The effects of phthalates in the cardiovascular and reproductive systems: A review

Tributyltin role on the serotonin and histamine receptors in human umbilical artery

Some studies in animals suggest that TBT may constitute a risk factor for cardiovascular diseases. Hence, the main purpose of this study was to investigate in human umbilical artery (HUA) the effect of TBT on vascular reactivity, manly in serotonin (5-HT) and histamine receptors. Using standard organ bath techniques, rings of HUA without endothelium were contracted by 5-HT and histamine. We also investigated the effect of TBT on the expression of the receptors using Real-time PCR. The results show that TBT short term effects include concentration-dependent relaxation. Moreover, at long term exposures, the arteries treated with 100 μM of TBT do not have contraction capacity when 5-HT is added, and the gene expression of 5-HT2A receptor decrease. Regarding histamine, it was demonstrated that TBT induces a concentration-dependent relaxation and the H1 gene expression levels decrease. In conclusion TBT modifies the activity and expression of 5-HT and histamine receptors.

Phthalate esters on urban airborne particles: Levels in PM10 and PM2.5 from Mexico City and theoretical assessment of lung exposure

Endocrine disrupting chemicals (EDCs) from the environment are associated with reproductive abnormalities (i.e. decreased sperm concentration; increased endometriosis) and alterations of the cardiovascular system (i.e. increased blood pressure and risk of coronary disease). Some phthalates esters have been identified as EDCs, for which inhalation is considered as one of the routes of exposure. However, only little is known regarding inhalational exposure to EDCs via urban airborne particles. In the present study, we report the monthly concentration of 8 phthalate esters measured in PM₁₀ and PM_2.5 collected and recovered during 7 months in a highly populated area of Mexico City. Using the levels of PM₁₀ and PM_2.5 reported by the automatized network of environmental monitoring of Mexico City for the sampling site, we estimated exposure levels for people of different ages and gender. Two endocrine disrupting compounds, the phthalate esters DEHP and DnBP, were found on the particles in higher concentrations during the warmer months of the year. The highest concentration was reported for DEHP (229.7μg/g of particles) in PM_2.5 collected in May 2013. After calculations of the DEHP concentration in the atmosphere, and using the respiratory flow rate, we determined males were potentially exposed to larger quantities of DEHP, reaching up to 18ng/8h in April 2013. Despite the concentrations of phthalates seem to be rather small, a comprehensive characterization of its presence is necessary in order to evaluate the overall exposure to these compounds, providing a clear view of exposure on children, adolescents and pregnant women.

Exposure to phthalates in patients with diabetes and its association with oxidative stress, adiponectin, and inflammatory cytokines

Epidemiologic studies have revealed higher concentrations of the metabolites of phthalic acid esters (mPAEs) in patients with type 2 diabetes. On the other hand, oxidative stress, adiponectin, and inflammatory cytokines play important roles in the pathogenesis of diabetes and its complications. However, little information is known about the association between exposure to PAEs and these physiological parameters. Hence, paired urine and blood samples were collected from a total of 329 volunteers, and 11 main mPAEs and malondialdehyde (MDA), as a biomarker of oxidative stress, were measured in the urine samples. Serum adiponectin and tumor necrosis factor-α (TNF-α), a biomarker of inflammation, were also measured. Multivariable linear regression was used to assess the association between urinary mPAEs and these physiological parameters in the total subjects and subjects stratified by age, sex, and body mass index (BMI) to elucidate their possible interactions. All 11 mPAEs were detected in the urine with detection rates of 42.9%-100% and geometric means of 0.30-54.52ng/mL (0.44-79.93μg/g creatinine). The mPAEs were all positively associated with MDA levels. There were significant positive associations between monomethyl phthalate (mMP) and TNF-α, and inverse associations between mMP and adiponectin levels. In the stratified analysis, there were age-, sex-, and BMI-specific differences for these associations. The positive associations between mPAEs and MDA were insignificant in some subgroups, especially in the larger age group. However, in the larger BMI group, summed metabolites of di-(2-ethylhexyl) phthalate (∑DEHP) and mono(2-ethylhexyl) phthalate were positively associated with TNF-α, and the concentrations of ∑DEHP were negatively associated with adiponectin. Our findings suggested that PAE exposure is associated with oxidative stress, adiponectin, and inflammatory cytokines in diabetic patients; further studies on toxicology and a comparison with general population are needed.

Characterization and health risk assessment of PM2.5-bound organics inside and outside of Chinese smoking lounges

PM_2.5 samples were collected at six indoor public places that contained dedicated smoking lounges. Samples were taken in the smoking lounges, at two indoor locations outside of the lounges, and in outdoor air near the venues. Organic carbon (OC), elemental carbon (EC), and non-polar organic compounds including polycyclic aromatic hydrocarbons (PAHs), n-alkanes (n-C₁₆ to n-C₄₀), iso/anteiso-alkanes (C₂₉ to C₃₃), hopanes and phthalate esters (PAEs) were quantified. Average PM_2.5 levels of 170.2 ± 85.9 μg/m³ in the lounges exceeded limits of 25 μg/m³ set by World Health Organization (WHO); these levels were 5.4 and 3.9 times higher than those indoors and outdoors, respectively. High ratios of OC to PM_2.5, OC to EC, and PAHs diagnostic ratios in the lounges indicated contributions from environmental tobacco smoke (ETS). The maximum carbon number (C_max) and carbon preference indices (CPI) for n-alkanes showed ETS transport from the enclosed lounges to nearby indoor non-smoking areas. Iso/anteiso-alkanes in the lounges were 876.5 ng/m³, ∼80 times higher than outdoor levels. 17α(H)-21β(H),30-norhopane and 17α(H)-21β(H),(22R)-homohopane were much higher in the lounges than outdoor air, but they cannot be directly attributed to ETS. Estimated carcinogenic risks of PAHs in the lounges exceeded the acceptable level of 10^{- 6}.

In Vitro Toxicity Testing of Food Contact Materials: State-of-the-Art and Future Challenges

Currently, toxicological testing of food contact materials (FCMs) is focused on single substances and their genotoxicity. However, people are exposed to mixtures of chemicals migrating from food contact articles (FCAs) into food, and toxic effects other than genotoxic damage may also be relevant. Since FCMs can be made of more than 8 thousand substances, assessing them one-by-one is very resource-consuming. Moreover, finished FCAs usually contain non-intentionally added substances (NIAS). NIAS toxicity can only be tested if a substance's chemical identity is known and if it is available as a pure chemical. Often, this is not the case. Nonetheless, regulations require safety assessments for all substances migrating from FCAs, including NIAS, hence new approaches to meet this legal obligation are needed. Testing the overall migrate or extract from an FCM/FCA is an option. Ideally, such an assessment would be performed by means of in vitro bioassays, as they are rapid and cost-effective. Here, we review the studies using in vitro bioassays to test toxicity of FCMs/FCAs. Three main categories of in vitro assays that have been applied include assays for cytotoxicity, genotoxicity, and endocrine disruption potential. In addition, we reviewed studies with small multicellular animal-based bioassays. Our overview shows that in vitro testing of FCMs is in principle feasible. We discuss future research needs and FCM-specific challenges. Sample preparation procedures need to be optimized and standardized. Further, the array of in vitro tests should be expanded to include those of highest relevance for the most prevalent human diseases of concern.

Potential effects of low molecular weight phthalate esters (C16H22O4 and C12H14O4) on the freshwater fish Cyprinus carpio

The aim of the present study is to assess the toxic effect of dibutyl phthalate (DBP) and diethyl phthalate (DEP) on the freshwater fish Cyprinus carpio. The median lethal concentrations of DBP and DEP for 96 h are found to be 35 and 53 mg L-1, respectively. Fish were exposed to 3.5 mg L-1 (Treatment I) and 1.75 mg L-1 (Treatment II) of DBP and 5.3 mg L-1 (Treatment I) and 2.65 mg L-1 (Treatment II) of DEP for a period of 35 days. The DBP and DEP exposed fish show a concentration based toxic effect on the selected parameters of this study. The hematological parameters, such as hemoglobin (Hb), hematocrit (Hct) and erythrocyte (RBC), were found to decrease in the DBP and DEP treated fish, whereas their leucocyte (WBC) count increased compared to that of the control groups. A biphasic response is noted in the erythrocyte indices, such as mean cellular volume (MCV), mean cellular hemoglobin (MCH) and mean cellular hemoglobin concentration (MCHC), throughout the study period. Exposure to DBP and DEP caused a significant (p < 0.05) decrease in sodium (Na+), potassium (K+), and chloride (Cl-) levels in the gill and brain of the fish throughout the study period when compared to that of their respective controls. The plasma protein level decreased in all the treatments, whereas the plasma glucose level significantly increased in the DBP and DEP exposed fish. Maximum inhibition of Na+/K+-ATPase activity was noticed in the gill and brain of the fish exposed to DBP and DEP. The cholinesterase (ChE) activity in the brain of the fish significantly decreased throughout the study period. A significant (p < 0.05) increase in glutamate oxaloacetate transaminase (GOT) and glutamic pyruvate transaminase (GPT) activity was noted in the fish exposed to both toxicants. The antioxidant enzymatic parameters such as superoxide dismutase (SOD) and catalase (CAT) activities were found to decrease in the gill and liver of the DBP and DEP treated fish, whereas a significant (p < 0.05) increase in lipid peroxidation (LPO) was observed. The above mentioned parameters could be used as potential biomarkers in clinical trials for the assessment of plasticizers. This study provides indispensable information towards future research on the effect of plasticizers on non-target organisms including humans.

Facts about phthalate toxicity in humans and their occurrence in alcoholic beverages

Phthalates are esters of phthalic acid and aliphatic alcohol added to plastic to improve its softness, flexibility, and extensibility. They easily migrate from plastic products into the environment because of their physical and chemical properties. This review summarises their characteristics, distribution in the environment, monitoring, use, toxic effects on human health, regulatory limits in different matrices and products, and tolerable daily intake. The studies we have reviewed suggest that phthalates have a potential to affect reproduction and development in humans. Due to the inconsistent data, further studies are needed and, in the meantime, precautionary policies must be implemented. Here we draw attention to the methods of determining phthalate levels in alcoholic beverages and reported levels in plum spirits produced in Croatia. Legally produced and moderately consumed plum spirits do not seem to increase the risk of phthalate toxicity for human health. We conclude with recommendations for the effective monitoring of phthalate exposure in humans and for the implementation of alternative materials in alcohol production.

Plastic and Human Health: A Micro Issue?

Microplastics are a pollutant of environmental concern. Their presence in food destined for human consumption and in air samples has been reported. Thus, microplastic exposure via diet or inhalation could occur, the human health effects of which are unknown. The current review article draws upon cross-disciplinary scientific literature to discuss and evaluate the potential human health impacts of microplastics and outlines urgent areas for future research. Key literature up to September 2016 relating to accumulation, particle toxicity, and chemical and microbial contaminants was critically examined. Although microplastics and human health is an emerging field, complementary existing fields indicate potential particle, chemical and microbial hazards. If inhaled or ingested, microplastics may accumulate and exert localized particle toxicity by inducing or enhancing an immune response. Chemical toxicity could occur due to the localized leaching of component monomers, endogenous additives, and adsorbed environmental pollutants. Chronic exposure is anticipated to be of greater concern due to the accumulative effect that could occur. This is expected to be dose-dependent, and a robust evidence-base of exposure levels is currently lacking. Although there is potential for microplastics to impact human health, assessing current exposure levels and burdens is key. This information will guide future research into the potential mechanisms of toxicity and hence therein possible health effects.

Urinary concentrations of 25 phthalate metabolites in Brazilian children and their association with oxidative DNA damage

Exposure of humans to phthalates has received considerable attention due to the ubiquitous occurrence and potential adverse health effects of these chemicals. Nevertheless, little is known about the exposure of the Brazilian population to phthalates. In this study, concentrations of 25 phthalate metabolites were determined in urine samples collected from 300 Brazilian children (6-14years old). Further, the association between urinary phthalate concentrations and a biomarker of oxidative stress, 8-hydroxy-2'-deoxyguanosine (8OHDG), was examined. Overall, eleven phthalate metabolites were found in at least 95% of the samples analyzed. The highest median concentrations were found for monoethyl phthalate (mEP; 57.3ngmL^-1), mono-(2-ethyl-5-carboxypentyl) phthalate (mECPP; 52.8ngmL^-1), mono-isobutyl phthalate (mIBP; 43.8ngmL^-1), and mono-n-butyl phthalate (mBP; 42.4ngmL^-1). The secondary metabolites of di(2-ethylhexyl) phthalate (DEHP), and mEP, mIBP, and mBP were the most abundant compounds, accounting for >90% of the total concentrations. On the basis of the measured concentrations of urinary phthalate metabolites, we estimated daily intakes of the parent phthalates, which were 0.3, 1.7, 1.8, 2.1, and 7.2μg/kg-bw/day for dimethyl phthalate, di-n-butyl phthalate, diisobutyl phthalate, diethyl phthalate, and DEHP, respectively. Approximately one-quarter of the Brazilian children had a hazard index of >1 for phthalate exposures. Statistically significant positive associations were found between 8OHDG and the concentration of the sum of phthalate metabolites, sum of DEHP metabolites, mEP, mIBP, mBP, monomethyl phthalate, mono(3-carboxypropyl) phthalate, monobenzyl phthalate, monocarboxyoctyl phthalate, monocarboxynonyl phthalate, monoisopentyl phthalate, and mono-n-propyl phthalate. To the best of our knowledge, this is the first study to report the exposure of a Brazilian population to phthalates.

Parental contributions to early embryo development: influences of urinary phthalate and phthalate alternatives among couples undergoing IVF treatment

STUDY QUESTION

Are preconception urinary concentrations of phthalates and phthalate alternatives associated with diminished early stage embryo quality in couples undergoing IVF?

SUMMARY ANSWER

Male, but not female, urinary concentrations of select metabolites of phthalates and phthalate alternatives are associated with diminished blastocyst quality.

WHAT IS KNOWN ALREADY

Although phthalates are endocrine disrupting compounds associated with adverse reproductive health, they are in widespread use across the world. Male and female preconception exposures to select phthalates have been previously associated with adverse reproductive outcomes in both the general population and in those undergoing IVF.

STUDY DESIGN, SIZE, DURATION

This prospective cohort included 50 subfertile couples undergoing IVF in western Massachusetts.

PARTICIPANTS/MATERIALS, SETTING, METHODS

This study includes the first 50 couples recruited from the Baystate Medical Center's Fertility Center in Springfield, MA, as part of the Sperm Environmental Epigenetics and Development Study (SEEDS). Relevant data from both partners, including embryo quality at the cleavage (Day 3) and blastocyst (Day 5) stages, were collected by clinic personnel during the normal course of an IVF cycle. A spot urine sample was collected from both male and female partners on the same day as semen sample procurement and oocyte retrieval. Concentrations of 17 urinary metabolite were quantified by liquid chromatography mass spectrometry and normalized via specific gravity. Generalized estimating equations were used to estimate odds ratios (OR) and 95% CI, with urinary phthalates and phthalate alternatives fitted as continuous variables and embryo quality as a binary variable.

MAIN RESULTS AND THE ROLE OF CHANCE

The 50 couples contributed 761 oocytes, of which 423 progressed to the cleavage stage, 261 were high-quality cleavage stage embryos, 137 were transferrable quality blastocysts and 47 were high-quality blastocysts. At the cleavage stage, male urinary monoethyl phthalate concentrations were positively associated with high-quality cleavage stage embryos (OR = 1.20, 95% CI 1.01-1.43, P = 0.04); no other significant associations were observed at this stage. At the blastocyst stage, male urinary concentrations of monobenzyl phthalate (OR = 0.55, 95% CI 0.36-0.84, P = 0.01), mono-3-hydroxybutyl phthalate (OR = 0.37, 95% CI 0.18-0.76, P = 0.01), mono-n-butyl phthalate (OR = 0.55, 95% CI 0.42-0.73, P < 0.01) and monomethyl phthalate (OR = 0.39, 95% CI 0.26-0.60, P < 0.01) were inversely associated with high-quality blastocysts. A borderline statistically significant relationship was observed for male concentrations of mono(2-ethylhexyl) phthalate (OR = 0.52, 95% CI 0.27-1.00, P = 0.05) and cyclohexane-1,2-dicarboxylic acid-monocarboxy isooctyl ester (OR = 0.21, 95% CI 0.04-1.03, P = 0.05) at the blastocyst stage. Similar inverse associations were observed between male urinary phthalate metabolite concentrations and likelihood of transferrable quality blastocysts. For female partners, select metabolites were positively associated with odds of high or transferrable blastocyst quality, but the observed associations were not consistent across blastocyst quality measures or between sex-specific and couples-level models. All models were adjusted for age of both partners, urinary metabolite concentrations of female partners and male infertility status, while models of blastocysts were additionally adjusted for embryo quality at cleavage stage.

LIMITATIONS, REASONS FOR CAUTION

Our modest sample included only 50 couples contributing one cycle each. In addition, non-differential misclassification of exposure remains a concern given the single-spot urine collection and the short half-life of phthalates.

WIDER IMPLICATIONS OF THE FINDINGS

Our results suggest an inverse association between male preconception concentrations of select phthalate metabolites and blastocyst quality, likely occurring after genomic activation. If corroborated with other studies, such findings will have public health and clinical significance for both the general population and those undergoing IVF.

STUDY FUNDING/COMPETING INTERESTS

This work was generously supported by grant K22-ES023085 from the National Institute of Environmental Health Sciences. The authors declare no competing interests.

TRIAL REGISTRATION NUMBER

N/A.