Seminar Series

Postgraduate Talks:

Speaker

Gemma Wadworth: Impacts of Antimicrobial Compounds in Urban Waterways Receiving Sewer Overflows Nicholas McKitterick: Dibutyl Phthalate (DBP) Regulates Key Genes in Testosterone Biosynthesis

Institute

Time & Place

Mon, 01 Feb 2016 16:00:00 NZDT in Room 531

All are welcome

Abstract

Impacts of antimicrobial compounds in urban waterways receiving sewer overflows: 

Pharmaceuticals and personal care products (PPCPs) are used every day in households resulting in the release of chemical ingredients, along with degradation products, into the environment. There is growing concern regarding the risk PPCPs, including antimicrobial compounds and parabens pose to human and ecosystem health. Personal care products can contain antimicrobial compounds which are designed to kill or prevent the growth of potentially harmful microorganisms. The release of domestic wastewater into streams via sewer overflows can result in non-target microorganisms being exposed to antimicrobial compounds. Resulting changes to the benthic microbial structures have the potential to alter the nutrient processing capacity and natural food web structure of affected streams. There is limited data available regarding the occurrence and impact of PPCPs in New Zealand waterways. This project aims to provide baseline data on the fate and potential effects of a suite of phenolic antimicrobial compounds including triclosan and paraben preservatives in two urban streams in the city of Christchurch, New Zealand. Water and sediment samples collected from two Christchurch urban streams at upstream and downstream sites of sewer overflow outfalls over a 6 month period will be analysed by GC-MS. The data obtained from the stream water and sediment samples will be discussed along with the implications for urban streams receiving inputs of these contaminants via waste water overflows.

Dibutyl Phthalate (DBP) Regulates Key Genes in Testosterone Biosynthesis:

Dibutyl phthalate (DBP), a widespread environmental contaminant has well known antiandrogenic like effects in males. High dose exposure in animals has been shown to produce serious developmental effects in male offspring; namely, hypospadias (defect of the urethra), cryptorchidism (undescended testes) and reductions in anogenital distance. Human data are scarce, however, DBP exposure has been linked to increased incidences of developmental disorders; particularly the male offspring of soldiers exposed to high levels of DBP in the Malayan Emergency (1948-1960). To date, no mechanism of toxicity has been established. To investigate the potential mechanism of toxicity, cultured rat Leydig cells (LC-540) were exposed to DBP at two levels: the daily (0.1 µg/mL) and industrial (1 µg/mL) exposure of humans. The expression of key genes in the steroidogenesis pathway were then analysed using the nanostring® gene expression assay. A background ‘no-gene expression’ (NE) threshold level was calculated from controls and gene expression fold-change was calculated for normalized NanoString nCounter® data for exposed cultures compared to control cultures. Several key genes in testosterone biosynthesis were affected by DBP at statistically significant levels. Therefore, the observed toxicity of DBP may be through a gene regulatory mechanism which could explain developmental toxicity observed in the offspring of exposed Malayan Emergency soldiers.