Researcher Highlights
The Toxic Avenger

The goal of Dr Ayanka Wijayawardena's research is to perfect testing methods for the bioavailability of heavy metals (including metalloids) to precisely inform human and environmental health risk assessment processes.

Although naturally occurring within the earth, heavy metals (including metalloids) can become dangerously concentrated through human activity, such as industrial waste disposal.

Assessing the threat these contamination sites pose to human and environmental health is the first and most essential step in the remediation process.

Ayanka believes that accurate predictions pertaining to the bioavailability of contaminants is an essential factor in the risk assessment equation.

"Bioavailability is a concept which has many definitions depending on the sector in which it is being used," Ayanka explains.

"Simply speaking, the bioavailability of a contaminant is expressed as the fraction of contaminant - heavy metals in our case - that crosses gastrointestinal lining and therefore becomes available to react with metabolic machinery in the body."

A Research Fellow at the Global Centre for Environmental Remediation, Ayanka's expertise in the area of toxicology means she is well positioned to minimise uncertainty in the risk assessment of contaminants.

"My ultimate goal is to come up with more reliable and cost effective methods for contaminant bioavailability testing," she adds.

CONTAMINATION AND REMEDIATION

A significant global issue, heavy metal contamination in Australia is generally a historical by-product of energy, manufacturing and processing industries.

It is believed that around 60% of contaminated sites are located within urban environments, creating significant potential for human exposure to contaminants.

The Environment Protection Authority lists close to 1400 contaminated sites in NSW, including long closed industrial areas, quarries and currently operating service stations. More than 10% of those sites are situated within the Hunter. 

Once a site is known to be contaminated, it must be remediated, or 'cleaned', for safe use before rehabilitation can take place.

Heavy metal contaminants can be difficult to contain, obtaining release through wind, water, and soil movement. They may enter the human body through ingestation, inhalation, or surface contact, or enter the food chain through absorption by plants and animals.

It is this process, through which contaminants enter the body that interests Ayanka.

"As a scientist, I believe we should be more worried about the fraction of a contaminant that poses the actual risk to the human and environmental health as opposed to the total contamination itself," she says. 

HAND-TO-MOUTH RISKS

Ayanka notes that not all heavy metals are toxic to the human body, in fact, some are essential to health.

"Some heavy metals, such as zinc and copper contribute to the healthy functioning of organisms at low concentrations. In excessive concentration, however, they become toxic," Ayanka notes. 

"Lead, on the other hand, is an example of a heavy metal that has no known biological function. It is also non-biodegradable. It may accumulate in living organisms, where it can cause illness and disease."

The human body has difficulty metabolising toxic heavy metals, which may lead to bioaccumulation. They can bind to cells, interfering with healthy cellular function.

This in turn can lead to a myriad of health complications, depending on the metal involved in the contamination.

"Some groups are more prone to coming into contact with contaminants and are showing resultant health issues related to toxicities compared to other groups," Ayanka states.

"For example, toddlers' hand-to-mouth behaviour puts them at a greater risk of heavy metal related risks."

"As a scientist, a responsible citizen, and a mother of two, I am concerned about the health and safety of the community. This drives my research."

A RISING STAR

Ayanka is well-versed in the study of the bioavailability of compounds.

She began her research career with a Bachelor of Science (Pharmacy) with Honors from the University of Colombo, Sri Lanka, for which she was awarded the Astron scholarship and the Gulamhusein A. J. Noorbhai gold medal for pharmacy in recognition of her excellent performance.

She went on to create the course material for the undergraduate toxicology course at the Open University of Sri Lanka.

Ayanka then joined the South Asian Clinical Toxicology Research Collaboration (SACTRC) as an analytical chemist based at the University of Peradeniya, Sri Lanka. 

Partly funded by an National Health and Medical Research Council (NHMRC) International Collaborative Research Grant, SACTRC's research focus is acute pesticide toxicity, a major public health issue in Sri Lanka and Asia. 

A stint in the USA followed, where Ayanka earned a Masters of Medical Biology, with a specialisation in medical microbiology and immunology, from Long Island University, New York, USA.

Once she returned to Sri Lanka she taught in the areas of pharmacognosy and pharmaceutical microbiology as a visiting lecturer at the University of Colombo.

Ayanka then joined the Faculty of Medical Sciences at the University of Sri Jayewardenepura and taught undergraduate courses in hospital pharmacy, pharmacognosy, pharmaceutical microbiology, pharmaceutics and conducted practical classes on pharmacognosy and pharmaceutical microbiology for B.Pharm undergraduate students.

CARING FOR THE ENVIRONMENT

Ayanka then completed a PhD in Environmental Remediation and Public Health at the University of South Australia, on bioavailability and human health risk of heavy metal(loid)s.

Focusing on four main types of heavy metals - arsenic, zinc, lead and cadmium, her PhD thesis delivered new knowledge on metal biotransformation, metal-metal interactions, metal bioaccumulation, bioavailability and toxicity with respect to ecological as well as human health.

She used swine models to test the toxicity of heavy metals, applying a two compartment pharmacokinetic model to calculate pharmacokinetic data.

The effect of heavy metal toxicity on avoidance behavior, mortality and weight loss of earthworms (Eisenia fetida) were also investigated in Ayanka's study of the effect of heavy metals on ecological health.

In 2013, Ayanka was chosen to present at the 7^th International Workshop on Chemical Availability in Keyworth, Nottingham in the United Kingdom.

Whilst in the UK, Ayanka observed novel bioavailability testing methods presented by the British Geological Survey, a pioneering research centre in her field. 

A visit to the former Avenue Coking Works, once one of the most polluted sites in Europe, presented Ayanka with an opportunity to observe best practice international remediation processes in the field.

COLLABORATIVE POWERS

During her time in Adelaide, Ayanka joined the Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), Australia's leading contamination and remediation research centre.

In early 2015, the head office of CRC CARE moved from the University of South Australia to the Callaghan campus of the University of Newcastle, to capture fresh opportunities in industrial clean-up through close collaboration with the flagship Newcastle Institute for Energy and Resources (NIER).

Ayanka, and several of her CRC CARE University of South Australia colleagues, made the move to Newcastle to start the Global Centre for Environmental Remediation (GCER) at the University of Newcastle.

Still working in close collaboration with the University of South Australia node, the University of Newcastle CRC CARE cohort join a virtual network of 28 different research, industry and government organisations, covering the whole of Australia and extending research with partners in China, India, Bangladesh and South Korea.

Ayanka and her colleagues at GCER are currently undertaking a study investigating the effect of sources, and soil properties, on the bioavailability of arsenic and lead.

This project sees the GCER team collaborating with Lancaster University, UK and British Geological Survey, UK.