Influence of sunscreen formulation on the transfer of mineral and organic ultraviolet filters from skin to seawater in simulated ocean bathing tests.

OBJECTIVE: Significant research and regulatory attention have been focussed on the potential for some ultraviolet filters (UVFs) to rinse off from beachgoers' skin into seawater leading to exposure to sea life, especially coral reefs. The amount of UVFs potentially rinsed from skin during recreational beach activities has not been well studied, leading to uncertainty about the potential magnitude of aquatic UVF exposure due to changes in sunscreen use patterns. This study quantifies rinse-off of UVFs in sunscreen from skin into synthetic seawater and identifies differences in rinse-off quantity due to formulation type with a goal of informing future modelling efforts aimed at estimating UVF exposure to sea life associated with recreational activities at the beach. METHODS: UVF rinse-off from skin during recreation in seawater was simulated by applying eight different sunscreen products to porcine skin samples followed by three periods of shaking in synthetic seawater totalling 40 min. The rinsed mass of six UVFs - zinc oxide, titanium dioxide, avobenzone, homosalate, octisalate, and octocrylene - was determined analytically in synthetic seawater and in extractant rinsate from glassware for organic UVFs and compared among formulas. RESULTS: Among the 22 UVF-formulation combinations tested, 19 resulted in less than 10% of the applied UVF rinsed from skin. All formulation-UVF combinations where the formula types were water-in-oil (reverse phase) emulsions or anhydrous resulted in 5% or less of the applied UVF rinsed to synthetic seawater. Sunscreens formulated as oil-in-water emulsions yielded higher rinse-off percentages for all UVFs tested, with a maximum of 20% rinse-off of avobenzone in one lotion. CONCLUSION: The potential for sunscreen UVF rinse-off is significantly influenced by formulation and is generally well below the prior assumed rinse-off levels used to estimate risk. Formulation consideration is therefore essential for accurate exposure models used in environmental risk assessment. Anhydrous and reverse phase (water-in-oil) sunscreen formulations tested resulted in lower UVF transfer from skin to synthetic seawater in simulated ocean bathing tests and as a result, are expected to yield lower UVF exposures to sea life. This approach can be used in predictive environmental exposure models to support ecologically safe sunscreen formulation design.

OBJECTIF: Des recherches importantes ont été effectuées et l'attention réglementaire a été portée sur le potentiel de certains filtres ultraviolets (UVF) à être rincés de la peau de baigneurs par l'eau de mer à la plage, entraînant une exposition à la vie marine, en particulier aux récifs coralliens. La quantité d'UVF potentiellement rincée de la peau pendant les activités récréatives sur la plage n'a pas été étudiée de manière approfondie, ce qui entraîne une incertitude quant à l'ampleur potentielle de l'exposition aux UVF dans l'eau en raison des changements dans les habitudes d'utilisation de la crème solaire. Cette étude quantifie le rinçage des UVF contenus dans la crème solaire appliquée sur la peau par de l'eau de mer reconstituée et identifie les différences dans la quantité UVF rinçés selon le type de formulation afin d'éclairer les futurs efforts de modélisation visant à estimer l'exposition des UVF à la vie marine associée aux activités récréatives à la plage. MÉTHODES: Le rinçage des UVF pendant les loisirs en eau de mer a été simulé en appliquant huit produits de protection solaire différents sur des échantillons de peau porcine, suivis de trois périodes d'agitation dans de l'eau de mer reconstituée d'une durée totale de 40 min. La masse rincée de six UVF - oxyde de zinc, dioxyde de titane, avobenzone, homosalate, octisalate et octocrylène - a été déterminée analytiquement dans l'eau de mer reconstituée et en solution pour les UVF organiques, et une comparaison entre les formules a été effectuée. RÉSULTATS: Parmi les 22 combinaisons de formulations UVF testées, 19 ont entraîné le rinçage de moins de 10 % des UVF appliqués sur la peau. Toutes les combinaisons de formulations UVF où les types de formule étaient des émulsions eau dans huile (phase inverse) ou anhydres ont entraîné 5 % ou moins de rinçage des UVF appliquées dans l'eau de mer reconstituée. Les écrans solaires formulés sous forme d'émulsions huile dans l'eau ont produit des pourcentages de rinçage plus élevés pour tous les UVF testés, avec un maximum de 20 % de rinçage pour l'avobenzone pour une lotion. CONCLUSION: Le potentiel de rinçage des UVF de l'écran solaire est significativement influencé par la formulation et est généralement bien inférieur aux niveaux de rinçage précédemment supposés, utilisés pour estimer le risque. La prise en compte de la formulation est donc essentielle pour obtenir des modèles d'exposition exacts utilisés dans l'évaluation des risques environnementaux. Les formulations de crème solaire anhydre et en phase inverse (eau dans l'huile) testées ont entraîné un transfert plus faible des UVF dans l'eau de mer reconstituée dans des tests de simulation de bain de mer et, par conséquent, devraient entrainer une exposition plus faible des UVF à la vie marine. Cette approche peut être utilisée dans des modèles prédictifs d'exposition environnementale pour soutenir une conception de crème solaire écologiquement sûre.

Development of a novel rinse-off method for improved sunscreen exposure assessment.

Recent legislative measures restricting the sale of sunscreens containing certain ultraviolet light filtering ingredients (UVFs) have been based on a perception of risk to aquatic life despite the lack of a robust data set to support these decisions. Concerns were focused on the potential for recreational swimmers' and divers' sunscreen use to result in exposures to coral already stressed due to climate change, disease, and other local conditions. In published environmental risk assessments for UVFs, exposure estimates were based on episodic environmental monitoring or estimates of typical sunscreen use, arbitrarily assuming the portion rinsed off from skin in seawater. To improve the accuracy of exposure estimates and thereby develop more robust risk assessments, we measured the amount of the UVFs, avobenzone, homosalate, octisalate, octocrylene, and oxybenzone released to seawater from four sunscreen products (two lotions, one spray, one stick) in a novel porcine skin model of typical human sunscreen use. Sunscreen was applied to porcine skin, allowed to briefly dry, then exposed to four rinse cycles in artificial seawater. The mass of each UVF in seawater, partitioned from seawater onto glassware, and extractable from skin after rinsing were determined. The proportion rinsed from skin varied by UVF, by formula type, and by application rate. Less than 1.4% of applied octisalate, homosalate, and octocrylene was detected in seawater samples (independent of formula) increasing to an average of 4% and 8% for avobenzone in stick and lotion forms, and to 24% for oxybenzone in lotions. The initial data show substantial differences in rinse-off among formulation types and sunscreen application rates, and stress the importance of using UVF-specific rinse-off values rather than a single value for all UVFs. This new method provides a tool for more robust exposure estimates, with initial data supporting lower rinse-off values than adopted in published risk assessments. Integr Environ Assess Manag 2021;17:961-966. © 2021 Johnson & Johnson Consumer Companies Inc. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Evaluating landfill disposal of chromated copper arsenate (CCA) treated wood and potential effects on groundwater: evidence from Florida.

Chromated copper arsenate (CCA) treated wood has been used for more than 50 years. Recent attention has been focused on appropriate disposal of CCA-treated wood when its service life ends. Groups in the US and Europe concerned with the possibility of arsenic migration to groundwater from disposed CCA-treated wood have proposed that consumers be required to dispose of the wood as a hazardous waste, in the most protective of landfills. We examined available data for evidence of arsenic migration from unlined construction and demolition (C&D) debris landfills in Florida, where CCA-treated wood is disposed. Florida was chosen because soil, groundwater, landfill design, weather, and levels of CCA-treated wood use make the state a uniquely sensitive indicator for observing arsenic migration from CCA-treated wood disposal sites, should it occur. We developed and quality-checked a CCA-treated wood disposal model to estimate the amount of wood and associated arsenic disposed. By 2000, an estimated 13 million kg of arsenic in CCA-treated wood was disposed in Florida; however, groundwater monitoring data do not indicate that arsenic is migrating from unlined C&D landfills. Our results provide evidence that highly stringent regulation of CCA-treated wood disposal, such as treatment as a hazardous waste, is unnecessary.

Correlation of the partitioning of dissolved organic matter fractions with the desorption of Cd, Cu, Ni, Pb and Zn from 18 Dutch soils.

Eighteen Dutch soils were extracted in aqueous solutions at varying pH. Extracts were analyzed for Cd, Cu, Ni, Pb and Zn by ICP-AES. Extract dissolved organic carbon (DOC) was also concentrated onto a macroreticular resin and fractionation into three operationally defined fractions: hydrophilic acids (Hyd), humic acids (HA) and fulvic acids (FA). In this manner, change in absolute solution concentration and relative percentage for each fraction could be calculated as a function of extraction equilibrium pH. The soils were also analyzed for solid phase total organic carbon and total recoverable metals (EPA Method 3051). Partitioning coefficients were calculated for the metals and organic carbon (OC) based on solid phase concentrations (less the metal or OC removed by the extraction) divided by solution concentrations. Cu and Pb concentrations in solution as a function of extract equilibrium pH are greatest at low and high pH resulting in parabolic desorption/dissolution curves. While processes such as proton competition and proton promoted dissolution can account for high solution metal concentrations at low pH, these processes cannot account for higher Cu and Pb concentrations at high pH. DOC increases with increasing pH, concurrently with the increase in Cu and Pb solution concentrations. While the absolute concentrations of FA and HA generally increase with increasing pH, the relative proportional increase is greatest for HA . Variation in HA concentrations spans three orders of magnitude while FA concentrations vary an order of magnitude over the pH range examined. Correlation analysis strongly suggests that HA plays a major role in increasing the concentration of solution Cu and Pb with increasing pH in the 18 soils studied. The percentage of the OC that was due to FA was nearly constant over a wide pH range although the FA concentration increased with increasing pH and its concentration was greater than that of the HA fraction at lower pH values (pH = 3-5). Thus, in more acidic environments, FA may play a larger role than HA in governing organo-metallic interactions. For Cd, Ni, and Zn, the desorption/dissolution pattern shows high metal solution concentrations at low pH with slight increases in solution concentrations at extremely high pH values (pH>10). The results presented here suggest that the effects of dissolved organic carbon on the mobilization of Cd, Ni, and Zn may only occur in systems governed by very high pH. At high pH, it is difficult to distinguish in this study whether the slightly increased solution-phase concentrations of these cations is due to DOC or hydrolysis reactions. These high pH environments would rarely occur in natural settings.

Predicting the bioavailability of copper and zinc in soils: modeling the partitioning of potentially bioavailable copper and zinc from soil solid to soil solution.

This research produced statistically based, semimechanistic models describing partitioning of Cu and Zn in 40 soils from the United States, Canada, the United Kingdom (UK), The Netherlands, and Chile with widely varying characteristics. Two different types of models were constructed, partitioning models and competitive adsorption models. Multiple linear regression (MLR) was employed to prioritize over 30 different soil characteristics. Multiple linear regression yielded equations predicting the partitioning of Cu and Zn. Equations were also created that estimated the potentially bioavailable fraction of Cu and/or Zn. Data from plant uptake studies (which are reported separately) governed the choice of a suitable chemical soil extraction that estimated bioavailable Cu (0.01 M HCl) and bioavailable Zn (0.01 M CaCl2). Soil pH (1:1 soil:deionized water [DI H2O]) and percent organic matter accounted for approximately 70% of the variability in Cu partitioning and 80% of the variability in bioavailable Cu in the 40 soils studied. For Zn, soil pH alone accounted for roughly 75% of the partitioning variability and 80% of the variability for the estimated bioavailable portion. The results presented here were used in conjunction with results from the plant uptake studies for the creation of models to assess the potential bioavailable metal associated with any given soil from a wide variety of locations.