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Every day painkillers and anti-inflammatory drugs such as ibuprofen that are flushed out into the environment are stunting the growth of important food crops, new research suggests.

Scientists have assessed the impact of a range of commonly used non-steroidal anti-inflammatory medication on edible crops like lettuce and radish.

They found that the drugs could change the way the roots and stems of the plants grow in the first few weeks after germinating.

Some of the drugs caused radishes to grow shorter roots, which may impact on the size and quality of the food

In some cases the drugs suppressed growth and led to roots being shorter while others enhanced the growth of leaves. They could also alter the way the crops took up water.

More than 30 million of these drugs are prescribed across the world every day and find their way into the environment.

Dr Clare Redshaw, who led the study at the European centre for environmental and human health at the University of Exeter, said that the findings raised serious questions about how the medication we use is altering the environment around us.

Environmental researchers have in the past warned that hormones like estrogen from contraceptive drugs are having a devastating impact on fish and amphibian.

Now the latest work suggests that many other common drugs are also having unexpected impacts on the environment and the food we eat.

Dr Redshaw said: 'These are some of the most widely used drugs in the world, yet we know very little about their effects on flora and fauna.

'The roots and stems seemed to be the most affected in the plants we looked at, but some of the drugs had opposing effects in different plants.'

For example, diclofenac, a non-steroidal anti-inflammatory drug used to treat arthritis and migraine headaches, seemed to suppress the growth of radishes while enhanced lettuce growth.

By comparison, Ibuprofen exposure delayed the opening of lettuce leaves and had a significant influence on early root development in lettuce but enhanced the growth of radish roots.

'We only ran these experiments for a number of weeks but if we continued for several months we may see the affects change,' said Dr Redshaw.

'Early development is a crucial time for plants and it is likely we would see continuing impacts in these plants.

'Clearly it is not catastrophic, otherwise all out fields would be empty, but it is clear these drugs are changing the way plants grow.'

Dr Redshaw and her colleague Dr Wiebke Schmidt studied how six different non-steroidal anti-inflammatory drugs changed the germination and growth of lettuce and radish plants.

Non-steroidal anti-inflammatories like ibuprofen can escape into the environment through waste water and when old unused drugs are are thrown away in to landfill, which could be having a major impact on plants

Although the researchers from Exeter University only tested the changes in lettuce and radishes, they fear painkillers and other drugs may also cause changes in the way other crops and wild plants develop

They looked at ibuprofen, diclofenac, naproxen, tolfenamic acid, meclofenamic acid and mefenamic acid - which are all used to treat arthritis, migraines or menstrual pains.

They found that each of the drugs altered the way the plants photosynthesised, their overall size, their root and shoot length and how they took up water.

The findings, which are published in the Journal of Ecotoxicology and Environmental Safety, emphasis the need to find new ways to remove medication from waste water.

Dr Redshaw said although they only studied the impact of the drugs in two plants, it was clear they could also affect other crops.

She added that previous work she had conducted showed that many medications are absorbed by crop plants, which leads to them being eaten again by humans.

Dr Redshaw said: 'Many drugs we use are designed to be very stable which means they are resistant and can cycle around in the food chain.

Ibuprofen delayed the opening of lettuce leaves and altered the way the roots grew in early development

'The use of these drugs is rising in western and developed countries because of the aging population demographic.

'Clearly these drugs could also be having a combined affect on plants as they will not just be exposed to a single drug or pollutant in the environment.

'There are some 3,000 pharmaceuticals licensed for use in the UK. The next phase in our work will be to look at these mixture effects.'

The work builds on concerns that pharmaceuticals in the environment are posing a growing threat to human health and wildlife.

Overuse of antibiotics, which escape into the environment, are thought to be driving the spread of antibiotic resistant bacteria.

A recent special issue of the journal Philosophical Transactions of the Royal Society B warned the risk posed by pharmaceuticals to wildlife needed to be better explored.

In freshwater habitats, for example, where drugs tend to be most commonly found, around 75% of fish and amphibians had been lost.

Other research has also found that vultures in India are being wiped out by an anti-inflammatory drug given to cattle.

Dr Kathryn Arnold, an environmental research fellow at the University of York who edited the issue said: 'With thousands of pharmaceuticals in use globally, they have the potential to have potent effects on wildlife and ecosystems.

'We believe that it is time to explore emerging challenges.'