The number of water wells containing excessive amounts of pesticides has exploded. to the problem.
According to professor Hans-Jørgen Albrechtsen, DTU environment, technology offers the solution
How serious are the latest pesticide finds?
“It’s an unusual situation. We’ve never found so many unwanted substances in our drinking water supply within such a short period. I think it’s a serious problem. The new evidence clearly shows that our groundwater is affected. At the same time, we don’t know how long and in what quantities these substances have been in our drinking water.
Why are we seeing these substances now?
“Because we’ve begun looking for them in the drinking water. I was shocked to discover that the Danish authorities had access to information from Germany ten years ago suggesting that one of the substances—dimethyl sulfoxide (DMS)—posed a potential problem. It is a decomposition product of a now banned pesticide, but it can also stem from wood paint and waterproofing agents. As soon as water suppliers became aware of the problem, they began screening for the substance. But screening could have begun much earlier if the Danish authorities had reacted to the initial information.”
Is tap water a health hazard?
“We shouldn’t feel nervous about our tap water. In general, I feel that the water supplies are careful and focused on the quality of the water sent to consumers. That said, there is always room for improvement. In many places, for example, the supply is only below the limit values for the undesirable substances because the water is diluted with something that is cleaner. In my opinion it’s better to use technology to eliminate the problem substances to completely avoid them.
Are the technologies ready?
“No—not for all the substances. Activated carbon can remove quite a lot of pesticide residues, but DMS has proven to be feisty, so we have developed a new solution. At DTU, we are examining membrane solutions, and we’ve also achieved some promising results with microbiological water purification. However, the methods must be further refined before they can be used.
What we need is a technological contingency response so that we have several off-the-shelf solutions in the future. It takes up to 50-100 years for groundwater to form, so there is a risk of increased pesticide incidence. At the same time, there’s a growing consumer desire to decalcify the water in regions where it is particularly hard. We can solve several problems at once if we integrate the technologies. By having multiple barriers, we will also be able to safeguard against any substances that we have not yet identified.”
Won’t cleaning simply increase pesticide use?
“It’s a recurrent discussion. Opponents maintain that cleaning can be used to support the argument that you can just spray whatever you like on the fields because the water will be cleaned afterwards anyway. But the thing is that we’re already cleaning the water of many other substances. It is an illusion to think that we drink untreated groundwater.
In reality, close to 100 per cent of all the water we receive from public water supplies has been treated in one way or another. Moreover, it is not my experience that there are people with a strong desire to pollute our groundwater.
Agriculture is a business, of course, but the vast majority of farmers I know want to do the right thing, so it’s just a question of helping them in the best possible way. It could also be interesting to determine whether the use of pesticides used in the right quantities at the right times actually poses a problem.”
Should we find alternative sources to groundwater?
“Whether we choose to extract drinking water from surface water such as lakes—or to desalinate seawater—undesirable substances must be removed from the water and others added in order to ensure a pleasant taste.
We can keep using groundwater, but we have to realize that it is necessary to apply technological solutions in order to clean it.
That said, we mustn’t lead ourselves to believe that technology has all the answers. We still need to think in terms of prevention in order to avoid continued contamination. And the new technology isn’t a viable solution if it creates worse problems or costs us dearly in energy consumption.”