MCCP: are medium-chain chlorinated paraffins of concern for humans?

Calibration and Application of PUF Disk Passive Air Samplers To Assess Chlorinated Paraffins in Ambient Air in Australia, China, and Vietnam

Ambient air samples were collected in Brisbane (Australia), Dalian (China), and Hanoi (Vietnam) during Mar 2013-Feb 2018 using polyurethane foam based passive air samplers. A sampling rate calibration experiment was conducted for chlorinated paraffins (CPs, i.e., short-chain, medium-chain, and long-chain CPs), where the sampling rates were 4.5 ± 0.7, 4.8 ± 0.3, and 4.8 ± 2.1 m3 day-1 for SCCPs, MCCPs, and LCCPs, respectively. The atmospheric concentration of CPs was then calculated and the medians of ∑CPs were 0.079, 1.0, and 0.89 ng m-3 in Brisbane, Dalian, and Hanoi, respectively. The concentration of CPs in Brisbane's air remained at low levels, with no significant differences observed between the city background site and the city center site, indicating limited usage and production of CPs in this city. The highest concentration of MCCPs was detected in Dalian, while the highest concentration of SCCPs was detected in Hanoi. A decrease of SCCP concentration and an increase of MCCPs' were found in Brisbane's air from 2016 to 2018, while increasing trends for both SCCPs and MCCPs were observed in Dalian. These results indicated impacts from different sources of CPs in the investigated cities.

Toxic effects and toxicological mechanisms of chlorinated paraffins: A review for insight into species sensitivity and toxicity difference

Chlorinated paraffins (CPs), a group of chlorinated alkane mixtures, are frequently detected in various environmental matrices and human bodies. Recently, CPs have garnered considerable attention owing to their potential to induce health hazards in wildlife and human. Several reviews have discussed short-chain CPs (SCCPs) induced ecological risk; however, a comprehensive understanding of the underlying toxic mechanisms and a comparison among SCCPs, medium-, and long-chain CPs (MCCPs and LCCPs, respectively) are yet to be established. This review summarizes the latest research progress on the toxic effects and the underlying molecular mechanisms of CPs. The main toxicity mechanisms of CPs include activation of several receptors, oxidative stress, disturbance of energy metabolism, and inhibition of gap junction-mediated communication. The sensitivity of different species to CP-mediated toxicities varies markedly, with aquatic organisms exhibiting the highest sensitivity to CP-induced toxicity. The toxicity comparison analysis indicated that MCCPs may be unsafe as potential substitutes for SCCPs.

Concentrations and homologue patterns of SCCPs and MCCPs in the serum of the general population of adults in Hangzhou, China

Due to their ubiquitous presence in the environment and humans, chlorinated paraffins (CPs) are a major environmental and public health concern. CPs are known to persist, bioaccumulate and potentially threaten human health, but reports on their internal exposure in the adult general population are still scarce. In this study, serum samples collected from adults living in Hangzhou, China, were quantified for SCCPs and MCCPs using GC-NCI-MS methods. A total of 150 samples were collected and subjected to analysis. ∑SCCPs were detected in 98% of the samples with a median concentration of 721 ng/g lw. MCCPs were found in all serum samples with a median concentration of 2210 ng/g lw, indicating that MCCPs were the dominant homologous group. For SCCPs and MCCPs, ∑C₁₀ and ∑C₁₄ were found to be the dominant carbon chain length homologues. Our results showed that age, BMI and lifestyle were not found to be significantly associated with internal exposure to CPs for the samples in this study. Based on PCA analysis, an age-specific distribution of CP homologues was observed. This suggests that internal exposure to CPs in the general population is related to exposure scenarios and history. The results of this study may contribute to a better understanding of the internal exposure to CPs in the general population and may provide a direction for the investigation of the source of exposure to CPs in the environment and daily life.

Short- and medium-chain chlorinated paraffins in polyvinyl chloride consumer goods available in the Japanese market

Chlorinated paraffins (CPs), including short-chain CPs (SCCPs) and medium-chain CPs (MCCPs), are hazardous chemical additives widely applied as plasticizers and flame retardants in polymers, mainly in polyvinyl chloride (PVC). In 2017, SCCPs were listed under the Stockholm Convention on Persistent Organic Pollutants (POPs). MCCPs were proposed for listing as POPs in 2021. SCCPs are also restricted under the Basel Convention, with two tentative low POP content (LPC) limits (100 and 10,000 mg kg^-1) for SCCPs in waste. As a signatory Party of both conventions, Japan must ensure their implementation and manage SCCP wastes in environmentally sound ways. Therefore, we aimed to assess the occurrence of SCCPs and MCCPs in PVC consumer goods (n = 87) available in the Japanese market. CPs were detected in 48% of the samples. Regarding positive samples, children's products and toys (1.3-120,000 mg kg^-1) were more impacted by SCCPs whereas electrical and electronic cables (1.2-59,000 mg kg^-1) and house interior products (3.5-550 mg kg^-1) were more impacted by MCCPs. Fourteen and four samples exceeded the LPC limit of 100 and 10,000 mg kg^-1 for SCCPs, respectively. Most products were impacted by CP contents (<1 % w/w) considerably below those reported as intentional CP uses in PVC. However, 11 samples with total CP contents ranging from 1.3% to 15 % (w/w) might have been impacted by intentional CP use as secondary plasticizer in PVC. Most of the impacted consumer goods available in the Japanese market were manufactured overseas, highlighting that only restricting POPs nationally is not enough for thorough implementation of the Basel and Stockholm Conventions. Therefore, imported PVC consumer goods, PVC waste and PVC recycling streams need to be monitored as relevant potential sources of SCCPs worldwide, even where the national industry strictly follows the restriction of such chemicals.

Monitoring temporal trends of dioxins, organochlorine pesticides and chlorinated paraffins in pooled serum samples collected from Northern Norwegian women: The MISA cohort study

The ubiquitous presence of legacy and emerging persistent organic pollutants (POPs) in the environmental matrices poses a potential hazard to the humans and creating public health concerns. The present study aimed to evaluate dioxins, dioxin-like polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and chlorinated paraffins (CPs) concentrations in serum of women (postpartum, pregnant and non-pregnant) from Northern Norway to better understand their exposure and contamination status as well as temporal trends across 2007-2009 (MISA 1) to 2019 (MISA 2). Sixty-two blood samples from the MISA 1 cohort and 38 samples from MISA 2 were randomly selected in this study (n = 100). Ninety samples from postpartum (MISA 1) and pregnant women (MISA 2) were randomly combined into 9 pools, with 9-11 individual samples contributing to each pool keeping the groups of pregnant and postpartum women. Remaining 10 samples from non-pregnant women (MISA 2) were allocated into separate group. Geometric mean, minimum and maximum were used to describe the serum concentrations of pooled POPs in MISA cohort. Mann-Whitney U test and independent sample t-test were applied for trend analysis of blood levels of POPs between MISA 1 and MISA 2. We found the serum concentrations of selected POPs in this study to be at lower range. Serum concentrations of dibenzo-p-dioxins (PCDDs) (p = 0.010), polychlorinated dibenzofurans (PCDFs) (p = 0.002), dioxins-like PCBs (p = 0.001), hexachlorobenzene (HCB) (p < 0.001) and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) (p = 0.002) were decreased between the studied time. In contrast, the serum concentrations of medium chain chlorinated paraffins showed an increasing trend between 2007 and 2009 and 2019 (p = 0.019). Our findings report a particular concern of emerging contaminant medium chain chlorinated paraffin exposure to humans. Future observational studies with repeated measurements of chlorinated paraffins in general populations worldwide and large sample size are warranted.

Chlorinated paraffins - A historical consideration including remarks on their complexity

Chlorinated paraffins (CPs) are high production volume chemicals currently produced and used in higher quantities than any other medium-size polyhalogenated compound (class). In addition, the composition of industrial CP mixtures is highly complex and poorly understood. In this article, we searched in the literature for the beginning of the chlorination of alkanes and how this substance class developed from niche applications to unmatched quantities in various industrial applications. Also, an estimation was made on the theoretical variety of chloroparaffins and the possible complexity of industrial CP mixtures. These data may explain why little is known about CPs although the production volume throughout the industrial generation was virtually always higher than the one of PCBs and has continued to increase after the ban of the latter.

Inventory approach for short-chain chlorinated paraffins for the Stockholm Convention implementation in Brazil

Chlorinated paraffins (CPs) are chemicals with multipurpose applications. Their global production has increased despite their adverse impacts on the environment and human health. In 2017, short-chain chlorinated paraffins (SCCPs) were listed as persistent organic pollutants (POPs) in the Stockholm Convention. Yet, specific exemptions were granted for their applications despite the recycling prohibition for products containing SCCPs. Therefore, we aimed to produce the first Brazilian inventory of SCCPs following its respective guidance to evaluate the applicability of the SCCP inventory guidance and to provide technical insights regarding SCCPs in the update of the Brazilian National Implementation Plan (NIP). Moreover, we performed a review of SCCP occurrence in Brazil to fulfil data gaps in the inventory development. We identified and consulted nationwide stakeholders and assessed foreign trade data of CPs and products that might contain CPs in relevant amounts. The Brazilian production of CPs was discontinued in 1994. However, CPs are still imported and used in the country. CPs have been mostly applied as plasticizers, flame retardants and lubricants in Brazil. The import of products containing CPs also pose a significant route of CP entrance into Brazil. Thus, the current end-of-life management of CP-containing products is a bottleneck towards the Convention implementation. The guidance application was feasible and useful despite the low engagement of stakeholders. To assess foreign trade of CPs and CP-containing products, we recommend the use of more specific tracking codes. Besides, the review of SCCP occurrence is not a demanded part for an inventory but was a useful complementation.

Determination of chlorinated paraffins (CPs): Analytical conundrums and the pressing need for reliable and relevant standards

The determination of chlorinated paraffins (CPs) has posed an intractable challenge in analytical chemistry for over three decades. The combination of an as yet unspecifiable number (tens - hundreds of thousands) of individual congeners in mass produced commercial CP mixtures and the steric interactions between them, contrive to defy efforts to characterise their residual occurrences in environmental compartments, food and human tissues. However, recent advances in instrumentation (mass spectrometric detectors and nuclear magnetic resonance), combined with interlaboratory studies, have allowed a better insight into the nature of the conundrums. These include the variability of results, even between experienced laboratories when there is insufficient matching between analytical standards and occurrence profiles, the poor (or no) response of some instrumentation to some CP congener configurations (multiple terminal chlorines or < four chlorines) and the occurrence of chlorinated olefins in commercial mixtures. The findings illustrate some limitations in the existing set of commercially available standards. These include cross-contamination of some standards (complex CP mixtures), an insufficient number of single chain standards (existing ones do not fully reflect food/biota occurrences), lack of homologue group standards and unsuitability of some configurationally defined CP congeners/labelled standards (poor instrument response and a smaller likelihood of occurrence in commercial mixtures). They also indicate an underestimation in reported occurrences arising from those CPs that are unresponsive during measurement. A more extensive set of standards is suggested and while this might not be a panacea for accurate CP determination, it would reduce the layers of complexity inherent in the analysis.

A new synthesis approach for the generation of single chain CP mixtures composed of a few major compounds

Chlorinated paraffins (CPs) are complex mixtures, which consist of thousands of individual compounds with no dominant representative. Consequently, knowledge on structure and environmental relevance of individual CP congeners is poor. Similarly to the synthesis of individual CPs, the generation of less complex CP mixtures that can be thoroughly analyzed may be used to overcome some drawbacks of the highly complex technical CP mixtures. Here, we present a new synthesis approach to generate such simple CP mixtures by decarboxylation of polyunsaturated fatty acids followed by saturation of the double bonds by chlorination. Specifically, α-linolenic acid (18:3Δ9,12,15) was decarboxylated to heptadecatriene. The resulting raw product was chlorinated with SO₂Cl₂. Purification by column chromatography led to a main fraction consisting of four major peaks originating from hexachloroheptadecane (C₁₇H₃₀Cl₆) isomers (∼80% of the total peak area) along with ∼20 low abundant by-products, according to gas chromatography with electron capture negative ion mass spectrometry. In the same way, decarboxylation and subsequent chlorination of other polyunsaturated fatty acids may lead to further simple CP mixtures with other chain lengths. Although these simple CP mixtures cannot fully reflect the various structural features present in technical mixtures they could be beneficial for transformation studies because changes in the CP pattern can easily be noted which is in contrast to technical CP mixtures. Such simple CP mixtures could also be used in toxicity tests which are difficult to perform with technical CP mixtures because of their high complexity.

Fungal Enzymes as Catalytic Tools for Polyethylene Terephthalate (PET) Degradation

The ubiquitous persistence of plastic waste in diverse forms and different environmental matrices is one of the main challenges that modern societies are facing at present. The exponential utilization and recalcitrance of synthetic plastics, including polyethylene terephthalate (PET), results in their extensive accumulation, which is a significant threat to the ecosystem. The growing amount of plastic waste ending up in landfills and oceans is alarming due to its possible adverse effects on biota. Thus, there is an urgent need to mitigate plastic waste to tackle the environmental crisis of plastic pollution. With regards to PET, there is a plethora of literature on the transportation route, ingestion, environmental fate, amount, and the adverse ecological and human health effects. Several studies have described the deployment of various microbial enzymes with much focus on bacterial-enzyme mediated removal and remediation of PET. However, there is a lack of consolidated studies on the exploitation of fungal enzymes for PET degradation. Herein, an effort has been made to cover this literature gap by spotlighting the fungi and their unique enzymes, e.g., esterases, lipases, and cutinases. These fungal enzymes have emerged as candidates for the development of biocatalytic PET degradation processes. The first half of this review is focused on fungal biocatalysts involved in the degradation of PET. The latter half explains three main aspects: (1) catalytic mechanism of PET hydrolysis in the presence of cutinases as a model fungal enzyme, (2) limitations hindering enzymatic PET biodegradation, and (3) strategies for enhancement of enzymatic PET biodegradation.

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

BACKGROUND

The current production and use of chlorinated paraffins (CPs) at >1 million tons/y likely exceeds the lifetime production of polychlorinated biphenyls (PCBs). These persistent organic pollutants (POPs) are a concern to human health.

OBJECTIVES

The United Nations Environment Programme conducts global surveys of human milk samples from individual countries as a noninvasive method of investigating levels and trends in human exposures to POPs such as CPs. We measured CP concentrations and assessed their relation to other POPs in pooled samples collected during 2012-2019.

METHODS

We analyzed 57 official nationwide pooled milk samples from 53 countries on five continents (Africa, Central/South America, Asia, Europe, and Australia/Oceania). CP concentrations were further characterized by subgroups and compared with concentrations of 19 other POPs, including PCBs and a variety of pesticides.

RESULTS

CPs were detected in pooled samples from all 53 countries, with concentrations of 23-700 ng/g lipid. CPs accounted for 18-46% of the total summed POPs in human milk, second only to dichlorodiphenyltrichloroethane (DDT). CP concentrations exceeded PCB concentrations in pooled samples from most countries.

DISCUSSION

The presence of CPs in all samples, including samples from isolated locations (e.g., Pacific Island countries), emphasizes the ubiquitous presence of these compounds, whereas differences in subgroup ratios indicate a delay in the shift toward nonregulated medium-chain CPs (MCCPs) for these regions. The predominance of MCCPs in samples from many countries suggests a need for regulation and research on health effects. https://doi.org/10.1289/EHP7696.

Structural Identification and Quantification of Chlorinated Paraffins in Fish Samples Using Comprehensive Two-Dimensional Gas Chromatography with Negative Chemical Ionization Quadrupole Time-of-Flight Mass Spectrometry and Comparison to a Direct Injection-Atmospheric Pressure Chemical Ionization-Orbitrap/Mass Spectrometry Method

This study presents a comprehensive two-dimensional gas chromatography with negative chemical ionization quadrupole time-of-flight mass spectrometry (GC × GC-NCI-QTOF/MS) method, which allows for a precise chromatographic separation of short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs). A new reversed-phase column setup was used, which allows for more accurate separation of MCCPs compared to known GC × GC methods. In a pilot study, 25 freshwater fish samples were analyzed with this method to characterize chlorinated paraffin (CP) compositions. The CP composition was similar in the samples, an observation that is important for the development of a suitable routine method. MCCP contamination was considerably higher than SCCP contamination, with concentrations of 1.3-410 ng/g of wet weight and 0.67-6.5 ng/g of wet weight, respectively. These results were compared to those obtained using a second method, direct injection-atmospheric pressure chemical ionization (APCI)-Orbitrap/mass spectrometry (MS). GC × GC separation was considered to be advantageous for accurate quantification of CP contamination.

Transport of chlorinated paraffins (CPs) from baking oven doors into the food

Chlorinated paraffins (CPs) have been repeatedly detected in the kitchen environment. Especially baking ovens were contaminated with high CP amounts on the insides of the doors. To investigate if CPs could be transferred into baked food, we spiked self-synthesized single chain C₁₂-CP and C₁₅-CP standards onto the inside door of an unused, CP-free baking oven. Experiments were performed under different conditions to assess possible CP transportation pathways. Coconut fat was used as food simulant, the exhaust air was monitored with cellulose filter paper and remaining CPs were collected via cotton wipes. In all experiments, both C₁₂- and C₁₅-CPs could be identified in both the food simulant and the cellulose samplers. Mean transfer rates into the food simulant amounted to 2.2% for C₁₂-CPs and 5.8% for C₁₅-CPs. Baking of food in CP-containing baking ovens may perceptibly increase the CP intake of consumers.

Chlorinated paraffins in hinges of kitchen appliances

Chlorinated paraffins (CPs) are anthropogenic pollutants of growing environmental concern. These highly complex mixtures of thousands of homologs and congeners are usually applied as additives in lubricants or as flame retardants and plasticizers in polymers and paints. Recent studies indicated the presence of high amounts of CPs in the kitchen environment whose sources could not be unequivocally identified. One option was the use of CPs as or in lubricants of hinges. To test this hypothesis, we performed wipe tests on lubricants on 29 hinges of different types of kitchen appliances (refrigerators, baking ovens, dishwashers, freezers, microwave oven, pasta machine, food processor, steam cooker) and analyzed them for short-chain CPs (SCCPs) and medium-chain CPs (MCCPs). CPs were detected in 21 samples (72%). Per wipe, SCCP concentrations ranged between 0.02 and 10 µg (median 0.23 µg), while MCCPs ranged from 0.09 to 750 µg (median 1.0 µg). Highest MCCP amounts (380 and 750 µg per wipe, respectively) were determined in new and unused appliances. A medium correlation between SCCP content and appliance age was observed, but no additional statistic correlation between SCCP/MCCP amount and appliance type or manufacturer could be observed. CPs released from hinges by volatilization, abrasion, and cleaning processes could enter the environment and come in contact with persons living in the corresponding households.

Transformation pathways of chlorinated paraffins relevant for remediation: a mini-review

In the past decades, the environmental presence and ecological risks of chlorinated paraffins (CPs), an emerging class of organic halogen compounds, have been receiving increasing attention worldwide. Short-chain CPs (SCCPs) and medium-chain CPs (MCCPs) constitute the important CPs of considerable concern. In this review article, the state-of-the-art research status on the environmental transformation of CPs, including thermal decomposition, photolytic and photocatalytic degradation, biological metabolism, and atmospheric transformation, was summarized and integrated in detail. The degradation efficiency and transformation products of CPs in these environmental processes were evaluated, in which dechlorination was considered as the major reaction pathway. Notably, waste incineration of CPs has been demonstrated to generate a variety of persistent chlorinated aromatic hydrocarbons such as polychlorinated biphenyls and polychlorinated naphthalenes, which have more significant environmental impacts. Additionally, photodegradation and photocatalysis are suggested as the feasible techniques for efficient removal of SCCPs from water matrices. Overall, the current transformation studies of CPs could facilitate the comprehensive understanding of their environmental behaviors and fate as well as the development of promising remediation strategies for pollution control.

Impurities in technical mixtures of chlorinated paraffins show AhR agonist properties as determined by the DR-CALUX bioassay

Chlorinated paraffins (CPs) are produced at more than one million tons per year. Technical CPs mixtures may contain impurities, which end up in consumer products. In the present study, 17 technical CPs mixtures were investigated for the potential occurrence of potential impurities. By applying the DR-CALUX bioassay, 3 out of 17 technical mixtures were shown to elicit responses at 4 h exposure time, but much lower at 48 h. Constitutional defined CPs materials did not show responses. Subsequently different groups of known AhR-agonists and compounds suspected to be present in technical CPs mixtures were investigated. Benzene, (poly)chlorobenzene, non-dioxin like polychlorinated naphthalenes (PCNs), and three-ringed polyaromatic hydrocarbons (PAHs) did not result in a significant response at 4 h or 48 h. TCDD, non-ortho PCBs, dioxin-like PCNs, four or five ringed PAHs and their chlorinated analogues resulted in a significant response. TCDD and the non-ortho PCBs showed the highest potency and stability, while dioxin-like PCNs, PAHs, and the chlorinated PAHs were clearly inactivated (metabolized) at longer incubation. Altogether, the present findings substantiate that AhR-mediated responses of CPs technical mixtures in the DR-CALUX bioassay are caused by impurities, most likely some intermediate stable AhR-agonists such as dioxin-like PCNs or (chlorinated) PAHs. The current study shows that impurities in CPs technical mixtures need to be investigated for assessing the safety of technical CPs mixtures.

Human Exposure to Chlorinated Paraffins via Inhalation and Dust Ingestion in a Norwegian Cohort

Very-short- (vSCCPs, C_6-9), short- (SCCPs, C_10-13), medium- (MCCPs, C_14-17), and long-chain chlorinated paraffins (LCCPs, C_>17) were analyzed in indoor air and dust collected from the living rooms and personal 24 h air of 61 adults from a Norwegian cohort. Relatively volatile CPs, i.e., vSCCPs and SCCPs, showed a greater tendency to partition from settled indoor dust to paired stationary indoor air from the same living rooms than MCCPs and LCCPs, with median logarithmic dust-air partition ratios of 1.3, 2.9, 4.1, and 5.4, respectively. Using the stationary indoor air and settled indoor dust concentrations, the combined median daily exposures to vSCCPs, SCCPs, MCCPs, and LCCPs were estimated to be 0.074, 2.7, 0.93, and 0.095 ng/kg bw/d, respectively. Inhalation was the predominant exposure pathway for vSCCPs (median 99%) and SCCPs (59%), while dust ingestion was the predominant exposure pathway for MCCPs (75%) and LCCPs (95%). The estimated inhalation exposure to total CPs was ∼ 5 times higher when the personal 24 h air results were used rather than the corresponding stationary indoor air results in 13 paired samples, indicating that exposure situations other than living rooms contributed significantly to the overall personal exposure. The 95^th percentile exposure for CPs did not exceed the reference dose.

Short- and Medium-Chain Chlorinated Paraffins in Foods from the Sixth Chinese Total Diet Study: Occurrences and Estimates of Dietary Intakes in South China

Food consumption has been identified as a major pathway for human exposure to short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs), but evaluations of SCCP and MCCP intake from major dietary sources are limited. We used the sixth Chinese Total Diet Study to perform a comprehensive investigation of SCCPs and MCCPs in cereals, vegetables, potatoes, legumes, eggs, milk, meats, and aquatic foods from nine southern provinces. The geographical distribution of CP concentrations showed higher levels in Jiangsu, Hubei, and Zhejiang provinces. The CP concentrations in most animal-origin foods were higher than those in foods of plant origin. The total estimated daily intakes (EDIs) of SCCPs and MCCPs, with average values of 7.0 × 10² and 4.7 × 10² ng kg^-1 day^-1, respectively, were mostly contributed by cereals, vegetables, and meats. Risk assessment indicated the EDIs of CPs posed no significant risk to residents in South China.