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.

Bio-removal of rare earth elements from hazardous industrial waste of CFL bulbs by the extremophile red alga Galdieria sulphuraria

In recent decades, a shift has been seen in the use of light-emitting diodes over incandescent lights and compact fluorescent lamps (CFL), which eventually led to an increase in wastes of electrical equipment (WEE), especially fluorescent lamps (FLs) and CFL light bulbs. These widely used CFL lights, and their wastes are good sources of rare earth elements (REEs), which are desirable in almost every modern technology. Increased demand for REEs and their irregular supply have exerted pressure on us to seek alternative sources that may fulfill this demand in an eco-friendly manner. Bio-removal of wastes containing REEs, and their recycling may be a solution to this problem and could balance environmental and economic benefits. To address this problem, the current study focuses on the use of the extremophilic red alga, Galdieria sulphuraria, for bioaccumulation/removal of REEs from hazardous industrial wastes of CFL bulbs and the physiological response of a synchronized culture of G. sulphuraria. A CFL acid extract significantly affected growth, photosynthetic pigments, quantum yield, and cell cycle progression of this alga. A synchronous culture was able to efficiently accumulate REEs from a CFL acid extract and efficiency was increased by including two phytohormones, i.e., 6-Benzylaminopurine (BAP - Cytokinin family) and 1-Naphthaleneacetic acid (NAA - Auxin family).

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.

Health safety of parabens evaluated by selected in vitro methods

Seven selected parabens (4 allowed, 3 banned in cosmetics) were tested in order to confirm and expand historical data on their toxicological properties and safety. The aim was to apply novel in vitro methods, which have been sufficiently technically and scientifically validated for the purposes of toxicological testing of chemicals. The study included several toxicological endpoints such as skin/eye irritation, skin sensitization, endocrine disruption and genotoxicity. The battery of selected methods comprised regulatory accepted EpiDerm™ skin model (OECD TG 439); EpiOcular™ corneal model (OECD TG 492) and scientifically valid test method HET-CAM (DB-ALM Protocol No. 47); in chemico test DPRA (OECD TG 442C); in vitro test LuSens (OECD TG 442D) and in vitro test h-CLAT (OECD TG 442E); Ames MPF™ (Xenometrix) and XenoScreen YES/YAS (Xenometrix). Overall, none of the 4 allowed parabens exhibited skin/eye irritation or genotoxicity. However, all allowed parabens in cosmetics were predicted as samples with potentially sensitizing properties in the LuSens and h-CLAT test methods, but not confirmed by DPRA. Endocrine disruption was recorded only at high concentrations, whereas methyl paraben and ethyl paraben exhibited the lowest activity. This study confirmed the safety of use of the allowed parabens in the highest recommended concentrations in cosmetics or pharmaceuticals.

Sensitization potential of medical devices detected by in vitro and in vivo methods

Medical devices must be tested before marketing in accordance with ISO EN 10993-10 in order to avoid skin sensi­tization. This standard predominantly refers to the in vivo test but does not exclude the use of in vitro methods that have been sufficiently technically and scientifically validated for medical device testing. It is foreseen that, due to the complexity of the sensitization endpoint, a combination of several methods will be needed to address all key events occurring in the sensitization process. The objective of this pilot study was to evaluate the sensitization potential of selected medical devices using a combination of in chemico (DPRA, OECD TG 442C) and in vitro (LuSens, OECD TG 442D) methods in comparison with the in vivo (LLNA DA, OECD TG 442A) method and to suggest a possible testing strategy for the safety assessment of medical device extracts. Overall, one of the 42 tested samples exhibited positive results in all employed test methods, while 33 samples were predicted as non-sensitizing in all three performed methods. This study demonstrated good agreement between in vitro and in vivo results regarding non-sensitizing samples; however, some discrepancies in positive classification were recorded. A testing strategy is suggested in which negative results are accepted and any positive results in the in chemico or in vitro tests are followed up with a third in vitro test and evaluated in accordance with the “2 out of 3 approach”. This strategy may reduce and replace animal use for testing the sensitization potential of medical devices.

Safety testing of adult novelties using in vitro methods

Despite widespread and prolonged use of adult novelties, their health safety is not regularly tested or legally regulated. In the EU, adult novelties are subjected to the General Product Safety Directive, placing the burden of proof regarding safe products onto the manufacturers. The aim of our pilot study was to expand knowledge on potential application of in vitro methods for hazard prediction of extracts from final products. We subjected extracts of 20 adult novelties, purchased on the Czech market to toxicological tests including NRU cytotoxicity assay, sensitization tests DPRA and LuSens and the YES/YAS endocrine assay. Four samples produced cytotoxicity. Sensitization potential was recorded by DPRA (three samples) while the LuSens reported ten samples. Regarding endocrine disruption, three samples produced antiestrogen and antiandrogen effects. Six samples exhibited androgenic potential and one sample showed estrogenic potential. Positive results with possible health effects were recorded repeatedly for samples made of ABS, PVC and latex. The study has confirmed promising usefulness of our test methods combination with regard to safety testing of this type of consumer products. The results should be evaluated with care, however, the data bring added-value to the limited knowledge of mixture toxicology and are indicative for further testing.

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.

Selected bisphenols and phthalates screened for estrogen and androgen disruption by in silico and in vitro methods

OBJECTIVES

The aim of this study was to detect endocrine disruption potential of selected bisphenols and phthalates, compare in silico prediction with results from two in vitro methods and bring up-to-date information on development of EU legislation, available in vitro methods and biomechanisms involved in endocrine disruption.

MATERIAL AND METHODS

In silico approach based on the OECD QSAR Toolbox was used for prediction of estrogen receptor α binding. OECD TG 455 assay and a yeast-based YES/YAS assay was used to determine the interactions with human estrogen (ERα) and androgen receptors.

RESULTS

In silico results predicted the screened phthalates as non binders and bisphenols as very strong binders of the ERα. In vitro results differed from in silico prediction in several cases but exhibited concordance mainly for strong binders of ERα. Most of the substances exhibited parallel activity (agonist-antagonist) on both estrogen and androgen receptors. Agonistic studies showed the effective concentration of 10% activity (EC10) from 5.0E-07 for strong agonists (e.g. BPC, BPTMC). Cytotoxicity was observed after 48 h exposure of S. cerevisiae to BPFL, BPG, BPM, BPTMC in concentrations starting at 3.6E-05 mol/l.

CONCLUSION

Our results suggest multiple parallel interactions of tested compounds and emphasize the importance of determination of an appropriate battery of in vitro methods that will include more receptors and will be appropriate to target specific molecular mechanisms involved in endocrine disruption. Results in agonistic studies indicate agonistic potential and are supported by results of antagonistic studies with consideration of possible multiple interactions.

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.

Acute toxicity estimation by calculation--Tubifex assay and quantitative structure-activity relationships

A quantitative structure-activity relationship (QSAR) model dependent on log P(n - octanol/water), or log P(OW), was developed with acute toxicity index EC50, the median effective concentration measured as inhibition of movement of the oligochaeta Tubifex tubifex with 3 min exposure, EC50(Tt) (mol/L): log EC50(Tt) = -0.809 (+/-0.035) log P(OW) - 0.495 (+/-0.060), n=82, r=0.931, r2=0.867, residual standard deviation of the estimate 0.315. A learning series for the QSAR model with the oligochaete contained alkanols, alkenols, and alkynols; saturated and unsaturated aldehydes; aniline and chlorinated anilines; phenol and chlorinated phenols; and esters. Three cross-validation procedures proved the robustness and stability of QSAR models with respect to the chemical structure of compounds tested within a series of compounds used in the learning series. Predictive ability was described by q2 .801 (cross-validated r2; predicted variation estimated with cross-validation) in LSO (leave-a structurally series-out) cross-validation.

Acute toxicity of binary mixture benzene-ethanol and partition coefficient K(ow) of benzene and ethanol

The study related to partition coefficients between n-octanol and water of compounds in binary mixture benzene-ethanol was carried out. Partition coefficients of benzene and ethanol for different values of molar ratio of benzene in the mixture were determined. Collected results show statistically significant deviations the K(ow) of benzene for some molar ratios (0.2 to 0.6) from values for pure compound. For ethanol, there are no statistically significant deviations from values for pure compound, however there are some trends of changes of K(ow).

The glutathione-activated thiopurine prodrugs trans-6-(2-acetylvinylthio)guanine and cis-6-(2-acetylvinylthio)purine cause less in vivo toxicity than 6-thioguanine after single- and multiple-dose regimens

trans-6-(2-Acetylvinylthio)guanine (trans-AVTG) and cis-6-(2-acetylvinylthio)purine (cis-AVTP) are glutathione-activated prodrugs of 6-thioguanine (6-TG) and 6-mercaptopurine, respectively. In tumor cell lines, these prodrugs exhibit similar IC50 values that are comparable to or lower than those of 6-TG and 6-mercaptopurine, respectively. In this study, the in vivo toxicity and metabolism of the prodrugs were assessed. Mice given multiple treatments of 6-TG and, to a lesser extent, trans-AVTG exhibited decreased peripheral WBC and RBC counts and increased myeloid:erythroid ratios in bone marrow; no change was observed in mice given cis-AVTP. Similarly, intestinal epithelial crypt cell apoptosis was more extensive in mice treated with 6-TG than in those treated with trans-AVTG, whereas mice given cis-AVTP had little apoptosis. Epithelial crypt cell apoptosis was more extensive in the small intestine than in the large intestine in all treatment groups. Histopathological examination detected no kidney or liver toxicity, whereas mild increases in the activities of hepatocellular leakage enzymes were observed in mice treated with trans-AVTG. Only metabolites of trans-AVTG and cis-AVTP were recovered in urine. A higher fraction of the dose was recovered in urine as the parent thiopurine and the metabolites thiopurine riboside, thioxanthine, and thiouric acid after 6-TG treatment than after trans-AVTG treatment; cis-AVTP recovery was slightly less than that of 6-TG. Thioxanthine and thiouric acid comprised a higher fraction of the recovered dose after cis-AVTP treatment than after trans-AVTG or 6-TG treatment. Overall, the results suggest that the prodrugs exhibit less in vivo toxicity than 6-TG. Thus, investigations into their antitumor efficacy are warranted.

Novel glutathione-dependent thiopurine prodrugs: evidence for enhanced cytotoxicity in tumor cells and for decreased bone marrow toxicity in mice

Elevated glutathione (GSH) levels have been detected in many tumors compared with the healthy, surrounding tissue. Often, this GSH up-regulation is associated with drug resistance. The prodrugs 6-(2-acetylvinylthio)guanine (AVTG) and 6-(2-acetylvinylthio)purine (AVTP) contain a novel butenone moiety that allows the prodrugs to react selectively with sulfhydryl nucleophiles to release the chemotherapeutic drug 6-thioguanine (6-TG) or 6-mercaptopurine (6-MP), respectively. The cellular uptake and metabolism of trans-AVTG in two human renal carcinoma cell lines that were used as models were rapid and associated with depletion of intracellular GSH. Formation of 6-TG from trans-AVTG correlated positively with intracellular GSH concentrations, and was significantly reduced by diethyl maleate pretreatment. Intracellular concentrations of 6-TG after incubations with trans-AVTG were significantly higher than the 6-TG concentrations obtained after incubations with equimolar concentrations of 6-TG; thus, the prodrug delivered more 6-TG to the cell than did 6-TG itself. Cytotoxicity studies demonstrated that AVTG and AVTP had similar IC(50) values that were comparable with those of 6-TG, but were significantly lower than those of 6-MP. Furthermore, after in vivo treatment of mice with the prodrugs, no reduction was observed in circulating white blood cell counts, whereas white blood cell counts of mice treated with equimolar or 60% lower doses of 6-TG were reduced by 50 to 60%. Collectively, the results show that AVTG and AVTP are novel potential chemotherapeutic agents that may target tumors with up-regulated levels of GSH, and may exhibit less systemic toxicity than the parent thiopurines.

Prediction of acute toxicity of chemicals in mixtures: worms Tubifex tubifex and gas/liquid distribution

The aim of this contribution is to support our proposal of the procedure for predicting acute toxicity of binary mixtures by QSAR analysis techniques. The changes of a mixture composition are described by molar ratio R and visualized in the R-plot (QCAR--quantitative composition-activity relationships). The approach was inspired by Rault and Dalton's laws, their positive and negative deviations in the behavior of a mixture of real gases, by Loewe and Muischnek isoboles and by the Finney test of additivity. Acute toxicity was determined by the laboratory test with woms Tubifex tubifex. The additivity of the acute toxicity in the binary mixture benzene + nitrobenzene was confirmed and a new interaction is described: "mixed interaction" with the binary mixture aniline + ethanol. The "mixed interaction" means that depending on mixture composition, both potentiation and inhibition can occur. As the first physicochemical descriptor of the changes caused by the changing composition of binary mixtures, the gas/liquid equilibrium was studied and a composition of the gaseous phase was determined by a gas chromatographic method. The method for determination of concentrations in the gaseous phase was described. The gaseous phase composition of benzene + nitrobenzene. benzene + ethanol, benzene + aniline and ethanol + aniline mixtures was analyzed. It was found that if the concentrations of the mixture's components in the gaseous phase behave nonideally (they are not additive), the acute toxicity of the same mixture is not additive as well. Another descriptor to distinguish between potentiation and inhibition will be, however, necessary. The properties, both gaseous phase composition and the acute toxicity, of the benzene + nitrobenzene mixture are additive. In mixtures with the mixed interaction, the R-plot of the composition of the gaseous phase is complex with a large variation of results.

Acute toxicity of alcohols: prediction by QSAR analysis and by molecular similarity

The purpose of the paper is to demonstrate the usefulness of techniques of molecular similarity as an alternative method for estimation of both acute toxicity of chemicals and their partition coefficients. The technique of atom pairs was chosen. A series of aliphatic alcohols was treated. Acute toxicity was determined by the express laboratory method as the EC50 (inhibition of movement of the worms Tubifex tubifex). Partition coefficients were determined between oil and gas. The calculated results were sufficiently close to both experimental results and the estimates calculated by a technique of QSAR analysis.