Skin Effects Associated with Wearing Fabrics Washed with Commercial Laundry Detergents

Enzymes in cleaning products: an overview of toxicological properties and risk assessment/management

Enzymes used in cleaning products have an excellent safety profile, with little ability to cause adverse responses in humans. For acute toxicity, genotoxicity, sub-acute and repeated dose toxicity, enzymes are unremarkable. Reproductive toxicity and carcinogenicity are also not endpoints of concern. Exceptions are the ability of some proteases to produce irritating effects at high concentrations and more importantly, the intrinsic potential of these bacterial/fungal proteins to act as respiratory sensitizers. It is a reasonable assumption that the majority of enzyme proteins possess this hazard. However, methods for characterising the respiratory sensitisation hazard of enzymes are lacking and the information required for risk assessment and risk management, although sufficient, remains limited. Previously, most data was generated in animal models and in in vitro immunoassays that assess immunological cross-reactivity. Nevertheless, by the establishment of strict limits on airborne exposure (based on a defined minimal effect limit of 60ng active enzyme protein/m(3)) and air and health monitoring, occupational safety can be assured. Similarly, by ensuring that airborne exposure is kept similarly low, coupled with knowledge of the fate of these enzymes on skin and fabrics, it has proven possible to establish a long history of safe consumer use of enzyme containing products.

Relevance of sensitization to occupational allergy and asthma in the detergent industry

There exists considerable historic experience of the relationship between exposure and both the induction of sensitization and the elicitation of respiratory symptoms from industrial enzymes of bacterial and fungal origin used in a wide variety of detergent products. The detergent industry in particular has substantial experience of how the control of exposure leads to limitation of sensitization with low risk of symptoms. However, the experience also shows that there are substantial gaps in knowledge, even when the potential occupational allergy problem is firmly under control, and also that the relationship between exposure and sensitization can be hard to establish. The latter aspect includes a poor appreciation of how peak exposures and low levels of exposure over time contribute to sensitization. Furthermore, while a minority of workers develop specific IgE, essentially none appear to have symptoms, a situation which appears to contradict the allergy dogma that, once sensitized, an individual will react to much lower levels of exposure. For enzymes, the expression of symptoms occurs at similar or higher levels than those that cause induction. In spite of some knowledge gaps, medical surveillance programs and constant air monitoring provide the tools for successful management of enzymes in the occupational setting. Ultimately, the knowledge gained from the occupational setting facilitates the completion of safety assessments for consumer exposure to detergent enzymes. Such assessments have been proven to be correct by the decades of safe use both occupationally and in consumer products.

Defining occupational and consumer exposure limits for enzyme protein respiratory allergens under REACH

A wide range of substances have been recognized as sensitizing, either to the skin and/or to the respiratory tract. Many of these are useful materials, so to ensure that they can be used safely it is necessary to characterize the hazards and establish appropriate exposure limits. Under new EU legislation (REACH), there is a requirement to define a derived no effect level (DNEL). Where a DNEL cannot be established, e.g. for sensitizing substances, then a derived minimal effect level (DMEL) is recommended. For the bacterial and fungal enzymes which are well recognized respiratory sensitizers and have widespread use industrially as well as in a range of consumer products, a DMEL can be established by thorough retrospective review of occupational and consumer experience. In particular, setting the validated employee medical surveillance data against exposure records generated over an extended period of time is vital in informing the occupational DMEL. This experience shows that a long established limit of 60 ng/m(3) for pure enzyme protein has been a successful starting point for the definition of occupational health limits for sensitization in the detergent industry. Application to this of adjustment factors has limited sensitization induction, avoided any meaningful risk of the elicitation of symptoms with known enzymes and provided an appropriate level of security for new enzymes whose potency has not been fully characterized. For example, in the detergent industry, this has led to general use of occupational exposure limits 3-10 times lower than the 60 ng/m(3) starting point. In contrast, consumer exposure limits vary because the types of exposure themselves cover a wide range. The highest levels shown to be safe in use, 15 ng/m(3), are associated with laundry trigger sprays, but very much lower levels (e.g. 0.01 ng/m(3)) are commonly associated with other types of safe exposure. Consumer limits typically will lie between these values and depend on the actual exposure associated with product use.

The Behind-the-Knee test: an efficient model for evaluating mechanical and chemical irritation

BACKGROUND/PURPOSE

The 'Behind-the-Knee' method (BTK test), using the popliteal fossa as a test site, evaluates both the inherent chemical irritation, and the potential for mechanical irritation of substrates and products. This approach eliminates some of the difficulties of in-use clinical test systems while still providing reliable results. In this publication, examples of the results of BTK tests on several materials are presented with direct comparisons, where possible, with results of in-use clinical testing conducted on the same materials.

METHODS

In in-use clinical tests, volunteer panelists were provided with catamenial products to use in place of their normal product. In the BTK test, samples were applied daily to the popliteal fossa using an elastic athletic band. In both studies, irritation reactions were scored visually.

RESULTS

Levels of irritation in the BTK test are consistently higher than those of standard patch tests, illustrating the contribution of mechanical irritation to the overall irritant potential of materials and products. Repeated tests on identical test materials demonstrated that the BTK test results are reproducible. Side-by-side comparisons of the BTK test and in-use clinical tests demonstrated that the BTK test produces results of similar quality to the in-use clinical. By using several concurrent panels with a common test material, it is possible to compare the irritant properties of several materials at once.

CONCLUSIONS

We have tested over 25 different materials in over 35 BTK studies. The test method has proven reliable and versatile in testing a wide variety of materials, including menstrual pads, topsheets, interlabial pads, pantiliners, tampons and lotion coatings on products. Unlike in-use clinicals, the BTK test allows the direct comparison of two products at one time on the same individual, and is easily adapted to investigative programs. It is subject to fewer confounding factors, is much easier to implement, has a shorter turnaround time, and is less expensive than in-use clinical testing. Importantly, unlike standard patch tests, the BTK test evaluates both the inherent chemical irritation associated with materials and the mechanical irritation owing to friction. Although the BTK test was developed using catamenial products, the test system provides a valuable alternative for evaluating any material where mechanical irritation may play a role, including textiles, facial tissues, baby and adult diapers, and laundry products that may leave residues on fabrics.

Non-animal testing strategies for assessment of the skin corrosion and skin irritation potential of ingredients and finished products

The dermatotoxicologist today is faced with a dilemma. Protection of workers and consumers from skin toxicities (irritation and allergy) associated with exposure to products, and the ingredients they contain, requires toxicological skin testing prior to manufacture, transport, or marketing. Testing for skin corrosion or irritation has traditionally been conducted in animals, particularly in rabbits via the long established Draize test method. However, this procedure, among others, has been subject to criticism, both for its limited predictive capacity for human toxicity, as well as for its use of animals. In fact, legislation is pending in the European Union which would ban the sale of cosmetic products, the ingredients of which have been tested in animals. These considerations, and advancements in both in vitro skin biology and clinical testing, have helped drive an intensive effort among skin scientists to develop alternative test methods based either on in vitro test systems (e.g. using rat, pig or human skin ex vivo, or reconstructed human skin models) or ethical clinical approaches (human volunteer studies). Tools are now in place today to enable a thorough skin corrosion and irritation assessment of new ingredients and products without the need to test in animals. Herein, we describe general testing strategies and new test methods for the assessment of skin corrosion and irritation. The methods described, and utilized within industry today, provide a framework for the practicing toxicologist to support new product development initiatives through the use of reliable skin safety testing and risk assessment tools and strategies.

An overview of the safety evaluation of the Thermomyces lanuginosus xylanase enzyme (SP 628) and the Aspergillus aculeatus xylanase enzyme (SP 578)

Xylanases SP 628 and SP 578 were produced by submerged fermentation of Aspergillus oryzae, containing a gene code originating from Thermomyces lanuginosus and Aspergillus aculeatus, respectively. Both enzymes were subject to the same series of toxicological tests to document their safety in use. The enzymes are to be applied as processing aids in the baking industry and in wheat starch separation. Neither enzyme was found to be mutagenic in the Salmonella typhimurium reverse mutation assay, nor did they cause chromosomal aberrations in cultured human peripheral lymphocytes. No evidence of inhalation toxicity or skin and eye irritation was found. The enzymes are not regarded as skin-sensitizers, although the Buehler test with guinea-pigs revealed a minor potential. Oral administration up to 10.0 ml/kg bw/day (equivalent to a Total Organic Solids amount of 13.3% for SP 628 and of 11.3% for SP 578) in 13-week rat studies did not show any adverse effect.