Imidazolidinyl Urea Research Articles

Susceptibility of Some Bacterial Contaminants Recovered from Commercial Cosmetics in Jordan to Preservatives and Antibiotics

Purpose: To investigate the susceptibility of bacterial contaminants recovered from cosmetics to preservatives and antibiotics. Methods: Nine bacterial isolates recovered from various brands of commercially available cosmetics marketed in Jordan were tested for their susceptibility pattern against two paraben esters and two formaldehyde donors in addition to nine commonly used antibiotics. The biocidal effect for three preservatives was tested at 0.2 % concentration while the fourth was determined at a strength of 0.3 %. Antibiotic sensitivity test was carried out using standard disc diffusion method. Results: Isolates of Pseudomonas aeruginosa exhibited high resistance pattern to most of the tested preservatives and antibiotics; only one isolate was sensitive to imidazolidinyl urea while others were resistant to the 4 preservatives tested. Each of these isolates exhibited resistance to at least 5 antibiotics. Other organisms, including Escherichia coli and Staphylococcus aureus, were resistant to the class of preservatives used in the various formulations from which they were recovered and demonstrated resistance to fewer antibiotics. Coagulase-negative staphylococci were the most sensitive to both categories of antimicrobials used. One isolate was sensitive to all preservatives whereas the same isolate was resistant to only co-trimoxazole. Ciprofloxacin and norfloxacin demonstrated the highest in vitro antimicrobial effect against the contaminants investigated. Conclusion: The bacterial contaminants of cosmetics exhibited variable cross resistance between preservatives and antibiotics. This cross resistance was species- and even strain-specific.

Cutaneous delayed-type hypersensitivity in patients with atopic dermatitis: Reactivity to topical preservatives

Patients with atopic dermatitis (AD) have chronic dry skin to which they frequently apply skin care products containing preservatives, and they are predisposed to developing cutaneous delayed-type hypersensitivity. We sought to compare the rates of positive patch test reactions to allergens on the North American Contact Dermatitis Group (NACDG) standard tray among patients with and without AD and to assess whether atopic patients in our database were more likely to patch test positive to preservatives. A total of 2453 patients underwent patch testing to the NACDG standard screening series. The incidence of positive patch test reaction among patients with AD (n = 342) and without AD (n = 2111) was assessed. Statistical analysis was done using a χ(2) test. Compared with nonatopic patients, patients with AD were statistically more likely to have positive patch tests. AD was associated with contact hypersensitivity to quaternium-15, imidazolidinyl urea, DMDM hydantoin, and 2-bromo-2-nitropropane-1,3-diol but not to parabens, formaldehyde, or diazolidinyl urea. Only patients suspected of having allergic contact dermatitis were tested. Our population was geographically limited to metropolitan Kansas City, MO, and metropolitan New York City, NY. Patients with AD should avoid the use of skin care products preserved with formaldehyde releasers.

A novel reverse osmosis membrane with regenerable anti-biofouling and chlorine resistant properties

Currently, biofouling and the chlorine degradation of membrane during the control of biofouling are still the major obstacles to the development of reverse osmosis (RO) membranes technology. In this work, both the anti-biofouling and the chlorine resistant properties of a commercial aromatic polyamide RO membrane (RE4021-TL, Woongjin Chemical Co., Ltd.) are improved by carbodiimide-induced grafting with imidazolidinyl urea (IU). The grafted IU not only endows the membrane with high anti-biofouling property by acting as an anti-microbial agent but also endows the membrane with the other durable and regenerable anti-biofouling and chlorine resistant properties by acting as the precursor of N-halamine. The grafting of IU and the grafting amount are analyzed by ATR-FTIR and XPS, respectively. The hydrophilicity of the membrane surface is improved obviously and the isoelectric point of the membrane surface shifts toward higher value. A cycling experiment indicates the high regeneration abilities of both the anti-biofouling and the chlorine resistant properties. Moreover, the long-term investigation (100 days) results show that the IU modification accompanied with the periodical free chlorine pretreatment in the RO systems is a potential strategy to increase the lifetime of the commercial RO membranes in practical application.

Frequency of positive patch test reactions to preservatives: The Australian experience

Preservatives are important causes of allergic contact dermatitis. The frequency of allergy to preservatives in Australia has been unknown to date. Our objectives are to report the frequency of positive preservative patch test reactions in Australia, comparing them to the published international data, as well as exploring the current regulations in place for preservative use in Australia. This was the first retrospective study of patch testing results, aggregated from four patch test clinics in three centres in Melbourne and Sydney. In all, 6845 patients were patch-tested during 1993-2006 and in this period the five most frequent preservative allergens were formaldehyde (4.6%), Euxyl K400 (containing methyldibromo glutaronitrile and phenoxyethanol) (3.3%), quaternium-15 (2.9%), diazolidinyl urea (2.4%), and methylchloroisothiazolinone/methylisothiazolinone (2.3%). These were followed by dimethylol dimethyl DMDM hydantoin (2.1%), chloroacetamide (2.1%) and imidazolidinyl urea (1.9%). The least frequent sensitisers were parabens (1.1%), 2-bromo-2-nitropropane-1, 3-diol (0.9%) and benzyl alcohol (0.4%). Formaldehyde was the most prevalent preservative allergen. Chloroacetamide allergy was more commonly seen in Australia. Parabens, 2-bromo-2-nitropropane-1,3-diol and benzyl alcohol were the least frequent sensitisers. Household products in Australia are not required to list all ingredients preventing sensitised individuals from properly assessing their exposure.

Cell Chip-Based Monitoring of Toxic Effects of Cosmetic Compounds on Skin Fibroblast Cells

The present study estimated the efficacy of electrochemical detection of imidazolidinyl urea-induced cell toxicity in skin human fibroblast cells (HFF cells). The gold nanopunct structures were fabricated through a nanoporous alumina mask, and the structural formations were confirmed via scanning electron microscopy. The HFF cells were allowed to attach to RGD (Arg-Gly-Asp) peptide nanopatterned surfaces, and electrochemical tools were applied to skin cells attached to the chip surface. The HFF cells evidenced inflammation responses to allergens such as imidazolidinyl urea. The cells were subsequently treated with different concentrations of imidazolidinyl urea for 24 h in culture, which induced a change in the cyclic voltammetry (CV) current peak. Treatment with imidazolidinyl urea induced a loss of cell viability and accelerated inflammation in a concentration-dependent manner. The expression level of inflammation-related proteins such as IL-1 beta were increased in imidazolidinyl urea-treated cells. The CV results demonstrated that imidazolidinyl urea significantly reduced the current peaks in a dose-dependent manner. The results showed that the current peak was reduced in accordance with the increases in imidazolidinyl urea-induced inflammation. In conclusion, the results of this study suggest that the electrochemical-based chip provides crucial information for improvements to a cell chip system for drug screening applications.

Simultaneous Determination of Eleven Preservatives in Cosmetics by Micellar Electrokinetic Chromatography

A new method for the simultaneous quantitation of 11 preservatives-imidazolidinyl urea, benzyl alcohol, dehydroacetic acid, sorbic acid, phenoxyethanol, benzoic acid, salicylic acid, and four parabens (methyl, ethyl, propyl, and butyl)-in cosmetics by micellar electrokinetic capillary chromatography was established and validated. The separation was performed using an uncoated fused-silica capillary (50 pm id x 60.2 cm, effective length 50 cm) with a running buffer consisting of 15 mmol/L sodium tetraborate, 60 mmol/L boric acid, and 100 mmol/L sodium dodecyl sulfate. A 1:10 dilution of the running buffer was used as the sample buffer to extract the cosmetic samples. The key factors, such as the concentration and pH of the running and sample buffers, which influence quantitative analysis of the above 11 preservatives in cosmetic samples, were investigated in detail. The linear ranges of the calibration curves for imidazolidinyl urea and the other 10 preservatives were 50-1000 and 10-200 mg/L, respectively. The correlation coefficients of the standard curves were all higher than 0.999. The recoveries at the concentrations studied ranged from 93.0 to 102.7%. RSDs were all less than 5%. The new method with simple sample pretreatment met the needs for routine analysis of the 11 preservatives in cosmetics.

Characterization of the decomposition of compounds derived from imidazolidinyl urea in cosmetics and patch test materials

Imidazolidinyl urea releases formaldehyde through decomposition. However, there have been few reports on the chemistry of imidazolidinyl urea in cosmetics. The aim of this study was to characterize imidazolidinyl urea-derived compounds in cosmetics and to determine which compounds are responsible for the cross-reactivity with diazolidinyl urea. We analysed imidazolidinyl urea dissolved in aqueous solutions, imidazolidinyl urea patch test materials and imidazolidinyl urea-preserved cosmetics by high-performance liquid chromatography/photodiode array detection and liquid chromatography/mass spectrometry. The results were compared with those obtained with a diazolidinyl urea aqueous solution. In the analysed cosmetic samples and patch test materials, imidazolidinyl urea was primarily composed of allantoin, (4-hydroxymethyl-2,5-dioxo-imidazolidine-4-yl)-urea (HU), (3,4-bis-hydroxymethyl-2,5-dioxo-imidazolidine-4-yl)-urea (3,4-BHU), and (3-hydroxymethyl-2,5-dioxo-imidazolidine-4-yl)-urea. Two of the imidazolidinyl urea-derived major decomposition compounds - HU and 3,4-BHU - are common in the diazolidinyl urea-decomposed compound present in cosmetics. These compounds are possible causative agents of the cross-reactivity between diazolidinyl urea and imidazolidinyl urea.

Contact Sensitization to Allergens in the Spanish Standard Series at Hospital Costa del Sol in Marbella, Spain: A Retrospective Study (2005–2010)

BackgroundThe prevalence of contact allergy to different compounds can vary according to the population studied, the technique used, and the materials employed in patch tests. The Spanish Contact Dermatitis and Skin Allergy Research Group (GEIDAC) has proposed a panel of 29 allergens for use in patients with suspected allergic contact dermatitis. ObjectiveTo determine the prevalence of contact sensitization in a group of Spanish patients and to analyze potential associations with sociodemographic and clinical variables (sex, age, site of lesions, occupation, and diagnosis of atopic dermatitis). Materials and methodsA retrospective study of patients with suspected contact dermatitis was undertaken at Hospital Costa del Sol in Marbella, Spain, for the period between January 1, 2005 and December 31, 2010; 839 patients were included in the analysis. Patch tests were carried out with 34 allergens, including the 29 compounds that comprise the Spanish standard panel proposed by the GEIDAC. ResultsSensitization to at least 1 allergen in the panel was observed in 48% of patients. Women had a higher frequency of sensitization than men (56.9% vs 33.1%). The hands were the most commonly affected site (36.1%). The most frequently involved allergens were nickel sulfate (25.9%), potassium dichromate (7.6%), thiomersal (5.1%), cobalt chloride (4.5%), and fragrance mix I (3.8%). In contrast, preservatives such as paraben mix (0.1%), imidazolidinyl urea (0.1%), diazolidinyl urea (0.2%), and quinoline mix (0.2%) had low rates of sensitization. Sensitization to sesquiterpene lactones and methyldibromo glutaronitrile (euxyl K 400) were not observed. ConclusionsOur results are similar to those previously reported for Spanish patients. The low level of sensitization to certain allergens such as most preservatives and sesquiterpene lactones may suggest that their use in standard patch test series should be reconsidered.

Sensibilización de contacto a alérgenos de la serie estándar en el Hospital Costa del Sol: Estudio retrospectivo (2005-2010)

BackgroundThe prevalence of contact allergy to different compounds can vary according to the population studied, the technique used, and the materials employed in patch tests. The Spanish Contact Dermatitis and Skin Allergy Research Group (GEIDAC) has proposed a panel of 29 allergens for use in patients with suspected allergic contact dermatitis. ObjectiveTo determine the prevalence of contact sensitization in a group of Spanish patients and to analyze potential associations with sociodemographic and clinical variables (sex, age, site of lesions, occupation, and diagnosis of atopic dermatitis). Material and methodsA retrospective study of patients with suspected contact dermatitis was undertaken at Hospital Costa del Sol in Marbella, Spain, for the period between January 1, 2005 and December 31, 2010; 839 patients were included in the analysis. Patch tests were carried out with 34 allergens, including the 29 compounds that comprise the Spanish standard panel proposed by the GEIDAC. ResultsSensitization to at least 1 allergen in the panel was observed in 48% of patients. Women had a higher frequency of sensitization than men (56.9% vs 33.1%). The hands were the most commonly affected site (36.1%). The most frequently involved allergens were nickel sulfate (25.9%), potassium dichromate (7.6%), thiomersal (5.1%), cobalt chloride (4.5%), and fragrance mix I (3.8%). In contrast, preservatives such as paraben mix (0.1%), imidazolidinyl urea (0.1%), diazolidinyl urea (0.2%), and quinoline mix (0.2%) had low rates of sensitization. Sensitization to sesquiterpene lactones and methyldibromo glutaronitrile (euxyl K 400) were not observed. ConclusionsOur results are similar to those previously reported for Spanish patients. The low level of sensitization to certain allergens such as most preservatives and sesquiterpene lactones may suggest that their use in standard patch test series should be reconsidered.

Sensibilización a formaldehído y sus liberadores en dermatología profesional: estudio de los últimos 6 años

Introduction Sensitization to formaldehyde or formaldehyde-releasing substances is sometimes an occupational hazard, producing serious consequences in the exercise of some professions. Materials and methods Patients’ medical histories were reviewed and a retrospective examination was performed of those with positive results in skin contact tests to formaldehyde, quaternium-15, diazolidinyl urea or imidazolidinyl urea in the standard battery (TRUE TEST ®), as well as in standard batteries to cosmetics, cutting oils, etc. (Chemotecnique ®) between 2005 and 2010, both inclusive. Results Of 3037 patients who underwent a dermatology examination at work, 38 were sensitized to formaldehyde. Among sensitized patients (17 monosensitized), 32 showed a direct association between exposure and symptoms. Concomitant sensitization to formaldehyde and quaternium-15 was found in 78%. Among metallurgical workers with positive skin tests to formaldehyde (n = 17), nine showed concomitant sensitization to quaternium-5 and eight to biobans and all showed cosensitization to formaldehyde. One-third of the patients sensitized to diazonidyl urea (n = 3) and to imidazolinyl urea (n = 3), showed cosensitization to formaldehyde. Among women hairdressers, three showed sensitization to formaldehyde and only two showed sensitization to quaternium-15 without cosensitization to formaldehyde. In other professions, all cases of positivity to formaldehyde showed cosensitization to formaldehyde-releasing substances. Conclusions Formaldehyde and formaldehyde-releasing substances should be evaluated and studied in the differential diagnosis of contact eczema at work, especially in metallurgical workers, since most cases show a clear association between exposure and symptoms.

Patch testing with formaldehyde and formaldehyde-releasers: multicentre study in Spain (2005-2009)

Formaldehyde and formaldehyde-releasers are common causes of allergic contact dermatitis. To determine the frequency of sensitization to formaldehyde and seven formaldehyde-releasers. To establish and characterize groups of patients according to the results of patch testing. We performed a 5-year retrospective study, in six Spanish hospitals, of patients with positive patch test reactions to formaldehyde or any of seven formaldehyde-releasers. The most frequent allergens were formaldehyde (1.72%), imidazolidinyl urea (1.05%), quaternium-15 (0.88%), and diazolidinyl urea (0.79%). Patients with sensitization to only formaldehyde had a higher frequency of occupational dermatitis (25%) than patients with sensitization to only formaldehyde-releasers (9.5%). The most common sites of dermatitis were the hands (31.7%) in patients with sensitization to only formaldehyde and the face and legs (31.3% and 24.6%) in patients with sensitization to only formaldehyde-releasers. We found a subgroup of 25 patients who were sensitized to both imidazolidinyl urea and diazolidinyl urea, and only 6 of these (24%) were also sensitized to formaldehyde. The inclusion of imidazolidinyl urea and diazolidinyl urea in the baseline series of the Spanish Contact Dermatitis and Skin Allergy Research Group (GEIDAC) should enable better classification of patients allergic to formaldehyde, and could aid in their management.

Time trends of contact allergy to a modified European baseline series in Beijing between 2001 and 2006

Monitoring trends of sensitivity rates in a population is useful for epidemiological surveillance. The time trends for sensitivity rates of allergens have not previously been reported in China. The aim of the present study was to determine the prevalence and trends of contact allergy in patients with suspected allergic contact dermatitis in Beijing, China. A retrospective analysis of all patch test data from our database was performed. A total of 1354 patients with suspected allergic contact dermatitis between 2001 and 2006 were studied. Patch tests with 20 allergens or mixtures of allergens were performed and analysed. Sensitivity to potassium dichromate (50.1%) was most frequent, and sensitivity to imidazolidinyl urea (3.0%) was least frequent. Increasing trends in sensitivity rates for 10 allergens with significant linear regression were observed (p < 0.05), including mercapto mix, black rubber mix, potassium dichromate, formaldehyde, epoxy resin, benzocaine, ethylenediamine dihydrochloride, paraben mix, tixocortol-21-pivalate, and sesquiterpene lactone mix. Sensitivity rates for the other 10 allergens remained stable or showed only a trend (fragrance mix) towards an increase (p(trend) > 0.05). High sensitivity rates were observed in the study. Significant increasing trends in sensitivity rates for 10 allergens, probably reflecting increasing changes in exposure, were found.

Positive patch test reactions in older individuals: Retrospective analysis from the North American Contact Dermatitis Group, 1994-2008

Relatively little is known about the epidemiology of allergic contact dermatitis in older individuals. We sought to determine the frequency of positive and clinically relevant patch test reactions in older individuals (≥ 65 years old) referred for patch testing, and to compare these results with those of adults (≤ 64-19 years) and children (<18 years). This was a retrospective cross-sectional analysis of North American Contact Dermatitis Group data from 1994 to 2008. A total of 31,942 patients (older n = 5306; adults n = 25,028; children n = 1608) were patch tested. The overall frequency of at least one allergic reaction in older individuals was 67.3% as compared with 66.9% for adults (P = .5938) and 47% for children (P = .0011). Reaction rates that were statistically higher in older individuals as compared with both adults and children included: Myroxylon pereirae, fragrance mix I, quaternium-15, formaldehyde, imidazolidinyl urea, diazolidinyl urea, neomycin, bacitracin, methyldibromo glutaronitrile, methyldibromo glutaronitrile/phenoxyethanol, ethyleneurea melamine formaldehyde mix, and carba mix (P values < .0004). Patch test reaction rates that were significantly lower in older individuals than both comparison groups included: nickel, thimerosal, and cobalt (P values < .0001). Referral population was a limitation. Older individuals were more likely to have at least one positive patch test reaction as compared with children, but had similar rates to adults. The frequency of positive reactions to specific allergens differed by age group, most likely as a result of exposures.

Contact allergy to preservatives. Analysis of IVDK data 1996-2009

Preservatives are well-known and important contact allergens. To examine the frequency of sensitization to preservatives, including time trends. Retrospective analysis of data on patch testing of preservatives contained in the standard series and special series collected by the IVDK during 1996-2009. Some 120,000 and 80,000 patients were tested with the baseline and the preservative series, respectively. Sensitization frequencies of the standard series allergens all ranged above 1%: methyldibromoglutaronitrile (MDBGN) 2·36-4·5%, methy(chloro)isothiazolinone (MCI/MI) 2·22%, formaldehyde 1·54%, paraben mix 1·33% and Bronopol® 1·25%. Regarding the special preservative series, 1·54% reacted positive to methylisothiazolinone (MI), and < 1% to the other preservatives. Concomitant reactions to formaldehyde in formaldehyde releasers ranged from 15% to almost 50%, and 67% of MI positives reacted to MCI/MI. As indicated by the MOAHLFA index, sensitization to MI, iodopropynylbutyl carbamate (IPBC) and quaternium 15 was associated more often with occupational dermatitis, whereas sensitization to imidazolidinyl urea and diazolidinyl urea was associated with face dermatitis, indicating cosmetic exposure. Epidemiologically relevant decreases (> 10%) were seen in chloroacetamide, benzyl alcohol and MDBGN. Epidemiologically relevant increases were noted in IPBC, sodium benzoate and MI. Preservatives are still important contact allergens. The introduction of new preservatives should consider the specific characteristics of occupational and of nonoccupational (cosmetic, household) exposure, and preventive measures should aim equally at both areas.

Use of IL-8 release and p38 MAPK activation in THP-1 cells to identify allergens and to assess their potency in vitro

The local lymph node assay (LLNA) has been developed to assess skin sensitization, and based on the EC3 value, it can also be used to evaluate allergen potency. Therefore, in the development of in vitro alternatives to the LLNA assay, one should not only consider the hazard identification but also the possibility to classify allergens relatively to their potency. We have recently described a selective release of interleukin-8 (IL-8) by chemical allergens in THP-1 cell line, and identified the activation of p38 mitogen-activated protein kinase (p38 MAPK) as a common pathway. Therefore, the purpose of this study was to expand the number of chemicals tested and to investigate whether IL-8 production and p38 MAPK activation can be used to classify allergens according to their potency. THP-1 cells were exposed to the contact allergens ( p-benzoquinone, 2-aminophenol, isoeugenol, diethyl maleate, citral and imidazolidinyl urea), selected according to their potency in the LLNA, and to lactic acid and propylene glycol as non-sensitizers. p38 MAPK activation was evaluated 5–15 min after treatment by FACS analysis, while IL-8 release was assed by ELISA following 24 h of incubation. p38 MAPK was activated by all contact allergens, including the pro-apten isoeugenol, whereas IL-8 release was significantly increased after stimulation with all allergens tested, except for isoeugenol. The failure of isoeugenol may be due to decrease in the stability of IL-8 mRNA. Irritants exposure, as expected, failed to induce both p38 MAPK activation and IL-8 release. A significant correlation between IL-8 release and the LLNA EC 3 was found (Pearson correlation r = 0.743, p = 0.0036, n = 12). On the contrary, the activation of p38 MAPK showed no significant correlation between LLNA data and vigor of p38 MAPK activation. Overall, data presented confirm our previous observations and reveal IL-8 as potential tool not only to identify sensitizers, with the exception of pro-haptens, but also to classify them according to their potency, while p38 MAPK activation allows the identification of all sensitizers, including pro-haptens, but was not useful for potency classification.

Positive concomitant test reactions to allergens in the standard patch test series

Patch testing is performed to evaluate suspected allergic contact dermatitis. Common wisdom suggests that various allergens cross-react but only a few larger studies have published confirmations of this. The purpose of our study was to identify significant correlations between positive test reactions in a screening series. A total of 1235 patients undergoing patch testing to the Hermal standard series at the Massachusetts General Hospital, Contact Dermatitis Clinic between 1990 and 2006 were investigated. Two or more positive reactions were seen in 411 patients (33.3%). Sensitizations to eight pairs of allergens were found to have significant correlation (P <or= 0.0001). A strong association was observed for cross reactions between formaldehyde and its releasers quaternium 15 and imidazolidinyl urea and between balsam of Peru and fragrance mix. Moreover, significant co-sensitization was identified for potassium dichromate and colophony. Three significant pairings in our study were associations between fragrances and metals. Our data confirm the previously published cross-reactions in the literature between fragrance components, and formaldehyde and formaldehyde-releasing preservatives. The increased numbers of patients with metal and fragrance sensitization can be considered as a random finding due to independent sensitization. Being aware of cross-reacting allergens is essential to success in resolving allergic dermatitis when counseling patients.

Survey of Formaldehyde (FA) Concentration in Cosmetics Containing FA-donor Preservatives

We measured the amount of formaldehyde (FA) in cosmetics containing FA-donor preservatives [imidazolidinyl urea (IU), dimethyloldimethyl hydantoin (DM), diazolidinyl urea (DU), quaternium-15 (QU), and bronopol (BP)] and explored the factors affecting FA release. FA was detected in all the 89 cosmetic products tested. FA concentrations of cosmetics declared to contain DM and DU were significantly higher than those of cosmetics declared to contain IU and BP. Detected FA concentration of samples produced in the U.S.A. was significantly higher than thatof samples produced in European countries. A weak proportional relationship was observed between the pH value and the released FA concentration of the cosmetic products containing DM and DU. There were no significant differences in the FA concentrations of various categories of cosmetics (lotion, gel, conditioner, shampoo, body wash, and others). Cosmetics containing a blend of amines, amides, or hydrolyzed proteins together with FA-donor preservatives had a lower FA concentration than the others.

Formaldehyde‐releasers in cosmetics: relationship to formaldehyde contact allergy

In this part of a series of review articles on formaldehyde-releasers and their relationship to formaldehyde contact allergy, formaldehyde-releasers in cosmetics are discussed. In this first part of the article, key data are presented including frequency of sensitization and of their use in cosmetics. In Europe, low frequencies of sensitization have been observed to all releasers: 2-bromo-2-nitropropane-1,3-diol 0.4-1.2%, diazolidinyl urea 0.5-1.4%, imidazolidinyl urea 0.3-1.4%, quaternium-15 0.6-1.9% (for DMDM hydantoin no recent data are available). All releasers score (far) higher prevalences in the USA; the possible explanations for this are discussed. The relevance of positive patch test reactions has been insufficiently investigated. In the USA, approximately 20% of cosmetics and personal care products (stay-on products: 17%, rinse-off products 27%) contain a formaldehyde-releaser. The use of quaternium-15 is decreasing. For Europe, there are no comparable recent data available. In the second part of the article, the patch test relationship of the releasers in cosmetics to formaldehyde contact allergy will be reviewed and it will be assessed whether products preserved with formaldehyde-releasers may contain enough free formaldehyde to pose a threat to individuals who have contact allergy to formaldehyde.

Formaldehyde‐releasers in cosmetics: relationship to formaldehyde contact allergy

This is the second part of an article on formaldehyde-releasers in cosmetics. The patch test relationship between the releasers in cosmetics to formaldehyde contact allergy is reviewed and it is assessed whether products preserved with formaldehyde-releasers may contain enough free formaldehyde to pose a threat to individuals with contact allergy to formaldehyde. There is a clear relationship between positive patch test reactions to formaldehyde-releasers and formaldehyde contact allergy: 15% of all reactions to 2-bromo-2-nitropropane-1,3-diol and 40-60% of the reactions to the other releasers are caused by a reaction to the formaldehyde in the test material. There is only fragmented data on the amount of free formaldehyde in cosmetics preserved with formaldehyde donors. However, all releasers (with the exception of 2-bromo-2-nitropropane-1,3-diol, for which adequate data are lacking) can, in the right circumstances of concentration and product composition, release >200 p.p.m. formaldehyde, which may result in allergic contact dermatitis. Whether this is actually the case in any particular product cannot be determined from the ingredient labelling. Therefore, we recommend advising patients allergic to formaldehyde to avoid leave-on cosmetics preserved with quaternium-15, diazolidinyl urea, DMDM hydantoin, or imidazolidinyl urea, acknowledging that many would tolerate some products.

In Vitro Synergistic Activities of Essential Oils and Surfactants in Combination with Cosmetic Preservatives Against Pseudomonas aeruginosa and Staphylococcus aureus

The aim of this study is to evaluate possible synergistic antimicrobial interactions between common cosmetic preservatives and selected essential oils or surfactants. The antimicrobial efficacy of six essential oils, three surfactants and five preservatives against Pseudomonas aeruginosa ATCC 9027 and Staphylococcus aureus ATCC 43387 was assessed by a broth micro-dilution assay. MICs for individual and combined antimicrobials were determined and then transformed to fractional inhibitory concentration (FIC) indexes. All essential oils exhibited antibacterial activity; among surfactants, bacteria resulted most susceptible to the cationic agent. Synergy was observed when essential oils of eucalyptus and mint were combined with methylparaben against P. aeruginosa, while essential oils of mint, oregano and sage combined with propylparaben and imidazolidinyl urea acted against S. aureus. Many binary mixtures of preservatives and surfactants produced synergistic activity with the most effective interactions involving the cationic and amphoteric compounds under study. FIC indexes demonstrated synergistic effects when preservatives were combined with either essential oils or surfactants against both bacterial strains. These results highlight the potential usefulness of essential oils and surfactants to enhance the activities of conventional biocides. This kind of study should contribute to the selection and optimization of preservative systems for cosmetic preparations.