What is boron?
Boron is a rare, inert semimetal and one of the most decisive elements. It occurs as oxygen compounds borax and kernite and in several modifications. Boron compounds have been known to humanity for a long time. Egyptian mummies were treated with boron-containing sodium bicarbonate. There is evidence that borax glass was produced in the Chinese and Roman Empires.
Boron and its compounds play a significant role in the industry. It is ubiquitous as a bleaching agent in detergents (the brand name Persil comes from the two chemicals perborate and silicate). For example, its heat resistance and hardness are used in the glass and ceramics industry, semiconductor industry, space travel and nuclear energy. Because of their extreme strength, boron fibres and crystalline boron are processed in components with high stability requirements—pyrotechnics value boron for its intense green flame colour.
From record scanning needles, fishing rods, brake pads, magnets, pesticides, bulletproof vests, radiation protection clothing, fertilisers, and cosmetics to airbags, rocket propellants, eye drops and combat aircraft, there are countless applications. Boracite, boric oxide, boric acid, boron carbide, boron nitride, colemanite, pandermite, sassolin and tourmaline are also crucial for industry.
How does boron get into drinking water?
Since elemental boron does not react with water, it is mainly boron salts and ethers that are detectable in groundwater. Boric acid has the best water solubility. The boron content of surface waters and groundwater is between 10 and 50 micrograms per litre, while seawater contains 4-5 micrograms. Boron leaches from soil sediments and weathered rocks into groundwater. Kernite, borax, ulexite, colemanite and shale are boron-rich rocks. Fumaroles, the steam emission points of volcanic areas, have exceptionally high boron concentrations. From there, the dust rises into the atmosphere to reach the earth’s crust and the water cycle via rain.
Results are reflected in improved wastewater values. In water bodies, higher boron concentrations of 10 to 300 mg/L are toxic for fish. Aquatic plants also react sensitively. A positive fact is the use of environmentally friendly percarbonates instead of perborates. Poorly old secured landfills also appear as environmental polluters through their contaminated leachate. Boron found in wastewater can also be evaluated as an indicator substance for other potential pollutants.
How does boron affect the human body?
Whether boron has an essential function for humans is currently unclear. The scientific conclusions could be more specific. Humans take about 1-3 mg of boron daily through food and drinking water. Foods rich in boron are, for example, avocados, cucumbers, nuts, prunes, almonds, dates or red wine. Boron is involved in numerous biochemical processes. The organism contains about 0.7 ppb (parts per billion) of boron. Borates and boric acid are entirely absorbed and excreted by the body quickly.
Boron deficiency has so far only been proven experimentally. The fact is that a significantly high boron intake is toxic and manifests itself as headaches, vomiting or kidney damage. A connection between boron-poor soils and increased arthritis in the population is suspected. Neither mutagenic nor carcinogenic properties have been proven so far. On the other hand, boron-containing minerals are highly toxic to arthropods, which also explains their use as insecticides.
Boron compounds are trace elements for plants; they influence their cell growth and metabolism. For this reason, they are introduced into the soil in agriculture through fertilisers.
Drinking water polluted by boron: What to do?
The UK Drinking Water Ordinance sets the limit value for the parameter boron at 1mg/L. This value corresponds to the standard of the European Drinking Water Directive 1998. The World Health Organisation (WHO) of 2006 demands 0.5mg/L.
For wastewater treatment of waterworks, removing boron compounds is fraught with difficulties, as the chemical substances are difficult to dissolve in the ion exchange process.
Have your tap water tested for boron
The only way to determine precisely how much boron is in your drinking water is to have it tested. Samples taken from your tap are analysed in a recognised laboratory and presented to you. At the same time, you can learn more about the classic test substances from the Drinking Water Ordinance (e.g. lead, nitrate, nitrite, iron, arsenic, phosphate, legionella) in your domestic drinking water.