Review of Fate, Exposure, and Effects of Sunscreens in Aquatic Environments and Implications for Sunscreen Usage and Human Health (2022) / Chapter Skim
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Pages 70-104
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From page 70... ...
The importance of these properties are well recognized in the conduct of environmental risk assessments and explains why they are generally required prior to conducting risk assessments. FATE CHARACTERISTICS OF UV FILTERS The physico-chemical properties of chemicals largely drive environmental behavior (i.e., fate and effects)
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From page 71... ...
Dubelcco's media contained 34 mg/L zinc compared to nanopure water which had 7.40 mg/L, and suggests that in biological FIGURE 4.1 Inorganic UV filter fate processes in surface waters. SOURCE: Adapted from Suhendra et al., 2020.
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From page 72... ...
Solubility The solubility of organic UV filters in pure water can be used as a baseline predictor for other more environmentally relevant fate parameters. A chemical compound's aqueous solubility can also be used to estimate relevant dosing levels in aquatic toxicity tests, as it is uncommon that environmental exposure exceeds solubility except in certain scenarios such as pure chemical spills.
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From page 73... ...
(Log Kow)
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From page 74... ...
(=O) O Titanium dioxide 13463-67-7b O=[Ti]
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From page 75... ...
is generally lower than in pure water due to salting-out effects.1 However, solubility for some organic chemicals can also vary with temperature. Reported solubilities (pure water, 25°C)
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From page 76... ...
. Hydrophobicity and Accumulation on Solid Phases For many organic chemicals, releases to aquatic environments can result in sorption to solid particles, some of which can settle out under non-turbulent flow conditions.
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From page 77... ...
They tend to have lower aqueous solubilities and as such may sorb, or stick to, solid particles present in water. High Kow compounds are therefore critical to assess in terms of long-term or chronic aquatic toxicity, as acute toxicity may not be expressed at the limit of solubility and longer exposures at these lower concentrations may elicit effects.
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From page 78... ...
Biodegradation can ultimately limit the concentration and spread of a chemical, can return elements to their natural biogeochemical cycles, can transform chemicals to generally less toxic metabolites, and -- when coupled with sorption -- is a key component of environmental exposure modeling in risk assessment. Studies of biodegradation in wastewater treatment plants (WWTPs)
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From page 79... ...
Metabolites formed in both Benzophenone-1a Fungus, Trametes Sewage sludge at 10 ~98% degradation of parent, high Badia-Fabregat et al., versicolor mg/L laccase activity; 4HB and 4DHB 2012a (metabolites) were slowly eliminated Benzophenone-1a Staphylococcus aureus Seeded on solid phase 2.5–26.7% removal; 1–24% removal Chiriac et al., 2021 and Enterococcus faecalis nutrient medium of the metabolite 4HB dosed alone (gram +)
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From page 80... ...
80 IMPLICATIONS OF SUNSCREEN USAGE FOR AQUATIC ENVIRONMENTS AND HUMAN HEALTH for higher removal from wastewater. Oxybenzone metabolites were more metabolized by Trametes versicolor (Badia-Fabregat et al., 2012a)
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From page 81... ...
. The extent to which similar behavior occurs for other UV filters remains largely unexplored, particularly in aquatic environments where macro-molecular assemblages with other anthropogenic organic compounds (i.e., other ingredients of sunscreen formulations)
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From page 82... ...
, vertical stratification of the water column, and sediment type and patterns of sediment movement. UV filters may enter both freshwater and marine environments from point sources of municipal wastewater treatment systems (Chapter 3)
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From page 83... ...
, some values may be biased by the addition of organic additives to enhance UV filter solubility. ESTIMATED AND MEASURED CONCENTRATIONS IN WATER AND SEDIMENTS Exposure assessments for chemicals in aquatic environments typically include estimates or measures of chemical concentrations in water, sediments, and/or internally in biota (i.e., tissue residue levels)
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From page 84... ...
Thus, to estimate the exposure of aquatic organisms to UV filters, it is helpful to understand the possible concentrations that may occur and the likelihood of their occurrence. To estimate these concentrations, a number of complementary approaches are often useful.
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From page 85... ...
While passive samplers deployed in surface waters may provide an indication of average exposure levels, they would likely not be able to characterize the short-term variations or pulses in exposure levels in the water. For sediments, temporal variations in UV filter concentrations are likely dampened relative to water concentrations, and passive samplers could provide a longer-term measure of exposure of organisms living on or within the sediments; an example is the evaluation carried out by Muz et al.
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From page 86... ...
In aquatic ecosystems where a number of sources of UV filters are likely (e.g., surface waters with a combination of municipal releases and recreational activities are present) , models will need to be developed to encompass these inputs to the system (e.g., Balmer et al., 2005)
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From page 87... ...
As many of the products used in the United States are used elsewhere, the measurements of these chemicals in surface waters and sediments provide insights into their behavior and possible exposures in U.S. waters.
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From page 88... ...
88 IMPLICATIONS OF SUNSCREEN USAGE FOR AQUATIC ENVIRONMENTS AND HUMAN HEALTH lower range of reported levels of detection. While there are scientific techniques for increased rigor when assigning numerical values, those methods go beyond the intended purpose of this graphical representation.
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From page 89... ...
for the two samples collected in April 2007 where more than 230 people entered the water with swimmers coming within 20 m of the coral reefs. Reported water concentrations of oxybenzone around Oahu, Hawaii, also span several orders of magnitude and highlight variability within and between locations, distance from shoreline, and time of day (Downs et al., 2016, 2021; Mitchelmore et al., 2019)
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From page 90... ...
This reflects spatial and temporal variations that bear on evaluating exposures and are discussed further below. As noted earlier, samples collected to date have varied considerably even at a single location, so this analysis can be viewed as providing qualitative insight into factors governing exposures to UV filters in water as represented by oxybenzone.
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From page 91... ...
FATE, TRANSPORT, AND POTENTIAL EXPOSURE IN THE ENVIRONMENT 91 FIGURE 4.6 Oxybenzone concentrations are arranged as four bins from high to low (left to right) in relation to the combined influences of source strength, proximity to source, and water residence time.
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at a beach in Hong Kong Harbor [Tsui et al., 2014b]
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From page 93... ...
. Beach visitation from local populations and tourists appears to be an important driver influencing the concentration of UV filters in nearshore aquatic environments (CasasBeltrán et al., 2021)
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From page 94... ...
will reflect the extensive literature on what is known for other hydrophobic chemicals introduced to aquatic environments; predominant factors are proximity to sources, dispersion patterns for suspended sediments, and depositional environments that have higher levels of organic content, and smaller particle sizes (i.e., fine sands and silts)
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From page 95... ...
Inorganic UV Filters in Water and Sediments Including the Sea Surface Microlayer (SML) In comparison to organic UV filters for which there are observations about concentrations in surface waters, data are limited on the incremental influence of inorganic UV filters on concentrations of titanium and zinc in the environment.
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From page 96... ...
A variety of analytical methods, typically either gas chromatography–mass spectrometry (GC-MS) or liquid chromatography–tandem mass spectrometry (LC-MS/MS)
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From page 97... ...
How and when these samples are collected during the test is important to ensure accurate representation of test exposures, especially when toxicity test designs do not use a continuous flow-through exposure regime but rather a static-renew design whereby exposure solutions are made and replaced over the course of the experiment, typically daily (see Chapter 6)
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From page 98... ...
• Number and mass concentrations of different particle sizes using single particle ICP-MS or TOF-MS (time-of-flight mass spectrometry) (Azimzada et al., 2020; Helsper et al., 2016; Mozhayeva and Engelhard, 2020; Venkatesan et al., 2018)
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From page 99... ...
FIGURE 4.12 Summary of analytical methods for inorganic UV filters across their life cycle from manufacturing through use and into the environment.
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From page 100... ...
Modeled estimates are typically designed to provide ranges, including upper estimates, of possible exposures based on estimates of loadings to the environment combined with fate characteristics (including adsorption and treatment within wastewater treatment systems for down-the-drain sources) and environmental fate and transport processes in the receiving water environment.
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From page 101... ...
While these models are fairly robust, they have been validated in a limited number of freshwater and estuarine aquatic environments. For example, the sorptive behavior of organic UV filters may be enhanced in marine environments (as compared to behavior in fresh or pure water)
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From page 102... ...
Knowledge Gap: Assessments that account for background concentrations of metals (naturally occurring or other sources of engineered nanomaterials beyond UV filters) , the form (dissolved, colloidal/nanoform, particulate)
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From page 103... ...
More hydrophobic/lipophilic compounds have a potential to accumulate in the tissues of organisms and, therefore, more emphasis on longer-term, chronic exposure versus shorter-term, acute exposure is important. While it is most common for responses to chemical exposures in toxicity tests to be expressed as external concentration (e.g., mg/L in aqueous media or mg/kg in sediment/soil)
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From page 104... ...
From a regulatory perspective, bioaccumulation, bioconcentration, and trophic magnification are expressed as ratios of tissue concentrations to exposure medium concentrations (Table 5.1)
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