The Institute of Environmental Science and Research (ESR) has changed its name to the New Zealand Institute for Public Health and Forensic Science (PHF Science) as of 1 July 2025. The website address is now www.phfscience.nz. Visitors are automatically redirected to the new address. Please check and update any links and bookmarks.

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Radiation science

Radiation is naturally occurring and man-made and is all around us. PHF Science provides expert radiation safety advice, services, training and research to safeguard Aotearoa.

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About

PHF Science's Environmental Radiochemistry Laboratory has been measuring radioactive forms of elements called radionuclides for more than 50 years.

PHF Science can identify radioactivity in substances ranging from soil to air samples. PHF Science tests for radioactivity in foodstuffs and drinking water. For clients working with radiation, PHF Science also offers dedicated training, advice and research capability to build knowledge of radiation safety, meet regulatory requirements and ensure best practice principles.

Radiation safety

Radiation
safety

PHF Science's radiation experts work with a wide range of private and public sector clients to provide advice, services and research capability on public, occupational and medical exposure to radiation. We provide radiation safety training, performance assessments of radiation protection equipment, and measurement of naturally occurring low-level radiation and radioactivity.

We have strong working relationships with global agencies including the International Atomic Energy Agency (IAEA) and have contributed to the development of the Comprehensive (nuclear) Test Ban Treaty Organisation (CTBTO). PHF Science is the preferred supplier of radiological safety expertise to New Zealand's Ministry of Health.

For information on licensing for use of radiation and import of irradiation equipment or radioactive material contact the Ministry of Health’s Office of Radiation Safety

Environmental radioactivity

Environmental
radioactivity

PHF Science specialised Environmental Radiochemistry Laboratory measures naturally occurring and man-made radionuclides. Our experts can determine and quantify the presence of radioactivity content in a wide range of substances, including food, water, soil, sediment, mining ore and products, biota and air.

Testing carried out by the lab includes testing of drinking waters to show radiological compliance with the New Zealand Drinking Water Standards or overseas standards, soil erosion measurements, sediment analyses for dating, and food certification for export.

Atmospheric transport modelling of time resolved 133Xe emissions from the isotope production facility ANSTO, Australia

The verification of the Comprehensive Nuclear-Test Ban Treaty (CTBT) relies amongst other things on the continuous and worldwide monitoring of radioxenon. The characterization of the existing and legitimate background, which is produced mainly by nuclear power plants and isotope production facilities, is of high interest to improve the capabilities of the monitoring network. However, the emissions from legitimate sources can usually only be estimated. For this paper historic source terms of 133Xe emissions from the isotope production facility at ANSTO, Sydney, Australia, have been made available in a daily resolution. Based on these high resolution data, different source term sets with weekly, monthly and yearly time resolution have been compiled. These different sets are then applied together with atmospheric transport modelling (ATM) to predict the concentration time series at two radioxenon monitoring stations. The results are compared with each other in order to examine the improvement of the prediction capability depending on the used time resolution of the most dominant source term in the region.

Global Radioxenon Emission Inventory from Nuclear Research Reactors

To monitor compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT), the International Monitoring System (IMS) is being established which will include 40 sensor systems for atmospheric xenon radioactivity. Radioactive isotopes of the noble gas xenon provide the most likely observable radioactive signatures of underground nuclear explosions. These isotopes are frequently detected by IMS noble gas systems as a result of normal operational releases from different types of nuclear facilities including nuclear power plants (NPPs), medical isotope production facilities (MIPFs), and nuclear research reactors (NRRs). Improved knowledge of the contribution of different emission sources on IMS observations strengthens the screening of radioxenon measurements to exclude observations not relevant to emissions from a nuclear explosion. The contribution of NPPs and MIPFs to the global radioxenon emission inventory is fairly well understood. NRRs have yet to be systematically assessed. This paper is the first attempt to assess the total emission inventory of NRRs expressed as annual total discharges. The results can enhance understanding of those sources most likely to impact IMS background observations and to guide future studies on contributions to IMS station background.

Radium in New Zealand agricultural soils: Crop uptake and estimation of current and future ionising radiation dose.

Crop uptake of 226Ra over a range of key New Zealand agricultural and horticultural growing areas was analysed to establish the dietary implications of an increase in soil 226Ra activity concentrations. Thirty crop samples, covering both feed and food commodities, were quantified for 226Ra activity concentrations, and concentration ratio (CRs) from the soil activity were calculated. The calculated CRs correlated with international default values for estimating crop uptake. Variation in CRs established that there was no increase in the crop activity concentration, relative to soil 226Ra from pasture foliage at a fertiliser impacted site, with a gradient of soil 226Ra activity concentrations. Based on the calculated CRs, the upper bound of the theoretical range of dietary exposures to 226Ra was 78.1 μSv/yr for teenage boys. Future forecasting of the increased dietary dose of 226Ra that might occur at the current soil loading rate, based on current fertiliser activity concentrations, confirmed that long-term loading of soil with 226Ra is unlikely to present a dietary risk. The forecast model calculated that the increase in dietary ionising radiation burden is unlikely to reach thresholds requiring regulatory intervention for two millennia.

Radium in New Zealand agricultural soils: Phosphate fertiliser inputs, soil activity concentrations and fractionation profiles.

Phosphate ores can contain high levels of 238U and its decay products. Of these decay products 226Ra is an important environmental contaminant, while 228Ra from 232 Th day may also be present, albeit at lower activity concentrations. Acid processing of phosphate ore to triple superphosphate elutes a large proportion of the 226Ra from the final product. However, fertiliser production in New Zealand generally avoids acid processing and instead uses single superphosphate and reactive phosphate rock to maintain crop yields, meaning that 226Ra is retained in the final product. As a first step towards characterising the human health impacts from fertiliser-borne radium, research was undertaken to identify loading and long-term accumulation of 226Ra and 228Ra in New Zealand agricultural soils, as well as the fractionation of 226Ra into different soil phases.

Activity concentrations of 137Caesium and 210Polonium in seafood from fishing regions of New Zealand and the dose assessment for seafood consumers

A study was undertaken to determine activity concentrations for 134Caesium, 137Caesium and 210Polonium in New Zealand seafood, and establish if activity concentrations varied with respect to species/ecological niche and coastal region. Thirty seafood samples were obtained from six fishing regions of New Zealand along with a further six samples of two commercially important species (hoki and arrow squid) with well-defined fisheries. 134Caesium was not detected in any sample. 137Caesium was detected in 47% of samples, predominantly in pelagic fish species, with most activities at a trace level. Detections of 137Caesium were evenly distributed across all regions. Activity concentrations were consistent with those expected from the oceanic inventory representing residual fallout from global nuclear testing. 210Polonium was detected above the minimum detectable concentration in 33 (92%) of the analysed samples. Molluscs displayed significantly elevated activity concentrations relative to all other species groups. No significant regional variation in activity concentrations were determined. Two dose assessment models for high seafood consumers were undertaken. Dose contribution from 137Caesium was minimal and far below the dose exemption limit of 1 mSv/year. Exposure to 210Polonium was significant in high seafood consumers at 0.44–0.77 mSv/year (5th–95th percentile). 137Caesium is concluded to be a valuable sentinel radionuclide for monitoring anthropogenic releases, such as global fallout and reactor releases, in the marine environment. 210Polonium is of importance as a natural radionuclide sentinel due to its high contribution to dietary committed dose in seafood consumers.

Natural and anthropogenic radionuclide activity concentrations in the New Zealand diet

To support New Zealand's food safety monitoring regime, a survey was undertaken to establish radionuclide activity concentrations across the New Zealand diet. This survey was undertaken to better understand the radioactivity content of the modern diet and also to assess the suitability of the current use of milk as a sentinel for dietary radionuclide trends. Thirteen radionuclides were analysed in 40 common food commodities, including animal products, fruits, vegetables, cereal grains and seafood. Activity was detected for 137Caesium, 90Strontium and 131Iodine. No other anthropogenic radionuclides were detected. Activity concentrations of the three natural radionuclides of Uranium and the daughter radionuclide 210Polonium were detected in the majority of food sampled, with a large variation in magnitude. The maximum activity concentrations were detected in shellfish for all these radionuclides. Based on the established activity concentrations and ranges, the New Zealand diet contains activity concentrations of anthropogenic radionuclides far below the Codex Alimentarius guideline levels. Activity concentrations obtained for milk support its continued use as a sentinel for monitoring fallout radionuclides in terrestrial agriculture. The significant levels of natural and anthropogenic radionuclide activity concentrations detected in finfish and molluscs support undertaking further research to identify a suitable sentinel for New Zealand seafood monitoring.

Deterministic and Semiprobabilistic Modeling of the Committed Dose from Radionuclides and the Chemical Burden from Uranium in the New Zealand Diet

To support New Zealand's food safety monitoring, estimates of the current population exposure to ionizing radiation through diet are needed. To calculate the committed dose from radionuclide activities in the food chain, dietary modeling was undertaken for different age and gender groupings of the New Zealand population. Based on a published survey of radionuclide activity concentrations in the New Zealand diet, deterministic and semiprobabilistic models were constructed to derive estimates of the effective dose via the diet. Deterministic estimated annual doses across the different age and gender groupings ranged from a minimum of 48 to 66 μSv/year for teenage girls to a maximum of 126 to 152 μSv/year for adult males. Polonium-210 was the main contributor to ingested dose, with anthropogenic radionuclides contributing very little. For adults, seafood represented the most important source of exposure, with the contribution from this source decreasing for younger age groups. Results of the semiprobabilistic model identified a range of possible ingested doses, with 2.5 to 97.5th percentile ranges of 0.01 to 1.44 μSv/day for adults and 0.02 to 1.84 μSv/day for children. Estimated doses to the New Zealand population show similarities to those of other countries and fall within the expected global range. The current level of exposure to ionizing radiation in the diet does not represent an elevated health risk.

Specialist services

Specialist
services

We provide advice, services and research capability on exposure to radiation, and the measurement of naturally occurring low-level radiation and radioactivity.

We work with a wide range of private and public sector clients to provide advice, services and research capability on public, occupational and medical exposure to radiation, radiation safety, performance assessment of radiation protection equipment, and the measurement of naturally occurring low-level radiation and radioactivity.

PHF Science's National Centre for Radiation Safety (NCRS) has strong working relationships with global agencies including the International Atomic Energy Agency (IAEA) and has contributed to the development of the Comprehensive (nuclear) Test Ban Treaty Organisation (CTBTO). PHF Science is the preferred supplier of radiological safety expertise to New Zealand's Ministry of Health.

For information on licensing for use of radiation and import of irradiation equipment or radioactive material contact the Ministry of Health’s Office of Radiation Safety

Radiation safety training and consultancy

Radiation safety training
Industrial radiation safety training courses
Medical radiation safety training courses
Instrument calibrations
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Testing & Analysis

Testing & analysis services

PHF Science's specialised Environmental Radiochemistry Laboratory tests a large range of sample types, including food, water, soil, sediment, mining ore and products, biota and air samples.

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Experts in the area

Experts in Radiation Science

Ahmed Al-Salim
Ahmed Al-Salim

Senior scientist

Cris Ardouin
Cris Ardouin

Technical Lead

Marilen Espinoza
Marilen Espinoza

Scientist

Maxie Christison
Maxie Christison

Quality Director – Health and Environment

Ross Tompkins
Ross Tompkins

Scientist