In a first of its kind study, scientists from six research institutes predict that 66% of the world’s soil selenium will decrease due to climate change by the end of the century. Published in the Proceeding from the Natural Academy of Sciences, the researchers warn that since the selenium content of our food largely depends on soil concentrations, human selenium deficiency could have global health implications.
The climate scientists are calling for greater awareness and attention from humanitarian agencies, food manufacturing and agricultural companies in order to improve selenium intake.
At present, nearly one billion people in the world are selenium deficient. That number will grow if conditions persist, say researchers. "We need selenium because it is plays a vital role in our immune system," says Lenny Wetchel PhD, the project lead from EAWAG Aquatic Research. She and her colleagues calls this study an early warning to the food, agricultural and humanitarian sectors. Watch the video on the right for more.
Selenium Deficiency in Soil
By studying precipitation patterns and clay content in soil, the researchers predicted a global decline of 9% in soil selenium. Today, certain regions of the world are known for selenium deficiency soil, such as Germany, Denmark, Scotland, Finland, select Balkan countries and Africa. This known problem is linked to higher risks of certain cancers and immune health concerns. The researchers say a nearly 10% loss could have significant human health implications if soil and food are not adequately replenished.
This study says newly affected agricultural areas will include western Europe, northern and central India, central and northern China, southern areas of South America, southern Africa and the south-western United States. While other regions in western Australia and other parts of central Africa and eastern China may see a slight improvement in soil selenium.
See the map for the global impact.
In this new study, soil scientists identified characteristics such as high pH, oxygen availability and organic carbon content as indicators of low soil selenium. For instance, climate-soil interactions, such as precipitation and the ratio to evaporation, plays a role in selenium distributions. “Precipitation leads to leaching of selenium from the soil,” say researchers. “Lower selenium concentrations are found in arid areas with high pH and low clay content.”
- The sixteen datasets assessed (1994-2016) comprised a total of 33,241 soil data points.
- Analysis of selenium concentrations in the top 30 centimetres of soil, together with 26 environmental variables, indicated the dominant role of climate-soil interactions in controlling soil selenium distributions.
- Higher selenium concentrations are most likely to occur in areas with low to moderate precipitation and high clay content, while lower concentrations are found in arid areas with high pH and low clay content.
- In the light of these findings, the scientists modelled mean soil selenium concentrations for the periods 1980-1999 and 2080-2099.
- Under a moderate climate change scenario, selenium levels are predicted to increase in parts of Australia, China, India and Africa.
- Selenium levels are expected to decrease: by the end of this century (2080-2099), 66% of croplands are predicted to lose selenium (mean decrease of almost 9% compared to 1980-1999).
- Particularly affected are agricultural areas of Europe and India, China, southern South America, southern Africa and the south-western United States.
In conclusion, this data could predict wide scale health implications as a result of selenium deficiency. Agricultural industries should pay attention to selenium amendments in soil. Food and dietary supplement manufacturing need to focus on food-form selenium as a replacement for declining soil levels.
For more on how food form selenium can help solve soil deficiencies, download our white paper, Dirt Poor, Why American Needs a Micronutrient Bailout.