Evaluating the potential genotoxicity of phthalates esters (PAEs) in perfumes using in vitro assays

Exposure to benzyl butyl phthalate (BBP) leads to increased double-strand break formation and germline dysfunction in Caenorhabditis elegans

Benzyl butyl phthalate (BBP), a plasticizer found in a wide range of consumer products including vinyl flooring, carpet backing, food packaging, personal care products, and children's toys, is an endocrine-disrupting chemical linked to impaired reproduction and development in humans. Despite evidence that BBP exposure perturbs the integrity of male and female gametes, its direct effect on early meiotic events is understudied. Here, using the nematode Caenorhabditis elegans, we show that BBP exposure elicits a non-monotonic dose response on the rate of X-chromosome nondisjunction measured using a high-throughput screening platform. From among the range of doses tested (1, 10, 100 and 500 μM BBP), we found that 10 μM BBP elicited the strongest effect on the germline, resulting in increased germ cell apoptosis and chromosome organization defects. Mass spectrometry analysis shows that C. elegans efficiently metabolizes BBP into its primary metabolites, monobutyl phthalate (MBP) and monobenzyl phthalate (MBzP), and that the levels of BBP, MBP, and MBzP detected in the worm are within the range detected in human biological samples. Exposure to 10 μM BBP leads to germlines with enlarged mitotic nuclei, altered meiotic progression, activation of a p53/CEP-1-dependent DNA damage checkpoint, increased double-strand break levels throughout the germline, chromosome morphology defects in oocytes at diakinesis, and increased oxidative stress. RNA sequencing analysis indicates that BBP exposure results in the altered expression of genes involved in xenobiotic metabolic processes, extracellular matrix organization, oocyte morphogenesis, meiotic cell cycle, and oxidoreduction. Taken together, we propose that C. elegans exposure to BBP leads to increased oxidative stress and double-strand break formation, thereby compromising germline genomic integrity and chromosome segregation.

Rapid and Comprehensive Analysis of 41 Harmful Substances in Multi-Matrix Products by Gas Chromatography-Mass Spectrometry Using Matrix-Matching Calibration Strategy

Harmful substances in consumer goods pose serious hazards to human health and the environment. However, due to the vast variety of consumer goods and the complexity of their substrates, it is difficult to simultaneously detect multiple harmful substances in different materials. This paper presents a method for the simultaneous determination of 41 harmful substances comprising 17 phthalates (PAEs), 8 organophosphate flame retardants (OPFRs), and 16 polycyclic aromatic hydrocarbons (PAHs) in five types of products using the matrix-matching calibration strategy. The method employs an efficient ultrasonic extraction procedure using a mixture of dichloromethane and methylbenzene, followed by dissolution-precipitation and analysis through gas chromatography-mass spectrometry. Compared with previous experiments, we established a universal pretreatment method suitable for multi-matrix materials to simultaneously determine multiple harmful substances. To evaluate the effects of the matrix on the experimental results, we compared neat standard solutions and matrix-matching standard solutions. The results demonstrated that all compounds were successfully separated within 30 min with excellent separation efficiency. Additionally, the linear relationships of all analytes showed strong correlation coefficients (R2) of at least 0.995, ranging from 0.02 mg/L to 20 mg/L. The average recoveries of the target compounds (spiked at three concentration levels) were between 73.6 and 124.1%, with a relative standard deviation (n = 6) varying from 1.2% to 9.9%. Finally, we tested 40 different materials from consumer products and detected 16 harmful substances in 31 samples. Overall, this method is simple and accurate, and it can be used to simultaneously determine multiple types of hazardous substances in multi-matrix materials by minimizing matrix effects, making it an invaluable tool for ensuring product safety and protecting public health.

DEHP and DINP accelerate aging effects in male and female of Drosophila melanogaster depend on AKT/FOXO pathway

Phthalates are commonly used as plasticizers. Numerous studies have focused on endocrine, reproductive, and developmental toxicity of phthalates exposure to male organisms. In recent years, some studies looking into the aging effects of phthalates exposure in D. melanogaster showed discrepant results. In this study, we compared the different concentrations of Di(2-ethylhexyl) phthalate (DEHP) and di-isononyl phthalate (DINP) for acute and chronic treatment for different gender D. melanogaster and explored the potential mechanism of DEHP and DINP exposure. The results showed that acute exposure to DEHP or DINP at a high dose significantly decreased the lifespan of female and male D. melanogaster under HFD stress. Chronic exposure significantly decreased the lifespan of flies in all exposure groups except for the low-dose DINP exposure female group. Among them, in the normal feeding group, we found that female flies seemed to be more resistant to DEHP or DINP exposure. Meanwhile, the locomotion ability and fertility of flies exhibited a dose-dependent decline. Furthermore, phthalates did not significantly reduce the lifespan or health status of akt and foxo mutant flies in the mutant fly assays, and real-time quantitative-PCR (q-PCR) data revealed akt and foxo significant change with 10 μM DEHP or DINP treatment. This suggests that akt and foxo played a role in the process by which DEHP and DINP caused age-related declines in D. melanogaster.

Occurrence and health risk assessment of phthalates in a typical estuarine soil: A case study of the various functional areas of the Yellow River Delta

In recent years, the extensive distribution of phthalates (PAEs) in soils has attracted increasing attention. In this study, the concentrations of six types of PAEs were measured in five dissimilar regions of the Yellow River Delta (YRD), and regional differences, pollution characteristics and health risks of PAEs pollution were investigated. The detection rate of PAEs was 100 %, and the concentration range of Σ6PAEs was 0.709-9.565 mg/kg, with an average of 3.258 ± 2.031 mg/kg. There were different spatial distribution differences of PAEs in soils of the YRD, with residential living, chemical industrial, and crop growing areas being the main areas of PAEs distribution. It was worth noting that di (2-ethylhexyl) phthalate (DEHP) and dibutyl phthalate (DBP) are prominent contributors to PAEs in soils of the YRD. Correlation analyses showed that soils physicochemical properties such as SOM, TN and CEC were closely correlated to the transport and transformation of PAEs. Use by petrochemical industries, accumulation of plasticizers, additives (derived from cosmetics, food, pharmaceutical), fertilizers, pesticides, plastics, and atmospheric deposition are the principal sources of PAEs in the YRD. A health risk assessment showed that the health risk caused by non-dietary intake of PAEs was low and considered acceptable. PAEs pollution in the YRD soil is particularly noteworthy, especially for the prevention and control of DEHP and DBP pollution. This study provides basic data for an effective control of soil PAEs pollution in the YRD, which is conducive to the sustainable development of the region.

Evidence of genotoxicity, neurotoxicity, and antioxidant imbalance in silver catfish Rhamdia quelen after subchronic exposure to diisopentyl phthalate

Diisopentyl phthalate (DiPeP) is a plasticizer with significant offer and application in Brazilian industries. This is attributed to its origin, which is closely linked to the refining process of sugarcane for ethanol production in the country. In this work, we developed a model for trophic exposure to environmentally relevant doses (5, 25, and 125 ng/g of DiPeP) to identify possible target tissues and toxic effects promoted by subchronic exposure to DiPeP in a Neotropical catfish species (Rhamdia quelen). After thirty days of exposure, blood, liver, kidney, brain, and muscle were collected and studied regarding DNA damage in blood cells and biochemical analyses. The kidney was the most affected organ, as in the head kidney, genotoxicity was evidenced in all groups exposed to DiPeP. Besides, the caudal kidney showed a reduction in the superoxide dismutase and glutathione peroxidase activities as well as a reduced glutathione concentration. In the liver, exposure to 125 ng/g of DiPeP increased glutathione S-transferase activity and reduced glutathione levels. In muscle, acetylcholinesterase (AChE) was reduced. However, in the brain, an increase in AChE activity was observed after the exposure to lowest doses. In contrast, a significant reduction of brain AChE activity after exposure to the highest dose was detected. The pronounced genotoxicity observed in head kidney cells is of concern, as it may compromise different functions performed by this organ (e.g., hematopoiesis, immune and endocrine functions). In our study, DiPeP proved to be a compound of environmental concern since we have evidenced its nephrotoxic and neurotoxic potential even in low doses.

DNA Damage Estimation after Chronic and Combined Exposure to Endocrine Disruptors: An In Vivo Real-Life Risk Simulation Approach

Exposure to chemical substances has always been a matter of concern for the scientific community. During the last few years, researchers have been focusing on studying the effects resulting from combined exposure to different substances. In this study, we aimed to determine the DNA damage caused after chronic and combined exposure to substances characterized as endocrine disruptors using comet and micronuclei assays, specifically glyphosate (pure and commercial form), bisphenol A, parabens (methyl-, propyl- and butylparaben), triclosan and bis (2-ethylhexyl) phthalate. The highest mean tail intensity was observed in the group exposed to a high-dose (10 × ADI) mixture of substances (Group 3), with a mean value of 11.97 (11.26-13.90), while statistically significant differences were noticed between the groups exposed to low-dose (1 × ADI) (Group 2) and high-dose (10 × ADI) (Group 3) mixtures of substances (p = 0.003), and between Group 3 and both groups exposed to high doses (10 × ADI) of the pure and commercial forms of glyphosate (Groups 4 (p = 0.014) and 5 (p = 0.007)). The micronuclei assay results were moderately correlated with the exposure period. Group 5 was the most impacted exposure group at all sampling times, with mean MN counts ranging between 28.75 ± 1.71 and 60.75 ± 1.71, followed by Group 3 (18.25 ± 1.50-45.75 ± 1.71), showing that commercial forms of glyphosate additives as well as mixtures of endocrine disruptors can enhance MN formation. All exposure groups showed statistically significant differences in micronuclei counts with an increasing time trend.

Pollution characteristics and health risk assessment of phthalate esters in agricultural soil of the Yellow River Delta, China

A total of 100 agricultural soil samples, collected in the Yellow River Delta, China, were analyzed for six U.S. Environmental Protection Agency priority phthalate esters (PAEs), focusing on the characteristics of PAEs contamination and potential health risks. The detection frequencies of ∑₆PAEs were 100%, where the concentration ranged from 1.087 to 14.391 mg·kg^-1, with a mean value of 4.149 mg·kg^-1. The most abundant PAEs were di(2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DnBP). The areas with higher contents of ∑₆PAEs are distributed in the western and central parts of the Yellow River Delta region and around Laizhou Bay. PAEs in the Yellow River Delta agricultural soil were attributed to pollutant emissions from petrochemical industries, plasticizers or additives, fertilizers, and pesticides. The non-carcinogenic risk of human exposure to PAEs in agricultural soils is relatively low, but the non-carcinogenic risk is higher in children than in adults, and children are a sensitive group. Under the dietary route, both DEHP and ∑₂PAEs (BBP, and DEHP) pose some degree of carcinogenic risk to both local adults and children. Efforts must be made to enhance the prevention and control of PAEs contamination of agricultural soils in the Yellow River Delta region to reduce the potential risk to humans.

First Data on PAE Levels in Surface Water in Lakes of the Eastern Coast of Baikal

The increasing consumption of phthalates (PAEs), along with their high toxicity and high mobility, poses a threat to the environment. This study presents initial data on the contents of six priority PAEs in the water of lakes located on the eastern shore of Lake Baikal-Arangatui, Bormashevoe, Dukhovoe, Kotokel, and Shchuchye. The mean total concentrations of the six PAEs in lakes Arangatui and Bormashevoe (low anthropogenic load) were comparable to those in Kotokel (medium anthropogenic load, 17.34 µg/L) but were significantly higher (p < 0.05) than in Dukhovoe and Shchuchye (high anthropogenic load, 10.49 and 2.30 µg/L, respectively). DBP and DEHP were the main PAEs in all samples. The DEHP content in lakes Arangatui and Bormashevoe was quite high, and at some sampling sites it exceeded the MACs established by Russian, U.S. EPA, and WHO regulations. The assessment showed that there is no potential risk to humans associated with the presence of PAEs in drinking water. However, the levels of DEHP, DBP, and DnOP in the water pose a potential threat to sensitive aquatic organisms, as shown by the calculated risk quotients (RQs). It is assumed that the origin of the phthalates in the studied lakes is both anthropogenic and biogenic.

Occurrence and dietary exposure risks of phthalate esters in food in the typical valley city Xi'an, Northwest China

Diet is an important exposure pathway of phthalate esters (PAEs) for humans. A total of 174 food samples covering 11 food groups were collected from Xi'an, a typical valley city in Northwest China, and analyzed to assess the occurrence and exposure risks for PAEs in the food. Twenty-two PAEs were detected. The sum of the 22 PAEs (∑22PAEs) varied between 0.0340 and 56.8 µg/g, with a mean of 3.94 µg/g. The major PAEs were di-iso-butyl phthalate (DiBP), di-n-butyl phthalate (DnBP), bis(2-ethylhexyl) phthalate (DEHP), di-iso-nonyl phthalate (DiNP), and di-iso-decyl phthalate (DiDP), which were associated mainly with the usage of plasticizers. Bio-availability of the PAEs in the combined gastro-intestinal fluid simulant of digestion was higher than that in the single gastric or intestinal fluid simulant. Bis(2-methoxyethyl) phthalate exhibited the highest bio-availability in each of the three simulants. Bio-availability of the PAEs was negatively correlated with the molecular weight and octanol-water partition coefficient of the PAEs and positively correlated with the solubility and vapor pressure of the PAEs. The estimated daily intake (EDI) of PAEs based on national and municipal food consumption data was lower than the reference dose (RfD) of the United States Environmental Protection Agency and the tolerable dairy intake (TDI) of European Food Safety Authority (EFSA), except for the EDI of DnBP and DiBP being higher than the TDI of EFSA. Grains and vegetables were the major sources of human dietary exposure to PAEs. The hazardous quotient for human dietary exposure to PAEs was less than the critical value of 1 and the cancer risk of butyl benzyl phthalate and DEHP was in the range of 10^-11-10^-6, suggesting relatively low health risks. The results indicated that human exposure to DnBP, DiBP, DEHP, DiNP, and DiDP in food is considerable and a health concern.

Biodeterioration of Compost-Pretreated Polyvinyl Chloride Films by Microorganisms Isolated From Weathered Plastics

Polyvinyl chloride (PVC) is a petroleum-based plastic used in various applications, polluting the environment because of its recalcitrance, large content of additives, and the presence of halogen. In our case study, a new, two-stage biodegradation technology that combined composting process used for PVC pretreatment with a subsequent PVC attack by newly-isolated fungal and bacterial strains under SSF conditions was used for biodegradation of commercial PVC films. The novelty consisted in a combined effect of the two biodegradation processes and the use for augmentation of microbial strains isolated from plastic-polluted environments. First, the ability of the newly-isolated strains to deteriorate PVC was tested in individual, liquid-medium- and SSF cultures. Higher mass-reductions of PVC films were obtained in the former cultures, probably due to a better mass transfer in liquid phase. Using the two-stage biodegradation technology the highest cumulative mass-reductions of 29.3 and 33.2% of PVC films were obtained after 110 days with Trichoderma hamatum and Bacillus amyloliquefaciens applied in the second stage in the SSF culture, respectively. However, FTIR analysis showed that the mass-reductions obtained represented removal of significant amounts of additives but the PVC polymer chain was not degraded.

Occurrence and cross-interface transfer of phthalate esters in the mangrove wetland in Dongzhai Harbor, China

Phthalate esters (PAEs), the most widely used plasticizers, are extensively present in various environmental media, and are continuously transported from land to sea. However, PAEs have not been well characterized in multiple media in mangrove wetlands, an important land-sea interface. This study investigated the distribution and transfer of six PAEs in water, sediment, mangroves, and fish in Dongzhai Harbor. The mangrove forest in Dongzhai Harbor is the largest in China and is surrounded by shrimp ponds and villages. PAEs are ubiquitous in the study area. The mean concentration range of ∑₆PAEs was 0.31-1.52 μg/L in water, 450-2096 μg/kg dry weight (dw) in sediment, 210-937 μg/kg dw in mangrove plants, and not detected (n.d.) -205 μg/kg in fish. Among the six PAEs, di-n-butyl phthalate (DBP) and di-ethylhexyl phthalate (DEHP) were predominant. The concentrations of the PAEs in mangrove plants tended to decrease from the river and coast to tidal gullies, which might be related to the periodic inundation of tides. A study of PAEs bioaccumulation showed that the concentration of PAEs in herbivorous fish was higher than that in carnivorous fish. In the same species, larger individuals had a lower concentration of ∑₆PAEs. Di-n-octyl phthalate (DnOP) and DEHP tended to transfer from water to sediments, while the four less-hydrophobic PAEs, such as DBP, were more likely to be released from sediments to water. Our results can provide important information of the distribution and fate of PAEs in mangrove wetlands.

Ecotoxicological and genotoxic effects of dimethyl phthalate (DMP) on Lemna minor L. and Spirodela polyrhiza (L.) Schleid. plants under a short-term laboratory assay

The environmental occurrence of phthalates (PAE) is of great concern for the ecosystem and human health. Despite of their recognized toxicity on biota, a lack of knowledge is still present about the effects of PAE on plants. In this scenario, the effects of dimethyl phthalate (DMP) on duckweed plants (Lemna minor L. and Spirodela polyrhiza (L.) Schleid.), two model plant species for ecotoxicological and trophic studies, were investigated. Under a 7-day lab assay, morphological (biometric indicators), physiological (pigment content and photosynthetic performance) and molecular (DNA damage) parameters were studied. No effects were observed at growth and physiological level in both plants at 3 and 30 mg/L DMP. On the contrary, at 600 mg/L DMP, a concentration used for plant acute toxicity studies, a remarkable growth inhibition and pigment content and photosynthetic parameters reduction compared to control were observed in both plants species, particularly in Spirodela. Alkaline Comet assay in 24 h-treated plants revealed a genotoxic damage induced by DMP, particularly relevant in Spirodela. These results described for the first time the adverse effects exerted by DMP on aquatic plants, contributing to highlight the environmental risk associated to the presence of this compound in the aquatic ecosystem.

Mechanistic insights into primary biotransformation of diethyl phthalate in earthworm and significant SOD inhibitory effect of esterolytic products

Phthalic acid esters (PAEs) are used as plasticizer or modifier in artificially-manufactured products. Though the rapid biotransformation of phthalates in microbes and plants have been well documented, it is less studied yet in terrestrial animals, e.g. earthworm. In this study, the major biotransformation of diethyl phthalate (DEP) in Eisenia fetida was illustrated using in vitro incubation of earthworm crude enzymes. DEP could be substantially biotransformed into phthalate monoester (MEP) and a small amount of phthalic acid (PA) through esterolysis, which was verified to be driven by endogenous carboxylesterase. Despite the inferior contribution, the oxidation of DEP might also occur under the initiated electron transfer by NADPH coenzyme. The dominant metabolite MEP showed a higher inhibition of superoxide dismutase (SOD) activity than DEP with EC₅₀ of 0.0082 ± 0.0016 mmol/L, so the higher ecological risks of MEP would be marked. The inhibition effect of PA was validated to be even stronger than MEP though it was slightly generated. The direct binding interaction with SOD was proved to be an important molecular event for regulation of SOD activity. Besides the static quenching mechanism, the caused conformational changes including despiralization of α-helix and spatial reorientation of tryptophan were spectrally believed to affect binding and underlie inhibition efficiency of SOD activity.

In vitro genotoxicity of dibutyl phthalate on A549 lung cells at air-liquid interface in exposure concentrations relevant at workplaces

The ubiquitous use of phthalates in various materials and the knowledge about their potential adverse effects is of great concern for human health. Several studies have uncovered their role in carcinogenic events and suggest various phthalate-associated adverse health effects that include pulmonary diseases. However, only limited information on pulmonary toxicity is available considering inhalation of phthalates as the route of exposure. While in vitro studies are often based on submerged exposures, this study aimed to expose A549 alveolar epithelial cells at the air-liquid interface (ALI) to unravel the genotoxic and oxidative stress-inducing potential of dibutyl phthalate (DBP) with concentrations relevant at occupational settings. Within this scope, a computer modeling approach calculating alveolar deposition of DBP particles in the human lung was used to define in vitro ALI exposure conditions comparable to potential occupational DBP exposures. The deposited mass of DBP ranged from 0.03 to 20 ng/cm² , which was comparable to results of a human lung particle deposition model using an 8 h workplace threshold limit value of 580 μg/m³ proposed by the Scientific Committee on Occupational Exposure Limits for the European Union. Comet and Micronucleus assay revealed that DBP induced genotoxicity at DNA and chromosome level in sub-cytotoxic conditions. Since genomic instability was accompanied by increased generation of the lipid peroxidation marker malondialdehyde, oxidative stress might play an important role in phthalate-induced genotoxicity. The results highlight the importance of adapting in vitro studies to exposure scenarios relevant at occupational settings and reconsidering occupational exposure limits for DBP.

Ovarian Toxicity and Epigenetic Mechanisms of Phthalates and Their Metabolites

Ovary plays an important role in the female reproductive system. The maintenance and regulation of ovarian function are affected by various physical and chemical factors. With the development of industrialization, environmental pollutants have caused great harm to public health. Phthalates, as a class of endocrine-disrupting chemicals (EDCs), are synthesized and used in large quantities as plasticizers due to their chemical properties. They are easily released into environment because of their noncovalent interactions with substances, causing human exposure and possibly impairing ovary. In recent years, more and more attention has been paid to the role of epigenetics in the occurrence and development of diseases. And it is urgent to study the role of methylation, gene imprinting, miRNA, and other epigenetic mechanisms in reproductive toxicology.

Endocrine disrupting chemicals may deregulate DNA repair through estrogen receptor mediated seizing of CBP/p300 acetylase

PURPOSE

Environmental pollutants are known to induce DNA breaks, leading to genomic instability. Here, we propose a novel mechanism for the genotoxic effects exerted by environmentally exposed endocrine-disrupting chemicals (EDCs).

METHODS

Bibliographic research and presentation of the analysis.

DISCUSSION

In mammals, nucleotide excision repair, base excision repair, homologous recombination and non-homologous end-joining pathways are some of the major DNA repair pathways. p300 along with CREB-binding protein (CBP) contributes to chromatin remodeling, DNA damage response and repair of both single- and double-stranded DNA breaks. In addition to its role in DNA repair, CBP/p300 also acts as a coactivator to interact with the estrogen receptor and androgen receptor during its estrogen- and androgen-dependent transactivation, respectively. Since activated estrogen receptors (ERs) seize p300 from the repressed genes and redistribute it to the enhancer genes to activate transcription, the cellular functioning may be based on a balance between these pathways and any disturbance in one may alter the other, leading to undesirable physiological effects.

CONCLUSION

In conclusion, CBP/p300 is important for DNA repair and nuclear hormone receptor transactivation. Activated hormone receptors can sequester p300 to regulate the hormonal effects. Hence, we believe that activation of ERs by EDCs results in sequestration of CBP/p300 for ER transactivation and transcription initiation of its target genes, leading to a competition for CBP/P300, resulting in the deregulation of all other pathways involving p300/CBP.

Pollution characteristics and health risk assessment of phthalate esters in agricultural soil and vegetables in the Yangtze River Delta of China

As an important environmental reservoir of phthalate esters (PAEs), soil-plant system constitutes a key exposure pathway to human health. In this study, agricultural soil and vegetable samples were collected from the Yangtze River Delta (approximately 211,700 km²), one of the most developed regions in China, to determine the contamination characteristics of priority PAEs. The total concentrations of six PAEs ranged from 5.42 to 1580 ng·g^-1 dry weight in soils and from 10.9 to 16,400 ng·g^-1 dry weight in vegetables. Di-(2-ethylhexyl) phthalate (DEHP) accounted for 88.3% and 61.9% of the total PAEs in soils and vegetables, respectively. The spatial distribution of PAEs in the soils was as follows: Shanghai city (70.8-1583 ng·g^-1 dw) > Anhui province (46.8-1530 ng·g^-1 dw) > Jiangsu province (14.4-558 ng·g^-1 dw) > Zhejiang province (5.40-488 ng·g^-1 dw). Non-cancer risks exist for adults and children in 6.5% and 7.8% of the sites, respectively. Carcinogenic risks were regarded unacceptable in 5.6% and 1.3% of the sites for adults and children, respectively. The bioconcentration factor (BCF) of PAEs showed positive correlation with lipid content of vegetables. A basic reference of the lipid-content threshold to guarantee the safety of leafy vegetables was proposed based on partition-limited model. We suggested to cultivate vegetables with lipid content <0.21% in most heavily contaminated area in the region. This study provides information for effectively controlling PAEs contamination in soil-plant system in developed districts.

Cytotoxic and genotoxic effects of e-liquids and their potential associations with nicotine, menthol and phthalate esters

In this study, we determined DNA damage and chromosome breakage (indicators of genotoxicity) and cell viability (an indicator of cytotoxicity) in human lymphoblastoid TK6 and Chinese hamster ovary (CHO) cells treated with 33 e-liquids using in vitro single cell gel (comet), micronucleus (MN), and trypan blue assays, respectively. We also measured the contents of nicotine, five phthalate esters, and DL-menthol in the e-liquids to examine their effects on DNA damage, chromosome breakage, and cell viability. Our chemical analyses showed that: (1) six e-liquids had nicotine ≥2-fold higher than the manufacture's label claim (2-3.5 mg); (2) both dimethyl- and dibutyl-phthalate levels were >0.1 μg/g, i.e., their threshold limits as additives in cosmetics; and (3) the DL-menthol contents ranged from 0.0003 to 85757.2 μg/g, with those of two e-liquids being >1 mg/g, the threshold limit for trigging sensory irritation. Though all the e-liquids induced DNA damage in TK6 cells, 20 resulted in cell viabilities ≤75%, indicating cytotoxicity, yet the inverse relationship between cell viability and DNA damage (r = -0.628, p = 0.003) might reflect their role as pro-apoptotic and DNA damage inducers. Fifteen e-liquids induced MN% in TK6 cells ≥3-fold that of untreated cells. Some of the increase in %MN might be false due to high cytotoxicity, yet six brands showed acceptable cell viabilities (59-71%), indicating chromosome damage. DNA damage and %MN increased when the TK6 cells were exposed to metabolic activation. The CHO cells were less sensitive to the genotoxic effects of the e-liquids than the TK6 cells. DL-menthol was found to be associated with decreased cell viability and increased DNA damage, even at low levels. We cannot dismiss the presence of other ingredients in e-liquids with cytotoxic/genotoxic properties since out of the 63 different flavors, 47 induced DNA damage (≥3-folds), and 26 reduced cell viability (≤75%) in TK6 cells.

Phthalate esters (PAEs) in atmospheric particles around a large shallow natural lake (Lake Chaohu, China)

The pollution of phthalate esters (PAEs) remains an important issue in the world. Current studies mainly focused on atmospheric PAEs in urban area with strong anthropogenic activities, but there were no studies on PAEs in the ambient air around large natural lake. This paper focused on two sites around Lake Chaohu to investigate the monthly occurrence, composition and source of PAEs in the atmospheric particles around large shallow natural lake. New insights into atmospheric PAEs in large shallow natural lake and the overall fate of PAEs in lake ecosystem were given. The concentrations of the Σ₁₃PAEs in atmospheric particles were at a significantly low level ranging from 2740 to 11,890 pg·m^-3 and 2622 to 15,331 pg·m^-3 in ZM (the lakeshore site) and HB (the downtown site), respectively. There were no statistically significant differences of PAEs between ZM and HB. The highest atmospheric PAE concentrations in August were likely related to the long-range transport from Guangdong Province. Di(2-ethylhexyl) phthalate (DEHP), diisobutyl phthalate (DIBP) and dibutyl phthalate (DBP) were the main PAE congeners. Temporally, DIBP and DBP had the highest fractions in winter and the lowest fractions in summer. It might be justified by the condensation of DIBP and DBP from gas phase to particulate phase at low temperature. Multimedia comparison of PAE profiles in Lake Choahu revealed that low molecular weight (LMW) congeners were transported mainly through water while high molecular weight (HMW) congeners were transported mainly through atmosphere.

The occurrence, composition and partitioning of phthalate esters (PAEs) in the water-suspended particulate matter (SPM) system of Lake Chaohu, China

The occurrence, composition, and partitioning of six phthalate esters (PAEs) (dimethyl phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DIBP), dibutyl phthalate (DBP), butyl benzyl phthalate (BBP) and di(2-ethylhexyl) phthalate (DEHP)) in the water-suspended particulate matter (SPM) system of Lake Chaohu were investigated in this study. Our results showed that PAEs were ubiquitous contaminants in Lake Chaohu. The concentration of the Σ₆ PAEs in dissolved and particulate phases ranged from 0.370 to 13.2 μg·L^-1 and from 14.4 to 7129 μg·L^-1, respectively. The Σ₆ PAEs in water and SPM phases exhibited different seasonal trends. PAEs with different degrees of hydrophobicity demonstrated different temporal distributions in the dissolved phase. In particulate phase, all PAEs exhibited the same temporal distribution. Regarding the occurrence of PAEs, significant spatial differences exist between lake and estuary. However, there were no specific differences in PAEs across lake zones and river types of Lake Chaohu. River input should be considered an important source of PAEs in Lake Chaohu. DIBP and DBP were the most abundant PAEs in Lake Chaohu, and DIBP should attract more attention in the future. The organic carbon normalized partitioning coefficient (logKoc) ranged from an average of 2.38 ± 0.86 L·g^-1 for BBP to 3.98 ± 0.66 L·g^-1 for DEHP, and approximately 2 to 3 unit variations of logKoc existed for the individual PAEs. It was difficult to ascertain whether the partitioning of PAEs was in, near or far from the equilibrium. No linear relationship was found between logKoc and the octanol-water partitioning coefficient (logKow) for PAEs. Koc might not be suitable for describing the partitioning of PAEs in the water-SPM system. The hydrophobicity of PAEs may have little impact on their partitioning in the complex environmental system, and the Kow model may be inappropriate to predict the partitioning of PAEs in natural large lakes.

Effects of Dimethyl Phthalate (DMP) on Serum Sex Hormone Levels and Apoptosis in C57 Female Mice

BACKGROUND

The effects of dimethyl phthalate (DMP) on the reproductive system of mammal females are unclear because no studies have been conducted on this topic.

METHODS

In this study, 40 C57 female mice were used as experimental subjects and evenly divided into 8 groups, which were fed with mixed DMP (0, 0.5, 1, and 2 g/kg bw/day) and corn oil. After 20 days and 40 days of gavage, the mice were weighed and their individual ovary organ coefficients measured.

RESULTS

Changes were discovered on progesterone, estradiol, follicle-stimulating hormone and luteinizing hormone in mouse serum, and on the apoptosis rate of ovarian granulosa cells.

CONCLUSIONS

Prolonged exposure to DMP led to decreased secretion of FSH hormones and increased secretion of E2 and LH hormones. Furthermore, DMP interfered with the pituitary-ovary axis and increased the apoptosis rate of ovarian granulosa cells. Therefore, prolonged exposure to DMP is likely to have negative effects on reproduction and development.

Exposure to phthalates in couples undergoing in vitro fertilization treatment and its association with oxidative stress and DNA damage

This prospective study of 599 couples seeking fertility treatment and who were recruited between 2015 and 2017 was conducted to (a) explore the associations between phthalate exposure and in vitro fertilization (IVF) outcomes; and (b) examine the implication of oxidative stress as a mediator of these. We measured eight phthalate metabolites in two spot urine samples; oxidative stress biomarkers such as malondialdehyde, 8-hydroxy-2-deoxyguanosine, hydrogen peroxide, catalase (CAT), and total antioxidant capacity in follicular fluid and seminal plasma. We also examined DNA damage in sperm and granulosa cells. Couples were exposed to a broad range of phthalate compounds and seven metabolites were detected in over 94% of the urine samples, whereas monobenzyl phthalate was found in only 24% of women and 26% of men. Our results showed high levels of seven urinary phthalate metabolites (except monobenzyl phthalate) and a notable increase in many oxidative stress markers in both follicular fluid and seminal plasma. However, their associations with exposure were rather limited. Multivariate binomial regression modeling showed higher levels of follicular CAT levels reduced the probability of fertilization rate (≤ 50%) [Adjusted relative risk (RR_adj) = 0.52, p = 0.005] and unsuccessful live birth (RR_adj = 0.592, p = 0.023). We observed a 46% decrease in the probability of clinical pregnancy in association with an elevated percentage of DNA in the tail (RR_adj = 0.536, p = 0.04). There was a 32% and 22% increase in the probability of clinical pregnancy and unsuccessful live birth associated with higher levels of mono-(2-ethylhexyl) phthalate (RR_adj = 1.32, p = 0.049) and monoethyl phthalate (RR_adj = 1.22, p = 0.032) in women, respectively. In contrast, the probability of clinical pregnancy reduced by 20% with higher levels of mono-(2-ethyl-5-carboxypentyl) phthalate (RR_adj = 0.797, p = 0.037) and 19.6% with mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) (RR_adj = 0.804, p = 0.041) in men. Other oxidative stress biomarkers or urinary phthalate metabolites showed suggestive relationships with certain IVF outcomes. Lastly, our results demonstrated that elevated levels of CAT in follicular fluid might have a positive impact on fertilization rate ≥ 50% and successful live birth. CAT seems to play a potential role in mediating the relationship between the risk of poor fertilization rate and MEOHP and mono-isobutyl phthalate. Additional data are required to understand the clinical implications of oxidative stress and its contribution to the reproductive toxicity of phthalate exposure.