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.

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.

Development of a topical tissue cross-linking solution using sodium hydroxymethylglycinate (SMG): viscosity effect

Hyperviscosity agents are commonly used in ophthalmic formulations for improving corneal drug penetration by increasing tissue contact time. One such viscosity agent is hydroxypropyl methylcellulose (HPMC). HPMC has been used in riboflavin solutions for photochemical UVA cross-linking (CXL). Sodium hydroxymethylglycinate (SMG) is a small molecule formaldehyde releaser that can function as a therapeutic tissue cross-linker for corneal and scleral applications. The present study was undertaken in order to study formulation factors using HPMC and SMG that could positively influence the cross-linking effect in these ocular tissues. Formulations containing 10 mM SMG and 100 mM sodium bicarbonate were prepared with varying HPMC concentrations from 0 to 4.4%. Their cross-linking effects on porcine and rabbit eyes were measured using differential scanning calorimetry (DSC), expressed as the change/difference in melting temperature (ΔT_m) compared with the control. SMG in 4.4% HPMC solution resulted in ΔT_m of 6.3 ± 1.21, while other concentration showed no differences in T_m shift on porcine cornea. In ex vivo rabbit cornea, there was a trend toward an increasing cross-linking effect with higher viscosity albeit mild differences. While a significant T_m shift was observed in porcine and rabbit sclera, there was no difference in effect of cross-linking between four HPMC concentrations. Increasing the HPMC concentration does not negatively affect the cross-linking efficacy attributed by SMG and could still be a positive cross-linking enhancer by virtue of increasing tissue contact time in a dynamic biological system. This information will be useful for planning further animal and human studies.

A proposal to create an extension to the European baseline series

BACKGROUND

The current European baseline series consists of 30 allergens, and was last updated in 2015.

OBJECTIVES

To use data from the European Surveillance System on Contact Allergies (ESSCA) to propose an extension to the European baseline series in response to changes in environmental exposures.

METHODS

Data from departmental and national extensions to the baseline series, together with some temporary additions from departments contributing to the ESSCA, were collated during 2013-2014.

RESULTS

In total, 31689 patients were patch tested in 46 European departments. Many departments and national groups already consider the current European baseline series to be a suboptimal screen, and use their own extensions to it. The haptens tested are heterogeneous, although there are some consistent themes. Potential haptens to include in an extension to the European baseline series comprise sodium metabisulfite, formaldehyde-releasing preservatives, additional markers of fragrance allergy, propolis, Compositae mix, and 2-hydroxyethyl methacrylate.

CONCLUSION

In combination with other published work from the ESSCA, changes to the current European baseline series are proposed for discussion. As well as addition of the allergens listed above, it is suggested that primin and clioquinol should be deleted from the series, owing to reduced environmental exposure.