Designation of substances as skin sensitizing chemicals: a commentary

During the last 10 years there have been several attempts to define criteria for the integration of experimental and clinical data into schemes that can be used for the designation of chemicals as skin sensitizers (and in some instances respiratory allergens). The last such proposal was made recently in this journal by Schnuch and colleagues (Hum Exp Toxicol 2002; 2: 439-44) who invited critical discussion and debate of the area. In this present article we have sought to build upon and refine further those previous recommendations and suggest here a modified scheme for the classification of chemicals as confirmed or probable skin sensitizers. This new scheme we believe provides a realistic framework within which informed decisions can be reached about likely skin sensitizing activity based upon judicious consideration of clinical and experimental information.     

The isolated chicken eye test as a suitable in vitro method for determining the eye irritation potential of household cleaning products

Eye irritation is an important endpoint in the safety evaluation of consumer products and their ingredients. Several in vitro methods have been developed and are used by different industry sectors to assess eye irritation. One such in vitro method in use for some time already is the isolated chicken eye test (ICE). This investigation focuses on assessing the ICE as a method to determine the eye irritation potential of household cleaning products, both for product safety assurance prior to marketing and for classification and labeling decisions. The ICE involves a single application of test substances onto the cornea of isolated chicken eyes. Endpoints are corneal swelling, corneal opacity and fluorescein retention. The ICE results were compared to historic LVET data in this study due to availability of such in vivo data and the ability to correlate LVET to human experience data on the outcome of accidental exposures to household cleaning products in general. The results of this study indicate that the ICE test is a useful in vitro method for evaluating the eye irritation/corrosion potential and establishing classification and labeling for household cleaning products. For new product formulations, it is best used as part of a weight-of-evidence approach and benchmarked against data from comparable formulations with known eye irritation/corrosion profiles and market experience.     

Eye irritation responses in rabbit and man after single applications of equal volumes of undiluted model liquid detergent products.

A criticism of the use of the rabbit low-volume eye test to determine eye irritation hazard for man is the lack of comparative data in man and rabbit with undiluted products. To address this, such a study has been performed in man and rabbit using undiluted model liquid detergents. The hypothesis tested was that if, under identical test conditions, the effects in the rabbit were the same or greater than the response in man, then it is valid to use the low-volume eye test to assess eye irritation hazard for man. The studies were carried out using 29 human volunteers and 12 rabbits. The effects in the rabbit were unequivocally greater than the effects observed in man, but clearly less than the expected response from these types of product in the Draize test. The results from this study confirm the sensitivity of the rabbit as a test species, and support the use of the low-volume eye test to assess eye irritation hazard for man. Any in vitro/ex vivo alternative to assess eye irritation should be developed against the rabbit low-volume eye test or human data where available.     

Human volunteer studies; a consumer products company view

The term 'contact dermatitis' refers to a range of adverse effects whose causation is quite varied. Manufacturers of consumer products have an important responsibility to minimise the extent to which their products cause such skin reactions. In meeting this responsibility, use may be made of humans, e.g. in studies related to skin irritation, to try to ensure the highest possible safety standards are achieved. The purpose of this short review paper is to outline the principles that must be followed before initiating studies with human volunteers. In addition, these principles are considered in the context of European legislation on chemicals and preparations.     

Skin sensitisation testing--new perspectives and recommendations.

Various methodological aspects of skin sensitisation testing have been explored, particularly in the context of animal welfare considerations and reliability and sensitivity of test methods. Recommendations are made for the conduct of current and proposed OECD skin sensitisation tests with respect to appropriate test configurations for the purposes of hazard identification and labelling, and the requirement for positive controls. Specifically, the following aspects of guinea pig sensitisation test methods have been addressed: (1) the number of test and control animals required; (2) the option of using joint positive controls between independent laboratories; (3) the choice of positive control chemicals; (4) the optimal conduct and interpretation of rechallenge; and (5) the requirement for pretreatment with sodium lauryl sulfate. In addition, the use of the murine local lymph node assay (LLNA) has been considered. A number of conclusions have been drawn and recommendations made as follows: In many instances, particularly with the conduct of the guinea pig maximisation test, it is acceptable to halve the number of test and control animals used. An optional scheme for the conduct of joint positive control studies within a co-ordinated group of laboratories is appropriate. Only one positive control chemical (alpha-hexyl cinnamic aldehyde) is necessary for the routine assessment of assay sensitivity. The proper conduct and interpretation of rechallenge can provide valuable information and confirmation of results in guinea pig sensitisation tests. Sodium lauryl sulfate should no longer be used as a pretreatment in the guinea pig maximisation test. The LLNA is a viable and complete alternative to traditional guinea pig test methods for the purposes of skin sensitisation hazard identification. These recommendations provide the opportunity for both animal welfare benefits and improved hazard identification.     

Shifting policy responses to domestic violence in the Netherlands and Spain (1980-2009)

This article seeks to understand differences in the evolution of policies to combat domestic violence against women in the Netherlands and Spain. Although policy change is often viewed as incremental change toward more progressive policies, the two countries studied here reflect opposing dynamics. The Netherlands moved from being a pioneering country to one that gradually marginalized the policy issue, whereas Spain, in contrast, recently developed innovative and far-reaching policies after a long period of low to moderate state responses. The case study points to the central role of frame negotiation, left-wing governments, and strong feminist mobilization.     

Relation between benzo[a]pyrene-DNA adducts, cell proliferation and p53 expression in tracheal epithelium of hamsters fed a high {beta}-carotene diet

Vitamin A and ß-carotene protect against respiratorytract cancer by inhibiting the formation of DNA damage and controllingcellular proliferation and differentiation. Recently, it hasbeen shown that the p53 tumor-suppressor gene plays a crucialrole in the etiology of respiratory tract cancer. In the presentstudy, we investigated the relationship between benzo[a]pyrene(B[a]P)-DNA adducts, cell proliferation and p53 expression andthe possible effect of ß-carotene on such a relationshipin tracheal epithelium of hamsters given intratracheal instillationsof B[a]P-Fe₂O₃ particles suspended in saline. DNA-adducts werequantified by the ³²P-postlabeling assay, cell proliferationwas quantified by immunocytochemical detection of incorporatedBrdU during S-phase, and p53 protein was detected by immuno-histochemistrywith an antibody that recognized both the wild-type and themutated protein (BioGenex, Clone BP53–12–1). A clearrelationship appeared to exist between the extent of B[a]P-DNAadduct formation, the induction of cell proliferation and theexpression of p53 protein in hamster tracheal epithelium. Theseresults suggest that B[a]P induces cell proliferation in hamstertracheal epithelial cells most likely by the induction of mutationsin the p53 gene. Furthermore, ß-carotene was not foundto influence the formation of B[a]P-DNA adducts, which is probablydue to the high B[a]P dose. Moreover, ß-carotene didnot statistically significantly affect cell proliferation andp53-protein expression in hamster tracheal epithelial cells.     

Comparative 32P-postlabeling analysis of benzo[a]pyrene--DNA adducts formed in vitro upon activation of benzo[a]pyrene by human, rabbit and rodent liver microsomes

An interspecies comparison was made of the DNA-adducts formedin vitro upon incubation of rat liver DNA (RL-DNA) with benzo[a]pyrene(BP) in the presence of liver microsomes. Incubations were carriedout with RL-DNA, BP (100 µM) and liver microsomes fromhamsters, mice, rabbits, rats, 3-methylcholanthrene (3MC) pretreatedrats and from humans. To analyse the adduct profiles, the ³²P-postlabelingtechnique with the nuclease P1-enhancement procedure was used.The total amount of adduct formed varied greatly with the species;also the number of adduct spots detected was different, rangingfrom 1 to 5. In all incubations the BP-N²-deoxyguanosine adductwas formed. Relative to the total adduct level, the level ofthis adduct varied from 26% with rat, 54% with hamster, 56%with 3MC-pretreated rat, 58% with mouse and 75% with rabbit,to 100% with human liver microsomes. In human liver microsomesboth the total amount of cytochrome P-450 per mg microsomalprotein and the ethoxyresorufin O-deethylation (EROD) activitywere low compared to that in animal liver microsomes. In microsomesfrom 3MC-pretreated rats the EROD activity was strongly induced.There was no correlation between EROD activity in non-inducedmicrosomes and total adduct level. To compare BP—DNA adductformation in human white blood cells (WBC) with that in RL-DNA,WBC were incubated with BP and 3MC-pretreated rat microsomes.The adduct profile in WBC-DNA differed from that observed afterincubation of RL-DNA: the BP-N²-deoxyguanosine adduct in WBC-DNAaccounted for 97% of the total adduct level. It is concludedthat the ³²P-postlabeling method is a suitable technique toinvestigate both qualitative and quantitative differences inBP — DNA adduct formation between species. Furthermore,the incubation of microsomes from the liver (or other sources)with a genotoxic agent and isolated DNA or cells can be a usefulapproach to study the formation and stability of reactive intermediatesthat are able to bind to DNA, also with respect to differencesbetween species or tissue.     

A skin sensitization safety assessment of a new bleach activator technology in detergent applications

A new chemical called nonanoyl amido caproylacid oxybenzenesulphonate (NACAOBS) is being developed for use as a bleach activator in laundry detergents. Bleach activators, like NACAOBS, are typically used at levels between 2% and 6% in laundry detergents. NACAOBS is stable in aqueous solutions, but undergoes rapid perhydrolysis when combined with water and peroxygen bleach in laundry detergents. Animal testing demonstrated that NACAOBS, as a raw material, is a weak skin sensitizer. Clinical testing, including extended simulated laundry pretreatment, human repeat insult patch testing and home use testing was then undertaken, following sufficient reassurance of 1) the weak sensitization potential of the substance, 2) its rapid degradation in laundry wash solutions and, consequently, 3) low-to-negligible consumer dermal exposures to the native substance. Results confirmed the skin sensitization safety profile of laundry detergents containing NACAOBS, namely the absence of any reaction suggestive of contact sensitization (even under exaggerated dermal exposure conditions in a detergent matrix), and a skin compatibility profile comparable to that of current detergents. Further confirmation of the skin safety profile was obtained from a successful 12-month market test of a granular detergent containing 3.6% of the new substance, during which not a single adverse skin reaction was reported. In addition, NOBS (an oxybenzenesulphonate structural analogue to NACAOBS) has similar toxicological properties and has been safely marketed in detergents at similar levels for many years. It can be concluded that the likelihood of NACAOBS to induce skin sensitization or even elicit allergic reactions in consumer detergent use scenarios is negligible.