The Safety Assessment of Cosmetic Perfumes by Using In Chemico and In Vitro Methods in Combination with GC-MS/MS Analysis

Animal testing has been prohibited for the safety assessment of cosmetic ingredients or finished products. Thus, alternative non-animal methods, followed by confirmatory clinical studies on human volunteers, should be used as the sole legally acceptable approach within the EU. The safety assessment of cosmetic products requires the involvement of multiple scientific disciplines, including analytical chemistry and biomedicine, as well as in chemico, in vitro and in silico toxicology. Recent data suggest that fragrance components may exert multiple adverse biological effects, e.g. cytotoxicity, skin sensitisation, (photo)genotoxicity, mutagenicity, reprotoxicity and endocrine disruption. Therefore, a pilot study was conducted with selected samples of fragrance-based products, such as deodorant, eau de toilette and eau de parfum, with the aim of integrating results from a number of alternative non-animal methods suitable for the detection of the following toxicological endpoints: cytotoxicity (with 3T3 Balb/c fibroblasts); skin sensitisation potential (in chemico method, DPRA); skin sensitisation potential (LuSens in vitro method, based on human keratinocytes); genotoxicity potential (in vitro Comet assay with 3T3 Balb/c cells); and endocrine disruption (in vitro YES/YAS assay). The presence of twenty-four specific known allergens in the products was determined by using GC-MS/MS. The strategies for estimation of the NOAEL of a mixture of allergens, which were proposed by the Scientific Committee on Consumer Products in their 'Opinion on Tea tree oil' document and by the Norwegian Food Safety Authority in their 'Risk Profile of Tea tree oil' report, were used as models for the NOAEL estimation of the mixtures of allergens that were identified in the individual samples tested in this study.

Low-cost and prototype-friendly method for biocompatible encapsulation of implantable electronics with epoxy overmolding, hermetic feedthroughs and P3HT coating

The research of novel implantable medical devices is one of the most attractive, yet complex areas in the biomedical field. The design and development of sufficiently small devices working in an in vivo environment is challenging but successful encapsulation of such devices is even more so. Industry-standard methods using glass and titanium are too expensive and tedious, and epoxy or silicone encapsulation is prone to water ingress with cable feedthroughs being the most frequent point of failure. This paper describes a universal and straightforward method for reliable encapsulation of circuit boards that achieves ISO10993 compliance. A two-part PVDF mold was machined using a conventional 3-axis machining center. Then, the circuit board with a hermetic feedthrough was placed in the mold and epoxy resin was injected into the mold under pressure to fill the cavity. Finally, the biocompatibility was further enhanced with an inert P3HT polymer coating which can be easily formulated into an ink. The biocompatibility of the encapsulants was assessed according to ISO10993. The endurance of the presented solution compared to silicone potting and epoxy potting was assessed by submersion in phosphate-buffered saline solution at 37 °C. The proposed method showed superior results to PDMS and simple epoxy potting.

Toxicological testing of a photoactive phthalocyanine-based antimicrobial substance

The aim of the study was toxicological testing of an innovative and efficient antimicrobial agent based on photoactive phthalocyanine (Pc) derivative. A promising Aluminium phthalocyanine (AlPc) with efficient and stable antimicrobial effects was subjected to a battery of toxicological tests to avoid local and systemic toxicity hazard. In compliance with the current European legislation restricting the use of experimental animals, the methods comprised exclusively in vitro procedures based on cellular and tissue models of human origin or mimicking human tissues. The battery of toxicological tests to identify local toxicity included skin corrosion/irritation, eye irritation, and phototoxicity. The basic systemic toxicity tests included acute toxicity, skin sensitization, genotoxicity, and endocrine disruption. The results showed that AlPc induced skin and eye irritation, exhibited borderline sensitization potential and mutagenic potential in one test strain of the Ames test, which was not confirmed in the chromosome aberration test. The AlPc was found to be phototoxic. The results from the cytotoxicity test designed for acute oral toxicity estimation were not conclusive, the acute toxicity potential has to be determined by conventional tests in vivo. Regarding endocrine disruption, no agonistic activity of the AlPc on human estrogen receptor α, nor human androgen receptor was observed. The skin penetration/absorption test revealed that the AlPc has not penetrated into the dermis and receptor fluid, confirming no risk of systemic exposure via the bloodstream.

Alternative methods in vitro for screening of endocrine disruptors

OBJECTIVES

The aim of this study was to compare in silico data with results obtained in two alternative in vitro methods; and to investigate the potential endocrine activity of bisphenol A analogues. This article contributes to recent findings and brings up-to-date information on development of EU legislation and in vitro testing methods of endocrine disruption.

METHODS

In silico approach based on the OECD QSAR Toolbox was used for prediction of potential ligands of human estrogen receptor α. Estrogen Receptor Transactivation in vitro Assay to Detect Estrogen Receptor Agonists and Antagonists (OECD TG 455/457) using the VM7Luc4E2 (formerly designated BG1Luc4E2) cell line was performed for measurement of transactivation activity of the tested substances. Commercially available yeast-based microplate assay (XenoScreen YES/YAS, Xenometrix, Switzerland) for detection of compounds with estrogenic and androgenic agonistic/antagonistic activity was used as a comparative test to estrogen receptor transactivation assay (OECD TG 455/457) and for screening of the agonistic/antagonistic potential of human estrogen receptor and agonistic/antagonistic activity of tested compounds on human androgen receptor.

RESULTS

The study showed good correlation between the two in vitro assays and significant correlation with in silico data. All tested substances were identified as agonists for human estrogen receptor α by methods in silico and in vitro, four substances showed a potentially higher estrogenic activity comparing to bisphenol A, two substances were identified as very weak antagonists of human androgen receptor and one compound showed a potential of agonistic activity to human androgen receptor.

CONCLUSIONS

The study contributes to recent findings and brings new in silico and in vitro data of bisphenol A analogues, revealing that these analogous substances should be further tested as they may show similar or higher activity in vivo comparing to bisphenol A, which has been recently legislatively regulated.

Adverse Phototoxic Effect of Essential Plant Oils on NIH 3T3 Cell Line after UV Light Exposure

AIM

Natural or artificial substances have become an inseparable part of our lives. It is questionable whether adequate testing has been performed in order to ensure these substances do not pose a serious health risk. The principal aim of our research was to clarify the potential risk of adding essential oils to food, beverages and cosmetic products.

METHODS

The toxicity of substances frequently employed in cosmetics, aromatherapy and food industry (bergamot oil, Litsea cubeba oil, orange oil, citral) were investigated using cell line NIH3T3 (mouse fibroblasts) with/without UV irradiation. The MTT assay was used to estimate the cell viability. Reactive oxygen species (ROS) which are products of a number of natural cellular processes such as oxygen metabolism and inflammation were measured to determine the extent of cellular stress. DNA damage caused by strand breaks was examined by comet assay.

RESULTS

MTT test determined EC50 values for all tested substances, varying from 0.0023% v/v for bergamot oil to 0.018% v/v for citral. ROS production measurement showed that UV radiation induces oxidative stress to the cell resulting in higher ROS production compared to the control and non-irradiated samples. Comet assay revealed that both groups (UV, without UV) exert irreversible DNA damage resulting in a cell death.

CONCLUSIONS

Our findings suggest that even low concentrations (lower than 0.0464% v/v) of orange oil can be considered as phototoxic (PIF value 8.2) and probably phototoxic for bergamot oil (PIF value 4.6). We also found significant changes in the cell viability, the ROS production and the DNA after the cells were exposed to the tested chemicals. Even though these substances are widely used as antioxidants it should be noted that they present a risk factor and their use in cosmetic and food products should be minimized.

Eye irritation hazard of chemicals and formulations assessed by methods in vitro

BACKGROUND

The aim of this study was to compare human and animal skin irritation data with results of selected in vitro methods, including HET-CAM test, Neutral Red Release Assay, Neutral Red Uptake Assay and EpiOcular eye irritation test and with already existing data of eye irritation obtained from animal experiments.

METHODS

Chemicals employed in previous skin irritation validation studies and commercially available cosmetic formulations were subjected to further testing using in vitro methods Neutral Red Release (NRR) assay, Neutral Red Uptake (NRU) assay, HET-CAM test and EpiOcular assay.

RESULTS

The study revealed that skin irritants are not necessarily eye irritants; specifically volatile or solid materials may be misclassified. NRR assay provided false negative results in case of substances with fixative effect or not removable under standard washing procedure, emphasizing the role of microscopical evaluation as a crucial additional endpoint. Although overpredictive, HET-CAM test provided the lowest false negative rate. The most aggressive cosmetic formulation was correctly identified by EpiOcular assay, in accordance with NRU and NRR assays results, while HET-CAM test correctly identified the mildest formulation.

CONCLUSIONS

Each of the in vitro methods is related to a specific endpoint of ocular irritation and provides only partial information on the mode of action of the tested material. Despite good reproducibility of individual in vitro assays, only the weight-of-evidence approach and results of multiple selected in vitro tests can allow for estimation of eye irritation hazard in vivo.

Phototoxicity of bergamot oil assessed by in vitro techniques in combination with human patch tests

The aim of this study was to clarify the differences in the phototoxicity of bergamot oil obtained from four different suppliers. Spectral and chemical analyses were performed to identify presence of photoactive compounds in the test samples. The phototoxicity was assessed in vitro by the 3T3 NRU phototoxicity test (PT) and subsequently in a phototoxicity test on reconstructed human skin model (H3D PT). Confirmatory photopatch tests in a group of volunteers were performed using the first non-phototoxic concentration determined in the H3D PT. The spectral and chemical analyses revealed, that two samples of bergamot oil exhibited a potential for photoactivation. These oils were subsequently classified as phototoxic in the 3T3 NRU PT, however, only on the basis of borderline results and depending on the solvent used. H3D PT revealed clear classifications, correlating well with the findings of spectral and chemical analysis. The test was, however, not yet capable of precise prediction of safe, non-phototoxic concentrations. Additional endpoints, e.g. interleukin determination might be employed to increase the sensitivity of the test. Although the study showed the usefulness of the tiered testing strategy, currently, the extrapolation of in vitro results to human situation may be performed only to a limited extent.

In vitro approaches to evaluation of Sun Protection Factor

The efficacy of sunscreen products has been recognized as an important public health issue. Adequate methods for assessment of the level of protection should be developed and standardised. While the SPF COLIPA testing method in vivo has been used for years, preference should be given to in vitro testing methods as in vivo methods raise ethical concern. The present study aims to assess possible in vitro approaches based on diffuse transmission spectroscopy, published previously by Diffey, and two methods based on measurements of UVB transmission through a defined layer of a sunscreen product applied on various UV-transparent substrates. The attenuated UVB intensity, using different UV light sources, is detected radiometrically and transformed to real SPF value by means of a calibration curve, which is based on an extensive number of measurements performed using both in vivo and in vitro method The outcome of the three in vitro methods employed in the study showed great differences in the obtained SPF values in comparison with reference SPF determined by means of the COLIPA method in vivo. The high variability of in vitro results suggests that main attention should be focused on substrate selection simulating the human skin surface and homogenous product application. The in vitro screening methods may represent a fast and reasonable tool reducing the number of in vivo experiments and risks related to UV exposure of human subjects, when the technical test parameters are adjusted and optimized.

Phototoxicity of bituminous tars—correspondence between results of 3T3 NRU PT, 3D skin model and experimental human data

Bituminous tars (Ichthammol and Ichthyol Pale) are widely used in pharmaceutical, veterinary and cosmetic industries for their anti-microbial, anti-inflammatory and anti-pruritic effects. In contrast to coal tar, no phototoxicity of bituminous tars has been reported in man, although both Ichthammol and Ichthyol Pale exhibit UV absorption which is higher and broader for the former. The validated 3T3 NRU phototoxicity test indicated phototoxic potential of both substances. The phototoxicity test in a 3D human skin model (EpiDerm) only confirmed phototoxicity for Ichthammol. Human data on Ichthammol phototoxicity are missing. A photopatch test in human volunteers was performed in order to clarify the discrepancy between the phototoxicity found in the skin model and the absence of reported human phototoxicity. Following 4h exposure to 5% and 10% aqueous solutions of Ichthammol and Ichthyol Pale the test sites were irradiated with a UVA dose of 5 J/cm(2). Early phototoxic reaction (erythema) within 4-6h after irradiation was only elicited by Ichthammol and not by Ichthyol Pale. These data correspond well with those from the 3D skin model test and suggest the necessity to employ several test systems for final phototoxicity assessment. In addition to the results obtained in 3T3 NRU PT, further testing on 3D skin models may better reflect bioavailability of a given chemical in the skin, relevant to the situation in humans.

Hydrophilic polymers—biocompatibility testing in vitro

Biocompatibility is one of the main prerequisites for safe use of medical devices. Estimation of cytotoxicity is a part of the initial evaluation laid down in ISO standards on biological evaluation of medical devices. Hydrophilic polymers (based on 2-hydroxyethyl methacrylate HEMA) doped by addition of selected additives with antioxidant and/or free radical scavenging potential (vitamin C and hindered amine stabilizer N-(2,2,6,6-tetramethylpiperidin-4-yl)methacrylamide) were tested in different in vitro systems (3T3 Balb/c cell culture and a 3D human skin model) for biocompatibility and suitability for use as wound dressings. The results of the 3T3 NRU cytotoxicity test using both the direct and indirect contact approaches and a 3D skin model modified irritation test (EpiDerm) confirmed high biocompatibility and good skin tolerance of both the basic polymers and those enriched with specific additives up to a balanced level. HEMA polymer showed a beneficial effect against cytotoxicity of an irritant (sodium dodecyl sulfate). The in vitro biocompatibility test results were confirmed by human local skin tolerance testing.

The benefits of the 3T3 NRU test in the safety assessment of cosmetics: long-term experience from pre-marketing testing in the Czech Republic

We have introduced the 3T3 NRU cytotoxicity test for methodological, economical and ethical reasons as a regular part of tier pre-marketing testing to assess local tolerance of raw materials for cosmetics, household chemicals and final cosmetic products. Using the 3T3 cell line according to the standard INVITTOX protocol No.64 (NRU Assay) the borderline concentration, relevant to the highest tolerated dose, is determined for each material. The toxic effect is reached at different concentration levels specific for individual cosmetics categories, depending on their chemical characteristics. Typical ranges of cytotoxicity for specific categories of cosmetics were established after testing of hundreds of materials. The range lies between 1 microg/ml (anti-dandruff shampoos), up to 2000 microg/ml (toothpastes and mouthwashes). The 3T3 NRU cytotoxicity test is a sensitive tool able to identify more aggressive products, that are also more likely to evoke irritation in human skin. It was even possible to detect protective effects of one natural herbal ingredient. The comparative study of cytotoxicity test results and human patch test results from a group of essential oils is presented. Cytotoxicity tests represent a highly ethical approach for estimation of irritancy. On the basis of in vitro test results suggesting low risk we can proceed to confirmatory tests in human volunteers.

Immunotoxic effects of carbon tetrachloride--the effect on morphology and function of the immune system in mice

Carbon tetrachloride (CCL4), a polychlorinated hydrocarbon, is known for its hepatotoxicity, neurotoxicity and skin irritancy. Some epidemiological studies suggest possible carcinogenicity of CCl4. This substance is still present in industrial wastes and in the environment. As the major role of the immune system is immunosurveillance against cancer, we decided to follow the morphological and functional changes of the immune system during acute and subchronic exposures to CCL4 in mice. Mice (A/PhJ) were exposed i.p. to 1.7 mmol CCl4/kg b.w./day administered in olive oil (total volume 0.2 ml), for 2, 7, 14, 23 days. We evaluated: morphology of thymus, spleen and peripheral lymph nodes, immunopathology (thymus and spleen weight, spleen cellularity, number of peripheral blood leukocytes), non-specific immunity (phagocytosis, NK activity), humoral immunity (number of PFC after SRBC immunization, LPS mitogen response), cell-mediated immunity (PHA, ConA mitogen response). Morphological examination showed significant activation of lymphoid tissues in T-cell dependent areas. B-cell areas were also activated, but the formation of active germinal centers in lymphatic follicles has not been observed. The natural immunity was affected in a time dependent manner. A slightly hepatotoxic dose of CCl4 had a significant stimulative effect on phagocytosis and natural killer activity when administered in short-term schedule ("acute exposure"). Subchronic administration of the same dose led to suppression of phagocytosis and Nk activity. Similarly, the lymphocyte response to non-specific mitogens was enhanced during short-term exposure and significantly impaired when CCl4 was administered in long-term schedule. Antigen specific immune response to SRBC was impaired immediately after short-term exposure to CCl4 which suggests that the substance might affect the immunoglobuline proteosynthesis at the cellular level.