Plastic has been used in many areas such as agriculture, electronics, automotive, construction and packaging. Due to its characteristics, polyvinyl chloride (PVC) has been used as a material for water transportation and storage. However, recent studies have reported a possible leaching of chemicals from the material which may pose a threat on human health. Phthalates, a group of chemicals that can possibly be leached, are considered as endocrine disrupting chemicals (EDCs). Constituting up to 40% of the final weight of PVC, phthalates have been detected in the various bodies of water in the environment. Therefore, the leaching of phthalates from various PVC types was investigated such as unplasticised PVC (uPVC), modified unplasticised PVC (MuPVC) and tygon tube. With the presen...[ Read more ]

Plastic has been used in many areas such as agriculture, electronics, automotive, construction and packaging. Due to its characteristics, polyvinyl chloride (PVC) has been used as a material for water transportation and storage. However, recent studies have reported a possible leaching of chemicals from the material which may pose a threat on human health. Phthalates, a group of chemicals that can possibly be leached, are considered as endocrine disrupting chemicals (EDCs). Constituting up to 40% of the final weight of PVC, phthalates have been detected in the various bodies of water in the environment. Therefore, the leaching of phthalates from various PVC types was investigated such as unplasticised PVC (uPVC), modified unplasticised PVC (MuPVC) and tygon tube. With the presence of residual chlorine in water, the leaching of phthalates was accelerated compared to pure water. The intensity of detected phthalates in water increased as the concentration of chlorine was increased. The presence of phthalates led to a change in bioactivity of the water. There was a positive correlation between leached phthalates and the estrogenic activity. As an effort to study the individual phthalate, diethyl phthalate (DEP) and di(2-ethylhexyl) phthalate (DEHP) were chosen as they accounted for the largest percentage of total phthalates detected in water from three PVC types. In evaluating the impact of disinfectants on the structures of DEP and DEHP, chlorination and chloramination were conducted in water with dissolved phthalate. A reduction in the concentration of each phthalate was observed for both disinfection methods. A formation of new species was observed with DEP but not DEHP. The product of DEP from chlorination and chloramination were found to be identical which was monoethyl phthalate (MEP). The proposed mechanism for the product was hydrolysis between phthalates and hydroxide ions produced from sodium hypochlorite (NaOCl) and ammonia (NH₃). DEP and DEHP in water showed an anti-estrogenic activity which decreased after disinfection due to removal of phthalates. There was relatively low significant effect of the product on the bioactivity of water.

Keyword: phthalates, PVC, leaching, chlorination, chloramination, hydrolysis, bioactivity