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Table 3 ELoC of 1,4-dioxane compared to PBT/vPvB substances

From: Persistent, mobile and toxic (PMT) and very persistent and very mobile (vPvM) substances pose an equivalent level of concern to persistent, bioaccumulative and toxic (PBT) and very persistent and very bioaccumulative (vPvB) substances under REACH

Category to assess Case study III: 1,4-dioxane
Serious effects to human health
 Poses a threat to human health? Exposure to 1,4-dioxane occurs through ingestion of contaminated water and food, dermal contact or inhalation of vapours. Mobility of 1,4-dioxane means reaching drinking water sources is highly likely. Ingestion of 1,4-dioxane through drinking water is the dominant pathway of exposure [54, 55]. Previously reported that over 25% of the American population received drinking water with concentrations of 1,4-dioxane that were above the recommended guideline value for human ingestion [52]. In addition, 1,4-dioxane has been proposed as Carcinogenic 1B [50]
 Irreversible health effects? 1,4-Dioxane is classified for carcinogenicity in Annex VI of regulation (EC) No 1272/2008 as follows: Carc 2 (suspected human carcinogen; H351: suspected of causing cancer). CLP classification as Eye Irrit. 2 (causes serious eye irritation) and STOT SE 3 (may cause respiratory irritation after a single exposure) and Carc 2. The suspected human carcinogen is based on evidence from experimental animal studies. Organ systems primarily affected by 1,4-dioxane include the liver and kidneys. Adverse nasal and ocular effects have also been reported [56, 57]. Taken together, these various concerns can lead to a high potential of irreversible effects
 Delayed health effects? Chronic exposure is reported leading to effects that are felt long after the release [58]
 Impaired quality of life? Drinking water quality compromised in addition to aforementioned health effects
Serious effects to the environment
 Irreversible exposure? Recognized as a recalcitrant to biodegradation, based on the evidence " No significant biodegradation in 301F test" and QSARs that consistently predict persistence [1, 59]. Dioxane is considered to have been an emerging compound for the last 40 years [58]
 Irreversible effect? Chronic background concentrations result in continuous exposure that may also lead to the irreversibility of adverse effects. Mixture effects are likely [51]
 Intergenerational exposure and effect? Half-lives of 2–5 years have been reported for ground water and 56 days reported for surface water, implying long releases from ground water plumes long after the time of release could occur [52]
 Unknown/uncertain spatial scale? 1,4-dioxane has a high solubility (100 mg/mL), low octanol–water partitioning coefficient (log Kow =  − 0.27) and weak adsorption into mineral phases and onto organic matter [50]. These intrinsic properties result in a high mobility and rapid spreading to different environmental compartments and from soil to water. This is highlighted by the ubiquitous presence of 1,4-dioxane in groundwater [60], drinking water, wastewater effluents, river water [61], oceans [62] surface water [54] and bank filtrate [63]. 1,4-dioxane has been detected in Japanese, Canadian, American and European waters
 Disparity between point of release and point of effect? As observed from monitoring studies, chronic background concentrations result in continuous exposure that may also lead to the irreversibility of adverse effects
 Unknown/uncertain temporal scale? High quality groundwater and surface models to predict advective–dispersive transport and reactions that transform and immobilize contaminants over large temporal and spatial domains have not yet been used for 1,4-dioxane in groundwater due to the absence of data required to accurately quantify mass transfer and complex transformations diverse types of subsurfaces [64]
 Uncertain/difficult to predict long term fate and toxic effects? Long-term, low dose exposure through ground water and drinking water, which has been documented, may potentially lead to unexpected or even still unknown effects
 Harmful to the aquatic environment? Does not appear to meet the ecotoxicity threshold of Annex XIII of REACH. However, co-occurrence with other chlorinated solvents is very often reported, and therefore, mixture toxicity effects cannot be ruled out [52]. Furthermore, treatment by chlorination can lead to the formation of the chlorinated byproducts that are more toxic than the parent 1,4-dioxane [64]
 Potential to reach remote pristine areas? Half lives of 2 to 5 years have been reported for ground water and 56 days reported for surface water [52]. This combined with a log Koc of 0.5 implies that in ground water it moves just as quickly ground water itself, particularly if there is little organic carbon content. Therefore, dioxane can be transported for several decades at the speed of groundwater or bank filtrate before degrading to trace amounts from original emissions
Other effects
 Increased societal costs? The ubiquitous occurrence of 1,4-dioxane in water and the intrinsic hazardous properties of this substance mean that society will bear a cost of healthcare that is needed following exposure. The mobility and difficulty of removing 1,4-dioxane from drinking water also implies costs
 Negative effect on resources? There are few methods that can be used to treat water on the larger scale. This presents a negative effect on resources. Even expensive techniques, such as air stripping or adsorption by activated carbon, are unsuitable. Removal by membrane filtration is also ineffective; even reverse osmosis fails to reach higher than 70% rejection due to its small size and neutrality [65]. These physical removal processes, even if they are effective, simply transfer 1,4-dioxane from one phase to another, wherein it is more concentrated and requires subsequent treatment
 Do emissions need to be minimized? The intrinsic properties mean that emission reduction mitigation measures are needed and current spreading and toxic effects on affected populations may be difficult to reverse
  1. Details shown are based on a literature review and the CLP classification of 1,4-dioxane [50]