Dr Ayanka Wijayawardena
Global Centre for Environmental Remediation
- Phone: (02) 4913 8745
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.
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 7th 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.
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.
My research expertise is on assessing the bioavailability and human health risk of heavy metals.My research responsibilities include developing predictive tools for bioaccessibility/bioavailability of heavy metals. My career aspiration is to excel in research for the development of cutting edge technologies and knowledge to assess the bioavailability and human health risk of heavy metals and to address burning issues in medical, pharmaceutical and environmental fields.
Prior to the current position I was employed as a Research Associate at the Centre for Environmental Risk Assessment and Remediation (CERAR), UniSA (July 2014-May 2015). My research responsibilities included conducting in vivo and in vitro bioavailability studies to investigate the factors affecting the heavy metal bioavailability/bioaccessibility in human and ecological health.
I completed my PhD in Environmental Remediation and Public Health at the University of South Australia. My PhD thesis focused on four main types of heavy metals - arsenic, zinc, lead and cadmium. My PhD study delivered new knowledge on metal biotransformation, metal-metal interactions, metal bioaccumulation, bioavailability and toxicity with respect to ecological as well as human health. I was awarded University President Scholarship and CRC CARE PhD top up scholarship for my doctoral study. During my PhD study period I was awarded Best student poster award for the CRC CARE project during the Communicate12 conference in September 2012 in Adelaide, Australia. I also won the first place in Bright ideas competition held by CRCCARE in 2012. I was awarded UniSA travel grant to deliver an oral presentation in the 7th International workshop on chemical bioavailability in Keyworth, Nottingham, UK (4th – 7th November 2013).
Prior to commencing PhD at UniSA, I was employed as a Lecturer in Pharmacy, University of Sri Jayewardenapura, Sri Lanka (12th Jan 09-2014). During this period I delivered lectures on Hospital pharmacy, Pharmacognosy, Pharmaceutical Microbiology, pharmaceutics and conducted practical classes on Pharmacognosy and Pharmaceutical Microbiology for B.Pharm undergraduates. I have performed my duties as a member of the Panel of Examiners in Pharmacy in the Ceylon Medical College Council for Pharmacists’ Internal Examination held in October 2009. I also performed duties as a Lecturer for the Diploma in community Pharmacy course organized by Pharmaceutical Society of Sri Lanka (June 2009). I was a visiting lecturer in Department of Chemistry, University of Colombo from February 2008 to December 2008. During this time I delivered lectures on Pharmacognosy and Pharmaceutical Microbiology for 3rd and 4th year BSc (Pharmacy) undergraduates. I was the Toxicology unit author for writing Toxicology course materials for B.Pharm undergraduates, Open University of Sri Lanka (01.05.2008-31.10.2008). I was an analytical Chemist in South Asian Toxicology Research Collaboration (SACTRC), Faculty of Medicine, University of Peradeniya from April 2008 to January 2009. During this period I worked in the South Asian Clinical Toxicology Research Collaoraboration (SACTRC www.sactrc.org). It is in an international group based in Sri Lanka but funded by the Welcome Trust and the National Health and Medical Research Council (NHMRC) of Australia International Collaborative Research Grant (GR071669MA). SACTRC’s research focus is on acute toxicity of pesticides as this is a major public health problem in Sri Lanka and Asia.
I completed my MSc in Medical Biology with specialization in Medical Microbiology in 2007 from Long Island University, New York, USA. My MSc thesis title was “Can the smallpox vaccination be successfully carried out in a possible threat of a Bioterrorism?”. I was a straight A student during my MSc studies and obtained a GPA of 4.0 out of 4.0 in my MSc studies.
Before this I completed my BSc Honours degree in Pharmacy obtaining a First class from University of Colombo, Sri Lanka (2001-2005). I was the batch top of the Pharmacy batch and was awarded Gulamhusein A. J. Noorbhai gold medal for Pharmacy, in 2005. I was awarded Astron Scholarship for Pharmacy, 2004 for obtaining best results in first three years of study among Pharmacy undergraduates in my batch. During my undergraduate study my experimental thesis title was “Effect of tea on paracetamol pharmacokinetics in rat models” and my library thesis title was “Vitamin C induced decomposition of lipid hydroperoxides to endogenous genotoxins”.
After obtaining my BSc Pharmacy degree I performed duties as a Teaching assistant, Department of Chemistry, University of Colombo (2005-2006). My main responsibilities included conducting Pharmaceutical Laboratory sessions for B.S Pharmacy undergraduates, preparing culture plates, broths and designing microbiological assays. Also assisted professors with daily session plans, designed Medical Chemistry experiments and assays, prepared titration material, extraction equipment and conducted Medical Chemistry laboratory sessions for undergraduates.
- PhD, University of South Australia
- Master of Science, Long Island University
- Heavy metals
- Human health risks
- Sinhalese (Mother)
- English (Fluent)
|Title||Organisation / Department|
|Dates||Title||Organisation / Department|
|30/8/2010 - 29/5/2014||PhD research scholar||University of South Australia
Division of IT, Engineering and the Environment
|1/7/2014 - 24/4/2015||Research Associate||University of South Australia
|1/5/2008 - 30/10/2008||Toxicology unit Author||Open University of Sri Lanka
|12/1/2009 - 20/8/2010||Lecturer in Pharmacy||University of Sri Jayewardenepura
B.Pharm unit, Faculty of Medical Sciences
|15/2/2008 - 31/12/2008||Visiting Lecturer||University of Colombo
Department of Chemistry
|14/4/2008 - 1/1/2009||Analytical Chemist||University of Peradeniya
South Asian Clinical Toxicology Research Collaboration (SACTRC)
Risk characterisation for human health
Faculty of Science | University of Newcastle | Australia
Ayanka was involved in the preparation of the course proposal of ERAR6005: Risk Characterisation for Human Health course in the MERAR (Master of Environment Risk Assessment and Remediation). She prepares and delivers lectures as well as practical sessions in this course. Her lectures and practicals are based on her specialty in bioavailability and bioaccessibility of heavy metal(loid)s and heavy metal(loid) mixtures. She has obtained Professional Certificate in University Assessment from University of Newcastle.
She was also involved in preparing standard operating procedures (SOPs) for the process and equipment used in the practicals, documentation for risk assessments for chemicals and equipment used in the practicals, the required list of consumables and equipment for practicals as well as safety application for the practicals assessing chemicals, and equipment.
|Course coordinator||16/3/2017 - 30/12/2018|
For publications that are currently unpublished or in-press, details are shown in italics.
Chapter (7 outputs)
Wijayawardena MAA, Liu Y, Yan K, Duan L, Umeh AC, Naidu R, Semple KT, 'Assessment of the Oral Bioavailability of Organic Contaminants in Humans', Handbook of Environmental Chemistry 191-218 (2020) [B1]
Bioavailability estimates the actual internal uptake or absorption of contaminants that enter the body (internal dose) and helps in providing a more accurate estimation of the hum... [more]
Bioavailability estimates the actual internal uptake or absorption of contaminants that enter the body (internal dose) and helps in providing a more accurate estimation of the human risks than the usage of total concentration. This is important for exposure assessment for children in relation to their hand-to-mouth activities. For example significant reductions of the bioavailability of long-term contaminated soils have been demonstrated using various animal models. The measurement for bioavailability involves various uncertainties for organic contaminants. It is crucial to determine the parameters that influence the results of bioavailability. This chapter provides a summary of the current state of knowledge for the determination of bioavailability for a range of organic contaminants. The information provided will be useful in facilitating further research efforts for the investigation of bioavailability of contaminants in conducting exposure assessments.
Wijayawardena A, Mallavarapu M, Naidu R, 'Exposure, toxicity, health impacts, and bioavailability of heavy metal mixtures', Advances in Agronomy, Elsevier, London 175-234 (2016) [B1]
|2010||Wijayawardena AMA, 'Poisoning due to solvents, drugs, household products and snake bites', PCU 3127 Pharmacology and Pharmacotherapeutics, The Open University of Sri Lanka, Sri Lanka (2010)|
|Show 4 more chapters|
Journal article (17 outputs)
Kulathunga MRDL, Wijayawardena MAA, Naidu R, 'Heavy metal(loid)s and health risk assessment of Dambulla vegetable market in Sri Lanka.', Environ Monit Assess, 193 230 (2021) [C1]
Bagherifam S, Brown TC, Wijayawardena A, Naidu R, 'The influence of different antimony (Sb) compounds and ageing on bioavailability and fractionation of antimony in two dissimilar soils', ENVIRONMENTAL POLLUTION, 270 (2021) [C1]
Yan K, Dong Z, Naidu R, Liu Y, Li Y, Wijayawardena A, et al., 'Comparison of in vitro models in a mice model and investigation of the changes in Pb speciation during Pb bioavailability assessments', Journal of Hazardous Materials, 388 (2020) [C1]
Kulathunga MRDL, Wijayawardena MAA, Naidu R, Wimalawansa SJ, Wijeratne AW, 'Association between body mass index and estimated glomerular filtration rate in patients with chronic kidney disease of unknown aetiology in Sri Lanka', Environmental Geochemistry and Health, 42 2645-2653 (2020) [C1]
Yan K, Dong Z, Wijayawardena MAA, Liu Y, Li Y, Naidu R, 'The source of lead determines the relationship between soil properties and lead bioaccessibility', Environmental Pollution, 246 53-59 (2019) [C1]
Kulathunga MRDL, Ayanka Wijayawardena MA, Naidu R, Wijeratne AW, 'Chronic kidney disease of unknown aetiology in Sri Lanka and the exposure to environmental chemicals: a review of literature', Environmental Geochemistry and Health, 41 2329-2338 (2019) [C1]
Wijayawardena MAA, Biswas B, Qi F, Biswas JK, Khan MAI, Naidu R, 'The Fate of Chemical Pollutants with Soil Properties and Processes in the Climate Change Paradigm- a review', Soil Systems, 2 51-71 (2018) [C1]
Wijayawardena MAA, Megharaj M, Naidu R, Stojanovski E, 'Chronic and reproductive toxicity of cadmium, zinc, and lead in binary and tertiary mixtures to the earthworm (Eisenia fetida)', JOURNAL OF SOILS AND SEDIMENTS, 18 1602-1609 (2018) [C1]
Plunkett SA, Wijayawardena MAA, Naidu R, Siemering GS, Tomaszewski EJ, Ginder-Vogel M, Soldat DJ, 'Use of Routine Soil Tests to Estimate Pb Bioaccessibility', Environmental Science and Technology, 52 12556-12562 (2018) [C1]
Yan K, Naidu R, Liu Y, Wijayawardena A, Duan L, Dong Z, 'A Pooled Data Analysis to Determine the Relationship between Selected Metals and Arsenic Bioavailability in Soil', International Journal of Environmental Research and Public Health, 15 (2018) [C1]
Sanderson P, Qi F, Seshadri B, Wijayawardena A, Naidu R, 'Contamination, Fate and Management of Metals in Shooting Range Soils - a Review', Current Pollution Reports, 4 175-187 (2018) [C1]
Yan K, Dong Z, Wijayawardena MAA, Liu Y, Naidu R, Semple K, 'Measurement of soil lead bioavailability and influence of soil types and properties: A review', CHEMOSPHERE, 184 27-42 (2017) [C1]
Wijayawardena AMA, Megharaj M, Naidu R, 'Bioaccumulation and toxicity of lead, influenced by edaphic factors: using earthworms to study the effect of Pb on ecological health', Journal of Soils and Sediments, 17 1064-1072 (2017) [C1]
Wijayawardena MAA, Naidu R, Megharaj M, Lamb D, Thavamani P, Kuchel T, 'Evaluation of relative bioaccessibility leaching procedure for an assessment of lead bioavailability in mixed metal contaminated soils', Environmental Technology and Innovation, 7 229-238 (2017) [C1]
This study investigates the effect of contaminant zinc (Zn) on lead (Pb) bioavailability and bioaccessibility in six contrasting soils spiked with 1500 mg Pb/kg and aged 12 months... [more]
This study investigates the effect of contaminant zinc (Zn) on lead (Pb) bioavailability and bioaccessibility in six contrasting soils spiked with 1500 mg Pb/kg and aged 12 months under laboratory conditions. Zn was added to the soils (7500 mgZn/kg soil) and aged for a further two weeks. In vivo studies were conducted using juvenile swine as a surrogate model for young children. Two compartment pharmacokinetic models were used to analyze the biological response produced by Pb oral solution and spiked soils. Absolute and relative bioavailability of Pb in soils (oral dose of 100 µ g Pb/kg body weight/day) were estimated by comparing them with intravenously administered soluble Pb salt (25 µ g Pb/kg/day) and orally administered the same Pb salt [Pb acetate =(CH COO) Pb·3H O] administered to 3 juvenile pigs per treatment. Lead bioaccessibility was calculated using the in vitro RBALP (i.e. relative bioaccessibility leaching procedure) method. The in vitro results of RBALP were compared to in vivo relative Pb bioavailability to ascertain whether the changes in bioaccessibility correlated with the in vivo data. Although the in vivo Pb relative bioavailability (RB) in all soils except in MLA (Mount Lofty Acidic) revealed an increase (18%¿159%) in the presence of Zn, the in vitro RBALP bioaccessibility results indicated otherwise (1%¿38% decrease). In vivo RB of Pb in MLA declined by 37% in the presence of Zn. However, the RBALP in vitro bioaccessible Pb did not correlate with the relative bioavailabilities of Pb in the juvenile swine dosing experiment. Caution is therefore needed when predicting Pb bioavailability/bioaccessibility in the presence of metal mixtures. The literature contains much information on the correlation of metal and metalloid bioaccessibility with their bioavailability. There is, however, a paucity of studies investigating the effects of other metals on Pb and their IVIVC (in vitro and in vivo correlations). The current study addresses this knowledge gap by assessing in vivoand in vitro bioavailability of Pb in the presence of Zn. 3 2 2
Dong Z, Yan K, Liu Y, Naidu R, Duan L, Wijayawardena A, et al., 'A meta-analysis to correlate lead bioavailability and bioaccessibility and predict lead bioavailability', Environment International, 92-93 139-145 (2016) [C1]
Wijayawardena MAA, Naidu R, Megharaj M, Lamb D, Thavamani P, Kuchel T, 'Using soil properties to predict in vivo bioavailability of lead in soils', CHEMOSPHERE, 138 422-428 (2015) [C1]
|Show 14 more journal articles|
Conference (18 outputs)
Kaihong Y, Naidu R, Liu Y, Dong Z, Wijayawardena M, Sanderson P, Li H, 'The changes in lead speciation during bioavailability assessment', Proceedings of international cleanup conference 2019, Adelaide convention Centre, Adelaide, South Australia (2019)
Wijayawardena M, Yan K, Liu Y, Naidu R, 'Validating bioaccessibility tests for assessing contaminants in mixed contaminated soils', Adelaide convention Centre, Adelaide, South Australia (2019)
Cave M, Wijayawardena M, Naidu R, 'The importance of bioaccessibility testing for metal(loid)s in soil at contaminated sites', Adelaide convention Centre, Adelaide, South Australia (2019)
Wijayawardena MAA, Megharaj M, Naidu R, 'Bioavailability and toxicity of arsenic to earthworms in three soils', Understanding the Geological and Medical Interface of Arsenic, As 2012 - 4th International Congress: Arsenic in the Environment (2012)
The acute toxicity of arsenate [As(V)] and arsenite [As(III)] to the earthworm Eisenia fetida was studied in three different soils in order to provide basic toxicity and bioavaila... [more]
The acute toxicity of arsenate [As(V)] and arsenite [As(III)] to the earthworm Eisenia fetida was studied in three different soils in order to provide basic toxicity and bioavailability data for formulating risk characterization benchmarks. Arsenic biotransformation in earthworms was also investigated to understand the mechanisms by which these organisms mitigate arsenic toxicity. Arsenic was more toxic to earthworms in acidic soil than in the alkaline soil. Earthworms transformed As(V) to more toxic As(III) which has implications to soil health. © 2012 Taylor & Francis Group.
|Show 15 more conferences|
Other (1 outputs)
Wijayawardena MAA, Kulathunga MRDL, Naidu R, 'Unravelling the link between kidney disease and environmental contaminants in the North Central Province of Sri Lanka', (2018) [O1]
Grants and Funding
|Number of grants||3|
Click on a grant title below to expand the full details for that specific grant.
20211 grants / $9,875
Funding body: Research and Innovation Services, The University of Newcastle
|Funding body||Research and Innovation Services, The University of Newcastle|
Dr.Ayanka Wijayawardena, Dr.Yanju Liu, Mr.Danidu Kudagamage, Dr.Kaihong Yan
|Scheme||Strategic Investment in Research Scheme|
|Type Of Funding||Internal|
20201 grants / $340,000
Funding body: CRC CARE Pty Ltd
|Funding body||CRC CARE Pty Ltd|
|Project Team||Professor Ravi Naidu, Doctor Yanju Liu, Doctor Ayanka Wijayawardena, Dr Sreenivasulu Chadalavada|
|Type Of Funding||CRC - Cooperative Research Centre|
20171 grants / $1,676,468
Funding body: CRC CARE Pty Ltd
|Funding body||CRC CARE Pty Ltd|
|Project Team||Doctor Yanju Liu, Doctor Luchun Duan, Doctor Ayanka Wijayawardena, Doctor Morrow Dong, Professor Ravi Naidu|
|Type Of Funding||CRC - Cooperative Research Centre|
Number of supervisions
|Year||Level of Study||Research Title||Program||Supervisor Type|
|2020||PhD||Identification of Factors Affecting Chronic Kidney Disease of Unknown Aetiology Prevailing in North Central Province of Sri Lanka||PhD (Environment Remediation), College of Engineering, Science and Environment, The University of Newcastle||Principal Supervisor|
|2019||PhD||Lead Bioavailability as Influenced by its Sources, Speciation and Soil Properties||PhD (Environment Remediation), College of Engineering, Science and Environment, The University of Newcastle||Co-Supervisor|
The map is a representation of a researchers co-authorship with collaborators across the globe. The map displays the number of publications against a country, where there is at least one co-author based in that country. Data is sourced from the University of Newcastle research publication management system (NURO) and may not fully represent the authors complete body of work.
|Country||Count of Publications|
November 25, 2015
Dr Ayanka Wijayawardena
Global Centre for Environmental Remediation (GCER)
Global Centre for Environmental Remediation
College of Engineering, Science and Environment
|Phone||(02) 4913 8745|
|Building||Advanced Technology Centre.|
Callaghan, NSW 2308