How far are we pushing chemical boundaries? Researchers alarmed by levels of chemical pollution in water and soil in both developed and developing countries
By Avit K. Bhowmik
- Global sustainability requires national level mitigation and remediation of chemical pollution of water and soil, but national level information on magnitude and distribution of chemical pollutants are missing
- Researchers show that soil and water resources in developed (i.e. Germany, France, the Netherlands and USA) and developing (i.e. Pakistan) countries, are alarmingly polluted by pesticides and heavy metals, respectively
- Herbicides are the dominant pesticides group largely appearing in the rivers of developed countries, while the children in Pakistan are at the highest health risk from exposure to heavy metals via dust particles
We need to talk about our chemical romance. One of the main triggers of global ecosystem disturbances is how chemicals pollute our water and soil systems. The diversity of pollutants as well as the severe lack of data and knowledge of how they affect ecosystems has prevented researchers from setting one single planetary boundary for chemical pollution. Strict policy interventions are sorely needed, particularly at national levels.
To lay the ground for efficient interventions, centre researcher Avit K. Bhowmik and an international team of colleagues from Germany, the Netherlands, France, Italy, China and Pakistan have measured and predicted the concentration of pesticides in more than 4000 rivers and heavy metals in dust particles.
In a series of articles (see citations in section to the right) they show how pesticides from intensified agriculture have accumulated in rivers across Germany, France, the Netherlands and the US, ultimately threatening biodiversity. In arid regions like Pakistan dust particles are heavily polluted by heavy metals from industrial and agricultural sources. This in turn has serious health consequences among the population, particularly children.
Chemical pollution, mostly triggered by agricultural intensification and rapid industrialization, is putting global biodiversity and human health at an enormous risk. Regions that are already geographically prone to heavy metal pollution, such as Pakistan, are experiencing much higher level of added pollutions from untreated agricultural and industrial runoffs
Pesticides in water and heavy metals in dust
The analysis shows that the herbicides are the dominant group of pesticides appearing in the rivers, followed by the fungicides and insecticides. At least two groups of pesticides were appearing in all rivers, while 40% of the sites exhibited the presence of five different groups of pesticides. This poses a serious threat to the biodiversity of the rivers’ ecosystems and could lead to extinction of sensitive species. The mix of pesticides in the rivers of Germany and the Netherlands had substantially higher number of chemical compounds than those in the US and France.
In Pakistan, levels of heavy metals such as arsenic and mercury are high above what is considered safe for humans. The levels of heavy metal pollution are particularly high in areas where forests have been converted into agricultural and urban lands. Forests provide important buffers from dust pollution and hence, deforestation releases dust particles and increases human exposure to polluted dust. At least 40% of the sample sites show high levels of heavy metal pollution of dust particles in Pakistan.
Due to geographic location and the nature of the soil, Pakistan is naturally prone to heavy metal pollution of the environment. However, the study shows that the levels of heavy metals in dust is highly associated with for example population density. Consequently, human activities are amplifying the health risks in the region.
Most heavily polluted were urban and industrial zones, and areas with high population density. There, the highest levels of heavy metals were also measured in blood tests from the inhabitants. This shows the urgent need for strict environmental regulations. Avit K. Bhowmik and his colleagues are concerned because this indicates that children are at substantially higher risks to be exposed to heavy metals via dust particles than adults. Avit K. Bhowmik explains: “Children are more exposed to the dust when they play outside, and they are also more sensitive to the heavy metals”. The researchers urge that the areas with the highest proportion of children should be given highest priority for mitigation and preventive interventions.
The researchers used government bio-monitoring data on the concentration of pesticides from 4 532 river sampling sites in Germany, France, the Netherlands and USA. The concentration of heavy metals was measured in samples from 26 sites across Pakistan. Geostatistical methods were applied to estimate pesticide and heavy metal concentrations at unsampled locations. The measured and estimated concentrations of pesticides and heavy metals were compared with the ecological and human health safety thresholds set by the Environmental Protection Agencies of USA and Pakistan. Thus, ecological and human health risk indices were computed.