Skin Sensitization Induction Risk Assessment of Common Ingredients in Commercially Available Cleansing Conditioners.

BACKGROUND: An essential step in ensuring the toxicological safety of cosmetic or personal care products is the evaluation of the skin sensitizing potential of product ingredients. OBJECTIVE: We used a standardized protocol from cosmetic trade industry and consumer safety groups to evaluate the sensitization potential of ingredients in 3 commercially available cleansing conditioners. METHODS: A total of 33 ingredients were evaluated. Each ingredient underwent (1) dermatological evaluation, (2) in silico analysis for irritation and sensitization potential, and (3) a literature evaluation to determine risk of sensitization. Consumer exposure level was compared with the weight-of-evidence no-expected sensitization induction level for the constituent. If a no-expected sensitization induction level for a specific ingredient was not available, the dermal sensitization threshold approach was used. A margin of safety was calculated for each constituent. RESULTS: The margins of safety for all evaluated ingredients in the cleansing conditioners were greater than 1. CONCLUSIONS: This analysis indicates that exposure to the individual ingredients present in these cleansing conditioners would not be expected to induce dermal sensitization in a consumer under the examined exposure scenario.

Tier-based skin irritation testing of hair cleansing conditioners and their constituents.

Purpose/Aim: The U.S. Food and Drug Administration (FDA) does not require specific testing to demonstrate the safety of personal care and cosmetic products or their ingredients. Recently, there have been reports of skin irritation associated with the use of commercially available cleansing conditioners. The goal of this study was to implement a tier-based safety assessment to evaluate the skin irritation potential of six commercially available cleansing conditioners and their ingredients. MATERIALS AND METHODS: The first tier of testing utilized the Organization for Economic Co-operation and Development (OECD) QSAR Toolbox to perform an in silico evaluation of the skin irritation potential of the product ingredients, and the second tier of testing utilized an OECD in vitro guideline test to evaluate the skin irritation potential of each product. RESULTS: Thirty-two ingredients were evaluated using the OECD QSAR Toolbox profiler for the tier one analysis; nine ingredients received a structural alert for skin irritation/corrosion. In the tier two in vitro analysis, the evaluated cleansing conditioner products were all classified as non-irritants. CONCLUSIONS: These results provide evidence that use of the evaluated commercially available cleansing conditioners would not be expected to cause skin irritation among consumers. Additionally, this study demonstrates that the presence of structural alerts does not always accurately predict the safety of a product, as focused tier-based testing is necessary to comprehensively evaluate a product. This study illustrates a tier-based safety assessment approach, applicable to a wide variety of health endpoints, which efficiently and adequately evaluates the safety of personal care and cosmetic products and their ingredients.

Skin Sensitization Induction Potential From Daily Exposure to Fragrances in Personal Care Products.

BACKGROUND: Many chemicals used for fragrance purposes in a diversity of products have allergenic potential. Based on such concerns, industry groups developed concentration limits for use of fragrance chemicals in personal care and cosmetic products. OBJECTIVE: The aim of this study was to use a quantitative risk assessment to evaluate the potential for skin sensitization induction resulting from daily exposure to fragrance chemicals present in personal care and cosmetic products. METHODS: Product-specific dermal consumer exposure levels were calculated based on product use data in US adult females and benchmarked against acceptable exposure levels based on reported no expected sensitization induction levels to determine a margin of safety for each fragrance under evaluation. CONCLUSIONS: The results demonstrate an increased risk of skin sensitization induction for several leave-on products (lipstick, solid antiperspirant, eye shadow, face cream) for most of the evaluated fragrance chemicals, particularly under high-use exposure scenarios. In contrast, rinse-off products (shampoo, conditioner, facial cleanser) were not associated with risk of skin sensitization induction. Because the approach was based on maximum use limits for fragrance chemicals with skin sensitization concerns, the results suggest these limits may not be protective, particularly in the United States.

Risk Assessment of the Skin Sensitization Induction Potential of Kathon CG in Rinse-off and Leave-on Personal Care and Cosmetic Products.

BACKGROUND: Kathon CG is a commonly used cosmetic-grade preservative that contains active ingredients methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI). OBJECTIVE: The aim of the study was to perform a skin sensitization induction risk assessment of daily exposure to Kathon CG after use of various personal care and cosmetic products. METHODS: We calculated an estimated daily consumer exposure level for rinse-off and leave-on products using the amount of product applied per application, number of applications per day, a retention factor, the MCI/MI concentration, and body surface area values. We assumed that the products contained the maximum recommended safe concentration of MCI/MI: 15 ppm in rinse-off products and 7.5 ppm in leave-on products. We compared estimated consumer exposure levels with the no expected sensitization induction level for MCI/MI and applied sensitization assessment factors to calculate product-specific margins of safety (MOSs). CONCLUSIONS: The MOSs for rinse-off products ranged from 5 to 63, whereas the MOSs for leave-on products ranged from 0.03 to 1.49. Overall, our results provide evidence that some leave-on products containing the maximum recommended safe concentration of Kathon CG may increase the risk of sensitization induction due to exposure to MCI/MI. In contrast, rinse-off products were not associated with a potential increased risk of skin sensitization induction.

The 2014 crude 4-methylcyclohexanemethanol chemical release and birth outcomes in West Virginia.

Approximately 10,000 gallons of crude 4-methylcyclohexanemethanol and propylene glycol phenyl ether were accidentally released into the Elk River upstream from a water treatment facility in West Virginia. The objective of this study was to use logistic and Poisson regression analyses to determine the effect potential exposures had on adverse birth outcomes (birth weight, small for gestational age, and abnormal Apgar score). We adjusted for confounding factors and assessed prevalence of adverse birth outcomes by residential location and timing of the pregnancy. There were no statistically significant interactions between residential location and timing of the pregnancy (range of p values: .157-.806). Changes in the prevalence of birth outcomes were consistent before and after the spill regardless of residential location. There was no evidence of an association between adverse birth outcomes and potential exposure to the released chemicals.

Crude 4-methylcyclohexanemethanol (MCHM) did not cause skin irritation in humans in 48-h patch test.

Crude 4-methylcyclohexanemethanol (MCHM) is an industrial chemical used to wash and clean coal. On January 9th, 2014 approximately 10,000 gallons of a mixture containing crude MCHM were released into the Elk River near Charleston, West Virginia, contaminating the local water supply. Following the spill, residents reported numerous health complaints, and sought medical attention for ailments including rashes and itching. The relationship between the complaints and the spill were unknown, as such symptoms are reported frequently in the background. In this study, the primary irritation potential of crude MCHM was evaluated in 206 individuals who underwent 48 hour semi-occluded patch testing. MCHM concentrations assessed in this study were 1, 5, 15, and 100 ppm. No appreciable skin reactions were observed in individuals at any concentration. Three of the five concentrations evaluated were above the highest measured concentration of MCHM in the tap water of residents in West Virginia (3.7 ppm). The results of this study suggest that crude MCHM would not be a dermal irritant for the vast majority, if not all, potentially exposed persons at the concentrations in the water reported after the spill.

The toxicity of crude 4-methylcyclohexanemethanol (MCHM): review of experimental data and results of predictive models for its constituents and a putative metabolite.

Crude 4-methylcyclohexanemethanol (MCHM) is an industrial solvent used to clean coal. Approximately 10 000 gallons of a liquid mixture containing crude MCHM were accidently released into the Elk River in West Virginia in January 2014. Because of the proximity to a water treatment facility, the contaminated water was distributed to approximately 300 000 residents. In this review, experimental data and computational predictions for the toxicity for crude MCHM, distilled MCHM, its other components and its putative metabolites are presented. Crude MCHM, its other constituents and its metabolites have low to moderate acute and subchronic oral toxicity. Crude MCHM has been shown not to be a skin sensitizer below certain doses, indicating that at plausible human exposures it does not cause an allergic response. Crude MCHM and its constituents cause slight to moderate skin and eye irritation in rodents at high concentrations. These chemicals are not mutagenic and are not predicted to be carcinogenic. Several of the constituents were predicted through modeling to be possible developmental toxicants; however, 1,4-cyclohexanedimethanol, 1,4-cyclohexanedicarboxylic acid and dimethyl 1,4-cyclohexanedicarboxylate did not demonstrate developmental toxicity in rat studies. Following the spill, the Centers for Disease Control and Prevention recommended a short-term health advisory level of 1 ppm for drinking water that it determined was unlikely to be associated with adverse health effects. Crude MCHM has an odor threshold lower than 10 ppb, indicating that it could be detected at concentrations at least 100-fold less than this risk criterion. Collectively, the findings and predictions indicate that crude MCHM poses no apparent toxicological risk to humans at 1 ppm in household water.

The effect of clothing care activities on textile formaldehyde content.

Textiles are commonly treated with formaldehyde-based residues that may potentially induce allergic contact dermatitis in sensitive individuals. This study examined the initial formaldehyde content in clothing and resulting changes due to care activities. Twenty clothing articles were examined and 17 of them did not have detectable levels of formaldehyde. One shirt contained a formaldehyde concentration of 3172 ppm, and two pairs of pants had formaldehyde concentrations of 1391 ppm and 86 ppm. The two highest results represent formaldehyde levels that are up to 40-fold greater than international textile regulations. The two items with the greatest formaldehyde content were washed and dried in a manner similar to that used by consumers, including hand and machine washing in hot or cold water followed by air or machine drying. The washing and drying procedures reduced formaldehyde levels to between 26 and 72% of untreated controls. Differences in the temperature or type of washing and drying did not result in a clear trend in the subsequent formaldehyde content. In addition, samples were hot ironed, which did not affect the formaldehyde content as significantly. Understanding the formaldehyde content in clothing and its potential reduction through care activities may be useful for manufacturers and formaldehyde-sensitive individuals.

Estimation of the safe use concentrations of the preservative 1,2-benzisothiazolin-3-one (BIT) in consumer cleaning products and sunscreens.

1,2-Benzisothiazolin-3-one (BIT; CAS # 2634-33-5) is a preservative used in consumer products. Dermal exposure to BIT at sufficient dose and duration can produce skin sensitization and allergic contact dermatitis in animals and susceptible humans.The purpose of this study is to derive a maximal concentration of BIT in various consumer products that would result in exposures below the No Expected Sensitization Induction Level (NESIL), a dose below which skin sensitization should not occur. A screening level exposure estimate was performed for several product use scenarios with sunscreen, laundry detergent, dish soap, and spray cleaner. We calculated that BIT concentrations below the following concentrations of 0.0075%, 0.035%, 0.035%, 0.021% in sunscreen, laundry detergent, dish soap, and spray cleaner, respectively, are unlikely to induce skin sensitization. We completed a pilot study consisting of bulk sample analysis of one representative product from each category labelled as containing BIT, and found BIT concentrations of 0.0009% and 0.0027% for sunscreen and dish soap, respectively. BIT was not detected in the laundry detergent and spray cleaner products above the limit of detection of 0.0006%. Based on publically available data for product formulations and our results, we were able to establish that cleaning products and sunscreens likely contain BIT at concentrations similar to or less than our calculated maximal safe concentrations and that exposures are unlikely to induce skin sensitization in most users.

An analysis of historical exposures of pressmen to airborne benzene (1938-2006).

Benzene is an aromatic hydrocarbon that, with sufficient cumulative lifetime doses, can cause acute myelogenous leukemia. Because of its volatility and solvent properties, it was used in the printing industry in inks, ink solvents, and cleaning agents from the 1930s to the 1970s. This analysis represents the first known attempt to gather and synthesize the available data on historical airborne benzene concentrations in printing facilities and exposures to pressmen. The sources of fugitive benzene vapors from printing operations have been identified as evaporation from ink fountains, exposed sections of the printing cylinder, the paper web, the paper post exit, and spilled ink. In addition, specific activities that could lead to benzene exposure, such as filling the fountains, using solvents to clean the press, and using solvents as personal cleaning agents, potentially occurred multiple times per work period. Eighteen studies were identified that reported workplace airborne concentrations in printing facilities between 1938 and 2006. Typical benzene air concentrations, considering both personal and area samples of various durations, were as high as 200 p.p.m. in the 1930s through the 1950s, 3-35 p.p.m. in the 1960s, 1.3-16 p.p.m. in the 1970s, 0.013-1 in the 1980s, and far less than 1 p.p.m. in the 1990s and 2000s. The decrease in benzene air concentrations by the late 1970s was likely to be linked to the decreased benzene content of printing materials, increased engineering controls, and to more stringent occupational exposure limits.

Isoform distinct time-, dose-, and castration-dependent alterations in flavin-containing monooxygenase expression in mouse liver after 2,3,7,8-tetrachlorodibenzo-p-dioxin treatment.

Flavin-containing monooxygenase (FMO) expression in male mouse liver is altered after 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure or castration. Because TCDD is slowly eliminated from the body, we examined hepatic Fmo mRNA alterations for up to 32 days following 10 or 64 microg/kg TCDD exposure by oral gavage in male C57BL/6J mice. Fmo2 mRNA was significantly induced at 1, 4, and 8 days whereas Fmo3 mRNA was also induced at 32 days relative to controls. Fmo3 mRNA levels exhibited a dose-dependent increase at 4, 8, and 32 days after exposure; Fmo1, Fmo4, and Fmo5 mRNA did not exhibit clear trends. Because castration alone also increased Fmo2, Fmo3, and Fmo4 mRNA we examined the combined effects of castration and TCDD treatment on FMO expression. A greater than additive effect was observed with Fmo2 and Fmo3 mRNA expression. Fmo2 mRNA exhibited a 3-5-fold increase after castration or 10 microg/kg TCDD exposure by oral gavage, whereas an approximately 20-fold increase was observed between the sham-castrated control and castrated TCDD-treated mice. Similarly, treatment with 10 microg/kg TCDD alone increased Fmo3 mRNA 130- and 180-fold in the sham-castrated and castrated mice compared to their controls respectively, whereas, Fmo3 mRNA increased approximately 1900-fold between the sham control and castrated TCDD-treated mice. An increase in hepatic Fmo3 protein in TCDD-treated mice was observed by immunoblotting and assaying methionine S-oxidase activity. Collectively, these results provide evidence for isoform distinct time-, dose-, and castration-dependent effects of TCDD on FMO expression and suggest cross-talk between TCDD and testosterone signal transduction pathways.

Differential localization of flavin-containing monooxygenase (FMO) isoforms 1, 3, and 4 in rat liver and kidney and evidence for expression of FMO4 in mouse, rat, and human liver and kidney microsomes.

Flavin-containing monooxygenases (FMOs) play significant roles in the metabolism of drugs and endogenous or foreign compounds. In this study, the regional distribution of FMO isoforms 1, 3, and 4 was investigated in male Sprague-Dawley rat liver and kidney using immunohistochemistry (IHC). Rabbit polyclonal antibodies to rat FMO1 and FMO4, developed using anti-peptide technology, and commercial anti-human FMO3 antibody were used; specificities of the antibodies were verified using Western blotting, immunoprecipitation, and IHC. In liver, the highest immunoreactivity for FMO1 and FMO3 was detected in the perivenous region, and immunoreactivity decreased in intensity toward the periportal region. In contrast, FMO4 immunoreactivity was detected with the opposite lobular distribution. In the kidney, the highest immunoreactivity for FMO1, -3, and -4 was detected in the distal tubules. FMO1 and FMO4 immunoreactivity was also detected in the proximal tubules with strong staining in the brush borders, whereas less FMO3 immunoreactivity was detected in the proximal tubules. Immunoreactivity for FMO3 and FMO4 was detected in the collecting tubules in the renal medulla and the glomerulus, whereas little FMO1 immunoreactivity was detected in these regions. The FMO1 antibody did not react with human liver or kidney microsomes. However, the FMO4 antibody reacted with male and female mouse and human tissues. These data provided a compelling visual demonstration of the isoform-specific localization patterns of FMO1, -3, and -4 in the rat liver and kidney and the first evidence for expression of FMO4 at the protein level in mouse and human liver and kidney microsomes.

Purification and characterization of flavin-containing monooxygenase isoform 3 from rat kidney microsomes.

Rats are a common animal model for metabolism and toxicity studies. Previously, the enzymatic properties of rat flavin-containing monooxygenase (FMO) 1 purified from hepatic and renal microsomes and that of FMO3 purified from hepatic microsomes were characterized. This study investigated the physical, immunological, and enzymatic properties of FMO3 purified from male rat kidney microsomes and compared the results with those obtained with isolated rat liver FMO3. Renal FMO3 was purified via affinity columns based on the elution of L-methionine (Met) S-oxidase activity and reactivity of the eluted proteins with human FMO3 antibody. In general, Met S-oxidase-specific activity was increased 100-fold through the purification steps. The resulting protein had similar mobility (approximately 56 kDa) as isolated rat liver FMO3 and cDNA-expressed human FMO3 by SDS-polyacrylamide gel electrophoresis. When the isolated kidney protein band was subjected to trypsin digestion and matrix-assisted laser desorption ionization/time of flight mass spectral analysis, 34% of the sequence of rat FMO3 was detected. The apparent K(m) and V(max) values for rat kidney FMO3 were determined using the known FMO substrates Met, seleno-L-methionine, S-allyl-L-cysteine (SAC), and methimazole (N-methyl-2-mercaptoimidazole). The stereoselectivity of the reactions with Met and SAC were also examined using high-performance liquid chromatography. The obtained kinetic and stereoselectivity results were similar to those we obtained in the present study, or those previously reported, for rat liver FMO3. Taken together, the results demonstrate many similar properties between rat hepatic and renal FMO3 forms and suggest that renal FMO3 may play an important role in kidney metabolism of xenobiotics containing sulfur and selenium atoms.