Increasing exposure to the UV filters octocrylene and 2-ethylhexyl salicylate in Germany from 1996 to 2020: Human biomonitoring in 24-h urine samples of the German Environmental Specimen Bank (ESB)

Assessing the exposure to the UV filter DHHB in urine samples from the German Environmental Specimen Bank (2000-2021): Evaluating the impact of a potential impurity of di-n-hexyl phthalate in DHHB

Human biomonitoring (HBM) has become a crucial tool for assessing exposure to emerging chemicals. We analyzed 250 24-h urine samples from the German Environmental Specimen Bank (ESB), collected between 2000 and 2021, for exposure to diethylamino hydroxybenzoyl hexyl benzoate (DHHB), a UV filter increasingly used in sunscreens. Three major metabolites were examined: 2-(4-diethylamino)-, 2-(4-ethylamino)-, and 2-(4-amino)-2-hydroxybenzoyl)benzoic acid (DHB, EHB, AHB), with detection rates of 18°%, 13°%, and 87°%, respectively. While EHB and DHB were specific to DHHB, AHB suggested other exposure sources, making it unreliable for assessing DHHB exposure. DHB and EHB were first detected in 2012, with increased detection rates thereafter. The median daily intake of 37 ng/kg bw/d was much lower than the derived no-effect level of 2900 mg/kg bw/d, indicating low risk from DHHB exposure. However, since the analyzed ESB samples were collected in winter, they likely reflect exposure from other products and the environment rather than sunscreen-related exposure. Recently, concerns have emerged regarding the DHHB impurity di-n-hexylphthalate (DnHexP), a reproductive toxicant not authorized in the EU. Retrospective analysis of oral DHHB dosing experiments indeed revealed impurity related dose-dependent excretion of DnHexP metabolites (MnHexP, oxidized 5-OH-MnHexP, and 5-oxo-MnHexP). Due to uncertainties in dose allocation, only a rough excretion fraction of 45°% for MnHexP was derived. Our findings suggest that the DHHB impurity DnHexP may contribute to DnHexP exposure in sunscreen users applying products with contaminated DHHB. Given DnHexP's toxicity, this warrants re-assessment of DHHB's safety in cosmetics and enhanced surveillance of both DHHB and DnHexP in HBM studies.

Individual and combined toxicity of personal care products and pharmaceuticals at environmentally relevant concentrations due to chronic exposure of the freshwater microcrustacean Daphnia magna

Personal care products and pharmaceuticals, namely sodium diclofenac (DCF), octocrylene (OCT), and sodium dodecyl sulfate (SDS), are relevant chemical products classified as contaminants of emerging concern (CECs). They can enter aquatic ecosystems from various anthropogenic sources. This study examined the acute and chronic toxic effects of exposure to these substances, individually and in binary mixtures (OCT + SDS, SDS + DCF, DCF + SDS). Chronic effects were evaluated at environmentally relevant concentrations. To evaluate the mixtures, the Abbott method was used to predict acute toxicity using the inhibition ratio value, while for chronic effects, the concentration addition (CA) and independent action (IA) models were used for predictive assessment. According to EC5048h values, the toxicity levels to D. magna were OCT > SDS > DCF. When exposed to binary mixtures, these compounds predominantly exhibited antagonistic interaction for acute effects. Regarding chronic effects, there were no observed effects at the environmentally relevant concentrations tested for individual and mixed exposure compared to the control. The locomotion parameter exhibited a difference in dispersion with increasing chemical concentration. These results can improve understanding of the damage produced by exposure to mixtures of different CECs.

Mode of action approach supports a lack of carcinogenic potential of six organic UV filters

Ultraviolet (UV) filters, the active ingredients in sunscreens, have been used for several decades to reduce the risk of acute and chronic damage to the skin from solar UV radiation, which can lead to skin cancer. Based on recent clinical studies showing that certain UV filters are absorbed systemically at low levels in humans, the US Food and Drug Administration (FDA) has requested supplementing existing safety data with preclinical studies including oral and dermal 2-year rodent carcinogenicity studies. Although the conduct of 2-year rodent carcinogenicity studies has been the standard approach for evaluating the carcinogenic potential of chemicals and new drugs for approximately 6 decades, there are multiple examples showing that such studies are not predictive of human cancer risk. Given these concerns with 2-year rodent carcinogenicity studies, we have developed and applied an alternative approach for supplementing existing data related to carcinogenic potential for six of the most commonly used UV filters in sunscreen products (i.e. avobenzone, ensulizole, homosalate, octinoxate, octisalate, and octocrylene). This approach evaluates their mode of action (MOA) based on in vivo, in vitro, and in silico data combined with an assessment of exposure margins. This approach is based on the substantial progress in understanding the MOAs that are responsible for tumor induction in humans. It is consistent with those being developed by the International Council for Harmonization (ICH) and other health authorities to replace 2-year carcinogenicity studies given their limitations and questionable biological relevance to humans. The available data for the six UV filters show that they are not genotoxic and show no evidence of biologically relevant carcinogenic MOAs. Furthermore, their systemic exposure levels in humans fall well below concentrations at which they have biologic activity. In conclusion, these data support the continued safe use of these six filters in sunscreen products.

Next Generation Risk Assessment to Address Disease-Related Vulnerability-A Proof of Concept for the Sunscreen Octocrylene

Risk assessment for cosmetics in the European Union (EU) are triggered by a ban on animal testing and concerns of endocrine disruption (ED). The risk assessment focuses on healthy populations and, for potential ED, includes specific developmental stages as vulnerable due to specific concerns on endocrine effects. However, the assessment focuses on healthy individuals and does not consider that some pathologies may increase dermal absorption and even vulnerability to endocrine disruptors. Data from the EU risk assessment, human pharmacokinetic studies and ToxCast bioactivity were combined in a hypothesis-driven Next-Generation Risk Assessment to identify possible risk drivers for vulnerable populations including oncological patients and atopic dermatitis. In vitro effects are observed at concentration in the order of measured plasmatic levels under normal use patterns. The induction of hepatic enzymes is the most relevant bioactivity endpoint, in line with animal findings. The information on endocrine potential is inconclusive, and the possibility for skin effects and endocrine mechanism linked to tumor induction require further elucidation. The information on octocrylene (CAS number: 6197-30-4) bioactivity is limited, lacking information on the metabolites and the immunotoxicity potential, particularly relevant for oncological patients.

A novel approach for unveiling co-occurrence patterns of UV filter mixtures in sunscreens: Prioritization for hazard and risk assessment

In recent years, concerns regarding the toxicity of organic UV filters in sunscreen products have increased. While sunscreen products contain multiple UV filters in combination, current understanding on their co-occurrence patterns and mixture toxicities is still limited. This study utilized a public database, "Hwahae", and analyzed 2183 sunscreen products marketed in South Korea as of 2019, using an association rule mining (ARM) to elucidate their co-occurrence patterns. We identified twenty-two UV filters in the sunscreen products, with titanium dioxide (TiO2) being the most prevalent (68 %), followed by ethylhexyl methoxycinnamate (EHMC, 60 %) and ethylhexyl salicylate (EHS, 49 %). Sunscreen products typically contained a median of five UV filters per product. Usage patterns of UV filter mixtures varied by the target user group of the product, i.e., general, susceptible, and male users. EHMC and EHS were commonly combined in most products, except those marketed for susceptible users. For susceptible users, inorganic UV filters such as TiO2 and zinc oxide (ZnO) were dominantly used. Combinations of UV filters that provide protection against different types of UV light, e.g., butyl methoxydibenzoylmethane (BMDBM) for UVA, and octocrylene (OCT), EHS, or homosalate (HS) for UVB, were also frequently used together, with high lift values. In conclusion, our study demonstrated that ARM approach can be useful to identify major combinations of UV filters present in sunscreen products, and prioritize the UV filter combinations requiring safety assessment and regulatory attention.

Plasticizer exposure in Germany from 1988 to 2022: Human biomonitoring data of 20 plasticizers from the German Environmental Specimen Bank

The German Environmental Specimen Bank (ESB) annually archives 24-h urine samples since the early 1980s. In this study, we analyzed 420 of these samples from the years 2014 to 2022 for metabolites of 18 phthalates and two substitutes. We merged the new data with the data from previous measurement campaigns to a combined dataset of 1825 samples covering a 35-year period from 1988 to 2022 to investigate time trends, calculate daily intakes and perform an anti-androgenic mixture risk assessment. With the extended set of 41 biomarkers, we are now able to monitor the exposure to all EU-labelled reprotoxic phthalates. Most phthalate exposures continued to decrease since first measurements in the 80s, with biggest drops for DnBP (96.6 %) and DEHP (90.9 %). DiNP and DiDP, seen on the rise in earlier campaigns, now declined. Exposures to the newly included, reprotoxic phthalates were generally negligible. Regarding mixture risk, 5 % of the highly exposed still exceeded the Hazard Index (HI) of 1 in 2009. In the current measurement campaign only three individuals (0.7 %) exceeded the HI of 1 (with exceedances still driven by DEHP and DnBP).In 2022, 20 % of the individuals still had an HI > 0.2, which we propose as a benchmark for interpreting phthalate mixture risk, considering concurrent exposures to other anti-androgens. Exposure to the substitutes DINCH and DEHTP continues to increase, with daily intakes of DEHTP exceeding those of DEHP since 2018. Compared with the United States (US) National Health and Nutrition Examination Survey (NHANES) phthalate exposures seem to align, except for DEHTP with up to ten times higher levels in the US. Human biomonitoring (HBM) is the ideal tool to capture actual mixture exposures per individual, integrating all external exposure sources and pathways, thus we will continue to use HBM in exposure and risk assessment of phthalates and other (anti-androgenic) chemicals.

Distribution, sources, ecological and human health risks of organic ultraviolet filters in coastal waters and beach deposits in Hainan, China

Organic ultraviolet filters (OUVFs) are extensively incorporated into both cosmetic items and industrial products and have been commonly found in water ecosystems. This study aims to examine the environmental levels, sources, ecological and human health risks of 14 commonly used OUVFs both in coastal water and beach deposit samples collected from the nearshore regions of Hainan Island and the South China Sea. This is first study highlighting the contamination of OUVFs in Hainan Island and utilizing economic and tourism data to confirm the potential source of OUVF pollution in costal aquatic and coastal ecosystem. Along the coastal tourist regions of Hainan Island, the median concentrations in coastal waters and beach deposits of these OUVFs fall within the range from 1.2 to 53.2 ng/L and 0.2-17.0 ng/g dw, respectively. In coastal water and beach deposit, the concentration of BP-3 was the highest, with median concentrations of 53.2 ng/L and 17.0 ng/g dw, respectively. Regarding human health risks, the daily intake of all 14 OUVFs through swimming was found to be 40-48 ng/kg/day. Ecological risk assessment indicates that BP-3 presents a medium risk for marine microalgae with a concurrent low risk for corals. The correlation analysis underscores a substantial interrelation of OUVFs in both coastal waters and beach deposits with various economic indicators, including annual rainfall, overnight tourists, total hotel rooms (unit), room occupancy rate, and sewage treatment capacity.

Toxicokinetics of 2-ethylhexyl salicylate (EHS) and its seven metabolites in humans after controlled single dermal exposure to EHS

The chemical UV filter 2-ethylhexyl salicylate (EHS) is used in various personal-care products. The dermal and oral metabolism of EHS have already been targeted by different studies. However, toxicokinetic data after a single dermal exposure to EHS was missing. In our study, three volunteers were dermally exposed to a commercial EHS-containing sunscreen for 9 h with an application dose of 2 mg sunscreen per cm2 body surface area. The exposure was performed indoors, and sunscreen was applied on about 75% of the total skin area. Complete urine voids were collected over 72 h and eight blood samples were drawn from each subject. Urine samples were analyzed for EHS and seven known metabolites (5OH-EHS, 4OH-EHS, 2OH-EHS, 6OH-EHS, 4oxo-EHS, 5oxo-EHS, and 5cx-EPS) by online-SPE UPLC MS/MS. The peaks of urinary elimination occurred 10-11 h after application. The elimination half-lives (Phase 1) were between 6.6 and 9.7 h. The dominant urinary biomarkers were EHS itself, followed by 5OH-EHS, 5cx-EPS, 5oxo-EHS, and 4OH-EHS. 2OH-EHS, 6OH-EHS, and 4oxo-EHS were detected only in minor amounts. An enhanced analysis of conjugation species revealed marginal amounts of unconjugated metabolites and up to 40% share of sulfate conjugates for 5OH-EHS, 5oxo-EHS, and 5cx-EPS. The results demonstrated a delayed systemic resorption of EHS via the dermal route. Despite an extensive metabolism, the parent compound occurred as main urinary parameter. The delayed dermal resorption as well as the slow elimination of EHS indicate an accumulation up to toxicological relevant doses during daily repeated dermal application to large skin areas.

Thyroid, neurodevelopmental, and kidney toxicities of common organic UV filters in embryo-larval zebrafish (Danio rerio), and their potential links

Organic UV filters (OUVFs) have been commonly used in sunscreen and many consumer products. Following dermal application, these compounds can enter circulation and may cause systemic effects in humans. In the present study, we chose four OUVFs frequently detected in the environment, i.e., avobenzone (AVB), benzophenone-3 (BP-3), octocrylene (OC), and octyl methoxycinnamate (OMC), and evaluated their thyroid, neurodevelopmental, and kidney toxicities. For this purpose, zebrafish embryos (<4 h post fertilization, hpf) were exposed to sublethal concentrations of AVB, BP-3, OC, or OMC until 120 hpf. Exposure to all OUVFs decreased thyroid hormone (TH) levels, probably by enhanced metabolism and excretion of THs (ugt1ab and/or sult1 st5) in the larval fish. Exposure to the OUVFs also induced hypoactivities and/or anxiety-like behaviors: Regulatory changes of mbp, gfap, c-fos, syn2a, sty1a, and stxbp1b genes, support the changes in normal neurobehavior of the larval fish. Moreover, the OUVFs exposure caused increased proteinuria in the fish, along with transcriptional changes of wt1, nephrin, podocin, and cdh17 genes, which could explain the observed reduction in kidney functions. Principal component analysis (PCA) implied the potential interplay of THs with neurogenesis, or podocyte differentiation of the larval fish. Toxicological consequences of altered TH homeostasis, neurobehavior, and kidney function at the early life stage warrant further investigations not only in humans but also in aquatic ecosystems.

New metabolites of 2-ethylhexyl salicylate in human urine after simulated real-life dermal sunscreen application

2-Ethylhexyl salicylate (EHS) is an organic UV filter which is used in sunscreen and other personal care products. The dermal uptake of EHS was studied in several dermal-exposure experiments. This paper aims to coherently assess urine samples after dermal exposure for the biomarkers EHS, 5OH-EHS, 5oxo-EHS, and 5cx-EPS as well as further biomarkers of interest, specifically 4OH-EHS, 4oxo-EHS, 2OH-EHS, and 6OH-EHS, for the first time. Samples from 18 participants of a pre-existing dermal exposure study under real-life conditions were reassessed using a comprehensive LC-MS/MS method. EHS accounts for 34 % of the cumulative excretion of all analytes within 24 h after exposure, followed by 5OH-EHS (19 %), 5cx-EPS (18 %), 4OH-EHS (15 %) and 5oxo-EHS (11 %). Further metabolites were only quantified in minor amounts. EHS as the most prominent excretion parameter in this study demonstrates the missing first-pass effect after dermal absorption. Furthermore, the applied novel comprehensive analytical procedure revealed oxidation at the ω (5cx-EPS, 6OH-EHS), ω-1 (5OH-EHS, 5oxo-EHS), and ω-2 positions (4OH-EHS, 4oxo-EHS) in the main chain of the ethylhexyl group as well as oxidation in the side chain (2OH-EHS). The presented data are of high relevance for a reliable toxicological risk assessment of dermal exposure to EHS.

Toxicokinetics of homosalate in humans after dermal application: applicability of oral-route data for exposure assessment by human biomonitoring

Homosalate (HMS) is a UV filter used in sunscreens and personal care products as a mixture of cis- and trans-isomers. Systemic absorption after sunscreen use has been demonstrated in humans, and concerns have been raised about possible endocrine activity of HMS, making a general population exposure assessment desirable. In a previous study, it was shown that the oral bioavailability of cis-HMS (cHMS) is lower than that of trans-HMS (tHMS) by a factor of 10, calling for a separate evaluation of both isomers in exposure and risk assessment. The aim of the current study is the investigation of HMS toxicokinetics after dermal exposure. Four volunteers applied a commercial sunscreen containing 10% HMS to their whole body under regular-use conditions (18-40 mg HMS (kg bw)-1). Parent HMS isomers and hydroxylated and carboxylic acid metabolites were quantified using authentic standards and isotope dilution analysis. Further metabolites were investigated semi-quantitatively. Elimination was delayed and slower compared to the oral route, and terminal elimination half-times were around 24 h. After dermal exposure, the bioavailability of cHMS was a factor of 2 lower than that of tHMS. However, metabolite ratios in relation to the respective parent isomer were very similar to the oral route, supporting the applicability of the oral-route urinary excretion fractions for dermal-route exposure assessments. Exemplary calculations of intake doses showed margins of safety between 11 and 92 (depending on the approach) after single whole-body sunscreen application. Human biomonitoring can reliably quantify oral and dermal HMS exposures and support the monitoring of exposure reduction measures.