Our lifestyle and daily routine can impact significantly the environment. A 2016 study of pollutants in Great Britain showed, not surprisingly, traces of pesticides, derived from farming, and PAHs, polycyclic-aromatic-hydrocarbons derived from burning fuel, in the groundwater.
More surprisingly, immediately after such common pollutants, the researchers found large amounts of caffeine in the groundwater. Caffeine is an organic molecule found in coffee, tea and soft-drinks. Coffee is the world’s most popular drink, a comfort to millions and a daily necessity to many more due to its stimulating effects. The annually produced 120,000 tonnes of coffee are enough that every person on the planet could consume at least one caffeinated beverage every day. The concentration of caffeine as found by the research is highest under major cities, especially London.
The caffeine most likely enters the underground groundwater reservoirs from leaking sewer sources. Aquifers in chalk and limestone are especially vulnerable. As limestone is a water-soluble rock, large cavities are found in limestone formations, allowing wastewater to seep into the ground in urban and agricultural areas.
Consumption of one gram of caffeine per day is associated with a condition known as caffeinism in humans. Symptoms of caffeine poisoning include nervousness, irritability, restlessness, insomnia, headaches and an irregular heartbeat. A massive caffeine overdose of more than fourteen gram (as found in 75 to 100 cups of coffee) can result in death. The highest concentration measured in the groundwater study was around 10 micrograms. A cup of Espresso contains almost one thousand times the concentration of caffeine. There are likely no direct effects on human health, however, caffeine is known to be toxic to birds and domestic animals. The effects of such contaminants on the environment are still poorly studied. Similar studies showed also that the widespread use of legal and illegal drugs can be detected in groundwater.