Fera Science Provides Analytical Solutions for the “unexpected” Impact of Changing Climatic Conditions
Agriculture and food production systems are commonly cited as a major source of Green House Gas (GHG) production contributing to the “greenhouse effect” and climate change [1]. Agricultural intensification practises to compensate for the reduced production and increases in demand for animal products could further increase these emissions. The changing global climatic system is having wide reaching impacts on global agricultural production. Climate change is considered a significant contributor factor to food insecurity by increasing food prices as a result of changes to, or reduction in the annual food production. At present, the principal barrier to food security is access to safe, nutritious food [2]. Food prices have been seen to rise as a direct result of climate events for example; water required for food production may become more scarce due to increased crop water use and drought; energy prices increase as a result of climate mitigation efforts and as competition for land increases when certain areas become climatically unsuitable for production [3].
The gradual increases in temperature and atmospheric carbon dioxide levels reported in the 2021 IPCC report [4] could potentially result in more favourable growing conditions that can increase the yields of some crops in certain geographical regions. Future crop yield projections are subject to uncertainties; however, many researchers predict a substantial decrease in crop yield during the 21st century as a result of extremes in weather events (flooding and drought) and rising global temperature [5]. Major crops including corn, wheat and soybeans being the most sensitive to heat extremes with up to a c. 30% decrease in expected yield for corn [6]. The data indicates that rising temperatures have the strongest effect on crop growth, while moderate or cold temperatures have little effect. When the impact of increased atmospheric carbon dioxide (CO2) levels is included in the models, C4 plants (e.g. maize, sorghum and sugarcane) yields increase only slightly whereas yields of C3 plants (e.g. rice, barley, oats and soybeans) are predicted to increase. Increasing CO2 stimulates the photosynthetic rate of C3 plants, increasing water and nutrient use efficiency and allocation of more photosynthetic product to the root resulting in greater biomass and ultimately, yield.
As more than half of the world’s population depend on rice (Oryza sativa L. and Oryza glaberrima Steud) for subsistence [7] ensuring the future production of major C3 crops such as rice is crucial. Both empirically derived, and modelled projections on rice production reference climate change as a constraining factor to yields whereas other biotic and abiotic stressors (coupled to climate change) are not considered [8]. One such example is the presence of arsenic, a plant and human toxin present in rice paddy fields. Arsenic is the most relevant chemical contaminant in flooded rice paddies as it occurs ubiquitously in soils and often in the groundwater used for irrigation [9]. Arsenic can accumulate in the groundwater with each successive irrigation cycle exacerbating the effects of contamination with time. Flood water can increase the partitioning of arsenic from solids to pore-water and thus plant availability of arsenic via induction of reductive dissolution of iron oxyhydroxide minerals and the reduction of arsenic adsorbed on soil minerals. Soil-borne microbial communities methylate arsenic in a stepwise and reductive process to monomethylarsonic acid (MMAs(V)) dimethylarsinic acid (DMAs(V)) and trimethylarsine oxide (TMAs(V)O) which accumulate in the edible rice grain. Plant growth and development is diminished in terms of reducing grain yields and panicle development.
In a study designed to mimic the rapid temperature and CO2 transitions predicted over the coming decades [4], Muehe and co-workers reported the combined impact of changing climatic conditions and increased soil arsenic resulted in a 42% decrease in rice yield and elevated levels of inorganic arsenic in rice grain [8]. The impact of increased arsenic mobility and changes in speciation impact not only the grain yield but also safety and quality (inclusive of toxin and nutrient content). Higher soil arsenic concentrations lead to a saturation of total arsenic within the grain, shifting the species of arsenic from organic to inorganic under elevated temperature and future climatic conditions. Human exposure to the carcinogen inorganic in non-smokers is primarily through diet [10]. With grain-based processed products such as wheat, bread, rice and milk, dairy products and drinking water being the main sources of exposure to the more harmful inorganic forms for arsenic for the general population in Europe [11]. EU and US food safety Regulations for arsenic levels in rice based infant foods focus on restricting the inorganic arsenic to <100 µg.Kg-1 w.wt.
Fera food safety experts use leading detection techniques based on Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) to accurately identify levels of potentially toxic arsenic in food samples. Fera offers UKAS accredited methods (ISO 17025) for both total arsenic and inorganic arsenic (iAs). The inorganic method provides an excellent profile of the toxicity of the foodstuff. Both arsenic III and V transition states as well as the monomethylarsonic (MMA) species are efficiently extracted. There is mounting evidence relating to the toxicity of the MMA species [12,13].
For further information on this topic or to discuss the needs of your business in safeguarding against the “unexpected” impact of changing climatic conditions on food safety and security please contact us at foodsafety@fera.co.uk
Explore our Inorganic Arsenic (iAs) Test
References and further reading
[1] https://www.futurelearn.com/info/courses/climate-smart-agriculture/0/steps/26565 accessed on 01/11/2021
[2] https://www.fao.org/state-of-food-security-nutrition accessed on 01/11/2021
[3] https://voxeu.org/article/global-weather-disruptions-food-commodity-prices-and-economic-activity
[4] https://www.ipcc.ch/2021/08/09/ar6-wg1-20210809-pr/
[5] Muller, C. et al. Exploring uncertainties in global crop yield projections in a large ensemble of crop models and CMIP5 and CMIP6 climate scenarios. Environ. Res. Lett. 16 034040 (2021) https://doi.org.10.1088/1748-9326/abd8fc
[6] Petersen, L.K. Impact of climate change on twenty first century crop yields in the U.S. Climate 7,40 (2019). https://doi.org.10.3390/cli7030040
[7] Leading Innovations Annual Report 2016 by the International Rice Research Institute ISSN 0074-7793
[8] Muehe, E.M. Wang T. Kerl, C.F. Planer-Friedrich, B. Fendorf, S., Rice production threatened by coupled stresses of climate and soil arsenic. Nat Commun 10, 4985 (2019). https://doi.org.10.1038/s41467-09-12946-4
[9] Smedley, P.L. and Kinniburgh, D.G. A review of the source, behaviour and distribution of arsenic in natural waters. Appl. Geochem, 17,5, 527-568 (2002). https://doi.org.10.1016/S0883-2927(02)00018-5
[10] European Food Safety Authority, EFSA Journal 2009; 7(10):1351 https://doi.org/10.2903/j.efsa.2009.1351
[11] Shi, Z., Carey, M., Davidson, E. et al. Avoiding Rice-Based Cadmium and Inorganic Arsenic in Infant Diets Through Selection of Products Low in Concentration of These Contaminants. Expo Health 13, 229–235 (2021). https://doi.org/10.1007/s12403-020-00376-3
[12] Petrick, J.S., Ayala-Fierro, F., Cullen, W.R., Carter, D.E., Vasken Aposhian, H. Monomethylarsonous acid (MMA(III)) is more toxic than arsenite in Chang human hepatocytes. Toxicol Appl Pharmacol. 2000 Mar 1;163(2):203-7. https://doi.org/10.1006/taap.1999.8872
[13] Irvine, L., Boyer, I.J., DeSesso, J.M. Monomethylarsonic acid and dimethylarsinic acid: developmental toxicity studies with risk assessment. Birth Defects Res B Dev Reprod Toxicol. 2006 Feb;77(1):53-68. https://doi.org/10.1002/bdrb.20065.
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