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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From page 123... ...
The focus of Table 6.1 is on freshwater standard test species, as these are the most reliable QSARs and, as will be found in the subsequent sections for each UV filter, also constitute the bulk of measured ecotoxicity. The QSARs used to provide the toxicity predictions are noted per UV filter as well as the potential broad mode of action for the categorized chemical class as
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Sulisobenzone Phenols 462 1160 5580 Y Y Y (polar narcosis) Titanium dioxide (ionoregulatory disruption)
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From page 125... ...
Of these four, meradimate would likely have the highest priority as being the most potentially toxic of the four UV filters that do not currently have acute toxicity data. Several potential modes of action are indicated across all UV filters exemplifying the diversity of substitutions and functionalizations present.
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From page 126... ...
These key considerations are based on existing toxicity testing guidelines used by OECD and EPA. However, many guidelines were not included as considerations in this effort in order to be more inclusive, particularly given the number of toxicity tests conducted on nonstandard toxicity test species that were important to consider.
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a"Technically credible" endpoints are ECx- lowest concentration tested is below the ECx, confidence intervals are calculable, replication was > 1, treatments were > 3 and preferably 5 or more concentrations used in a concentration range (2–3x)
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Avobenzone Limited aquatic toxicity data is available for avobenzone on standard test organisms. Acute toxicity studies reported in ECHA5 report no effects under solubility (27 µg/L; Table 4.1)
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(2019c) found varying results between two coral species, Pocillopora damicornis and Seriatopora caliendrum, in toxicity tests on both larvae (14-d)
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Algal studies present the most variable range of acute toxicity data. The majority of studies report 72- to 96-h EC50s for growth inhibition from 670 to 5,220 µg/L (Du et al., 2017; Esperanza et al., 2019; Lee et al., 2020; Sieratowicz et al., 2011; ECHA)
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. Acute toxicity tests have been reported for four intact hard coral species using adult fragments or coral larvae.
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. Acute toxicity tests on algae report varying results.
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From page 133... ...
Therefore, results of toxicity testing on these UV filters can vary significantly, requiring consideration of these influential factors. Most toxicity studies have been conducted on nanoparticle sizes (< 100 nm)
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From page 134... ...
Silane coatings on ZnO nanoparticles create a more hydrophilic particle and greater acute toxicity to the marine copepod, Tigriopus japonicus, that is more due to the size-dependent uptake and therefore zinc exposure rather than ROS generation differences. A study with Escherichia coli found that carboxymethyl cellulose (CMC)
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TiO2 The EPA ECOTOX database contains 896 records for aquatic toxicity from 47 total studies for TiO2, which generally are studies on nanosized TiO2 with uncoated particles. Most data are related to standard freshwater toxicity test species D
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. In fact, there are more studies that find no impact up to 10,000 µg/L and above including acute toxicity in mature marine abalone (Haliotis diversicolor supertexta)
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Comparative Toxicity of UV Filters to Standard Test Organisms Standard test species provide an opportunity for comparison of the relative toxicity of UV filters. When studied using established standard methods with a narrower range of test conditions, they allow study results to be compared to each other.
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From page 138... ...
magna acute toxicity data were available. For these UV filters, ECOSAR v.
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Insoluble TiO2 is not toxic within the range of solubility and ZnO toxicity is close, but slightly below, the limit of solubility. Chronic toxicity to D
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Fish A similar analysis was conducted for acute toxicity values collected for standard fish species including fathead minnow, zebrafish, rainbow trout, and medaka. Similar to D
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. Comparison of Acute Toxicity Data for Daphnia magna and Corals D
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. This concentration is universally FIGURE 6.5 Plot of the ranges of coral acute toxicity data compared to Daphnia magna acute toxicity data.
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The chronic oxybenzone HC5 and underlying data suggest a non-specific (either polar or non-polar narcosis) mode of action for the UV filter; however, data are lacking for all other organic UV filters to broaden the conclusion.
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. The HC5 was 353 µg/L (95 percent confidence interval of 121–679 µg/L)
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REVIEW OF STUDIES ON THE EFFECTS OF UV FILTERS IN AQUATIC ENVIRONMENTS 145 FIGURE 6.6 Acute and chronic species sensitivity distributions for oxybenzone, octinoxate, TiO2, and ZnO. NOTE: LCL = lower confidence limit.
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. The HC5 using a logistic model was 42.3 µg/L with a 95 percent confidence interval of 1.116–309.0 µg/L.
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(2015) estimated that based on acute toxicity information the HC5 was 60 µg/L with a 90 percent confidence range of 30–150 µg/L.
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. Though they have not been the focus of studies on effects of UV filters, aquatic mammals and near-aquatic animals that spend part of their time in aquatic environments (typically in search of food)
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Given the diversity of chemical structural features it is certain that multiple MOAs exist for the UV filters. However, evidence is accumulating that oxidative stress, genotoxicity, and neurotoxic MOAs are present.
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Toxicity tests have been conducted on several standard freshwater species for 10 of the UV filters (described in Comparative Potency of UV Filters to Standard Test Organisms) , with several UV filters having measured 96-h LC50s under solubility limits.
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(2013a) found octocrylene in Franciscana dolphin (Pontoporia blainvillei)
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The three main types of impairment reported from organic UV filters on plants have been growth inhibition, oxidative stress, and dysfunction of photosynthesis (Chen et al., 2018b; Zhong et al., 2019, 2020a,b)
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. • Coral reefs: Coral reefs are home to an estimated 25 percent of the ocean's biodiversity, including fishes, invertebrates, algae, and a rich microbiome (NOAA, 2019)
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Effects on Primary Production Primary production by benthic or water column primary producers provides the base of the aquatic food web in most aquatic ecosystems. Studies are available for algae, typically freshwater algae, for all UV filters other than those with no toxicity information at all.
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UV filters may contribute their own effects independently or by interacting with other stressors, an idea explored in the next section on cumulative and interacting effects. Coral reefs are provided as an example for analysis due to the attention that has been given to them in regard to both climate change and local stressors, including UV filters.
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From page 156... ...
Additionally, there could be a greater suite of chemicals present for which possible interactions might be considered, such as other chemicals present in discharges from wastewater treatment plants, and in rinse-off from other personal care products and even sunscreens imported by tourists containing UV filters not marketed in the United States (studies on such mixtures have been conducted by, e.g., Cahova et al., 2021; Ozáez et al., 2016)
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(2019b) exposed two coral species to dilutions of a "wash-off" of a sunscreen product (containing 7 percent octinoxate, 3.6 percent octocrylene)
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From page 158... ...
Filling knowledge gaps in toxicity data will inform higher tiered risk assessments, including the creation of SSDs when deemed necessary, as well as information about potential effects on threatened and endangered species via data for surrogate species. Importantly, findings about toxicity, when possible, must be put in perspective with environmental exposure in order to ultimately determine risk.
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From page 159... ...
Knowledge Gap: There are very few studies on the toxicity of UV filter degradates, despite observations of degradation of avobenzone, padimate O, octinoxate, and oxybenzone during toxicity tests. Knowledge Gap: There are few studies on community and ecosystem dynamics, the need for which is supported by the few that indicate potential effects on ecosystem processes like nutrient cycling, organic matter decomposition, and effects on primary producers and other key species.
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Skin Cancer Skin cancers are the most commonly diagnosed cancers in the United States (CDC, 2021; Guy et al., 2015; NCI, 2021b)
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Merkel cell carcinoma, and squamous cell carcinomas of the ears and lips. Although melanoma accounts for only about 1 percent of all skin cancers, most skin cancer deaths are from melanoma (Rogers and Coldiron, 2013)
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