Evaluation of exposure to phthalate esters and DINCH in urine and nails from a Norwegian study population

Urinary metabolites of phthalates and di-iso-nonyl cyclohexane-1,2-dicarboxylate (DINCH)-Czech mothers' and newborns' exposure biomarkers

To assess human exposure to hazardous diesters of phthalic acid and their substitute di-iso-nonyl cyclohexane-1,2-dicarboxylate (DINCH), concentrations of their metabolites in urine should be determined. For the purpose of this biomonitoring study, a quick and easy sample preparation procedure for the simultaneous determination of eight phthalate and four DINCH metabolites in urine has been implemented and validated. Following the enzymatic hydrolysis and dilution with methanol, the sample is ready for the analysis by ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). The limits of quantification of this method ranged from 0.15 to 0.4 ng/mL urine with recoveries of 60-126% and repeatability in the range of 1-11%. The validated method was subsequently used for the analysis of urine samples collected from mothers and their newborn children living in two localities of the Czech Republic (Karvina and Ceske Budejovice, 2013-2014). Median concentrations of all measured metabolites (∑metabolites) were slightly lower in the urine samples collected from children (77.7 ng/mL urine) compared to their mothers (115.3 ng/mL urine), but no correlation was found between the concentrations of target compounds in children's and mothers' urine samples. The analyte with the highest concentration was monobutyl phthalate (MBP), with the median concentration of 32.1 ng/mL urine in the urine samples collected from mothers and 17.2 ng/mL urine in the samples collected from their children. This compound was also found in almost all of the measured samples. On the other hand, mono-isononyl-cyclohexane-1,2-dicarboxylate (MINCH) was not found in any urine sample. The most contaminated samples were collected from children living in the Karvina locality (median ∑metabolites 103.2 ng/mL urine), where the mono (2-ethyl-5-carboxypentyl) phthalate (cx-MEHP) compound contributed 43% to the total content of phthalate metabolites in newborns' urine. The results from our study are comparable with concentrations of the target compounds from Norway and Germany and lower compared to the results concluded in Sweden.

A Review of Biomonitoring of Phthalate Exposures

Phthalates (diesters of phthalic acid) are widely used as plasticizers and additives in many consumer products. Laboratory animal studies have reported the endocrine-disrupting and reproductive effects of phthalates, and human exposure to this class of chemicals is a concern. Several phthalates have been recognized as substances of high concern. Human exposure to phthalates occurs mainly via dietary sources, dermal absorption, and air inhalation. Phthalates are excreted as conjugated monoesters in urine, and some phthalates, such as di-2-ethylhexyl phthalate (DEHP), undergo secondary metabolism, including oxidative transformation, prior to urinary excretion. The occurrence of phthalates and their metabolites in urine, serum, breast milk, and semen has been widely reported. Urine has been the preferred matrix in human biomonitoring studies, and concentrations on the order of several tens to hundreds of nanograms per milliliter have been reported for several phthalate metabolites. Metabolites of diethyl phthalate (DEP), dibutyl- (DBP) and diisobutyl- (DiBP) phthalates, and DEHP were the most abundant compounds measured in urine. Temporal trends in phthalate exposures varied among countries. In the United States (US), DEHP exposure has declined since 2005, whereas DiNP exposure has increased. In China, DEHP exposure has increased since 2000. For many phthalates, exposures in children are higher than those in adults. Human epidemiological studies have shown a significant association between phthalate exposures and adverse reproductive outcomes in women and men, type II diabetes and insulin resistance, overweight/obesity, allergy, and asthma. This review compiles biomonitoring studies of phthalates and exposure doses to assess health risks from phthalate exposures in populations across the globe.

Identifying Greener and Safer Plasticizers: A 4-Step Approach

The health and economic burden of endocrine disrupting chemicals, such as the plasticizer di(2-ethylhexyl) phthalate (DEHP), is prompting industry to develop alternatives. However, the absence of requirements for manufacturers to ensure the safety of these alternatives has led to the generation of replacements that may have similar or worse effects than the original chemicals. Consequently, there is increasing recognition by scientists, regulators and industry that proactive approaches are needed to develop safe chemical substitutes. We propose a 4-step approach for the design, characterization and toxicological testing of responsible alternative chemicals that we illustrate with our ongoing studies on DEHP replacements. Our approach is comprised of: (1) the design and characterization of alternative chemicals based on innovative chemical structures and environmental considerations; (2) large-scale in vitro cell-based high throughput and selective ex vivo studies to preselect the most innocuous alternatives; (3) an acute toxicity in vivo study to rule out overt toxicity of the selected candidates; and (4) an in utero and lactational exposure study comparing the effects of selected candidates to those currently in use, emphasizing commonly described phenotypes after exposure to the latter. Using this 4-step approach, we have identified 2 alternative chemicals displaying good plasticizing properties, better biodegradability, and less leaching than DEHP without any apparent toxicity in vivo. This process has thus far proven useful in the proactive identification of responsible chemical replacements for DEHP.

Inhalation and Dermal Uptake of Particle and Gas-Phase Phthalates-A Human Exposure Study

Phthalates are ubiquitous in indoor environments, which raises concern about their endocrine-disrupting properties. However, studies of human uptake from airborne exposure are limited. We studied the inhalation uptake and dermal uptake by air-to-skin transfer with clean clothing as a barrier of two deuterium-labeled airborne phthalates: particle-phase D₄-DEHP (di(2-ethylhexyl)phthalate) and gas-phase D₄-DEP (diethyl phthalate). Sixteen participants, wearing trousers and long-sleeved shirts, were under controlled conditions exposed to airborne phthalates in four exposure scenarios: dermal uptake alone and combined inhalation + dermal uptake of both phthalates. The results showed an average uptake of D₄-DEHP by inhalation of 0.0014 ± 0.00088 (μg kg^-1 bw)/(μg m^-3)/h. No dermal uptake of D₄-DEHP was observed during the 3 h exposure with clean clothing. The deposited dose of D₄-DEHP accounted for 26% of the total inhaled D₄-DEHP mass. For D₄-DEP, the average uptake by inhalation + dermal was 0.0067 ± 0.0045 and 0.00073 ± 0.00051 (μg kg^-1 bw)/(μg m^-3)/h for dermal uptake. Urinary excretion factors of metabolites after inhalation were estimated to 0.69 for D₄-DEHP and 0.50 for D₄-DEP. Under the described settings, the main uptake of both phthalates was through inhalation. The results demonstrate the differences in uptake of gas and particles and highlight the importance of considering the deposited dose in particle uptake studies.

Daily intake of phthalates, MEHP, and DINCH by ingestion and inhalation

Phthalate esters, suspected endocrine disrupting chemicals, are used in a wide range of applications. Because phthalate esters are not covalently bound, they can easily leach into the indoor environment and associate to dust particles. Thus, exposure may occur through inhalation, ingestion, or contact with the skin. However, it is unclear to what degree indoor dust contributes to the daily intake of phthalate esters. This study investigates household dust as an exposure pathway for seven phthalate esters, the monoester MEHP, and the plasticizer DINCH. Household dust collected from children's sleeping rooms and from living rooms were analysed using gas and liquid chromatography tandem mass spectrometry. To compare two exposure pathways, different dust particle sizes were generated: a respirable fraction (<5 μm) and an ingested particle fraction in the anticipated size range of skin adherence (<75 μm). Modelling of dust inhalation and ingestion showed that the daily intake of dust-bound phthalate esters was likely to be 2 times (inhalation) to 12 times (ingestion) higher for 21-month-old children than for adults. These children's daily uptake of phthalate esters was 40-140 times higher through ingestion than inhalation. Furthermore, dust may be an exposure pathway for phthalate esters as well as for MEHP. Therefore, phthalate monoesters could be environmental contaminants of their own and need to be considered in health risk assessments.

Effects of In Utero and Lactational Exposure to New Generation Green Plasticizers on Adult Male Rats: A Comparative Study With Di(2-Ethylhexyl) Phthalate

Di(2-ethylhexyl) phthalate (DEHP), a widely used plasticizer, is a ubiquitous environmental contaminant and may act as an endocrine disruptor. Early life exposures to DEHP may result in anti-androgenic effects, impairing the development of the male reproductive tract. However, data on the long-lasting consequences of such DEHP exposures on adult male reproductive function are still rare and discrepant. Previously, we identified 2 novel plasticizers, 1,4-butanediol dibenzoate (BDB) and dioctyl succinate (DOS), as potential substitutes for DEHP that did not reproduce classically described endocrine disrupting phenotypes in prepubertal male offspring after maternal exposure. Here, we investigated the consequences of in utero and lactational exposure to BDB and DOS on adult male rat reproductive function in a comparative study with DEHP and a commercially available alternative plasticizer, 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH). Timed pregnant Sprague Dawley rats were gavaged with vehicle or a test chemical (30 or 300 mg/kg/day) from gestation day 8 to postnatal day 21. While DEHP exposure (300 mg/kg/day) significantly increased epididymal weight in the adult, exposure to DINCH, BDB, or DOS did not affect reproductive organ weights, steroid levels, or sperm quality. Using a toxicogenomic microarray approach, we found that adult testicular gene expression was affected by exposure to the higher dose of DEHP; transcripts such as Nr5a2, Ltf, or Runx2 were significantly downregulated, suggesting that DEHP was targeting estrogen signaling. Lesser effects were observed after treatment with either DINCH or BDB. DOS exposure did not produce such effects, confirming its potential as a responsible substitute for DEHP.

An analysis of cumulative risks based on biomonitoring data for six phthalates using the Maximum Cumulative Ratio

The Maximum Cumulative Ratio (MCR) quantifies the degree to which a single chemical drives the cumulative risk of an individual exposed to multiple chemicals. Phthalates are a class of chemicals with ubiquitous exposures in the general population that have the potential to cause adverse health effects in humans. This work used the MCR to evaluate coexposures to six phthalates as measured in biomonitoring data from the most recent cycle (2013-2014) of the National Health and Nutrition Examination Survey (NHANES). The values of MCR, Hazard Index (HI), and phthalate-specific Hazard Quotients (HQs) were determined for 2663 NHANES participants aged six years and older by using reverse dosimetry techniques to calculate steady-state doses consistent with concentrations of metabolites of six phthalates in urine and using Tolerable Daily Intake values. There were 21 participants (0.8% of the NHANES sample) with HI>1. Of those, 43% (9/21) would have been missed by chemical-by-chemical assessments (i.e. all HQs were less than one). The mean MCR value in the 21 participants was 2.1. HI and MCR values were negatively correlated (p<0.001) indicating that most participants, especially those with elevated HI values, had their cumulative risks driven by relatively large doses of a single phthalate rather than doses of multiple phthalates. The dominate phthalate varied across participants. Children (aged 6-17years) had a higher HI values (p<0.01) than adults (18+ years). However, the probability of having HI>1 was not driven by age, gender, or ethnicity. The cumulative exposures of concern largely originated from a subset of three of the fifteen possible pairs of the six phthalates. These findings suggest that cumulative exposures were a potential concern for a small portion of the surveyed participants involving a subset of the phthalates explored. The largest risks tended to occur in individuals whose exposures were dominated by a single phthalate.

Multi-pathway human exposure assessment of phthalate esters and DINCH

Phthalate esters are substances mainly used as plasticizers in various applications. Some have been restricted and phased out due to their adverse health effects and ubiquitous presence, leading to the introduction of alternative plasticizers, such as DINCH. Using a comprehensive dataset from a Norwegian study population, human exposure to DMP, DEP, DnBP, DiBP, BBzP, DEHP, DINP, DIDP, DPHP and DINCH was assessed by measuring their presence in external exposure media, allowing an estimation of the total intake, as well as the relative importance of different uptake pathways. Intake via different uptake routes, in particular inhalation, dermal absorption, and oral uptake was estimated and total intake based on all uptake pathways was compared to the calculated intake from biomonitoring data. Hand wipe results were used to determine dermal uptake and compared to other exposure sources such as air, dust and personal care products. Results showed that the calculated total intakes were similar, but slightly higher than those based on biomonitoring methods by 1.1 to 3 times (median), indicating a good understanding of important uptake pathways. The relative importance of different uptake pathways was comparable to other studies, where inhalation was important for lower molecular weight phthalates, and negligible for the higher molecular weight phthalates and DINCH. Dietary intake was the predominant exposure route for all analyzed substances. Dermal uptake based on hand wipes was much lower (median up to 2000 times) than the total dermal uptake via air, dust and personal care products. Still, dermal uptake is not a well-studied exposure pathway and several research gaps (e.g. absorption fractions) remain. Based on calculated intakes, the exposure for the Norwegian participants to the phthalates and DINCH was lower than health based limit values. Nevertheless, exposure to alternative plasticizers, such as DPHP and DINCH, is expected to increase in the future and continuous monitoring is required.

Phthalate metabolites in Norwegian mothers and children: Levels, diurnal variation and use of personal care products

Exposure to phthalates has been associated with reproductive and developmental toxicity. Data on levels of these compounds in the Norwegian population is limited. In this study, urine samples were collected from 48 mothers and their children in two counties in Norway. Eleven different phthalate metabolites originating from six commonly used phthalates in consumer products were determined. Concentrations of phthalate metabolites were significantly higher in children compared to mothers except for mono-ethyl phthalate (MEP). The mothers provided several urine samples during 24hours (h) and diurnal variation showed that the concentrations in the morning urine samples (24-8h) were significantly higher than at other time-periods for most of the phthalate metabolites. Intraclass correlation coefficients (ICCs) for 24-hour time-period were in the range of 0.49-0.81. These moderate to high ICCs indicate that one spot urine sample can be used to estimate the exposure to phthalates. Since a significant effect of time of day was observed, it is still advisable to standardize the collection time point to reduce the variation. For the mothers, the use of personal care products (PCPs) were less associated with morning urine samples than early day (8-12h) and evening (16-24h) urine samples. The use of perfume and hair products were positively associated with the urinary concentrations of low molecular weight phthalates. Use of shower soap and shampoo were positively associated with urinary concentration of di(2-ethylhexyl) phthalate (DEHP) metabolites. For children, face cream use was positively associated with phthalate metabolites in the morning samples, and hand soap use was negatively associated with concentration of urinary DEHP metabolites in afternoon/evening samples. Since different PCPs were associated with the urinary phthalate metabolites in different time-periods during a day, more than one spot urine sample might be required to study associations between urinary phthalate metabolites and the use of PCPs.

Probing the relationship between external and internal human exposure of organophosphate flame retardants using pharmacokinetic modelling

Human external exposure (i.e. intake) of organophosphate flame retardants (PFRs) has recently been quantified, but no link has yet been established between external and internal exposure. In this study, we used a pharmacokinetic (PK) model to probe the relationship between external and internal exposure data for three PFRs (EHDPHP, TNBP and TPHP) available for a Norwegian cohort of 61 individuals from 61 different households. Using current literature on metabolism of PFRs, we predicted the metabolite serum/urine concentrations and compared it to measured data from the study population. Unavailable parameters were estimated using a model fitting approach (least squares method) after assigning reasonable constraints on the ranges of fitted parameters. Results showed an acceptable comparison between PK model estimates and measurements (<10-fold deviation) for EHDPHP. However, a deviation of 10-1000 was observed between PK model estimates and measurements for TNBP and TPHP. Sensitivity and uncertainty analysis on the PK model revealed that EHDPHP results showed higher uncertainty than TNBP or TPHP. However, there are indications that (1) current biomarkers of exposure (i.e. assumed metabolites) for TNBP and TPHP chemicals might not be specific and ultimately affecting the outcome of the modelling and (2) some exposure pathways might be missing. Further research, such as in vivo laboratory metabolism experiments of PFRs including identification of better biomarkers will reduce uncertainties in human exposure assessment.

In Utero and Lactational Exposure Study in Rats to Identify Replacements for Di(2-ethylhexyl) Phthalate

Di(2-ethylhexyl) phthalate (DEHP) and other phthalates are ubiquitous environmental contaminants with endocrine disrupting properties. Two novel plasticizers, 1,4 butanediol dibenzoate (BDB) and dioctyl succinate (DOS), have been proposed as potential replacements. Both have desirable properties as plasticizers and minimal in vitro biological effects. Herein, we present an in utero and lactational exposure study comparing DEHP with BDB, DOS, and 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH), a commercial alternative. Timed-pregnant Sprague-Dawley rats were gavaged with vehicle or one of these chemicals at 30 or 300 mg/kg/day from gestational day 8 until postnatal day (PND) 21. The offspring were examined for effects on developmental and endocrine markers until PND 46. DEHP treatment (300 mg/kg) decreased heart weights in dams and induced a significant decrease in anogenital index and an increase in hemorrhagic testes and multinucleated gonocytes in PND 3 male pups. An increase in the incidence of hemorrhagic testes was also observed on PND 8 after exposure to DINCH (30 and 300 mg/kg). The only other effects observed were decreases in serum alanine transaminase and magnesium in BDB 30 exposed dams. These data suggest that both BDB and DOS are viable alternative plasticizers.

Phthalates, non-phthalate plasticizers and bisphenols in Swedish preschool dust in relation to children's exposure

Children are exposed to a wide range of chemicals in their everyday environments, including the preschool. In this study, we evaluated the levels of phthalates, non-phthalate plasticizers and bisphenols in dust from 100 Swedish preschools and identified important exposure factors in the indoor environment. In addition, children's total exposure to these chemicals was determined by urine analysis to investigate their relation with dust exposure, and to explore the time trends by comparing with children who provided urine fifteen years earlier. The most abundant plasticizers in preschool dust were the phthalates di-isononyl phthalate (DiNP) and di-(2-ethylhexyl) phthalate (DEHP) with geometric mean levels of 450 and 266μg/g dust, respectively, and the non-phthalate plasticizers bis(2-ethylhexyl) terephthalate (DEHT) and diisononylcyclohexane-1,2-dicarboxylate (DiNCH) found at 105 and 73μg/g dust, respectively. The levels of several substitute plasticizers were higher in newer preschools, whereas the levels of the strictly regulated phthalate di-n-butyl phthalate (DnBP) were higher in older preschools. The presence of foam mattresses and PVC flooring in the sampling room were associated with higher levels of DiNP in dust. Children's exposure from preschool dust ingestion was below established health based reference values and the estimated exposure to different phthalates and BPA via preschool dust ingestion accounted for 2-27% of the total exposure. We found significantly lower urinary levels of BPA and metabolites of strictly regulated phthalates, but higher levels of DiNP metabolites, in urine from the children in this study compared to the children who provided urine samples fifteen years earlier.

Exposure of Portuguese children to the novel non-phthalate plasticizer di-(iso-nonyl)-cyclohexane-1,2-dicarboxylate (DINCH)

Di-(iso-nonyl)-cyclohexane-1,2-dicarboxylate (DINCH) is used as substitute for high molecular weight phthalate plasticizers such as di-(2-ethylhexyl) phthalate (DEHP) and di-(iso-nonyl) phthalate (DINP). Due to a rapid substitution process we have to assume omnipresent and increasing DINCH exposures. The aim of this study was to evaluate DINCH exposure in 112 children (4-18years old) from Portugal, divided in two groups: 1) normal-/underweight following the usual diet; and 2) obese/overweight but under strict nutritional guidance. First morning urine samples were collected during the years 2014 and 2015. Oxidized DINCH metabolites (OH-MINCH, oxo-MINCH, cx-MINCH) were analyzed after enzymatic hydrolysis via on-line HPLC-MS/MS with isotope dilution quantification. We detected DINCH metabolites in all analyzed samples. Urinary median (95th percentile) concentrations were 2.14μg/L (15.91) for OH-MINCH, followed by 1.10μg/L (7.54) for oxo-MINCH and 1.08μg/L (7.33) for cx-MINCH. We observed no significant differences between the two child-groups; only after creatinine adjustment, we found higher metabolite concentrations in the younger compared to the older children. Median (95th percentile) daily DINCH intakes were in the range of 0.37 to 0.76 (2.52 to 5.61) μg/kg body weight/day depending on calculation model and subpopulation. Body weight related daily intakes were somewhat higher in Group 1 compared to Group 2, irrespective of the calculation model. However, in terms of absolute amounts (μg/day), DINCH intakes were higher in Group 2 compared to Group 1. In regard to age, we calculated higher intakes for the younger children compared to older children, but only with the creatinine-based model. This new data for southern European, Portuguese children adds information to the scarce knowledge on DINCH, confirming omnipresent exposure and suggesting higher exposures in children than adults. Significant sources and routes of exposure have yet to be unveiled. For now, all calculated daily intakes are far below established health benchmark levels (TDI, RfD). However, rapidly increasing exposures have to be expected over the next years.

Case Study on Screening Emerging Pollutants in Urine and Nails

Alternative plasticizers and flame retardants (FRs) have been introduced as replacements for banned or restricted chemicals, but much is still unknown about their metabolism and occurrence in humans. We identified the metabolites formed in vitro for four alternative plasticizers (acetyltributyl citrate (ATBC), bis(2-propylheptyl) phthalate (DPHP), bis(2-ethylhexyl) terephthalate (DEHTP), bis(2-ethylhexyl) adipate (DEHA)), and one FR (2,2-bis (chloromethyl)-propane-1,3-diyltetrakis(2-chloroethyl) bisphosphate (V6)). Further, these compounds and their metabolites were investigated by LC/ESI-Orbitrap-MS in urine and finger nails collected from a Norwegian cohort. Primary and secondary ATBC metabolites had detection frequencies (% DF) in finger nails ranging from 46 to 95%. V6 was identified for the first time in finger nails, suggesting that this matrix may also indicate past exposure to FRs as well as alternative plasticizers. Two isomeric forms of DEHTP primary metabolite were highly detected in urine (97% DF) and identified in finger nails, while no DPHP metabolites were detected in vivo. Primary and secondary DEHA metabolites were identified in both matrices, and the relative proportion of the secondary metabolites was higher in urine than in finger nails; the opposite was observed for the primary metabolites. As many of the metabolites present in in vitro extracts were further identified in vivo in urine and finger nail samples, this suggests that in vitro assays can reliably mimic the in vivo processes. Finger nails may be a useful noninvasive matrix for human biomonitoring of specific organic contaminants, but further validation is needed.

Estimating uptake of phthalate ester metabolites into the human nail plate using pharmacokinetic modelling

There is a lack of knowledge regarding uptake of phthalate esters (PEs) and other chemicals into the human nail plate and thus, clarity concerning the suitability of human nails as a valid alternative matrix for monitoring long-term exposure. In particular, the relative importance of internal uptake of phthalate metabolites (from e.g. blood) compared to external uptake pathways is unknown. This study provides first insights into the partitioning of phthalate-metabolites between blood and nail using pharmacokinetic (PK) modelling and biomonitoring data from a Norwegian cohort. A previously published PK model (Lorber PK model) was used in combination with measured urine data to predict serum concentrations of DEHP and DnBP/DiBP metabolites at steady state. Then, partitioning between blood and nail was assessed assuming equilibrium conditions and treating the nail plate as a tissue, assuming a fixed lipid and water content. Although calculated as a worst-case scenario at equilibrium, the predicted nail concentrations of metabolites were lower than the biomonitoring data by factors of 44 to 1300 depending on the metabolite. It is therefore concluded that internal uptake of phthalate metabolites from blood into nail is a negligible pathway and does not explain the observed nail concentrations. Instead, external uptake pathways are more likely to dominate, possibly through deposition of phthalates onto the skin/nail and subsequent metabolism. Modelling gaseous diffusive uptake of PEs from air to nail revealed that this pathway is unlikely to be important. Experimental quantification of internal and external uptake pathways of phthalates and their metabolites into the human nail plate is needed to verify these modelling results. However, based on this model, human nails are not a good indicator of internal human exposure for the phthalate esters studied.

Diverging temporal trends of human exposure to bisphenols and plastizisers, such as phthalates, caused by substitution of legacy EDCs?

Phthalates and phenolic substances were investigated in urine samples from first-time mothers in Uppsala, Sweden, collected between 2009 and 2014. These substances have a comparably fast metabolism and urinary metabolites are predominantly analysed. The main aim was to investigate if measures to decrease production and use of certain phthalates and bisphenol A (BPA) have resulted in decreased human exposure, and to determine if exposures to replacement chemicals have increased. Temporal trends were evaluated for metabolites (n=13) of seven phthalates, a phthalate replacer, four different bisphenols, triclosan, one organophosphate-based flame retardant, and for two pesticides. The results showed downward trends of several phthalates which are in the process of being regulated and phased out. Concomitantly, an increasing trend was seen for a metabolite of the phthalate replacer Di-iso-nonylcyclohexane 1,2-dicarboxylate (DiNCH). Bisphenol A (BPA) showed a downward trend, whereas bisphenol F, identified as one of the substitutes for BPA, showed an increasing trend. The decreasing trend of triclosan is likely due to declining use within the EU. Temporal trend studies of urine samples make it possible to investigate human exposure to rapidly metabolised substances and study how measures taken to regulate and replace problematic chemicals affect human exposure.