Medium‐chain chlorinated paraffins (MCCPs): A review of bioaccumulation potential in the aquatic environment

Abstract

Chlorinated paraffins (CPs) are high molecular weight organochlorine compounds that have been used in a variety of industrial applications for many years. Medium-chain chlorinated paraffins (MCCPs) (CAS 85535-85-9; Alkanes, C14-17 , chloro) are currently under investigation as potential persistent bioaccumulative toxic (PBT) compounds. In this article, the bioaccumulation potential of MCCPs is assessed using a tiered framework proposed after a recent Society of Environmental Toxicology and Chemistry (SETAC) Pellston Workshop in 2008. The framework proposes the use of physicochemical properties and modeling assessment, bioconcentration/bioaccumulation (BCF/BAF) assessment, biomagnification (BMF) assessment, and trophic magnification factor (TMF) assessment. It is hoped that use of this framework could harmonize and improve the efficiency and effectiveness of the chemical substance evaluation screening process for PBT properties. When applied to MCCPs, the following conclusions were made: empirical physiochemical data is available negating the use of models; laboratory BCFs range from 1000 to 15 000 (growth-corrected lipid normalized values) for 2 MCCP structures; field BAFs were an order of magnitude higher than the trigger criterion for "B status possible"; although results may not meet acceptance criteria for field studies, laboratory-derived BMFs for a number of C14-17 chlorinated alkanes were less than the trigger value of 1 (based on whole-body concentrations) whereas field-derived BMFs were less than 1 (based on lipid corrected values [generally used for field data] excluding one measure for sculpin, [Cottus cognatus]-Diporeia that was based on only one detectable sample); and finally, TMFs were less than the trigger criterion value of 1, which are considered the most convincing evidence for bioaccumulative properties of a compound and the "Gold Standard" measure of bioaccumulation. This article also discusses the uncertainties surrounding the published data, especially concerning field data where limited sampling points are available and the difficulty in assessing the bioaccumulative potential of MCCPs as mixtures of different congeners. In conclusion, although some laboratory bioaccumulation values have a potential for concern, the majority of field values are more favorable when assessing the bioaccumulative potential of MCCPs. Definitive conclusions on the PBT assessment of MCCPs can be eased with further testing in both areas of P and B in the laboratory in conjunction with further monitoring of biota in the field to derive more robust field data.

Selected EPs in the water of certain Polish lakes and rivers

“…The highest level of benzo(a)pyrene was the 3.51 ng·L -1 detected in Lake Wielgie. Compared with reports from abroad, the benzo(a)pyrene level in Lake Wielgie was, for example, significantly lower than those in the Great Bitter Lake and El Temsah Lake, Egypt [22]. Benzo(a)pyrene was the dominant PAH found in the saline waters of the latter lakes associated with the Suez Canal, with the average concentration being 3800 ng·L -1 .…”

“…The chloroalkanes' persistence, tendency to bioaccumulate, toxicity and occurrence in remote locations all give rise to concerns regarding possible harmful effects on a global scale. All chlorinated paraffins have the potential to form toxic products if heated in a fire; and chloroalkanes are listed as priority hazardous substances and priority substances in the EU's Water Framework Directive [22]. Concentrations of selected PAHs, brominated diphenyl ethers, chloroalkanes, di(2-ethylhexyl) phthalates and tributyltin compounds in the waters of lakes are given in Tables 4 and 5 Benzo(a)pyrene is often used as a marker for overall exposure to carcinogenic PAHs, as its contribution to the total carcinogenic potential is high [23].…”

Chlorinated Paraffin Levels in Relation to Other Persistent Organic Pollutants Found in Pooled Human Milk Samples from Primiparous Mothers in 53 Countries

“…Recently, toxicologists have called for more occurrence data and toxicological studies of MCCPs to expand on existing data ( Fisk et al. 2000 ; ECB 2005 ; Thompson and Vaughan 2014 ; Yuan et al. 2019 ) and better assess potential health risks and safety ( Swedish Chemicals Agency 2018 ; EFSA CONTAM Panel et al.…”

“…LCCPs could not be assigned a benchmark dose level for harmful effects to humans in the European Union (EFSA CONTAM Panel et al 2020) and were characterized as low risk in the United States (U.S. EPA 2015). Recently, toxicologists have called for more occurrence data and toxicological studies of MCCPs to expand on existing data (Fisk et al 2000;ECB 2005;Thompson and Vaughan 2014;Yuan et al 2019) and better assess potential health risks and safety (Swedish Chemicals Agency 2018; EFSA CONTAM Panel et al 2020;Zellmer et al 2020). Moreover, MCCPs have been classified as "may cause harm to breastfed children" under the harmonized classification of the EU Classification, Labeling and Packaging (CLP) Regulation (ECHA 2019).…”

Metabolism of SCCPs and MCCPs in Suspension Rice Cells Based on Paired Mass Distance (PMD) Analysis

“…Chlorinated paraffins (CPs) are divided into short- (SCCPs, C 10 -C 13 ), medium- (MCCPs, C 14 –C 17 ), and long-chain (LCCPs, C >17 ) chlorinated paraffins based on carbon numbers of the molecules. SCCPs and MCCPs are dominant components of CP commercial products, such as commercial CP-42 and CP-52, widely used as flame retardants, cutting fluids, and plasticizers. , After SCCPs were added into Annex A of the Stockholm convention in 2017 because of their persistence, long distance transport, bioaccumulation and high toxicity to organisms, and production of MCCPs as substitutes increased steadily . Recent studies showed that the concentrations of MCCPs in environmental matrices were occasionally more dominant than SCCPs. , …”