Phthalates are esters of Pthalic acid, compounds mainly used as plasticisers. Phthalates are widely used chemicals which are of significant research interest as their exposure causes various consequences for human health. There are several categories of phthalates extensively used in many commercial productions with diverse uses, physicochemical properties and toxicological effects. This chapter discusses the toxicity of Phthalates and its potential risks to human health.

As commonly used chemical plasticizers in plastic products, phthalate esters had become a serious ubiquitous environmental pollutant, such as in soil of plastic film mulch culture. Microbial degradation or transformation was regarded as a suitable strategy to solve the phthalate esters pollution. Thus, a new phthalate esters degrading strain Gordonia sp. GZ-YC7 was isolated in this study, which exhibited the highest di-(2-ethylhexyl) phthalate degradation efficiency under 1000 mg/L and the strongest tolerance to 4000 mg/L. The comparative genomic analysis showed that there exist diverse degradation pathways for various phthalate esters such as di-(2-ethylhexyl) phthalate and dibutyl phthalate in Gordonia sp. GZ-YC7, which possibly contributes to its broad substrate spectrum, high degrading efficiency and high tolerance to phthalate esters. Gordonia sp. GZ-YC7 is potential for bioremediation of phthalate esters in polluted soil environments.

A bacterial strain that could effectively degrade DEHP was isolated from the activated sludge and identified as Bacillus sp. by DNA sequencing. The biochemical degradation pathway of DEHP was further analyzed by GC-MS, and the results showed that DEHP was first decomposed into phthalates (DBP). Diuretic sylycol (DEP) was then generated, and phthalates (PA) were generated by a continuous de-ehelateization reaction. Phthalic acid (PA) was oxidized, dehydrogenated, and decarboxylated into protocatechins. Protocatechins enter the TCA cycle through orthotopic ring opening.　To enhance DEHP degradation, sodium alginate and calcium chloride were used as embedding and cross-linking materials, and the strain was immobilized. The immobilization conditions were optimized via an orthogonal experiment, and the results showed that the optimal immobilization conditions were SA mass fraction of 4%, CaCl2 mass fraction of 5%, ratio of bacteria to SA of 1:1, and the crosslinking time of 6 hours. The immobilized bacteria agent was further applied to MBR systems. The results showed that the removal rate of DEHP (5mg/L) in the system by immobilized bacteria was 91.9%, which is significantly higher than that of free bacteria. The 3, 4-dioxygenase gene and microbial community dynamics were analyzed by q-PCR and Illumina Miseq sequencing. The q-PCR results showed that the number of copies of 3, 4-dioxygenase gene in the immobilized system was significantly higher than that of free bacteria. Illumina Miseq sequencing results showed that Micromonospora, Rhodococcus, Bacteroides and Pseudomonas were the dominant generas in the MBR system. The analysis of bacterial community structure indicated that immobilization technology had a positive impact on the system stability. The results implied that this immobilized technique had potential applications in DEHP wastewater treatment.

DBP and DEHP are two of the most common plasticisers used in modern industries, which have aroused a major concern over their ubiquitous occurrence and hazardous environmental effects. This study presents the first data of phthalates’ occurrence and distribution in the Maltese shoreline sand. DBP and DEHP occurrences’ was investigated in three busy and secluded beaches, respectively. Analytical determination involved quantifying DBP and DEHP from 75 samples using UPLC-MS/MS through triple repeatability. The concentrations ranged between 0.0095–0.07034 µg/g and <LOQ–0.0977 µg/g for DBP and DEHP, respectively. Statistical analysis of the comparison of phthalates in different beaches demonstrated that the occurrence of DBP and DEHP in Maltese shoreline sand varies. The differences in the occurrence of phthalates were attributed to the beaches’ topography and anthropogenic pressures. Analysis of the effects of anthropogenic activities on the occurrence of phthalates showed a positive association. Distribution analysis showed that DBP and DEHP exhibit an uneven distribution along the shoreline. Conversely, different distributions were observed at distances away from the sea. The uneven distributions observed were associated with anthropogenic activities, different chemodynamic properties and wave action. Cluster analysis was performed to prove the interactions between the phthalates’ concentrations and the characteristics of the beaches.

Humans are often exposed to various environmental contaminants, among which phthalates are prevalent due to their extensive use as plasticizers in various consumer goods. Di(2-ethylhexyl) phthalate (DEHP), a widely used phthalate, is recognized as an endocrine disruptor chemical (EDC). DEHP is reported to affect various organs. Few studies have addressed the effects of phthalates on bone. However, the effects of DEHP on the bone forming cells (osteoblasts) are obscure. The present study was peformed to determine the cytotoxic effects of DEHP on human osteoblasts in vitro and to delineate the mechansims. In this study, we exposed the human osteo-blastic cell line MG-63 to various concentrations of DEHP (1, 25, 50 and 100 µM) for 24, 48 and 72 h. Cell viability was assessed by MTT assay. Total RNA and protein were collected after 48 h treatment with 1 and 100 µM DEHP and determined for the mRNA and/or protein expression of alkaline phosphatase (ALP), sex steroid receptors (androgen and estrogen receptors), receptor activator of nuclear factor kappa-Β ligand (RANKL), runt-related transcription factor 2 (RUNX2) and peroxisome proliferator-activated receptor alpha (PPARα). The mRNA expression was stud-ied by real-time RT-PCR analysis and the protein expression was determined by western blot analysis. Statistical analyses were done by one-way analysis of variance (ANOVA) followed by the Students–Newman–Keuls (SNK) test. The exposure of MG-63 cells to DEHP caused a signifi-cant decrease in osteoblast viability in all the treatment groups and at all the time points stud-ied. Interestingly, DEHP exposure decreased the mRNA expression of ALP, a bone formation marker. DEHP had differential effects on estrogen receptor alpha (ERα) mRNA and protein ex-pression. However, DEHP treatment downregulated the mRNA and protein expression of ERβ, and androgen receptor (AR). Surprisingly, DEHP downregulated the RANKL mRNA expression. DEHP decreased the protein expression of RUNX2, the key transcription factor and master regu-lator of bone formation. Furthermore, DEHP increased the PPARα protein expression in the os-teoblasts. Importantly, DEHP increased the reactive oxygen species (ROS) molecules and thus oxidative stress in osteoblasts, as observed by increased hydrogen peroxide, hydroxyl radical levels and lipid peroxidation. On the other hand, it decreased the enzymatic and non-enzymatic antioxidant levels namely catalase, superoxide dismutase, glutathione peroxidase activity and reduced glutathione. Our study demonstrated that in vitro exposure to DEHP reduces the osteo-blast viability possibly through alterations in the oxidant-antioxidant system and modulation of the key genes involved in bone formation, highlighting the cytotoxic effects of DEHP on bone forming cells.