Short‐Term Guideline Values for Chlorine in Marine Waters

Chlorination is commonly used to control biofouling organisms, but chlorine rapidly hydrolyzes in seawater to hypochlorite, which undergoes further reaction with bromide, and then with organic matter. These reaction products, collectively termed chlorine‐produced oxidants (CPOs), can be toxic to mar...

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Bibliographic Details
Published in:Environmental toxicology and chemistry 2020-04, Vol.39 (4), p.754-764
Main Authors: Batley, Graeme E., Simpson, Stuart L.
Format: Article
Language:English
Subjects:
Biofouling
Biota
Chlorine
Chlorine‐produced oxidants
Dilution
Ecotoxicology
Environmental chemistry
Geographical distribution
Organic matter
Oxidants
Oxidizing agents
Reaction products
Seawater
Species
Static tests
Toxicity
Toxicity testing
Water quality guidelines
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Summary:Chlorination is commonly used to control biofouling organisms, but chlorine rapidly hydrolyzes in seawater to hypochlorite, which undergoes further reaction with bromide, and then with organic matter. These reaction products, collectively termed chlorine‐produced oxidants (CPOs), can be toxic to marine biota. Because the lifetime of the most toxic forms is limited to several days, appropriate guideline values need to be based on short‐term (acute) toxicity tests, rather than chronic tests. Flow‐through toxicity tests that provide continuous CPO exposure are the most appropriate, whereas static‐renewal tests generate variable exposure and effects depending on the renewal rate. There are literature data for acute CPO toxicity from flow‐through tests, together with values from 2 sensitive 15‐min static tests on 30 species from 9 taxonomic groups. These values were used in a species sensitivity distribution (SSD) to derive guideline values that were protective of 99, 95, and 90% of species at 2.2, 7.2, and 13 µg CPO/L respectively. These are the first marine guideline values for chlorine to be derived using SSDs, with all other international guideline values based on the use of assessment factors applied to data for the most sensitive species. In applying these conservative guideline values in field situations, it would need to be demonstrated that concentrations of CPOs would be reduced to below the guideline value within an acceptable mixing zone through both dilution and dissociation. Environ Toxicol Chem 2020;39:754–764. © 2020 SETAC
ISSN:0730-7268
1552-8618
DOI:10.1002/etc.4661