Methods of Responsibly Managing End-of-Life Foams and Plastics Containing Flame Retardants: Part I

Abiotic degradations of legacy and novel flame retardants in environmental and food matrices - a review

Flame retardants (FRs) are commonly added to commercial products to achieve flammability resistance. Since most of them are not chemically bonded to the materials, they could be leached to the environment during the production and disposal cycle. These FRs were categorised based on their chemical nature, including brominated, organophosphorus-, mineral- and nitrogen-based. This review summarised the abiotic degradation reactions of these four classes of FRs, with a focus on thermal and photodegradation reactions in environmental and food matrices. Only 24 papers have reported related information on abiotic degradation reactions that could be useful for predicting possible degradation pathways, and most focused on brominated FRs. Most studies also investigated the thermal degradation of FRs under high temperatures (>400 °C), which exceeds the normal cooking temperature at 100-300 °C. For photodegradation, studies have used up to five times the energy typically used in UV radiation during food processing. It is recommended that future studies investigate the fate of these FRs in foods under more realistic processing conditions, to provide a more comprehensive picture of the estimated consumption of FRs and their degradation products from foods, and facilitate a better risk assessment of the use of these novel FRs.

Current status of indoor dust PBDE pollution and its physical burden and health effects on children

Polybrominated diphenyl ethers (PBDEs) are widely detected in indoor dust, which has been identified as a more important route of PBDE exposure for children than food intake. The physical burden and health hazards to children of PBDE exposure in house dust have not been adequately summarized; therefore, this article reviews the current status of PBDE pollution in indoor dust associated with children, highlighting the epidemiological evidence for physical burden and health risks in children. We find that PBDEs remain at high levels in indoor dust, including in homes, schools, and cars, especially in cars showing a significant upward trend. There is a trend towards an increase in the proportion of BDE-209 in household dust, which is indicative of recent PBDE contamination. Conversely, PBDE congeners in car and school indoor dust tended to shift from highly brominated to low brominated, suggesting a shift in current pollution patterns. Indoor dust exposure causes significantly higher PBDE burdens in children, especially infants in early life, than in adults. Exposure to dust also affects breast milk, putting infants at high risk of exposure. Although evidence is limited, available epidemiological studies suggest that exposure to indoor dust PBDEs promotes neurobehavioral problems and cancer development in children.

Addressing systemic problems with exposure assessments to protect the public's health

BACKGROUND

Understanding, characterizing, and quantifying human exposures to environmental chemicals is critical to protect public health. Exposure assessments are key to determining risks to the general population and for specific subpopulations given that exposures differ between groups. Exposure data are also important for understanding where interventions, including public policies, should be targeted and the extent to which interventions have been successful. In this review, we aim to show how inadequacies in exposure assessments conducted by polluting industries or regulatory agencies have led to downplaying or disregarding exposure concerns raised by communities; that underestimates of exposure can lead regulatory agencies to conclude that unacceptable risks are, instead, acceptable, allowing pollutants to go unregulated; and that researchers, risk assessors, and policy makers need to better understand the issues that have affected exposure assessments and how appropriate use of exposure data can contribute to health-protective decisions.

METHODS

We describe current approaches used by regulatory agencies to estimate human exposures to environmental chemicals, including approaches to address limitations in exposure data. We then illustrate how some exposure assessments have been used to reach flawed conclusions about environmental chemicals and make recommendations for improvements.

RESULTS

Exposure data are important for communities, public health advocates, scientists, policy makers, and other groups to understand the extent of environmental exposures in diverse populations. We identify four areas where exposure assessments need to be improved due to systemic sources of error or uncertainty in exposure assessments and illustrate these areas with examples. These include: (1) an inability of regulatory agencies to keep pace with the increasing number of chemicals registered for use or assess their exposures, as well as complications added by use of 'confidential business information' which reduce available exposure data; (2) the failure to keep assessments up-to-date; (3) how inadequate assumptions about human behaviors and co-exposures contribute to underestimates of exposure; and (4) that insufficient models of toxicokinetics similarly affect exposure estimates.

CONCLUSION

We identified key issues that impact capacity to conduct scientifically robust exposure assessments. These issues must be addressed with scientific or policy approaches to improve estimates of exposure and protect public health.

A review of the success and challenges in characterizing human dermal exposure to flame retardants

Since organic flame retardants (FRs) have several industrial applications, they have been largely detected in environmental and biological samples, and humans have been highly exposed to them. Although the effects of oral and inhaled FRs have been well studied, dermal exposure to them has only recently been pointed out as a potential route of human exposure. Consequently, the effects of FRs on the skin and secondary target organs have been poorly investigated. This review article summarizes the main findings regarding dermal exposure to FRs, points the limitation of the published studies, and suggests future perspectives for better understanding of how dermal exposure to FRs impacts the human health. This review lists some gaps that must be filled in future studies, including characterization of the bioavailable fraction and assessment of exposure for new FRs, to establish their physiological significance and to improve the development of 3D dermal tissue for more reliable results to be obtained.

Do flame retardant concentrations change in dust after older upholstered furniture is replaced?

Upholstered furniture has been a major source of chemical flame retardant (FR) exposures in US homes since the 1970s. FRs are a large group of chemicals, many of which are associated with adverse health effects, including cancer, reproductive toxicity, and neurotoxicity. California homes have some of the highest dust concentrations of FRs, due to Technical Bulletin 117 (TB117), California's outdated flammability standard for furniture foam that was generally followed across the US and Canada. In 2014, this standard was updated to a smolder standard for furniture fabric called TB117-2013, and it is no longer reliant on FRs. This update provided an opportunity to measure differences in FR dust levels in California homes before and after residents replaced older upholstered furniture, or its foam, with products that met the new standard and were expected to be FR-free. We collected dust from homes of participants who had plans to replace older upholstered furniture, or furniture foam, with FR-free options. We returned for follow-up dust collection six, 12, and 18 months following replacement. Concentrations of three polybrominated diphenyl ethers (PBDEs) (BDE-47, BDE-99, BDE-100), three chlorinated organophosphate ester FRs (tris(2-chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCIPP), and tris(1,3-dichloroisopropyl) phosphate (TDCIPP)), and one aryl organophosphate ester FR triphenyl phosphate (TPHP), were widely detected in participant homes. All measured FRs decreased in nearly all homes after the older upholstered furniture was replaced. The decreases in FRs were significant in both homes that replaced entire pieces of furniture and those that replaced only the furniture foam. This study demonstrates that replacing older upholstered furniture or foam significantly reduces concentrations of a range of FRs in the home. Foam replacement offers a potentially more economic alternative that produces a lower volume of waste.

About the environmental sustainability of the European management of WEEE plastics

A huge increase of waste of electrical and electronic equipment (WEEE) is observing everywhere in the world. Plastic component in this waste is more than 20% of the total and allows important environmental advantages if well treated and recycled. The resource recovery from WEEE plastics is characterised by technical difficulties and environmental concerns, mainly related to the waste composition (several engineering polymers, most of which containing heavy metals, additives and brominated flame retardants) and the common utilisation of sub-standard treatments for exported waste. An attributional Life Cycle Assessment quantifies the environmental performances of available management processes for WEEE plastics, those in compliance with the European Directives and the so-called substandard treatments. The results highlight the awful negative contributions of waste exportation and associated improper treatments, and the poor sustainability of the current management scheme. The ideal scenario of complete compliance with European Directives is the only one with an almost negligible effect on the environment, but it is far away from the reality. The analysed real scenarios have strongly negative effects, which become dramatic when exportation outside Europe is included in the waste management scheme. The largely adopted options of uncontrolled open burning and illegal open dumping produce huge impacts in terms of carcinogens (3.5·10⁺⁷ and 3.6·10⁺⁴ person⋅year, respectively) and non-carcinogens (1.7·10⁺⁸ and 2.0·10⁺⁶ person⋅year) potentials, which overwhelm all the other potential impacts. The study quantifies the necessity of strong reductions of WEEE plastics exportation and accurate monitoring of the quality of extra-Europe infrastructures that receive the waste.

Exposure evaluation and risk assessment of polybrominated diphenyl ethers in dust from microenvironments in Nsukka, Nigeria

The health risks of polybrominated diphenyl ethers (PBDEs) to toddlers, children, and adults in creches, nursery schools, cars, and offices in Nsukka, Nigeria, via inhalation, ingestion, and dermal exposure pathways were evaluated. Eight PBDEs congeners (BDE-28, BDE-47, BDE-100, BDE-99, BDE-154, BDE-153, BDE-183, and BDE-209) were determined using gas chromatography-mass spectrometry. This is the first study on PBDEs in creches and nursery schools in Africa. The mean (median) ∑8PBDEs (ng/g) in creches, nursery schools, offices, and cars were 4355 (1850), 2095 (1130), and 37741 (2620) respectively. The concentrations of PBDEs between the three microenvironments were significantly different (p ˂ 0.05), and the highest concentration was found in cars. Ingestion of dust was the predominant pathway of exposure to PBDEs for toddlers and children, while dermal absorption was the dominant pathway for adults. Dermal absorption and ingestion in cars, creches, and nursery schools were of the same magnitude. Toddlers with the highest ingestion rate of PBDEs in creches, nursery schools, and cars are at risk especially from prolonged exposure.

In Utero and Lactational Exposure to an Environmentally Relevant Mixture of Brominated Flame Retardants Induces a Premature Development of the Mammary Glands

In utero and prepubertal development of the mammary glands occurs minimally in a hormone independent manner until puberty where maturation of the hypothalamic-pituitary-gonadal axis drives an extensive remodeling. Nevertheless, because the immature glands contain functional hormone receptors, they are especially vulnerable to the effects of endocrine disruptors, such as brominated flame retardants (BFRs). BFRs are widespread chemicals added to household objects to reduce their flammability, and to which humans are ubiquitously exposed. We previously reported that in utero and lactational exposure to BFRs resulted in an impaired mammary gland development in peripubertal animals. Here, we assessed whether BFR-induced disruption of mammary gland development could manifest earlier in life. Dams were exposed prior to mating until pups' weaning to a BFR mixture (0, 0.06, 20, or 60 mg/kg/day) formulated according to levels found in house dust. The mammary glands of female offspring were collected at weaning. Histo-morphological analyses showed that exposure to 0.06 mg/kg/day accelerates global epithelial development as demonstrated by a significant increase in total epithelial surface area, associated with a tendency to increase of the ductal area and thickness, and of lumen area. Significant increases of the Ki67 cell proliferation index and of the early apoptotic marker cleaved caspase-9 were also observed, as well as an upward trend in the number of thyroid hormone receptor α1 positive cells. These molecular, histologic, and morphometric changes are suggestive of accelerated pubertal development. Thus, our results suggest that exposure to an environmentally relevant mixture of BFRs induces precocious development of the mammary gland.

Oxidation of Flame Retardant Tetrabromobisphenol A by a Biocatalytic Nanofiber of Chloroperoxidase

Background: Tetrabromobisphenol (TBBPA), a flame retardant compound, is considered a ubiquitous pollutant, with potential impact on the environment and human health. Several technologies have been applied to accelerate its degradation and minimize environmental impacts. Due to its aromaticity character, peroxidase enzymes may be employed to carry out its transformation in mild conditions. Therefore, the purpose of this work was to determine the capacity of the enzyme chloroperoxidase (CPO) to oxidize TBBPA in several water samples. Methods: The oxidation capacity of CPO was evaluated in catalytic conditions using water samples from surface and groundwater, as well as effluents from wastewater treatment plants. The biocatalytic performance of CPO was improved due to its immobilization on nanofibers composed of polyvinyl alcohol and chitosan (PVA/chitosan). Results: Free and immobilized CPO were able to transform more than 80% in short reaction times (60 min); producing more biodegradable and less toxic products. Particularly, the immobilized enzyme was catalytically active in a wider range of pH than the free enzyme with the possibility of reusing it up to five times. Conclusions: The biocatalytic oxidation of TBBPA under environmental conditions is highly efficient, even in complex media such as treated effluents of wastewater treatment plants.

A Review of a Class of Emerging Contaminants: The Classification, Distribution, Intensity of Consumption, Synthesis Routes, Environmental Effects and Expectation of Pollution Abatement to Organophosphate Flame Retardants (OPFRs)

Organophosphate flame retardants (OPFRs) have been detected in various environmental matrices and have been identified as emerging contaminants (EC). Given the adverse influence of OPFRs, many researchers have focused on the absorption, bioaccumulation, metabolism, and internal exposure processes of OPFRs in animals and humans. This paper first reviews the evolution of various types of flame retardants (FRs) and the environmental pollution of OPFRs, the different absorption pathways of OPFRs by animals and humans (such as inhalation, ingestion, skin absorption and absorption), and then summarizes the environmental impacts of OPFRs, including their biological toxicity, bioaccumulation, persistence, migration, endocrine disruption and carcinogenicity. Based on limited available data and results, this study also summarizes the bioaccumulation and biomagnification potential of OPFRs in different types of biological and food nets. In addition, a new governance idea for the replacement of existing OPFRs from the source is proposed, seeking environmentally friendly alternatives to OPFRs in order to provide new ideas and theoretical guidance for the removal of OPFRs.

Degradation of the Polymeric Brominated Flame Retardant "Polymeric FR" by Heat and UV Exposure

Monomeric brominated flame retardants often pose risks to the environment. The new group of polymeric flame retardants is claimed to be a safer alternative due to their high molecular weight and persistence by design. Within this publication, the degradation of a commercially widely applied example of this group-the polymer "Polymeric FR"-was studied during UV irradiation and long-term exposure to heat (60 °C) for up to 36 weeks. Both treatments led to a variety of degradation products, which might have potentially adverse environmental effects and an increased mobility compared to the mother polymer. Besides identifying some of the possible degradation products (including for instance 2,4,6-tribromo-3-hydroxybenzoic acid), the degradation via UV irradiation, which yields 75 different degradation products, and via heat, which led to significantly less products, was compared. In addition, further parameters like TOC and the concentration of free bromine were studied and it was demonstrated that the used type of water (distilled, reconstituted, and rainwater) does not influence the outcome of the degradation experiments.