Dr Laxmi P. Pokhrel on Environmental Toxicology and Public Health

Environmental toxicology examines how chemicals move through air, water, soil, food and living organisms, and how exposure can affect human and ecological health. For communities in Nepal and Australia, the subject connects laboratory science with everyday concerns such as drinking water, pesticide use, mining, household products and smoke pollution.

In this NepaChem interview, Dr Laxmi P. Pokhrel discusses why toxicology requires careful evidence, better monitoring and communication that people can use. Her perspective is relevant to students, researchers and anyone interested in how environmental contaminants are detected and managed across different communities.

Understanding Environmental Toxicology

Dr Pokhrel describes environmental toxicology as an interdisciplinary field. It brings together analytical chemistry, biology, public health, ecology and risk assessment to answer three practical questions: what contaminant is present, how much exposure occurs, and what harm may result. Finding a chemical in a sample does not automatically prove that it will cause illness; concentration, exposure route, duration and individual vulnerability all matter.

This distinction is important in Australia, where people may encounter contaminants through very different settings. A resident in Sydney could be concerned about urban air pollution, while a regional community near mining activity may focus on metals in soil or water. During a bushfire smoke event in Melbourne, exposure can involve a complex mixture of fine particles and organic compounds rather than one easily identified substance.

The same scientific principles apply in Nepal, although local conditions differ. Rapid urban growth, agricultural chemicals, unmanaged waste and limited monitoring capacity can create multiple exposure pathways. Toxicology helps researchers prioritise the contaminants that pose the greatest risk instead of treating every detected chemical as equally dangerous.

From Chemical Exposure to Health Effects

When discussing toxicity, Dr Pokhrel emphasises the importance of dose and route. A substance inhaled in workplace dust may behave differently from the same substance consumed in food or absorbed through skin. Children, pregnant people, older adults and workers with repeated occupational exposure may also respond differently from the general population.

Laboratory studies can reveal mechanisms such as oxidative stress, DNA damage, endocrine disruption or effects on the nervous system. However, those findings must be interpreted carefully when applied to real communities. Australian researchers may combine biomonitoring, environmental sampling and health data to understand exposure to substances such as lead, pesticides or PFAS, a group of persistent chemicals used in some industrial and consumer applications.

Dr Pokhrel also points to the value of prevention. People do not need to wait for every scientific uncertainty to disappear before reducing avoidable exposure. Safe chemical storage, protective equipment, proper disposal and clear workplace procedures can lower risks while researchers continue to study long-term effects.

The Role of Analytical Chemistry

Reliable toxicology begins with reliable measurement. Samples of water, sediment, food, blood or air must be collected using methods that prevent contamination and preserve the target compounds. In the laboratory, techniques such as gas chromatography–mass spectrometry, liquid chromatography–mass spectrometry and atomic absorption spectroscopy can help identify and quantify pollutants.

For students, Dr Pokhrel sees analytical chemistry as more than instrument operation. Quality assurance, calibration, reference materials, method validation and uncertainty estimation determine whether a result deserves confidence. A highly sensitive instrument cannot compensate for poor sampling or an unsuitable analytical method.

This is relevant to Australia’s chemical regulatory system. The Australian Industrial Chemicals Introduction Scheme, established under the Industrial Chemicals Act 2019, oversees the introduction of industrial chemicals into the country. Researchers and regulators still need dependable data to assess how chemicals behave after release, especially when they persist in water, accumulate in organisms or travel long distances.

Environmental Justice and Community Evidence

Environmental contamination is rarely distributed evenly. Communities close to industrial sites, waste facilities, intensive agriculture or transport corridors may experience greater exposure while having fewer resources to investigate it. Dr Pokhrel argues that environmental toxicology should therefore include community knowledge, transparent reporting and meaningful participation in decisions.

In Australia, concerns about PFAS contamination around some airports, defence sites and firefighting-training areas show why communication matters. The National Per- and Polyfluoroalkyl Substance (PFAS) Contamination Response framework and related guidance have supported investigation and management, but affected residents still need information that explains testing results in plain language. Technical terms such as “微grams per litre” or “reference value” have little value if people cannot understand what they mean for daily life.

Everyday habits also form part of exposure reduction. Australians who use pesticides in suburban gardens, store solvents in garages or discard batteries and e-waste in general rubbish can unintentionally increase environmental release. Choosing local household chemical collection services, following product labels and avoiding disposal down sinks are simple actions grounded in toxicological principles.

Building Skills for a Safer Future

Dr Pokhrel encourages young Nepali chemists to develop strong foundations in chemistry while learning to work across disciplines. Environmental problems rarely fit within one subject. A project on contaminated river sediment may require field sampling, instrumental analysis, statistical interpretation, ecological knowledge and communication with local residents.

Australia offers useful examples of how research, regulation and public services can connect. Water utilities in cities such as Brisbane, Perth and Adelaide routinely monitor drinking-water quality, while state and territory environmental agencies oversee pollution controls under national and local legislation. The Environment Protection and Biodiversity Conservation Act 1999 provides a broader federal framework for matters of national environmental significance, although many pollution decisions remain shared across jurisdictions.

Her broader message is that science should serve communities. Whether a researcher is studying pesticide residues in Nepal or contaminants associated with mining and industrial activity in Australia, careful evidence and honest communication are essential. A strong environmental toxicologist reports uncertainty clearly, avoids exaggerated claims and keeps public health at the centre of the work.

Environmental toxicology becomes meaningful when knowledge leads to safer practice. For a student or early-career chemist, the next concrete step is to choose one local exposure issue—such as household chemical disposal, urban air pollution or water contamination—and begin a small, well-documented project using credible sampling and analytical guidance.