The effectiveness of the Australian pesticide regulatory system: A case study on chlorpyrifos exposure among an urban South Australian population

Author: Maisarah Nasution Binti Waras

Waras, Maisarah Nasution Binti, 2020 The effectiveness of the Australian pesticide regulatory system: A case study on chlorpyrifos exposure among an urban South Australian population, Flinders University, College of Science and Engineering

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Australia has a well-developed agricultural industry with 394 million hectares of agricultural land out of 769 million hectares total land area. Agricultural pesticides are used on 73% of the total value of crops produced. In most countries, Australia included, exposure to pesticides is controlled by having regulations to restrict this chemical usage for the purpose of protecting the people and environment. Presently, there is no exposure monitoring programs to evaluate the effectiveness of pesticide regulation in Australia in controlling the population exposure to pesticides.

To understand the basis of Australian pesticide regulation, the differences between the regulatory systems in Australia (AU) and the European Union (EU) are explored in Chapter 2. It was discovered that the assessment to authorize a pesticide in the EU is based on the hazard of the pesticides. If a pesticide is not classified as hazardous, the pesticides will proceed to the next level of assessment. On the other hand, the assessment to authorize a pesticide in Australia is based on risks (the likelihood of being exposed to the pesticides and the potential of effects of the exposure to the pesticide). There is not any registration review period set for an active substance authorised in Australia. A registered active substance can be authorized for used until it is nominated for reconsideration. In contrast, active constituents are authorized for use in the EU for 10 years only. The Australian reconsideration process is conducted on an ad-hoc basis. This is concerning because as more research is conducted on various chemicals, a pesticide registered a number of years ago maybe uncovered to be more of a hazard than previously thought. Unless regular scientific review process is built into a regulatory system, there is a risk of hazardous pesticides continuing to be used. Another matter that is of concern is there are no regular systematic comprehensive chemical residue surveys for food commodities conducted in Australia. Therefore, we cannot make any formal conclusion on what pesticide residues are consumed by the Australian public. On the other hand, the EU has a systematic monitoring program called the National Control Programmes which are reported every year.

To understand the effectiveness of pesticide regulation in Australia, this thesis narrowed down its focus on the restriction of chlorpyrifos (CPF) use among the general public of Australia introduced in 2000- 2001. The restrictions were introduced as a result of CPF review that was undertaken by APVMA as part of the reconsideration process. The reconsideration process was triggered by extensive reviews and regulatory changes to chlorpyrifos registration in other jurisdictions (US and EU). Chapter 3 describes the literature review conducted to explore the availability of exposure data among the Australian population. The literature review revealed that the monitoring of CPF exposure among the Australian public is not done extensively. Pesticide contamination in food is not monitored frequently and systematically in Australia too. Therefore, we do not know the extent of CPF or any pesticides exposure among the Australian public. For this reason, there is not enough information to evaluate the effectiveness of Australian pesticide regulatory system to control pesticide exposure among the public. Particularly, the effectiveness of CPF use restriction introduced among the general public of Australia in 2000-2001 has not been reported because of the limited exposure monitoring done.

This thesis intended to address this gap by investigating the extent of chlorpyrifos exposures of an urban South Australia population after the interim regulatory measures introduced in 2000-2001. The overall aim of this thesis is to investigate the CPF exposure among an urban population in South Australia after the implementation of the said interim regulatory measures. Biomonitoring approach was chosen to be the means to investigate the exposure of CPF among the said population. Urinary 3,5,6-trichloro-2-pyridinol (TCPy) was selected as the biomarker of exposure for the study population, which was comprised of a random sample of adults and children. An analytical method was developed to analysed urinary TCPy as described in Chapter 4. Urinary TCPy of the collected sample was analysed with GCMS with modified QuEChERS extraction.

Analyses of urinary TCPy for the population of this study were compared in Chapter 5 with a study conducted in 2003-2006 when the implementation of restrictions of CPF usage was at the initial stage. The comparison revealed that there is a 76% decrease in the frequency of detection of urinary TCPy among this population. Moreover, the P95 level of this population is 0 ug/g (non-detected) whereas it was 12.5 ug/g in the 2003-2006 study. The range of concentration of TCPy in this study is 0- 69.53 µg/g while it was < LOD- 217.9 µg/g in the 2003-2006 study. We found that the CPF exposure among the urban South Australia population in this research has decreased seemingly because of the restriction of high concentration of CPF among the public of Australia. The findings of this study are unique and valuable in investigating the effectiveness of some parts as well as the whole Australian pesticide regulatory system.

Keywords: pesticide exposure, chlorpyrifos, General population, biomonitoring, pesticides regulations, public health, pesticide metabolite, urine, humans, South Australia, public health policy, GC-MS, organophosphorus compound, environmental exposure

Subject: Chemistry thesis

Thesis type: Doctor of Philosophy
Completed: 2020
School: College of Science and Engineering
Supervisor: Prof. Claire Lenehan