Negative effects of poly(butylene adipate-co-terephthalate) microplastics on Arabidopsis and its root-associated microbiome.

The degradable plastic poly(butylene adipate-co-terephthalate) (PBAT) is considered a potential replacement for low-density polyethylene (LDPE) as the main component of mulch film. However, it is not clear whether PBAT is harmful to the plant-soil system. Thus, we determined the effects of LDPE microplastics (LDPE-MPs) and PBAT microplastics (PBAT-MPs) on the growth of Arabidopsis. The inhibitory effect of PBAT-MPs was greater than that of LDPE-MPs on the growth of Arabidopsis. Transcriptome analysis showed that PBAT-MPs severely disrupted the photosynthetic system of Arabidopsis and increased the expression levels of genes in drug transport-related pathways. PBAT-MPs increased the relative abundances of Bradyrhizobium, Hydrogenophaga, and Arthrobacter in the bulk soil and rhizosphere soil. The abundances of Variovorax, Flavobacterium, and Microbacterium increased in the plant root zone only under PBAT-MPs. Functional prediction analysis suggested that microorganisms in the soil and plant root zone could degrade xenobiotics. Furthermore, the degradation products from PBAT comprising adipic acid, terephthalic acid, and butanediol were more toxic than PBAT-MPs. Our findings demonstrate that PBAT-MPs may be degraded by microorganisms to produce chemicals that are highly toxic to plants. Thus, biodegradable plastics may pose a great risk to the environment.

Ecotoxicity of the Adipate Plasticizers: Influence of the Structure of the Alcohol Substituent.

A significant increase in the production of plastic materials and the expansion of their areas of application contributed to the accumulation of a large amount of waste of polymeric materials. Most of the polymer composition is made up of plasticizers. Phthalate plasticizers have been recognized as potentially hazardous to humans and the environment due to the long period of their biodegradation and the formation of persistent toxic metabolites. It is known that the industrial plasticizer dioctyl adipate is characterized by reduced toxicity and a short biodegradation period. The paper describes the synthesis of a number of new asymmetric esters based on adipic acid and ethoxylated butanol by azeotropic esterification. The receipt of the products was confirmed by IR spectra. The physicochemical properties of the synthesized compounds were investigated. The glass transition temperatures of PVC composites plasticized with alkyl butoxyethyl adipates were determined using DSC analysis. The ecological safety of esters was assessed by the phytotesting method. Samples of adipates were tested for fungal resistance, and the process of their biodegradation in soil was also studied. It is shown that the synthesized esters have good plasticizing properties and are environmentally safe. When utilized under natural conditions, they can serve as a potential source of carbon for soil microorganisms and do not form stable toxic metabolites; therefore, they are not able to accumulate in nature; when the plasticizers under study are disposed of in the soil, toxic substances do not enter.

Di(2-ethylhexyl) adipate plasticizer triggers hepatic, brain, and cardiac injury in rats: Mitigating effect of Peganum harmala oil.

Di(2-ethylhexyl) adipate (DEHA) is a widely used plasticizer and prevalent environmental contaminant. In this study, DEHA concentrations in the milk, cheese, and butter samples wrapped with food-grade commercial polyethylene films and stored at 4 °C for 30 days were detected using gas chromatographic analysis. Also, the effects of exposure to a high dose of DEHA for a long duration on the liver, brain, and heart of Wistar rats were assessed. Besides, the possible beneficial effect of Peganum harmala oil (PGO), in relieving DEHA induced adverse effects was explored. For this purpose, four groups (8 rats/group) were orally given physiological saline, PGO (320 mg/kg bwt), DEHA (2000 mg/kg bwt), or PGO + DEHA for 60 days. The results revealed that the DEHA concentrations in the tested dairy products were ordered as follows: (butter > cheese > milk). Notably, the detected levels in butter were higher than the specific migration limit in foods. DEHA induced a significant increase in the serum levels of glucose, alanine transaminase, aspartate transaminase, acetylcholine esterase, creatine kinase-myocardium bound, malondialdehyde, tumor necrosis factor-α, and interleukin-1ß. But, significant hypoproteinemia, hypoalbuminemia, hypoglobulinemia, and hypocholesterolemia were evident following DEHA exposure. A significant reduction in the serum level of superoxide dismutase, reduced glutathione, and brain-derived neurotrophic factor was recorded. Besides, a significant downregulation in hepatic CYP2E1, brain glial fibrillary acidic protein, and cardiac troponin I gene expression was noticed. Moreover, DEHA exposure induced a significant decrease in Bcl-2 immunolabeling, but Caspase-3 immunoexpression was increased. On the contrary, PGO significantly recused DEHA injurious impacts. Therefore, PGO could represent a promising agent for preventing DEHA-induced hepatotoxicity, neurotoxicity, and cardiotoxicity.

Migration studies and toxicity evaluation of cyclic polyesters oligomers from food packaging adhesives.

Multilayer materials used in food packaging are commonly manufactured with a polyurethane adhesive layer in its structure that may contain cyclic esters oligomers as potential migrants. However, little is known about their toxicity. In this work, two cyclic esters of polyurethane are evaluated in migration from 20 multilayer packaging samples. They were composed by adipic acid (AA), diethylene glycol (DEG) and isophthalic acid (IPA) and their structure was AA-DEG and AA-DEG-IPA-DEG. The concentration of these compounds in migration exceeded the maximum level established by Regulation EU/10/2011 (10 ng g-1). Bioaccessibility of both compounds was evaluated by studying gastric and intestinal digestion. The studies showed that the concentration of the compounds decreased during digestion and that their hydrolysed molecules increased. Furthermore, endocrine activity in vitro assays were performed. A weak androgen receptor antagonism was identified, whereas no arylhydrocarbon receptor activity or binding to the thyroid hormone transport protein was found.

A crosslinking strategy to make neutral polysaccharide nanofibers robust and biocompatible: With konjac glucomannan as an example.

Neutral polysaccharides such as konjac glucomannan, starch and pullulan are abundant in nature and have unique property. Their nanofibers hold great potential for biomedicine, which however, are seldom applied in the field due to the lack of crosslinking method. In this work, we report a periodate oxidation - adipic acid dihydrazide (ADH) crosslinking strategy to prepare robust and biocompatible neutral polysaccharide nanofibers. Neutral polysaccharides with adjacent dihydroxyl groups are firstly partially oxidized with periodate to give dialdehyde polysaccharides, and their electrospun nanofibers are then crosslinked with ADH to form dihydrazone crosslinkers. The resulting crosslinked neutral polysaccharide nanofibers exhibit high water resistance and excellent mechanical properties because of the high reactivity of Schiff base crosslinking reaction. Moreover, the crosslinked neutral polysaccharide nanofibers show good biocompatibility due to the low toxicity of ADH. These robust and biocompatible neutral polysaccharide nanofibers are expected to seek extensive applications in a variety of biomedical fields.

Systemic toxicity of di (2-ethylhexyl) adipate (DEHA) in rats following 28-day intravenous exposure.

Di (2-ethylhexyl) adipate (DEHA) is a potential plasticizer alternative for di-2-ethylhexyl phthalate (DEHP). Toxicity of DEHA has been studied mostly via oral exposure but not assessed after repeated intravenous exposure. The present study shows the toxicity effects after intravenous administration for 28 consecutive days and the reversibility of the effects following a 14-day recovery period. The study was conducted under GLP conditions. Four groups of rats (15/sex/group) each received either vehicle or DEHA in vehicle (100, 200, or 450 mg/kg/day). Criteria for evaluation included clinical observations, body weight, food consumption, clinical pathology (hematology, serum chemistry, coagulation, urinalyses), gross (necropsy) evaluation, organ weight and histopathological evaluation. There were no DEHA-related changes in all the endpoints evaluated at 100 or 200 mg/kg/day. There were no test article-related changes in clinical pathology or gross necropsy observation at 450 mg/kg/day. At the high-dose, DEHA-related findings included clinical observations, decreased body weight gain and food consumption, increased liver weight in females associated with minimal hepatocellular hypertrophy, and decreased thymus weight in males and females without histopathology findings. All these findings were completely reversible within a 14-day recovery period. Therefore, the 200 mg/kg/day dose is considered to be the No-Observed-Effect Level (NOEL).

Detection and quantification analysis of chemical migrants in plastic food contact products.

Plastic food contact materials (FCM)-based products were widely used in everyday life. These products were normally imposed to strict regulations in order to pass the enforcement tests of compliance as a prefix condition. However, even in these "qualified" materials, unknown chemical substances, not involving in legislation lists, could migrate from FCM. In this perspective, the present work aims to thoroughly analyze by means of Gas Chromatography-Mass Spectrometry (GC-MS) the different substances/migrants in 120 qualified FCM plastic products. Unexpectedly, among the identified compounds (nearly 100), only 13% was included in the permitted list of Commission Regulation EU No 10/2011. All the identified compounds were classified into 11 categories according to their chemical structure and the FCM type, whereas toxicology data were in addition analyzed. Each plastic type exhibited different preferences of chemical migrants. Fortunately, most of the compounds identified were of low toxicity, and only 4 chemicals were included in priority lists and previous literature reports as potential risk factors. Subsequently, the accurate amount of these 4 chemicals was determined. The amount of Bis(2-ethylhexyl) adipate (DEHA) and Bis(2-ethylhexyl) phthalate (DEHP) were lower than the SML in Commission Regulation EU No 10/2011, and that of stearamide was under the recommended use quantity. The 2,4-di-tert-butylphenol (2,4-DTBP) was widely exist in the investigated FCM products. Among them, the highest level is obtained in polypropylene/low density polyethylene (BOPP/LDPE) materials, up to 45.568±31.513 mg/kg. In summary, a panel of unlisted chemical migrants were discovered and identified by GS-MS screening. The results implied that plastic FCMs were not so "inert" as they usually considered, and further safety evaluation should be performed toward the complete identification of new substances in FCM products.

Stress-Induced Transcriptional Changes and DNA Damage Associated with Bis(2-ethylhexyl) Adipate Exposure in Zebrafish (Danio rerio) Larvae.

The present study evaluates potential toxic effects of bis(2-ethylhexyl) adipate (DEHA) plasticizer to larval (72 h post fertilization) zebrafish (Danio rerio) by analyzing changes in expression levels of stress-related genes (p53, rad51 and xrcc5) and assessing possible DNA damage of DEHA in larvae. The lethal concentration for 50% mortality (LC50) in larval zebrafish exposed for 96 h to 0-200 mg L-1 DEHA was 89.9 ± 8.03 mg L-1. A concentration-dependent increase in DNA strand breaks was detected in cells from larvae exposed for 96 h to DEHA. There were some significant differences in induction of stress-related genes in larvae exposed to DEHA relative to control.

Mechanism of diethylhexylphthalate (DEHP) induced testicular damage and of grape seed extract-induced protection in the rat.

The aim of this study was to determine the effect of diethylhexylphthalate (DEHP) on testicular mitochondrial viability and lipid peroxidation as a possible novel mechanism of PEHP testicular toxicity and whether grape seed extract (GSE) beneficially influences the mitochondrial function in testes of rats exposed to diethylhexylphthalate (DEHP). Sixty male albino rats were divided into three groups (n = 20): group I: was used as a control, group II: received diethylhexylphthalate (DEHP) (500 mg/kg/day orally) alone for 30 days, and group III: received the same DEHP dose in combination with GSE (proanthocyanidins) (100 mg/kg body weight). DEHP administration significantly decreases the testicular mitochondrial viability, mRNA expression of androgen receptors (AR), testosterone hormone concentration, increases mRNA expression of INOS and as compared to control group. It also decreases reduced glutathione (GSH) concentration, glutathione reductase (GR), super oxide dismutase (SOD), Catalase activities and increases lipid peroxidation (LPO) and DNA fragmentation%. In synchronization, a substantial decrease of testicular & epididymal weight and volume which accompanied by considerable alteration of semen character. Grape seed extract (GSE) alleviates the toxic effects of DEHP by increasing the mitochondrial viability, decreases the lipid peroxidation, and increases the testicular antioxidant activity. Our results were confirmed by histopathological and immunhistochemical studies.

Correlation of foodstuffs with ethanol-water mixtures with regard to the solubility of migrants from food contact materials.

Today most foods are available in a packed form. During storage, the migration of chemical substances from food packaging materials into food may occur and may therefore be a potential source of consumer exposure. To protect the consumer, standard migration tests are laid down in Regulation (EU) No. 10/2011. When using those migration tests and applying additional conservative conventions, estimated exposure is linked with large uncertainties including a certain margin of safety. Thus the research project FACET was initiated within the 7th Framework Programme of the European Commission with the aim of developing a probabilistic migration modelling framework which allows one (1) to calculate migration into foods under real conditions of use; and (2) to deliver realistic concentration estimates for consumer exposure modelling for complex packaging materials (including multi-material multilayer structures). The aim was to carry out within the framework of the FACET project a comprehensive systematic study on the solubility behaviour of foodstuffs for potentially migrating organic chemicals. Therefore a rapid and convenient method was established to obtain partition coefficients between polymer and food, KP/F. With this method approximately 700 time-dependent kinetic experiments from spiked polyethylene films were performed using model migrants, foods and ethanol-water mixtures. The partition coefficients of migrants between polymer and food (KP/F) were compared with those obtained using ethanol-water mixtures (KP/F's) to investigate whether an allocation of food groups with common migration behaviour to certain ethanol-water mixtures could be made. These studies have confirmed that the solubility of a migrant is mainly dependent on the fat content in the food and on the ethanol concentration of ethanol-water mixtures. Therefore dissolution properties of generic food groups for migrants can be assigned to those of ethanol-water mixtures. All foodstuffs (including dry foods) when allocated to FACET model food group codes can be classified into a reduced number of food categories each represented by a corresponding ethanol-water equivalency.

Safety assessment of bis-diglyceryl polyacyladipate-2 and bis-diglyceryl polyacyladipate-1 as used in cosmetics.

The Cosmetic Ingredient Review Expert Panel assessed the safety of bis-diglyceryl polyacyladipate-2 and bis-diglyceryl polyacyladipate-1 as used in cosmetics, finding that these ingredients are safe in cosmetic formulations in the present practices of use and concentration. Both ingredients are lanolin substitutes and are reported to function in cosmetics as skin-conditioning agents--emollients. The Panel reviewed available animal and clinical data in making its determination of safety.

Uncommon occupational lung diseases: high-resolution CT findings.

OBJECTIVE: The purpose of this article is to describe the high-resolution CT (HRCT) features of uncommon occupational lung diseases. CONCLUSION: HRCT plays an increasing role in the evaluation of occupational lung diseases. We present several cases of unusual occupational lung diseases and their HRCT findings. The diseases studied were siderosis, talcosis, berylliosis, calcicosis, hypersensitivity pneumonitis (due to wheat flour and isocyanates), and Ardystil syndrome. The characteristic HRCT findings together with clinical features and related occupational history improve the diagnostic accuracy of these diseases.

Collaborative work on evaluation of ovarian toxicity. 9) Effects of 2- or 4-week repeated dose studies and fertility study of di(2-ethylhexyl)adipate (DEHA) in female rats.

The present study was designed to confirm whether or not the ovarian toxicity of di(2-ethylhexyl)adipate (DEHA), which is known to have effects on female fertility, could be evaluated by the new method of histopathological examination of the ovaries in repeated dose toxicity. DEHA was orally administered to Crl:CD(SD) female rats at the doses of 0, 200, 1,000 and 2,000 mg/kg for 2 or 4 weeks in repeated dose toxicity study and for 2 weeks before mating, throughout mating and until Gestation Days 7 in female fertility. In the repeated dose toxicity studies, increase in atresia of large follicle, decrease in currently formed corpus luteum and follicular cyst were observed in the 1,000 mg/kg and above groups, suggesting that DEHA disturbed ovulation and large follicle growth. In the fertility study, a significant increase in mean estrus cycle length and post-implantation loss rate were observed in the 1,000 mg/kg and above groups, and a significant decrease in implantation rate and number of live embryos and a significant increase in pre-implantation loss rate were observed in the 2,000 mg/kg group. The histopathological changes of ovary observed in the repeated dose toxicity studies were correlated with the result that DEHA affected the estrus cycle in the female fertility study. In conclusion, a 2-week administration period is sufficient for detection of the ovarian toxicities following treatment with DEHA by new histopathological examination of the ovaries.

Aqueous solubility and Daphnia magna chronic toxicity of di(2-ethylhexyl) adipate.

A water solubility of 5.5 (+/-0.22) microg/L for di(2-ethylhexyl) adipate (DEHA) was measured using the slow-stir method. This value is consistent with computer estimations and over two orders of magnitude lower than that previously determined using the shake-flask method. We performed a 21-day chronic Daphnia magna limit test at an average exposure of 4.4 microg/L in laboratory diluent water to avoid insoluble test material and avoid physical entrapment. One hundred percent of the DEHA-treated organisms survived compared to 90% survival in both the controls and solvent controls. Mean neonate reproduction was 152, 137, and 148 and mean dry weight per surviving female was 0.804, 0.779, and 0.742 mg in the DEHA treatment, control, and solvent control, respectively. No adverse effects were observed.

Plasticizers and related toxic degradation products in wastewater sludges.

Plasticizers can persist during the treatment of wastewaters in sewage treatment plants (STPs) and can be discharged in effluents and/or accumulated in sewage sludges. For example, di-2-ethylhexyl phthalate (DEHP) is a common plasticizer that is now considered a priority pollutant and is known to accumulate in sludges. This may add constraints to the exploitation of the beneficial uses of sludges that contain significant quantities of plasticizers. Recently, it was demonstrated in studies with pure cultures that the biodegradation of plasticizers including DEHP and di-ethylhexyl adipate (DEHA) generates toxic metabolites including 2-ethylhexanoic acid, 2-ethylhexanol, and 2-ethylhexanal. However, the environmental impacts and fate of the degradation products arising from plasticizers are unknown. Therefore, this work investigated the concentrations of DEHP and DEHA and their metabolites in the sludges from several STPs in Quebec, Canada. DEHP and DEHA were found in concentrations ranging from 15 to 346 mg kg(-1) and 4 to 743 mg kg(-1), respectively, in primary, secondary, digested, dewatered or dried sludges. Metabolites were detected in almost all sludges, except those that had undergone a drying process at high temperature. It is concluded that sludges can represent significant sources of plasticizers and their toxic metabolites in the environment.

Effect of surfactants on plasticizer biodegradation by Bacillus subtilis ATCC 6633.

The biodegradation of plasticizers has been previously shown to result in the accumulation of metabolites that are more toxic than the initial compound. The present work shows that the pattern of degradation of di-2-ethylhexyl adipate by Bacillus subtilis can be significantly altered by the presence of biosurfactants, such as surfactin, or synthetic surfactants, such as Pluronic L122. In particular, this work confirms that the monoester, mono-2-ethylhexyl adipate, is a metabolite in the breakdown of the plasticizer. This metabolite was proposed but not observed in earlier studies. Toxicity measurements showed it to be significantly more toxic than the plasticizer. Thus, the effect of the surfactants was to significantly increase the accumulation of one or both of the two most toxic metabolites; i.e., the monoester and 2-ethylhexanol. It was proposed that the most likely cause of the effect of the surfactants was the sequestering of these two metabolites into mixed micelles, resulting in their reduced availability for further degradation.

Toxicity of di(2-ethylhexyl)phthalate (DEHP) and di(2-ethylhexyl)adipate (DEHA) under conditions of renal dysfunction induced with folic acid in rats: enhancement of male reproductive toxicity of DEHP is associated with an increase of the mono-derivative.

F344 male rats were given five consecutive weekly subcutaneous injections of folic acid for induction of chronic renal dysfunction and then di(2-ethylhexyl)phthalate (DEHP) or di(2-ethylhexyl)adipate (DEHA) in the diet at a concentration of 0, 6000 or 25,000 ppm for 4 weeks in order to investigate whether male reproductive toxicity of the two chemicals might be enhanced under conditions of renal disease. Control animals also received DEHP or DEHA in the same manner but without folic acid pretreatment. Decreased testicular weights, seminiferous atrophy with vacuolization of sertoli cells and diminished sperm counts were more prominent in rats given folic acid and then 25,000 ppm DEHP as compared to those exposed to DEHP alone. No such reproductive toxicity was evident in rats given 6000 ppm DEHP or either dose of DEHA. An increased concentration of the mono-derivative of DEHP (mono(2-ethylhexyl)phthalate, MEHP) in the blood, testis and urine was considered relevant to the enhanced reproductive toxicity observed with DEHP.

Subacute oral toxicity study of di(2-ethylhexyl)adipate based on the draft protocol for the "Enhanced OECD Test Guideline no. 407".

We performed a 28-day repeated-dose toxicity study of di(2-ethylhexyl)adipate (DEHA) based on the draft protocol of the "Enhanced OECD Test Guideline 407" to investigate whether it has endocrine-mediated properties according to this assay. DEHA was orally administered to SD rats at doses of 0, 40, 200 and 1,000 mg/kg/day for at least 28 days, and disturbance of the estrous cycle and increased ovarian follicle atresia were detected in the 1,000 mg/kg group.

Testicular toxicity of DEHP, but not DEHA, is elevated under conditions of thioacetamide-induced liver damage.

As part of an investigation of possible enhancement by liver disease of testicular toxicity caused by phthalates, we tested the effects of di(2-ethylhexyl)phthalate (DEHP) and di(2-ethylhexyl)adipate (DEHA) in a thioacetamide (TAA)-induced rat liver damage model. Male, 6-week-old, F344 rats (n=60) were divided into ten groups. Animals of groups 1-5 received TAA (200 mg/kg, intraperitoneal, three times per week) for 4 weeks, and groups 6-10 served as controls without TAA. After a 1 week interval, at week 5, powder diet containing DEHP or DEHA was provided to the animals of groups 1 and 6 (DEHP 25000 ppm), groups 2 and 7 (DEHP 6000 ppm), groups 3 and 8 (DEHA 25000 ppm) and groups 4 and 9 (DEHA 6000 ppm), while groups 5 and 10 received basal diet. All animals were sacrificed at week 9. Significant decrease in sperm numbers and motility and increase in morphology abnormalities were evident in group 1 as compared to groups 5 and 6 (p<0.01). However, DEHA treatment was not associated with any apparent testicular toxicity in either TAA- or vehicle-treated animals. Histopathological examination of the testes revealed severe atrophy and degeneration of testicular tubules in all animals given TAA and DEHP at high dose, only mild to moderate lesions being found with DEHP alone. We conclude that liver toxicity induced by TAA is associated with the enhancement of testicular toxicity of DEHP, but not DEHA, in rats.