Ellen M. Cooper

Identification of Flame Retardants in Polyurethane Foam Collected from Baby Products

With the phase-out of PentaBDE in 2004, alternative flame retardants are being used in polyurethane foam to meet flammability standards. However, insufficient information is available on the identity of the flame retardants currently in use. Baby products containing polyurethane foam must meet California state furniture flammability standards, which likely affects the use of flame retardants in baby products throughout the U.S. However, it is unclear which products contain flame retardants and at what concentrations. In this study we surveyed baby products containing polyurethane foam to investigate how often flame retardants were used in these products. Information on when the products were purchased and whether they contained a label indicating that the product meets requirements for a California flammability standard were recorded. When possible, we identified the flame retardants being used and their concentrations in the foam. Foam samples collected from 101 commonly used baby products were analyzed. Eighty samples contained an identifiable flame retardant additive, and all but one of these was either chlorinated or brominated. The most common flame retardant detected was tris(1,3-dichloroisopropyl) phosphate (TDCPP; detection frequency 36%), followed by components typically found in the Firemaster550 commercial mixture (detection frequency 17%). Five samples contained PBDE congeners commonly associated with PentaBDE, suggesting products with PentaBDE are still in-use. Two chlorinated organophosphate flame retardants (OPFRs) not previously documented in the environment were also identified, one of which is commercially sold as V6 (detection frequency 15%) and contains tris(2-chloroethyl) phosphate (TCEP) as an impurity. As an addition to this study, we used a portable X-ray fluorescence (XRF) analyzer to estimate the bromine and chlorine content of the foam and investigate whether XRF is a useful method for predicting the presence of halogenated flame retardant additives in these products. A significant correlation was observed for bromine; however, there was no significant relationship observed for chlorine. To the authors knowledge, this is the first study to report on flame retardants in baby products. In addition, we have identified two chlorinated OPFRs not previously documented in the environment or in consumer products. Based on exposure estimates conducted by the Consumer Product Safety Commission (CPSC), we predict that infants may receive greater exposure to TDCPP from these products compared to the average child or adult from upholstered furniture, all of which are higher than acceptable daily intake levels of TDCPP set by the CPSC. Future studies are therefore warranted to specifically measure infants exposure to these flame retardants from intimate contact with these products and to determine if there are any associated health concerns.

Urinary Metabolites of Organophosphate Flame Retardants: Temporal Variability and Correlations with House Dust Concentrations

Background: A reduction in the use of polybrominated diphenyl ethers (PBDEs) because of human health concerns may result in an increased use of and human exposure to organophosphate flame retardants (OPFRs). Human exposure and health studies of OPFRs are lacking. Objectives: We sought to define the degree of temporal variability in urinary OPFR metabolites in order to inform epidemiologic study design, and to explore a potential primary source of exposure by examining the relationship between OPFRs in house dust and their metabolites in urine. Methods: Nine repeated urine samples were collected from 7 men over the course of 3 months and analyzed for bis(1,3-dichloro-2-propyl) phosphate (BDCPP) and diphenyl phosphate (DPP), metabolites of the OPFRs tris(1,3-dichloro-2-propyl) phosphate (TDCPP) and triphenyl phosphate (TPP), respectively. Intraclass correlation coefficients (ICCs) were calculated to characterize temporal reliability. Paired house dust and urine samples were collected from 45 men. Results: BDCPP was detected in 91% of urine samples, and DPP in 96%. Urinary BDCPP showed moderate-to-strong temporal reliability (ICC range, 0.55–0.72). ICCs for DPP were lower, but moderately reliable (range, 0.35–0.51). There was a weak [Spearman r (rS) = 0.31] but significant (p = 0.03) correlation between urinary BDCPP and TDCPP concentrations in house dust that strengthened when nondetects (rS = 0.47) were excluded. There was no correlation between uncorrected DPP and TPP measured in house dust (rS < 0.1). Conclusions: Household dust may be an important source of exposure to TDCPP but not TPP. Urinary concentrations of BDCPP and DPP were moderately to highly reliable within individuals over 3 months.

Predictors of tris(1,3-dichloro-2-propyl) phosphate metabolite in the urine of office workers.

Tris(1,3-dichloro-2-propyl) phosphate (TDCPP) is a flame retardant widely used in furniture containing polyurethane foam. It is a carcinogen, endocrine disruptor, and potentially neurotoxic. Our objectives were to characterize exposure of adult office workers (n=29) to TDCPP by measuring its primary metabolite, bis(1,3-dichloro-2-propyl) phosphate (BDCPP), in their urine; measuring TDCPP in dust from their homes; offices and vehicles; and assessing possible predictors of exposure. We identified TDCPP in 99% of dust (GM=4.43μg/g) and BDCPP in 100% of urine samples (GM=408pg/mL). Concentrations of TDCPP were significantly higher in dust from vehicles (GM=12.5μg/g) and offices (GM=6.06μg/g) than in dust from the main living area (GM=4.21μg/g) or bedrooms (GM=1.40μg/g) of worker homes. Urinary BDCPP concentrations among participants who worked in a new office building were 26% of those who worked in older buildings (p=0.01). We found some evidence of a positive trend between urinary BDCPP and TDCPP in office dust that was not observed in the other microenvironments and may be related to the timing of urine sample collection during the afternoon of a workday. Overall our findings suggest that exposure to TDCPP in the work environment is one of the contributors to the personal exposure for office workers. Further research is needed to confirm specific exposure sources (e.g., polyurethane foam), determine the importance of exposure in other microenvironments such as homes and vehicles, and address the inhalation and dermal exposure pathways.

Early Zebrafish Embryogenesis Is Susceptible to Developmental TDCPP Exposure

Background: Chlorinated phosphate esters (CPEs) are widely used as additive flame retardants for low-density polyurethane foams and have frequently been detected at elevated concentrations within indoor environmental media. Objectives: To begin characterizing the potential toxicity of CPEs on early vertebrate development, we examined the developmental toxicity of four CPEs used in polyurethane foam: tris(1,3-dichloro-2-propyl) phosphate (TDCPP), tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCPP), and 2,2-bis(chloromethyl)propane-1,3-diyl tetrakis(2-chlorethyl) bis(phosphate) (V6). Methods: Using zebrafish as a model for vertebrate embryogenesis, we first screened the potential teratogenic effects of TDCPP, TCEP, TCPP, and V6 using a developmental toxicity assay. Based on these results, we focused on identification of susceptible windows of developmental TDCPP exposure as well as evaluation of uptake and elimination of TDCPP and bis(1,3-dichloro-2-propyl)phosphate (BDCPP, the primary metabolite) within whole embryos. Finally, because TDCPP-specific genotoxicity assays have, for the most part, been negative in vivo and because zygotic genome remethylation is a key biological event during cleavage, we investigated whether TDCPP altered the status of zygotic genome methylation during early zebrafish embryogenesis. Results: Overall, our findings suggest that the cleavage period during zebrafish embryogenesis is susceptible to TDCPP-induced delays in remethylation of the zygotic genome, a mechanism that may be associated with enhanced developmental toxicity following initiation of TDCPP exposure at the start of cleavage. Conclusions: Our results suggest that further research is needed to better understand the effects of a widely used and detected CPE within susceptible windows of early vertebrate development.

Fluoride sorption and associated aluminum release in variable charge soils

Fluoride sorption and related aluminum (Al) release are evaluated in two iron-oxide-rich soils as a function of soil depth, composition, and physical-chemical properties and potential mechanisms of fluoride-surface interaction are suggested. Measured Al concentrations at equilibrium fluoride sorption, reflective of the net balance between Al dissolution and sequestration of the released Al by the solid phase, suggest net fluoride-assisted dissolution of Al-bearing amorphous and crystalline soil minerals. Strikingly, soils of similar depth and horizonation from the same soil order but of distinct soil series exhibited markedly different susceptibility to Al loss in the presence of fluoride, possibly a combined result of differences in the mechanism of fluoride sorption, soil mineralogy, reactivity of the surficial Al and Fe, and soil solution chemistry. Fluoride sorption is strongly correlated with soil Al and Fe present as high-surface-area amorphous and crystalline oxide phases. Fluoride complexation to surficial Al and Fe ions via ligand exchange with surficial OH groups and water molecules appears to be the dominant sorption mechanism. At high dissolved fluoride concentrations (>7 mM), other mechanisms of fluoride retention including adsorption of AlF solution complexes, entrapment in the interparticle pore fluid, and precipitation into solution and/or onto the soil surface are also likely.

Exploratory analysis of urinary metabolites of phosphorus-containing flame retardants in relation to markers of male reproductive health

The use of phosphorus-containing flame retardants (PFRs) has increased over the past decade. Widespread human exposure has been reported, but information on the safety or potential health risks of PFRs is lacking. We assessed the relationship between urinary concentrations of two PFR metabolites [bis(1,3-dichloro-2-propyl) phosphate (BDCPP) and diphenyl phosphate (DPHP)] and semen quality, sperm motion parameters, and serum hormone levels in 33 men. BDCPP and DPHP concentrations were significantly greater in urine samples collected in the afternoon compared with those collected in the morning (P < 0.05). In multivariable models, a number of statistically significant or suggestive associations were observed between the reproductive health measures and both PFR metabolites. While the study was limited by a small sample size, these results warrant further investigation in a larger study population. Additional studies on sources, pathways, and routes of PFR exposure, along with research on toxicokinetics and exposure measure utility, are also needed.

Results from Screening Polyurethane Foam Based Consumer Products for Flame Retardant Chemicals: Assessing Impacts on the Change in the Furniture Flammability Standards

Flame retardant (FR) chemicals have often been added to polyurethane foam to meet required state and federal flammability standards. However, some FRs (e.g., PBDEs and TDCIPP) are associated with health hazards and are now restricted from use in some regions. In addition, California’s residential furniture flammability standard (TB-117) has undergone significant amendments over the past few years, and TDCIPP has been added to California’s Proposition 65 list. These events have likely led to shifts in the types of FRs used, and the products to which they are applied. To provide more information on the use of FRs in products containing polyurethane foam (PUF), we established a screening service for the general public. Participants residing in the US were allowed to submit up to 5 samples from their household for analysis, free of charge, and supplied information on the product category, labeling, and year and state of purchase. Between February 2014 and June 2016, we received 1141 PUF samples for analysis from various products including sofas, chairs, mattresses, car seats and pillows. Of these samples tested, 52% contained a FR at levels greater than 1% by weight. Tris(1,3-dichloroisopropyl)phosphate (TDCIPP) was the most common FR detected in PUF samples, and was the most common FR detected in all product categories. Analysis of the data by purchasing date suggests that the use of TDCIPP decreased in recent years, paralleled with an increase in the use of TCIPP and a nonhalogenated aryl phosphate mixture we call “TBPP.” In addition, we observed significant decreases in FR applications in furniture products and child car seats, suggesting the use of additive FRs in PUF may be declining, perhaps as a reflection of recent changes to TB-117 and Proposition 65. More studies are needed to determine how these changes in FR use relate to changes in exposure among the general population.

Effect‐directed analysis of Elizabeth River porewater: Developmental toxicity in zebrafish (Danio rerio)

In the present study, effect-directed analysis was used to identify teratogenic compounds in porewater collected from a Superfund site along the Elizabeth River estuary (VA, USA). Zebrafish (Danio rerio) exposed to the porewater displayed acute developmental toxicity and cardiac teratogenesis, presumably because of elevated sediment levels of polycyclic aromatic hydrocarbons (PAHs) from historical creosote use. Pretreatment of porewater with several physical and chemical particle removal methods revealed that colloid-bound chemicals constituted the bulk of the observed toxicity. Size-exclusive chromatography and normal-phase high-performance liquid chromatography were used to fractionate Elizabeth River porewater. Acute toxicity of porewater extracts and extract fractions was assessed as the pericardial area in embryonic zebrafish. The most toxic fraction contained several known aryl hydrocarbon receptor (AhR) agonists (e.g., 1,2-benzofluorene and 1,2-benzanthracene) and cytochrome P450 A1 (CPY1A) inhibitors (e.g., dibenzothiophene and fluoranthene). The second most toxic fraction contained known AhR agonists (e.g., benzo[a]pyrene and indeno[1,2,3-cd]pyrene). Addition of a CYP1A inhibitor, fluoranthene, increased toxicity in all active porewater fractions, suggesting synergism between several contaminants present in porewaters. The results indicate that the observed acute toxicity associated with Elizabeth River porewater results from high concentrations of AhR agonistic PAHs and mixture effects related to interactions between compounds co-occurring at the Elizabeth River site. However, even after extensive fractionation and chemical characterization, it remains plausible that some active compounds in Elizabeth River porewater remain unidentified.

Temporal Trends in Exposure to Organophosphate Flame Retardants in the United States

During the past decade, use of organophosphate compounds as flame retardants and plasticizers has increased. Numerous studies investigating biomarkers (i.e., urinary metabolites) demonstrate ubiquitous human exposure and suggest that human exposure may be increasing. To formally assess temporal trends, we combined data from 14 U.S. epidemiologic studies for which our laboratory group previously assessed exposure to two commonly used organophosphate compounds, tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) and triphenyl phosphate (TPHP). Using individual-level data and samples collected between 2002 and 2015, we assessed temporal and seasonal trends in urinary bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) and diphenyl phosphate (DPHP), the metabolites of TDCIPP and TPHP, respectively. Data suggest that BDCIPP concentrations have increased dramatically since 2002. Samples collected in 2014 and 2015 had BDCIPP concentrations that were more than 15 times higher than those collected in 2002 and 2003 (10β = 16.5; 95% confidence interval from 9.64 to 28.3). Our results also demonstrate significant increases in DPHP levels; however, increases were much smaller than for BDCIPP. Additionally, results suggest that exposure varies seasonally, with significantly higher levels of exposure in summer for both TDCIPP and TPHP. Given these increases, more research is needed to determine whether the levels of exposure experienced by the general population are related to adverse health outcomes.

Ultraviolet Treatment and Biodegradation of Dibenzothiophene: Identification and Toxicity of Products

Biodegradation of pollutants often results in incomplete mineralization and formation of degradation products with unknown chemical and toxicological characteristics. Ultraviolet (UV) irradiation, a common technology used in water and wastewater treatment, may help reduce aqueous concentrations of degradation products produced during biological treatment and their associated hazards. Combined biological and UV transformations may be important in natural systems as well. We investigated the effects of UV irradiation (254 nm) on dibenzothiophene (DBT), a sulfur-containing polyaromatic hydrocarbon, in artificial seawater, and its effects on biodegradation products produced from mixed-community microbial transformations of DBT, including DBT sulfone, DBT sulfoxide, hydroxylated and carboxylated benzothiophenes, thiosalicylic acid, and others. Toxicity of solutions after UV exposure was monitored using bioluminescent bacteria (Vibrio fischeri) and by evaluating cardiac deformities in Fundulus heteroclitus embryos. The highest UV fluence reduced DBT concentration by 28% when DBT was present as the sole organic solute. In postbiodegradation solution, the same fluence reduced the initial concentration of DBT by 81%, and 11 DBT biodegradation products to trace levels. Regardless of UV fluence, DBT by itself produced minimal effects in Fundulus embryos but was moderately toxic to V. fischeri. Postbiodegradation solutions were highly toxic to both test organisms. The highest UV fluence slightly reduced toxicity of postbiodegradation solution to V. fischeri but exacerbated cardiac deformities in Fundulus embryos. Toxicity could not be attributed to specific products and was likely a result of mixture effects. These results emphasize that toxicity can increase during remediation and that multiple assays may be necessary for evaluation. The novel approach of combined biodegradation/UV treatment is promising, although further research is needed to reduce toxicity in the case of DBT.