An epidemic of isothiazolinone sensitization in a flax spinning mill

MI (2-methyl-4-isothiazolin-3-one) contained in detergents is not detectable in machine washed textiles

Background

European legislation has banned the preservative methylisothiazolinone (MI) from inclusion in leave-on cosmetics. However, the risk for allergic reactions depends on exposure. The aim of this study was to determine the risk of MI in laundry detergents for household machine washing.

Methods

Different formulations of laundry detergents with commercial MI levels, up to one thousand ppm were used and three different types of clothes were washed in a normal household machine setting one time and 10 times. The level of MI was measured by HPLC.

Results

While MI could be retrieved in the positive control of clothes drenched with washing powder but not washed afterwards, MI could not be detected in any specimen of clothes washed under household conditions. The detection limit was 0.5 ppm.

Conclusion

It is important to discuss the difference of risk and hazard. While MI clearly is a high hazard as a strong contact allergen, the risk depends on exposure. Regarding the risk of exposure levels for the consumer to MI in clothes it can be stated that the use of MI in laundry detergents is safe for the consumer if these products are used according to the instructions in the normal household setting machine wash.

Isothiazolinones in commercial products at Danish workplaces

BACKGROUND

In recent years, a steep increase in the frequency of occupational contact allergy to isothiazolinones has been reported from several European countries.

OBJECTIVE

To examine the extent and occurrence of isothiazolinones in different types of product at Danish workplaces.

METHODS

Seven different isothiazolinones were identified in the Dictionary of Contact Allergens: Chemical Structures, Sources, and References from Kanerva's Occupational Dermatitis. By use of the chemical names and Chemical Abstracts Service numbers for these chemicals, information on products registered in the Danish Product Register Database (PROBAS) was obtained.

RESULTS

All seven isothiazolinones were registered in PROBAS. The top three isothiazolinones registered were: benzisothiazolinone (BIT), registered in 985 products, methylisothiazolinone (MI), registered in 884 products, and methylchloroisothiazolinone (MCI)/MI, registered in 611 products. The concentration ranges were 0.01 ppm to 45% for BIT, 0.01 ppm to 10% for MI, and 0.01 ppm to 14.1% for MCI/MI. The most common product type was 'paint and varnish'; five of the seven isothiazolinones were registered in this type of product.

CONCLUSION

Isothiazolinones are present in multiple products registered for use at workplaces, and may occur in high concentrations.

Trace analysis of isothiazolinones in water samples by large-volume direct injection liquid chromatography tandem mass spectrometry

Isothiazolinones are used as preservatives, biocides and disinfectants in a variety of industrial and domestic applications. Some of the isothiazolinones are difficult to isolate from water due their high polarity. A sensitive and selective analytical method was developed and optimized for the determination of sub-microg/L levels of three isothiazolinones in water samples. Three isothiazolinones are described in this paper: 2-methyl-3-isothiazolinone, 5-chloro-2-methyl-3-isothiazolinone and 4,5-dichloro-2-methyl-3-isothiazolinone. The analytical method involves a robust large-volume direct on-column loop injection of 2 mL on an Aqua ODS HPLC column and tandem MS detection (HPLC-MS/MS). After filtration, samples are directly injected without further pretreatment. Detection limits of the individual target compounds were between 0.03 and 0.1 microg/L employing Multi-Reaction Monitoring (MRM) mass spectrometry. Based on the constant ratio of two selected product-ions together with the retention time, the identification is very selective and quantification is reliable. The method was successfully applied to real samples of membrane flushings, drinking water, surface waters and waste water. Additional investigations showed the instability of the isothiazolinones in river- and waste water. Preservation of river water and waste water samples with sodium azide (NaN(3)) promotes the stability of the isothiazolines in solution. In membrane flushings, waste water, surface waters and drinking water, levels of the three isothiazolinones were all below the limit of detection. In effluents of households containing washings from normal shampoo use, isothiazolinones could be detected.

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

Methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) has been widely used during the last 20 years for the preservation of aqueous systems in cosmetics, toiletries and in various industrial applications. MCI/MI has a broad spectrum of activity against fungi and bacteria at very low concentrations. The allergic contact potential of MCI/MI has been known for many years. This paper provides a review of pre-clinical and clinical experimental studies as well as experience from dermatology clinics worldwide. This forms the basis for an update of the risk assessment for the use of MCI/MI in rinse-off products. The scientific data indicate that the actual sensitization rate observed with a contact allergen is extremely dependent on dose and type of exposure. This review of the data leads to the conclusion that, under normal use conditions, within the current permitted/ recommended use concentrations for MCI/MI of up to 15ppm, the risk of primary sensitization from the use of rinse-off products is negligible, and elicitation of allergic contact dermatitis in MCI/MI-sensitized individuals rare, after exposure to MCI/MI-preserved rinse-off products.