Risk assessment of oral exposure to diisononyl phthalate from children's products

Prenatal exposure to an environmentally relevant phthalate mixture alters serum cytokine levels and inflammatory markers in the F1 mouse ovary

Phthalates are used as plasticizers and solvents in consumer products. Virtually 100% of the US population has measurable exposure levels to phthalates, however, the mechanisms by which prenatal exposure to phthalate mixtures affects reproductive health in the offspring remain unclear. Thus, this study tested the hypothesis that prenatal exposure to an environmentally relevant phthalate mixture promotes inflammation in F1 ovarian tissue. Pregnant CD-1 dams were dosed orally with vehicle control (corn oil) or phthalate mixture (20 μg/kg/d, 200 μg/kg/d, 200 mg/kg/d, 500 mg/kg/d). Pregnant dams delivered pups naturally and ovaries and sera from the F1 females were collected at postnatal day (PND) 21, PND 60, 3 mo, and 6 mo. Sera were used to measure levels of C-reactive protein (CRP). Ovaries and sera were used for cytokine array analysis. RNA was isolated from F1 ovaries and used to quantify expression of selected cytokine genes. Prenatal exposure to the mixture significantly increased the levels of CRP at 200 µg/kg/d on PND 21 compared with controls. The mixture altered 6 immune factors in sera at PND 21 and 33 immune factors in the ovary and sera at 6 mo compared with controls. The mixture increased ovarian expression of cytokines at PND 21 and decreased ovarian expression of cytokines at 6 mo compared with controls. These data suggest that prenatal exposure to a phthalate mixture interferes with the immune response in F1 female mice long after initial exposure.

Chronic exposure to a mixture of phthalates shifts the white and brown adipose tissue phenotypes in female mice

Phthalates are endocrine-disrupting chemicals used in consumer products. Although phthalates are obesogens and affect metabolic function, it is unknown if chronic exposure for 6 months to a phthalate mixture alters adipose tissue phenotype in female mice. After vehicle or mixture exposure, white adipose tissue and brown adipose tissue (WAT and BAT) were analyzed for expression of adipogenesis, proliferation, angiogenesis, apoptosis, oxidative stress, inflammation, and collagen deposition markers. The mixture altered WAT morphology, leading to an increase in hyperplasia, blood vessel number, and expression of BAT markers (Adipoq and Fgf2) in WAT. The mixture increased the expression of the inflammatory markers, Il1β, Ccl2, and Ccl5, in WAT. The mixture also increased expression of the proapoptotic (Bax and Bcl2) and antiapoptotic (Bcl2l10) factors in WAT. The mixture increased expression of the antioxidant Gpx1 in WAT. The mixture changed BAT morphology by increasing adipocyte diameter, whitening area, and blood vessel number and decreased expression of the thermogenic markers Ucp1, Pgargc1a, and Adrb3. Furthermore, the mixture increased the expression of adipogenic markers Plin1 and Cebpa, increased mast cell number, and increased Il1β expression in BAT. The mixture also increased expression of the antioxidant markers Gpx and Nrf2 and the apoptotic marker Casp2 in BAT. Collectively, these data indicate that chronic exposure to a phthalate mixture alters WAT and BAT lipid metabolism phenotypes in female mice, leading to an apparent shift in their normal morphology. Following long-term exposure to a phthalate mixture, WAT presented BAT-like features and BAT presented WAT-like features.

Simplified Unified BARGE Method to Assess Migration of Phthalate Esters in Ingested PVC Consumer Products

The unified bioaccessibility research group of Europe (BARGE) method (UBM) suggests using in vitro experimental conditions for simulating the release of chemicals from confined matrices, such as soils and sediments, in the human gastrointestinal tract. It contains comprehensive steps that simulate human digestion pathways and has good potential for application in the leaching of plastic additives from accidentally ingested plastic particles. However, its complexity could be a challenge for routine screening assessments of the migration of chemicals from consumer plastic products. In this study, the UBM was modified to assess the migration of plastic additives from consumer products with five model phthalate esters (i.e., dibutyl phthalate (DBP), benzyl butyl phthalate (BBP), bis(2-ethylhexyl) phthalate (DEHP), and di-n-octyl phthalate (DNOP)) from polyvinyl chloride (PVC). The migration of phthalate esters was observed in four digestive phases (saliva, gastric, duodenal, and bile). Three separate experiments were conducted with the addition of (1) inorganic constituents only, (2) inorganic and organic constituents, and (3) inorganic and organic constituents in combination with digestive enzymes. While using enzymes with the UBM solution, the migrated mass for leached compounds was comparatively low (0.226 ± 0.04 μg) in most digestion phases, likely due to a self-generated coating of enzymes on the plastic materials. However, higher mass migration (0.301 ± 0.05) was observed when phthalate esters were analyzed in the UBM solution, excluding the enzymes. A ring test among six independent laboratories confirmed the robustness of the modified method. Therefore, we propose a simplified version of the original UBM designed mainly for the migration of inorganic elements using only the inorganic and organic components of the solution throughout all phases of digestion.

Migration of hazardous contaminants from WEEE contaminated polymeric toy material by mouthing

This study evaluated the migration of brominated flame retardants (BFRs), phosphate flame retardants (PFRs), bisphenols (BPA, BPF), and phthalate ester-based plasticizers from recycled polymeric toy material, containing waste electrical and electronic equipment (WEEE), in artificial saliva simulating 1 h of mouthing. In total 12 parts of 9 different toys were tested in triplicate after confirming WEEE specific contamination. Up to 11 contaminants were detected in saliva from one toy sample. The highest migration rate up to 128 ng/(cm² x h) was found for BPA followed by bis(2-ethylhexyl) phthalate (DEHP) and diisobutyl phthalate (DIBP) with migration rates up to 25.5 and 8.27 ng/(cm² x h), respectively. In addition to DecaBDE, which was detected in 3 saliva samples at migration rates between 0.09 and 0.31 ng/(cm² x h), the decaBDE replacements 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine (TTBP-TAZ), decabromodiphenyl ethane (DBDPE), resorcinol bis(diphenyl phosphate) (RDP), and hexabromocyclododecane (HBCDD) were detected as well with comparable migration rates. 2,4,6-tribromphenol (246-TBP) reached migration rates up to 1.15 ng/(cm² x h) in correspondence to the presence of TTBP-TAZ. Tetrabromobisphenol A (TBBPA), BPA, 246-TBP, DEHP, DIBP and triphenyl phosphate (TPHP) were predominantly observed in saliva with a detection frequency between 50 and 75%. Daily intake (DI) values were calculated for relevant analytes and compared to tolerable daily intake (TDI) values. The highest DI values of 72.4, 14.3, 5.74, 2.28 and 2.09 ng/(kg BW x day), were obtained for BPA, DEHP, DIBP, TBBPA, and TPHP, respectively. None of them exceed the TDI value or respective reference dose (RfD).

Mechanisms of MEHP Inhibitory Action and Analysis of Potential Replacement Plasticizers on Leydig Cell Steroidogenesis

Steroid production in Leydig cells is stimulated mainly by the pituitary luteinizing hormone, which leads to increased expression of genes involved in steroidogenesis, including the gene encoding the steroidogenic acute regulatory (STAR) protein. Mono(2-ethylhexyl)phthalate (MEHP), the active metabolite of the widely used plasticizer DEHP, is known to disrupt Leydig steroidogenesis but its mechanisms of action remain poorly understood. We found that MEHP caused a significant reduction in hormone-induced steroid hormone production in two Leydig cell lines, MA-10 and MLTC-1. Consistent with disrupted cholesterol transport, we found that MEHP represses cAMP-induced Star promoter activity. MEHP responsiveness was mapped to the proximal Star promoter, which contains multiple binding sites for several transcription factors. In addition to STAR, we found that MEHP also reduced the levels of ferredoxin reductase, a protein essential for electron transport during steroidogenesis. Finally, we tested new plasticizers as alternatives to phthalates. Two plasticizers, dioctyl succinate and 1,6-hexanediol dibenzoate, had no significant effect on hormone-induced steroidogenesis. Our current findings reveal that MEHP represses steroidogenesis by affecting cholesterol transport and its conversion into pregnenolone. We also found that two novel molecules with desirable plasticizer properties have no impact on Leydig cell steroidogenesis and could be suitable phthalate replacements.

Prenatal exposure to phthalates and its effects upon cognitive and motor functions: A systematic review

Phthalates are chemicals widely used in packaging and consumer products, which have been shown to interfere with normal hormonal function and development in some human and animal studies. In recent decades, pregnant women's exposure to phthalates has been shown to alter the cognitive outcomes of their babies, and some studies have found delays in motor development.

METHODS

electronic databases including PubMed/MEDLINE and Scopus were searched from their inception to March 2021, using the keywords "phthalate", "cognitive" and "motor".

RESULTS

most studies find statistically significant inverse relationships between maternal urinary phthalate concentration during pregnancy and subsequent outcomes in children's cognitive and motor scales, especially in boys rather than girls. However, many associations are not significant, and there were even positive associations, especially in the third trimester.

CONCLUSION

the relationship between exposure to phthalates during pregnancy and low results on neurocognitive scales is sufficiently clear to adopt policies to reduce exposure. Further studies are needed to analyze sex differences, coordination and motor scales, and phthalate levels during breastfeeding.

Placental outcomes of phthalate exposure

Proper placental development and function relies on hormone receptors and signaling pathways that make the placenta susceptible to disruption by endocrine disrupting chemicals, such as phthalates. Here, we review relevant research on the associations between phthalate exposures and dysfunctions of the development and function of the placenta, including morphology, physiology, and genetic and epigenetic effects. This review covers in vitro studies, in vivo studies in mammals, and studies in humans. We also discuss important gaps in the literature. Overall, the evidence indicates that toxicity to the placental and maternal-fetal interface is associated with exposure to phthalates. Further studies are needed to better elucidate the mechanisms through which phthalates act in the placenta as well as additional human studies that assess placental disruption through pregnancy with larger sample sizes.

Potential applications of polycarbohydrates, lignin, proteins, polyacids, and other renewable materials for the formulation of green elastomers

Renewable resources including polycarbohydrates, lignin, proteins, and polyacids are the intrinsically valuable class of materials that are naturally available in great quantities. Their utilization as green additives and reinforcing bio-fillers, in substitution of environmentally perilous petroleum-based fillers, for developing high-performance green rubber blends and composites is presently a highly tempting option. Blending of these renewable materials with elastomers is not straight-forward and research needs to exploit the high functionality of carbohydrates and other natural materials as proper physicochemical interactions are essential. Correlating and understanding the structural properties of lignin, carbohydrates, polyacids, and other biopolymers, before their incorporation in elastomers, is a potential approach towards the development of green elastomers for value-added applications. Promising properties i.e., biodegradability, biocompatibility, morphological characteristics, high mechanical properties, thermal stability, sustainability, and various other characteristics along with recent advancements in the development of green elastomers are reviewed in this paper. Structures, viability, interactions, properties, and use of most common natural polycarbohydrates (chitosan and starch), lignin, and proteins (collagen and gelatin) for elastomer modification are extensively reviewed. Challenges in commercialization, applications, and future perspectives of green elastomers are also discussed. Sustainability analysis of green elastomers is accomplished to elaborate their cost-effectiveness and environmental friendliness.

Continuous artificial light at night exacerbates diisononyl phthalate-induced learning and memory impairment in mice: Toxicological evidence

Previously, we reported that exposure to diisononyl phthalate (DINP) resulted in cognitive deficits and anxiety in mice (https://doi.org/10.1038/srep14676). Artificial light at night (ALAN) is now recognized as being a potential threat to human health. However, toxicological evidence concerning exposure to a combination of ALAN and DINP in vivo is limited. To this end, mice were orally exposed to different concentrations of DINP for 28 consecutive days, and ALAN (intensity 150 lux, every night for 12 h). The results showed that oxidative stress levels increased with increasing DINP exposure concentrations, which triggered apoptosis (Bcl-2 levels decreased, Bax levels increased), resulting in nerve cell damage and a decline in the learning and memory abilities of mice. The combined effects of ALAN and DINP exposure on the learning ability and memory of mice are more serious than for DINP exposure alone. The antioxidant vitamin E was shown to have a certain antagonistic effect on the oxidative damage caused by ALAN and DINP exposure. These results highlight a previously unknown relationship between exposure to ALAN and DINP-induced learning and memory impairment, and provide evidence that ALAN may be exacerbating the effects of DINP.

Wood preservatives in children's wooden toys from China: Distribution, migration, oral exposure, and risk assessment

A total of 90 wooden toys were collected, and six wood preservatives (chlorophenols and lindane) were analyzed by using gas chromatography-tandem mass spectrometry to assess the exposure risk of children to wood preservatives through oral contact with wooden toys. The detection rates of six preservatives ranged from 2.2% to 22.2%. The contents of the preservatives ranged from 0.6 µg/kg to 9.6 µg/kg. 2,4-Dichlorophenol (2,4-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP) had higher detection rates and contents than other preservatives. Thus, their migration behaviors from toys to saliva were further investigated. In 11 positive samples, the max migration ratios of 2,4-DCP and 2,4,6-TCP ranged from 7.1% to 20.3% and from 11.1% to 24.8%, respectively. For children aged 3-36 months, the daily average 2,4-DCP exposure level associated with wooden toys ranged from 2.7 pg/(kg day) to 46.9 pg/(kg day), and the daily average 2,4,6-TCP exposure ranged from 3.6 pg/(kg day) to 69.4 pg/(kg day). The contribution to exposure provided by the saliva mobilization pathway was more than that provided by the ingestion of scraped-off toys, and the exposure level of 2,4,6-TCP was greater than that of 2,4-DCP. The max hazard quotient for 2,4-DCP was 1.9 × 10^-4, and the max cancer risk for 2,4,6-TCP was 1.2 × 10^-9. The above results indicated that although wood preservatives were distributed in wooden toys, exposure arising from directly mouthing these materials currently does not pose unacceptable risks to children.

Prenatal exposure to an environmentally relevant phthalate mixture accelerates biomarkers of reproductive aging in a multiple and transgenerational manner in female mice

Phthalates are known endocrine-disrupting chemicals that are found in many consumer products. Our laboratory previously developed a relevant phthalate mixture consisting of six phthalates and found that it disrupted female fertility in mice. However, it is unknown if prenatal exposure to phthalate mixtures can accelerate reproductive aging and if this occurs in multiple generations. Thus, we tested the hypothesis that prenatal exposure to a mixture of phthalates accelerates biomarkers of reproductive aging in multiple generations of female mice. Pregnant CD-1 mice were orally dosed with vehicle control or a phthalate mixture (20 μg/kg/day-500 mg/kg/day) daily from gestational day 10 to birth. Adult F1 females born to these dams were used to create the F2 and F3 generations by mating them with unexposed males. At 13 months, estrous cyclicity was monitored and ovaries and sera were collected for analysis. In the F1 generation, the mixture decreased testosterone and inhibin B levels, but increased follicle-stimulating hormone and luteinizing hormone levels compared to control. In the F2 generation, the phthalate mixture decreased the percent of antral follicles and testosterone hormone levels compared to control. In the F3 generation, prenatal exposure to the phthalate mixture increased ovarian weight, increased the time in metestrus/diestrus, altered follicle numbers, and decreased the levels of luteinizing hormone compared to control. Collectively, these data suggest that prenatal exposure to a phthalate mixture may accelerate several biomarkers of reproductive aging in a multi- and transgenerational manner in female mice.

Detecting phthalate esters in sludge particulates from wastewater treatment plants

This study proposed a method for analysis of 10 phthalate esters compounds from wastewater treatment plant sludges. The analytical efficiency of GC-MS for of target compounds was verified by a standard mixture of phthalate esters. The response factors related to the respective internal standards from a five-point calibration curve quantified the phthalate esters in individual compounds. Based on the literature compiled by environmental agencies, new generation phthalate compounds have been developed, such as di-iso-nonyl phthalate (DiNP), di-iso-decyl phthalate (DiDP), as alternative to conventional phthalates. The analytical results showed that the total PAEs concentration was in the range from 7.4 to 138.6 mg kg^-1 dw in these seven analyzed sludge samples. More, di-iso-nonyl phthalate (DiNP), di-iso-decyl phthalate (DiDP) and bis(2-ethylhexyl) phthalate (DEHP) contributed to over 99% of PAEs in the sludge. The correlation between total PAEs concentration in household and sewage flow treated at seven WWTPs and concentrations of DEHP, DiNP and DiDP was significant.

Inhibitions of HMGB1 and TLR4 alleviate DINP-induced asthma in mice

We studied the effects of high mobility group box chromosomal protein 1 (HMGB1) and toll-like receptor (TLR4) in diisonoyl phthalate (DINP)-induced asthma. Mice with DINP-induced asthma were treated with a TLR4-signaling inhibitor or anti-HMGB1 antibody, and various markers of asthma were measured 24 h later. DINP increased airway hyperresponsiveness, numbers of cells in BALF, numbers of inflammatory cells (leukocytes, lymphocytes, monocytes, eosinophils, neutrophils, basophils) in blood, mucus production, pulmonary fibrosis, Th2 type cytokine levels in BALF, and lung cell apoptosis. On the other hand, administrations of TLR4-signaling inhibitors (TAK-242) or anti-HMGB1 antibodies to a mouse model of DINP-induced asthma reduced biological markers of asthma. These results show TLR4 and HMGB1 both contribute to DINP-induced asthma, and that the inhibitions of TLR4 or HMGB1 offer potential means of treating asthma induced by phthalates like DINP.

Transgenerational Effects of Endocrine-Disrupting Chemicals on Male and Female Reproduction

Endocrine-disrupting chemicals are known to interfere with normal reproductive function and hormone signaling. Phthalates, bisphenol A, pesticides, and environmental contaminants such as polychlorinated biphenyls and dioxins are known endocrine-disrupting chemicals that have been shown to negatively affect both male and female reproduction. Exposure to these chemicals occurs on a daily basis owing to these compounds being found in plastics, personal care products, and pesticides. Recently, studies have shown that these chemicals may cause transgenerational effects on reproduction in both males and females. This is of concern because exposure to these chemicals prenatally or during adult life can negatively impact the reproductive health of future generations. This mini-review summarizes the endocrine-disrupting chemicals that humans are exposed to on a daily basis and what is known about the transgenerational effects that these chemicals may have on male and female reproduction.

DINP aggravates autoimmune thyroid disease through activation of the Akt/mTOR pathway and suppression of autophagy in Wistar rats

Di-isononyl phthalate (DINP) is used as a substitute for traditional phthalates, in a wide range of applications. However, there is growing concern regarding its toxicity. Studies have indicated that DINP is related to thyroid hormone disorder and that phthalates can affect thyroid normal function. In this study, we aim to determine any effects of DINP exposure on autoimmune thyroid disease (AITD), the most common autoimmune disease, and to understand the underlying causal mechanism. AITD model Wistar rats were exposed to 0.15 mg/kg, 1.5 mg/kg or 15 mg/kg DINP. We assessed the thyroid globulin antibody levels, Th1/Th2 balance, histopathological changes and caspase-3 levels in the thyroid. The data show that exposure to DINP does indeed aggravate AITD. To explore the underlying mechanisms, we examined the levels of microtubule-associated protein 1 light chain 3 B (LC3B), Sequestosome 1 (SQSTM1) and the appearance of autophagosomes or autolysosomes to assess autophagy in the thyroid. The results show that DINP can suppress normal autophagy. We found that DINP induced an exacerbation of oxidative stress and the activation of the Akt/mTOR pathway, indicating that oxidative stress and activation of mTOR may play a key role in these processes. Moreover, the activation of mTOR also promoted the expression of IL-17. Importantly, blocking oxidative stress with VE or blocking Akt/mTOR with rapamycin mitigated the exacerbation of AITD and the suppression of normal autophagy. All these results indicate that exposure to DINP, especially high doses of DINP, can aggravate oxidative stress and activate the Akt/mTOR pathway. This exposure then leads to a suppression of normal autophagy and expression of IL-17 in the thyroid, resulting in an eventual exacerbation of AITD.

Biodegradation of di-(2-ethylhexyl) phthalate by a halotolerant consortium LF

A halotolerant bacterial consortium capable of degrading di-(2-ethylhexyl) phthalate (DEHP) was enriched from activated sludge. Community analysis revealed that LF contained seven families and seven genera of bacteria. The predominant species was Gordonia sp. (54.93%), Rhodococcus. sp. (9.92%) and Achromobacter sp. (8.47%). The consortium could degrade 93.84% of 1000 mg/l DEHP after 48 h incubation. The optimal temperature and pH for LF to degrade DEHP were 30 °C and 6.0, respectively. LF degraded more than 91% of DEHP with salt concentrations ranging from 0–3%. The inoculum size had great effects on DEHP degradation (incubation time < 24h). LF could degrade high concentrations of DEHP (from 100 to 2000 mg/l) with the degradation ratio above 92% after 72 h incubation. Kinetics analysis revealed that the degradation of DEHP by LF was best fitted by the first-order kinetics when the initial concentration ranged from 100 to 2000 mg/l. The main intermediates (2-ethylhexyl pentyl phthalate, butyl (2-ethylhexyl) phthalate (BEHP), mono-ethylhexyl phthalate (MEHP), mono-hexyl phthalate (MHP), mono-butyl phthalate (MBP)) in DEHP degradation process were identified using gas chromatography–mass spectrometry (GC-MS), and a new complex biochemical pathway was proposed. Furthermore, LF could also degrade dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), di-n-octyl phthalate (DOP) and phthalic acid (PA).

Use of Monte Carlo analysis in a risk-based prioritization of toxic constituents in house dust

Many chemicals have been detected in house dust with exposures to the general public and particularly young children of potential health concern. House dust is also an indicator of chemicals present in consumer products and the built environment that may constitute a health risk. The current analysis compiles a database of recent house dust concentrations from the United States and Canada, focusing upon semi-volatile constituents. Seven constituents from the phthalate and flame retardant categories were selected for risk-based screening and prioritization: diethylhexyl phthalate (DEHP), butyl benzyl phthalate (BBzP), diisononyl phthalate (DINP), a pentabrominated diphenyl ether congener (BDE-99), hexabromocyclododecane (HBCDD), tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) and tris(2-chloroethyl) phosphate (TCEP). Monte Carlo analysis was used to represent the variability in house dust concentration as well as the uncertainty in the toxicology database in the estimation of children's exposure and risk. Constituents were prioritized based upon the percentage of the distribution of risk results for cancer and non-cancer endpoints that exceeded a hazard quotient (HQ) of 1. The greatest percent HQ exceedances were for DEHP (cancer and non-cancer), BDE-99 (non-cancer) and TDCIPP (cancer). Current uses and the potential for reducing levels of these constituents in house dust are discussed. Exposure and risk for other phthalates and flame retardants in house dust may increase if they are used to substitute for these prioritized constituents. Therefore, alternative assessment and green chemistry solutions are important elements in decreasing children's exposure to chemicals of concern in the indoor environment.

Effects of diisononyl phthalate on osteopenia in intact mice

Osteopenia is characterized by bone loss and deterioration of trabecular bone, which leads to osteoporotic fractures. This disease is highly prevalent in industrialized areas and is associated with exposure to endocrine disrupting chemicals (EDCs). Diisononyl phthalate (DINP) is one of these EDCs and is mainly used as a plasticizer in flexible polyvinyl chloride (PVC) products. Although it is well known that exposure to DINP is harmful to humans, no studies have been reported concerning its contribution to osteopenia. Therefore, in this study, we injected DINP (2, 20, and 200mg/kg) into C3H/HeN mice for 6weeks and found that the uterus weight, bone (femur and tibia) weight, and bone length of the DINP-exposed mice were reduced compared to those of the SHAM group. On the other hand, body weight, the serum alkaline phosphatase (ALP) and inorganic phosphorus (IP) levels in the DINP treated mice were increased compared with those of the SHAM group. The tartrate-resistant acid phosphatase (TRAP) activity (bone resorption marker) was increased and the bone alkaline phosphatase (BALP) activity was lowered by the treatment with DINP as compared with the SHAM group. Furthermore, the microarchitecture of the femur and tibia in the intact mice was destroyed by the DINP injection. The tissue volume (TV), bone volume (BV), BV/TV, bone surface (BS), BS/TV, trabecular thickness (Tb.Th), and trabecular number (Tb.N) were reduced and the trabecular pattern factor (Tb.Pf), structure model index (SMI), and trabecular separation (Tb.Sp) were increased by the DINP injection. The bone mineral density (BMD) of the femur and tibia was lower in the DINP group than in the SHAM group. These results indicate that DINP contributes to an increased risk of osteopenia via destruction of the microarchitecture and enhancement of osteoclast activity.

Exposure of hospitalised pregnant women to plasticizers contained in medical devices

Background

Medical devices (MDs) in polyvinyl chloride (PVC) are not a well-known source of exposure to plasticizers, in particular during pregnancy. Because of its toxicity, the di-(2-ethylhexyl) phthalate (DEHP) has been replaced by other plasticizers such as di (isononyl)-cyclohexane-1,2-dicarboxilic acid (DINCH), tri-octyltrimellitate (TOTM) and di-(isononyl) phthalate (DiNP). Our study aimed to quantify the plasticizers (DEHP and alternative plasticizers) contained in PVC medical devices used for hospitalised pregnant women and to describe which these MDs had been used (type, number, duration of exposure).

Methods

The plasticizers contained in the MDs used for daily care in the Obstetrics Department of a French University Hospital were extracted from PVC (after contact with a chloroform solution), identified and quantified by gas-chromatography-mass-spectrometry analysis. A total of 168 pregnant women hospitalised in the Obstetrics Department with at least one catheter were included in the observational study. The median number of MDs containing plasticizers used and the daily duration of exposure to the MDs were compared in three groups of pregnant women: “Pathology group” (women hospitalised for an obstetric disorder who did not give birth during this hospitalisation; n = 52), “Pathology and delivery group” (hospitalised for an obstetric disorder and who gave birth during this stay; n = 23) and “Delivery group” (admitted for planned or spontaneous delivery without obstetric disorder; n = 93).

Results

DiNP, TOTM and DINCH were the predominant plasticizers contained in the MDs at an amount of 29 to 36 g per 100 g of PVC. Women in the “Pathology group” (preterm labour or other pathology) were exposed to a median number of two MDs containing TOTM and one MD containing DiNP, fewer than those in the “Pathology and delivery group” (p < 0.05). Women in the “Pathology group” had a median exposure of 3.4 h/day to MDs containing DiNP and 8.2 h/day to MDs containing TOTM, longer than those in the “Delivery group” (p < 0.01).

Conclusions

Our study shows that the medical management of pregnant women in a hospital setting entails exposure to MDs containing alternative plasticizers (DiNP, TOTM and DINCH).

Electronic supplementary material

The online version of this article (doi:10.1186/s12905-017-0398-7) contains supplementary material, which is available to authorized users.

Oral and oropharyngeal cancer and the role of sexual behaviour: a systematic review

OBJECTIVES

This systematic review identified and evaluated the evidence for the role of sexual behaviours in the development of oropharyngeal cancers (OPCs) and oral cavity cancers (OCCs).

METHODS

Following the PRISMA guidelines, we identified observational and interventional studies reporting associations between several different sexual behaviours and OPC or OCC. Study quality was assessed independently by two reviewers using a validated scoring system.

RESULTS

From 513 papers identified, 21, reporting on 20 studies, fulfilled the inclusion criteria. Two cohort studies were rated as moderate quality. The 18 case-control studies were rated as weak; nine comparing people with OPC or OCC to people without cancer, eight comparing HPV-positive to HPV-negative cancer patients and one comparing OPCs to other head and neck cancers. One study was a pooled analysis of seven of the included studies with some additional information. Twelve sexual behaviours were assessed and 69 associations reported. The studies differed in the comparisons made, the sexual behaviours assessed, and how these were reported and categorized, so no quantitative meta-analyses were appropriate. Most studies combined OPC and OCC. Several significantly increased risks were seen with a high number of lifetime sexual partners (nine studies) and with the practice of oral sex (five studies), although two studies found a significant negative association with OCC and ever performing oral sex. Two cohort studies of men and women in homosexual relationships found increases in oral cancer risk, and a cohort study of men married to women who had a history of cervical cancer also showed an increased risk of oral cancers. Results for other sexual behaviours were limited and inconsistent, and these included the following: younger age at first sexual intercourse, number of lifetime oral sex partners, the practice of oral-anal sex, the number of oral-anal sex partners, and ever performing anal sex. Only one study assessed casual sex, never or rare use of a condom and having a sexual partner with a history of genital warts, finding significant associations in the two former behaviours.

CONCLUSION

The current evidence for sexual behaviours being risk factors for oral and oropharyngeal cancer is limited and inconsistent. Evidence suggests that the number of sexual partners and performing oral sex are associated with a greater risk. Furthermore men whose partners have had cervical cancer may have an increased risk. More studies looking at OPC specifically will be useful to determine whether these behaviours are subsite-selective.

Approaches to Children's Exposure Assessment: Case Study with Diethylhexylphthalate (DEHP)

Children's exposure assessment is a key input into epidemiology studies, risk assessment and source apportionment. The goals of this article are to describe a methodology for children's exposure assessment that can be used for these purposes and to apply the methodology to source apportionment for the case study chemical, diethylhexylphthalate (DEHP). A key feature is the comparison of total (aggregate) exposure calculated via a pathways approach to that derived from a biomonitoring approach. The 4-step methodology and its results for DEHP are: (1) Prioritization of life stages and exposure pathways, with pregnancy, breast-fed infants, and toddlers the focus of the case study and pathways selected that are relevant to these groups; (2) Estimation of pathway-specific exposures by life stage wherein diet was found to be the largest contributor for pregnant women, breast milk and mouthing behavior for the nursing infant and diet, house dust, and mouthing for toddlers; (3) Comparison of aggregate exposure by pathways vs biomonitoring-based approaches wherein good concordance was found for toddlers and pregnant women providing confidence in the exposure assessment; (4) Source apportionment in which DEHP presence in foods, children's products, consumer products and the built environment are discussed with respect to early life mouthing, house dust and dietary exposure. A potential fifth step of the method involves the calculation of exposure doses for risk assessment which is described but outside the scope for the current case study. In summary, the methodology has been used to synthesize the available information to identify key sources of early life exposure to DEHP.

A Toxicological Framework for the Prioritization of Children's Safe Product Act Data

In response to concerns over hazardous chemicals in children's products, Washington State passed the Children's Safe Product Act (CSPA). CSPA requires manufacturers to report the concentration of 66 chemicals in children's products. We describe a framework for the toxicological prioritization of the ten chemical groups most frequently reported under CSPA. The framework scores lifestage, exposure duration, primary, secondary and tertiary exposure routes, toxicokinetics and chemical properties to calculate an exposure score. Four toxicological endpoints were assessed based on curated national and international databases: reproductive and developmental toxicity, endocrine disruption, neurotoxicity and carcinogenicity. A total priority index was calculated from the product of the toxicity and exposure scores. The three highest priority chemicals were formaldehyde, dibutyl phthalate and styrene. Elements of the framework were compared to existing prioritization tools, such as the United States Environmental Protection Agency's (EPA) ExpoCast and Toxicological Prioritization Index (ToxPi). The CSPA framework allowed us to examine toxicity and exposure pathways in a lifestage-specific manner, providing a relatively high throughput approach to prioritizing hazardous chemicals found in children's products.

Human exposure, hazard and risk of alternative plasticizers to phthalate esters

Alternative plasticizers to phthalate esters have been used for over a decade, but data regarding emissions, human exposure and health effects are limited. Here we review 20 alternative plasticizers in current use and their human exposure, hazard and risk. Physicochemical properties are collated for these diverse alternatives and log KOW values range over 15 orders of magnitude and log KAW and log KOA values over about 9 orders of magnitude. Most substances are hydrophobic with low volatility and are produced in high volumes for use in multiple applications. There is an increasing trend in the total use of alternative plasticizers in Sweden compared to common phthalate esters in the last 10 years, especially for DINCH. Evaluative indoor fate modeling reveals that most alternatives are distributed to vertical surfaces (e.g. walls or ceilings). Only TXIB and GTA are predicted to be predominantly distributed to indoor air. Human exposure data are lacking and clear evidence for human exposure only exists for DEHT and DINCH, which show increasing trends in body burdens. Human intake rates are collected and compared with limit values with resulting risk ratios below 1 except for infant's exposure to ESBO. PBT properties of the alternatives indicate mostly no reasons for concern, except that TEHPA is estimated to be persistent and TCP toxic. A caveat is that non-standard toxicological endpoint results are not available and, similar to phthalate esters, the alternatives are likely "pseudo-persistent". Key data gaps for more comprehensive risk assessment are identified and include: analytical methods to measure metabolites in biological fluids and tissues, toxicological information regarding non-standard endpoints such as endocrine disruption and a further refined exposure assessment in order to consider high risk groups such as infants, toddlers and children.

Cognitive deficits and anxiety induced by diisononyl phthalate in mice and the neuroprotective effects of melatonin

Diisononyl phthalate (DINP) is a plasticizer that is frequently used as a substitute for other plasticizers whose use is prohibited in certain products. In vivo studies on the neurotoxicity of DINP are however, limited. This work aims to investigate whether DINP causes neurobehavioral changes in mice and to provide useful advice on preventing the occurrence of these adverse effects. Behavioral analysis showed that oral administration of 20 or 200 mg/kg/day DINP led to mouse cognitive deficits and anxiety. Brain histopathological observations, immunohistochemistry assays (cysteine-aspartic acid protease 3 [caspase-3], glial fibrillary acidic protein [GFAP]), oxidative stress assessments (reactive oxygen species [ROS], glutathione [GSH], superoxide dismutase [SOD] activities, 8-hydroxy-2-deoxyguanosine [8-OH-dG] and DNA-protein crosslinks [DPC]), and assessment of inflammation (tumor necrosis factor alpha [TNF-а] and interleukin-1 beta [IL-1β]) of mouse brains showed that there were histopathological alterations in the brain and increased levels of oxidative stress, and inflammation for these same groups. However, some of these effects were blocked by administration of melatonin (50 mg/kg/day). Down-regulation of oxidative stress was proposed to explain the neuroprotective effects of melatonin. The data suggests that DINP could cause cognitive deficits and anxiety in mice, and that melatonin could be used to avoid these adverse effects.

Defining Product Intake Fraction to Quantify and Compare Exposure to Consumer Products

There is a growing consciousness that exposure studies need to better cover near-field exposure associated with products use. To consistently and quantitatively compare human exposure to chemicals in consumer products, we introduce the concept of product intake fraction, as the fraction of a chemical within a product that is eventually taken in by the human population. This metric enables consistent comparison of exposures during consumer product use for different product-chemical combinations, exposure duration, exposure routes and pathways and for other life cycle stages. We present example applications of the product intake fraction concept, for two chemicals in two personal care products and two chemicals encapsulated in two articles, showing how intakes of these chemicals can primarily occur during product use. We demonstrate the utility of the product intake fraction and its application modalities within life cycle assessment and risk assessment contexts. The product intake fraction helps to provide a clear interface between the life cycle inventory and impact assessment phases, to identify best suited sentinel products and to calculate overall exposure to chemicals in consumer products, or back-calculate maximum allowable concentrations of substances inside products.

Assessment of health risks resulting from early-life exposures: Are current chemical toxicity testing protocols and risk assessment methods adequate?

Abstract Over the last couple of decades, the awareness of the potential health impacts associated with early-life exposures has increased. Global regulatory approaches to chemical risk assessment are intended to be protective for the diverse human population including all life stages. However, questions persist as to whether the current testing approaches and risk assessment methodologies are adequately protective for infants and children. Here, we review physiological and developmental differences that may result in differential sensitivity associated with early-life exposures. It is clear that sensitivity to chemical exposures during early-life can be similar, higher, or lower than that of adults, and can change quickly within a short developmental timeframe. Moreover, age-related exposure differences provide an important consideration for overall susceptibility. Differential sensitivity associated with a life stage can reflect the toxicokinetic handling of a xenobiotic exposure, the toxicodynamic response, or both. Each of these is illustrated with chemical-specific examples. The adequacy of current testing protocols, proposed new tools, and risk assessment methods for systemic noncancer endpoints are reviewed in light of the potential for differential risk to infants and young children.

Human biological monitoring of diisononyl phthalate and diisodecyl phthalate: a review

High molecular-weight phthalates, such as diisononyl phthalate (DINP), and diisodecyl phthalate (DIDP), are widely used as plasticizers in the manufacturing of polymers and consumer products. Human biological monitoring studies have employed the metabolites of DINP and DIDP as biomarkers to assess human exposure. In this review, we summarize and analyze publicly available scientific data on chemistry, metabolism, and excretion kinetics, of DINP and DIDP, to identify specific and sensitive metabolites. Human biological monitoring data on DINP and DIDP are scrutinised to assess the suitability of these metabolites as biomarkers of exposure. Results from studies carried out in animals and humans indicate that phthalates are metabolised rapidly and do not bioaccmulate. During Phase-I metabolism, ester hydrolysis of DINP and DIDP leads to the formation of hydrolytic monoesters. These primary metabolites undergo further oxidation reactions to produce secondary metabolites. Hence, the levels of secondary metabolites of DINP and DIDP in urine are found to be always higher than the primary metabolites. Results from human biological monitoring studies have shown that the secondary metabolites of DINP and DIDP in urine were detected in almost all tested samples, while the primary metabolites were detected in only about 10% of the samples. This indicates that the secondary metabolites are very sensitive biomarkers of DINP/DIDP exposure while primary metabolites are not. The NHANES data indicate that the median concentrations of MCIOP and MCINP (secondary metabolites of DINP and DIDP, resp.) at a population level are about 5.1 μg/L and 2.7 μg/L, respectively. Moreover, the available biological monitoring data suggest that infants/children are exposed to higher levels of phthalates than adults.

Inhalation exposure of children to fragrances present in scented toys

When utilized in the perfuming of children's toys, fragrances capable of inducing contact allergy in human skin may also become bioavailable to children via the inhalation route. The aim of this study was to determine the area-specific emission rates of 24 fragrances from a plasticized PVC reference material that was meant to mimic a real plastic toy. This material was introduced into an emission chamber for 28 days at handling conditions or at worst-case conditions. As a result, fragrances can be separated into three categories according to their emission rates ranging from 0.0041 to 16.2 mg/m² × h, i.e., highly volatile, semivolatile, and low-volatile compounds. Compounds of the first and second categories were monitored with decreasing emission rates. Substances of the third category were detected with increasing emission rates over time. Further, higher temperatures led to higher emission rates. The emission concentration of fragrances from four real scented toys varied between 1.10 and 107 μg/m³ at day 1 in the test chamber. Therefore, short-term inhalation exposure to fragrances originating from toys was in the range of 0.53-2700 ng/kg BW/d for the children of age 1 and older. Long-term exposure to these fragrances was calculated in the range of 2.2-220 ng/kg BW/d.

PRACTICAL IMPLICATIONS

Besides household products and cosmetics, fragrances can be found in toys for children. Some fragrances are known contact allergens in the skin, but there is a lack of information on their effects in the human respiratory tract. Here, we analyzed and categorized fragrances present in a plasticized PVC reference material according to their emission profiles and volatility. We also demonstrate that volatile fragrances are being emitted from real toys and thus may get inhaled under consumer conditions to different extents.

Sustainable and safe design of footwear integrating ecological footprint and risk criteria

The ecodesign of a product implies that different potential environmental impacts of diverse nature must be taken into account considering its whole life cycle, apart from the general design criteria (i.e. technical, functional, ergonomic, aesthetic or economic). In this sense, a sustainability assessment methodology, ecological footprint (EF), and environmental risk assessment (ERA), were combined for the first time to derive complementary criteria for the ecodesign of footwear. Four models of children's shoes were analyzed and compared. The synthetic shoes obtained a smaller EF (6.5 gm(2)) when compared to the leather shoes (11.1 gm(2)). However, high concentrations of hazardous substances were detected in the former, even making the Hazard Quotient (HQ) and the Cancer Risk (CR) exceed the recommended safety limits for one of the synthetic models analyzed. Risk criteria were prioritized in this case and, consequently, the design proposal was discarded. For the other cases, the perspective provided by the indicators of different nature was balanced to accomplish a fairest evaluation. The selection of fibers produced under sustainable criteria and the reduction of the materials consumption was recommended, since the area requirements would be minimized and the absence of hazardous compounds would ensure safety conditions during the use stage.

Assessing exposure to phthalates - the human biomonitoring approach

Some phthalates are developmental and reproductive toxicants in animals. Exposure to phthalates is considered to be potentially harmful to human health as well. Based on a comprehensive literature research, we present an overview of the sources of human phthalate exposure and results of exposure assessments with special focus on human biomonitoring data. Among the general population, there is widespread exposure to a number of phthalates. Foodstuff is the major source of phthalate exposure, particularly for the long-chain phthalates such as di(2-ethylhexyl) phthalate. For short-chain phthalates such as di-n-butyl-phthalate, additional pathways are of relevance. In general, children are exposed to higher phthalate doses than adults. Especially, high exposures can occur through some medications or medical devices. By comparing exposure data with existing limit values, one can also assess the risks associated with exposure to phthalates. Within the general population, some individuals exceed tolerable daily intake values for one or more phthalates. In high exposure groups, (intensive medical care, medications) tolerable daily intake transgressions can be substantial. Recent findings from animal studies suggest that a cumulative risk assessment for phthalates is warranted, and a cumulative exposure assessment to phthalates via human biomonitoring is a major step into this direction.

Proliferative and nonproliferative lesions of the rat and mouse hepatobiliary system

The INHAND Project (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) is a joint initiative of the Societies of Toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP) and North America (STP) to develop an internationally-accepted nomenclature for proliferative and non-proliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature and differential diagnosis for classifying microscopic lesions observed in the hepatobiliary system of laboratory rats and mice, with color microphotographs illustrating examples of some lesions. The standardized nomenclature presented in this document is also available for society members electronically on the internet (http://goreni.org). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous and aging lesions as well as lesions induced by exposure to test materials. A widely accepted and utilized international harmonization of nomenclature for lesions of the hepatobiliary system in laboratory animals will decrease confusion among regulatory and scientific research organizations in different countries and provide a common language to increase and enrich international exchanges of information among toxicologists and pathologists.

Effects of diisononyl phthalate on atopic dermatitis in vivo and immunologic responses in vitro

BACKGROUND

Diisononyl phthalate (DINP), a principal plasticizer in many polyvinyl chloride products, has been shown to have an adjuvant effect on immunoglobulin (Ig) production in mice. However, the effects of DINP on allergic diseases have not been fully elucidated.

OBJECTIVES

In the present study we investigated the effects of DINP on atopic dermatitis (AD)-like skin lesions induced by Dermatophagoides pteronyssinus (Dp) in atopic-prone NC/Nga mice.

METHODS

Mice were injected intradermally with Dp on their ears and were exposed to DINP (0, 0.15, 1.5, 15, or 150 mg/kg/day) intraperitoneally. We evaluated clinical scores, ear thickening, histologic findings, protein expression of cytokines/chemokines in the ear, and serum levels of Ig and histamine. Furthermore, we investigated the effects of DINP on bone-marrow-derived dendritic cells (BMDCs) or splenocytes in vitro. After exposure to DINP (0-100 microM), cells were evaluated for phenotype and function.

RESULTS

DINP aggravated AD-like skin lesions related to Dp. The aggravation was consistent with eosinophilic inflammation, mast cell degranulation, and thymic stromal lymphopoietin (TSLP) expression in the ear. DINP enhanced the expression of cell surface activation markers on BMDCs and their production of TARC/CCL17 (thymus- and activation-regulated chemokine) and MDC/CCL22 (macrophage-derived chemokine), as well as their capacity to stimulate Dp-specific T-cell proliferation. DINP also enhanced interleukin-4 production and Dp-stimulated proliferation of splenocytes.

CONCLUSIONS

DINP can aggravate AD-like skin lesions related to Dp. The mechanisms of the aggravation might be mediated, at least partly, through the TSLP-related activation of dendritic cells and by direct or indirect activation of the immune cells.

Phthalate risks, phthalate regulation, and public health: a review

As a result of concerns about the toxicity of phthalates to humans, several expert panels were convened toward the end of the 1990s to evaluate the implications of the scientific evidence for the risks of phthalates to humans of all ages. These panels concluded that the risks were low although they had concerns about specific applications of some phthalates, e.g., in medical devices. These groups identified data gaps and recommended additional studies on exposure and toxicity be conducted. In light of the additional data, reevaluations of the risks of phthalates were conducted. While these assessments were being undertaken, U.S. state governments and European authorities proposed and promulgated regulations to limit the use of certain phthalates, i.e., di-n-octyl phthalate (DnOP), di-isodecyl phthalate (DIDP), di-isononyl phthalate (DINP), butylbenzyl phthalate (BBP), dibutyl phthalate (DBP), and diethylhexyl phthalate (DEHP), especially in consumer products to which children are exposed. Very recently, similar regulations were promulgated in the United States under the Consumer Product Safety Improvement Act of 2008. This article summarizes recent evaluations of the risks of these phthalates, and addresses the public health implications of the regulations that were enacted. The analysis considers biomonitoring studies and epidemiological research in addition to laboratory animal evidence. Analysis of all of the available data leads to the conclusion that the risks are low, even lower than originally thought, and that there is no convincing evidence of adverse effects on humans. Since the scientific evidence strongly suggests that risks to humans are low, phthalate regulations that have been enacted are unlikely to lead to any marked improvement in public health.

Biodegradation of a phthalate plasticizer, di-isononyl phthalate (DINP), by Sphingobium chungbukense

In this study, di-isononyl phthalate (DINP) was efficiently degraded by Sphingobium chungbukense KCTC 2955. The optimal conditions for DINP (100 mg L(-1)) degradation by S. chungbukense in a mineral salts medium were found to be pH 7.0, 30 degrees C, and stirring at 200 rpm. The maximum specific rate of DINP degradation was found to be concentration dependent, with a maximum of 4.12 mg DINP L(-1) h(-1). DINP was transformed rapidly by S. chungbukense, with the formation of monoisononyl phthalate (MIP) and phthalic acid, which subsequently degraded further. These results highlight the potential of this bacterium for removing DINP-contaminated waste in the environment.

Urinary biomarkers of di-isononyl phthalate in rats

Commercial di-isononyl phthalate (DiNP) is a mixture of various branched-chain dialkyl phthalates mainly containing nine-carbon alkyl isomers. At high doses in rodents, DiNP is a carcinogen, and a developmental toxicant. After exposure, the diester isomers are de-esterified to form hydrolytic monoesters, monoisononyl phthalates (MiNP), which subsequently metabolize to form oxidative metabolites. These metabolites can be excreted in urine or feces. The urinary excretion of DiNP metabolites was monitored in adult female Sprague-Dawley rats after oral administration of a single dose (300 mg/kg) of commercial DiNP. The metabolites were extracted from urine, resolved with high performance liquid chromatography, analyzed by mass spectrometry, and tentatively identified based on their chromatographic separation and mass spectrometric fragmentation pattern. Because DiNP is an isomeric mixture, its metabolites were also isomeric mixtures that eluted from the HPLC column with close retention times. Mono(carboxy-isooctyl)phthalate (MCiOP) was identified as the major metabolite of DiNP; in addition, mono(hydroxy-isononyl)phthalate (MHiNP) and mono(oxo-isononyl)phthalate (MOiNP) were present. Furthermore, metabolites of di-isooctyl phthalate (DiOP) and di-isodecyl phthalate (DiDP) were also detected. Excretion toxicokinetics of the DiNP metabolites in urine followed a biphasic pattern with initial rapid decay in concentration. Despite potential differences in the metabolism of DiNP among species, MCiOP, MHiNP and MOiNP were detected in humans with no known exposure to DiNP at levels significantly higher than MiNP suggesting that these oxidative metabolites may be better urinary biomarkers of human exposure to DiNP than is MiNP.