methods, but not confirmed by DPRA. Endocrine disruption was recorded only at high concentrations, whereas methyl paraben and ethyl paraben exhibited the lowest activity. This study confirmed the safety of use of the allowed parabens in the highest recommended concentrations in cosmetics or pharmaceuticals.

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.

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.

Standard patch test results and clinical relevance: A cross-sectional study of 10-year retrospective experience

Background:

Allergic contact dermatitis (ACD) is a type IV hypersensitivity reaction, and The European Standard Series (ESS) Patch Test (PT) is widely used in determining the possible responsible allergens causing ACD. The dynamic nature of the industrial products, socioeconomic and environmental factors cause the frequency of common allergens to change over the years and among different regions.

Aims and Objectives:

This study aimed to retrospectively evaluate the results of ESS PT of our centre in the last decade, and determine the current spectrum of allergens and their clinical relevance.

Materials and Methods:

The data of patients who underwent ESS PT in our clinic between January 2010 and March 2020 were included in the study. The patient files were examined retrospectively. The clinical relevance was evaluated according to the COADEX system. Statistical analysis used: SPSS for Windows version 23.0 software program.

Results:

The data of 1037 patients [623 (60.1%) female, 414 (39.9%) male] were analysed. The mean age was 38.34 ± 14.55 years. The five most common allergens were nickel sulphate (23.1%), cobalt chloride (12%), potassium dichromate (9.5%), Fragrance mix II (7.3%) and balsam of Peru (5.7%). According to the COADEX coding system, current relevance was detected in 319 (49.3%) of 646 patients who had a positive reaction to any substance in the patch test.

Conclusion:

Our study showed that with increasing awareness in society, the tendency to avoid some well-known allergenic substances and consumer products causes changes in common allergens. These results prove the value of long-term surveillance of contact allergy.

Contact dermatitis associated with preservatives: Retrospective analysis of North American Contact Dermatitis Group data, 1994 through 2016

BACKGROUND

Preservatives are often necessary components of commercial products. Large-scale North American studies on preservative allergy are limited.

OBJECTIVE

To evaluate demographics, positive patch test reactions (PPTRs), clinical relevance, and trends for preservatives tested by the North American Contact Dermatitis Group.

METHODS

We conducted a retrospective cross-sectional analysis of North American Contact Dermatitis Group patch testing results of preservatives from 1994 through 2016.

RESULTS

A 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 < .005) had a significant increase in PPTRs over time.

LIMITATIONS

Collected variables are dependent on clinical judgment. Results may be prone to referral selection bias.

CONCLUSIONS

This large North American study provides insight on preservative PPTRs and trends from 1994 through 2016.

Patch Testing With Methylchloroisothiazolinone/Methylisothiazolinone Using a New Diagnostic Mix-A Multicenter Study From the International Contact Dermatitis Research Group

BACKGROUND

In the early 1980s, a preservative containing a mixture of methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI) in a ratio of 3:1 was introduced. This mixture (mix) has been patch tested at 100 ppm (0.01%) worldwide and at 200 ppm (0.02%) in Sweden since 1986 and also in the European baseline series since 2014.

OBJECTIVE

A new aqueous mix of MCI 0.015% and MI 0.2% was compared with patch testing with the 2 aqueous baseline preparations of MCI/MI 0.02% and MI 0.2%.

METHODS

Four thousand three hundred ninety-seven patients with dermatitis in 12 International Contact Dermatitis Research Group dermatology departments from 3 continents were patch tested simultaneously with the 3 preparations.

RESULTS

The frequency of positive patch tests to the allergens varied between 0% and 26.7% in the 12 test centers. The new mixture MCI/MI 0.215% in aqua (aq) detected significantly more patients with MCI/MI allergy than both MCI/MI 0.02% aq (P < 0.001) and MI 0.2% aq (P < 0.001) alone and combined.

CONCLUSIONS

The results favor replacing the preparations MCI/MI 0.02% aq and MI 0.2% aq with the mixture MCI/MI 0.215% aq in the International Contact Dermatitis Research Group baseline series.

A perspective on the safety of parabens as preservatives in wound care products

Antimicrobial and/or preservative ingredients incorporated in wound care products are subjected to certain safety restrictions. However, several of those agents, and paraben preservatives in particular, have been criticised. Conflicting reports on the potential of parabens to induce allergic contact dermatitis, and their assumed oestrogen‐like activity, raised public health concerns about their overall safety. Here, we seek to provide a balanced perspective on the most significant purported adverse health effects, and thereby allay the many misconceptions regarding the safety of parabens. Extensive and long‐term monitoring of paraben allergy frequencies illustrate that allergic reactions are quite uncommon, especially when compared with other antimicrobial and preservative agents. The estrogenic potential of parabens was illustrated to be far less potent than that of natural oestrogen receptor ligands, and the etiological significance of their presence in human tissue has not been established. The general consensus based on investigations by both the scientific community and regulatory agencies indicates that, with current safety regulations regarding their use in place, this effective and well‐documented group of preservatives should not warrant drastic measures to replace them. As such, despite the ongoing concern, it is indicated that, when used at typical concentrations, parabens are unlikely to affect human health.

Patch test results of the European baseline series among 1309 patients in Turkey between 2013 and 2019

BACKGROUND

Prevalences of sensitivity to contact allergens change over time as a result of variations in allergen exposure.

OBJECTIVES

The aim of the study was to describe trends in sensitisation to allergens of the European baseline series in Turkey between 2013 and 2019.

METHODS

The patch test results of 1309 patients with suspected allergic contact dermatitis (ACD) were analysed retrospectively, and the prevalence of contact allergies to European baseline series allergens was compared with previous data (for 1998-2005).

RESULTS

A total of 534 (40.8%) patients exhibited one or more positive patch test reaction. The five most frequent allergens were nickel sulfate (19.6%), potassium dichromate (6.5%), cobalt chloride (6%), Myroxylon pereirae resin (5%), and p-phenylenediamine (PPD; 3.7%). Statistically significant increases in the prevalence of sensitisation to methylchloroisothiazolinone/methylisothiazolinone (MCI/MI; P < .001), Myroxylon pereirae resin (P < .001), PPD (P = .008), and fragrance mix I (P = .036) were observed in the 2013 to 2019 period compared with the 1998 to 2005 period. Conversely, positive reactions to neomycin sulfate (P = .029), clioquinol (P = .031), and primin (P = .001) decreased significantly.

CONCLUSION

This study provides a comprehensive profile of ACD in Turkey. The remarkable increase in the MI and MCI/MI contact allergy observed underlines the urgent need for regulatory measures to reduce exposure to MI and MCI/MI in Turkey.

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.

Perianal Dermatitis

BACKGROUND

Perianal complaints are often consulted in dermatology clinics, and in many cases, a conclusive diagnosis is not easily made.

OBJECTIVE

The aim of this study was to study and identify the epidemiological, clinical, and contact allergy features of patients with perianal dermatitis who attended at a contact dermatitis unit in a tertiary hospital in Spain.

METHODS

Adult patients with long-lasting (>4 weeks) perianal dermatitis were recruited during the past 10 years for investigation and follow-up. Every patient underwent a diagnostic workup consisting of dermatological exploration and patch tests with the standard and specific series, as well as the patients' own products. General surgical exploration was also performed in some patients.

RESULTS

One hundred twenty-four patients were included. The MOAHLFA index was as follows: 43.5, 0, 4.8, 11.3, 1.6, 8.1, and 75. The main final diagnoses were allergic contact dermatitis (32.3%), psoriasis (24.2%), irritant contact dermatitis (17.7%), and lichen simplex (neurodermatitis) (10%). Eighty-one patients (66.1%) showed 1 or more positive reactions, and in 52 patients (43%), positive reactions relevant to the present disease were found.

CONCLUSIONS

Contact allergy in patients with long-lasting perianal complaints is frequent. It is mandatory for these patients to be referred to a dermatologist for an adequate evaluation and patch testing. Methylchloroisothiazolinone/methylisothiazolinone seems as the most common allergen implicated in perianal contact dermatitis.

An epidemic of allergic contact dermatitis caused by a new allergen, caprylhydroxamic acid, in moisturizers

BACKGROUND

In 2016, dermatologists in Finland suspected contact allergy in several patients using moisturizers under the trade name Apobase®. Following a formulation change, Phenostat™, which is a mixture of phenoxyethanol, caprylhydroxamic acid, and methylpropanediol, was used as a preservative in Apobase® moisturizers in Finland.

OBJECTIVES

To confirm the suspected contact allergy to Apobase® cream, oily cream, and/or lotion, and to identify the specific contact allergen and define its optimal patch test concentration.

METHODS

Thirty-nine patients with suspected contact allergy to Apobase® creams or lotion were patch tested in four Finnish dermatological clinics. The patch tests included old and new Apobase® formulas and their preservative agents: phenoxyethanol, methylpropanediol, and dilution series of Phenostat™ and caprylhydroxamic acid or its potassium salt.

RESULTS

The patch tests showed positive reactions to the new Apobase® formulas, Phenostat™, and caprylhydroxamic acid or its potassium salt, but not to the old Apobase® formulas, methylpropanediol, or phenoxyethanol.

CONCLUSIONS

We found a new contact allergen, caprylhydroxyamic acid, which caused an epidemic of allergic contact dermatitis in patients using moisturizers containing this preservative. Whether the sensitizing capacity of caprylhydroxamic acid depends on the other chemicals used in Apobase® moisturizers needs further investigation.

"Parabenoia" Debunked, or "Who's Afraid of Parabens?"

Parabens have been used as preservatives in foods, injectables, and topical preparations for nearly 10 decades. Present in nature, rapidly metabolized by skin and liver enzymes, they have an excellent safety record. However, in the past 15 years, they have been under scrutiny for their alleged estrogenic and antiandrogenic effects, as well as their putative role in promoting cancerogenesis through endocrine disruption. Scientific articles supporting these assertions have led the European Community to ban or restrict the use of some parabens. Despite that methylparaben and ethylparaben have negligible endocrine disruption activity, the food, pharmaceutical, and cosmetic industries are under pressure from scare campaigns in the media and are responding by replacing parabens with other biocides that cause multiple cases, and even worldwide epidemics, of allergic contact sensitization. In the present review, we present a balanced account of the published literature about the metabolism and potential toxicology of parabens.

In situ chemical behaviour of methylisothiazolinone (MI) and methylchloroisothiazolinone (MCI) in reconstructed human epidermis: a new approach to the cross-reactivity issue

BACKGROUND

Methylisothiazolinone (MI) [with methylchloroisothiazolinone (MCI) in a ratio of 1:3, a well-recognized allergenic preservative] was released as an individual preservative in the 2000s for industrial products and in 2005 for cosmetics. The high level of exposure to MI since then has provoked an epidemic of contact allergy to MI, and an increase in MI/MCI allergy. There are questions concerning the MI/MCI cross-reaction pattern.

OBJECTIVES

To bring a new perspective on the MI/MCI cross-reactivity issue by studying their in situ chemical behaviour in 3D reconstructed human epidermis (RHE).

METHODS

MI and MCI were synthesized with (13) C substitution at positions C-4/C-5 and C-5, respectively. Their in situ chemical behaviours in an RHE model were followed by use of the high-resolution magic angle spinning nuclear magnetic resonance technique.

RESULTS

MI was found to react exclusively with cysteine thiol residues, whereas MCI reacted with histidines and lysines. The reaction mechanisms were found to be different for MI and MCI, and the adducts formed had different molecular structures.

CONCLUSION

In RHE, different MI/MCI reactions towards different nucleophilic amino acids were observed, making it difficult to explain cross-reactivity between MI and MCI.

European Society of Contact Dermatitis guideline for diagnostic patch testing - recommendations on best practice

The present guideline summarizes all aspects of patch testing for the diagnosis of contact allergy in patients suspected of suffering, or having been suffering, from allergic contact dermatitis or other delayed-type hypersensitivity skin and mucosal conditions. Sections with brief descriptions and discussions of different pertinent topics are followed by a highlighted short practical recommendation. Topics comprise, after an introduction with important definitions, materials, technique, modifications of epicutaneous testing, individual factors influencing the patch test outcome or necessitating special considerations, children, patients with occupational contact dermatitis and drug eruptions as special groups, patch testing of materials brought in by the patient, adverse effects of patch testing, and the final evaluation and patient counselling based on this judgement. Finally, short reference is made to aspects of (continuing) medical education and to electronic collection of data for epidemiological surveillance.

Occupational dermatitis in health care workers evaluated for suspected allergic contact dermatitis

BACKGROUND

Contact dermatitides occur commonly among health care workers (HCWs).

OBJECTIVE

To contrast the atopic status and incidence, location, and final diagnosis of skin diseases afflicting HCWs versus non-HCWs (NHCWs) evaluated for suspicion of allergic contact dermatitis (ACD); and among the population diagnosed with ACD, to compare the incidence and occupational relatedness of allergens found in HCWs with the rates observed in NHCWs.

METHODS

Between July 1, 1994, and May 30, 2014, 2611 patients underwent patch testing by the senior author. Of these, 165 were classified as HCWs based on their primary occupation. Statistical analysis was done using a χ test.

RESULTS

Health care workers were more likely than NHCWs to be women and to have hand dermatitis. Women, but not men, HCWs suffered more irritant contact dermatitis. Health care workers had significantly more work-related ACD, especially to formaldehyde, quaternium-15, 2-bromo-2-nitropropane-1,3-diol, cocamide diethanolamine (DEA), thiuram mix, carba mix, thimerosal, benzalkonium chloride, glutaraldehyde, and bacitracin.

LIMITATIONS

Only patients suspected of having ACD were tested. Our population was geographically limited to metropolitan Kansas City, MO and metropolitan New York, NY.

CONCLUSIONS

Health care workers suffer more from occupational ACD, especially of the hands, than do NHCWs, including to allergens not present on available standard allergen series.

Methylisothiazolinone: dermal and respiratory immune responses in mice

Methylisothiazolinone (MI), a widely used chemical preservative in industrial and household products, and cosmetics, has been associated with allergic contact dermatitis. However, the asthmogenic capacity of MI is currently unknown. In this study, we investigated the capacity of MI to elicit asthma-like responses in a validated mouse model. On days 1 and 8, mice (C57Bl/6 and BALB/c) were dermally treated with MI or vehicle on each ear. On day 15, mice received a single intranasal challenge with MI or vehicle. Immediately after the challenge, the early ventilatory response was measured using a double chamber plethysmograph. One day later, airway hyperreactivity, pulmonary inflammation and immune-related parameters were assessed. Dermal treatment with MI in both C57Bl/6 and BALB/c mice induced increased T- and B-cell proliferation in the auricular lymph nodes, along with IFN-γ production and limited increases in total serum IgE, confirming dermal sensitization. An airway challenge with MI led to an early ventilatory response (decreased breathing frequency), indicative for acute sensory irritation. However, 24h later no allergic respiratory response (no airway hyperreactivity (AHR) nor pulmonary inflammation) was found in either mouse strains. Our study indicates that MI can be classified as a strong dermal sensitizer and irritant, but not an asthmogen after initial dermal sensitization, followed by an airway challenge.