Plastics should be better designed to encourage recycling and prevent wasteful single-use containers finding their way into our oceans, where they break up into small pieces and are swallowed by marine animals, scientists said on Thursday.

This could be as effective as a ban on microbeads, proposed by green campaigners as a way of dealing with the rising levels of microplastic waste - tiny pieces of near-indestructible plastic materials - that are harming marine life.

Richard Thompson, professor of marine biology at Plymouth University, told an experts’ briefing in London that better design was a key element in combating the rapidly growing problem: “The irony is that if most of these materials were better designed, they could be better recycled, and we could capture them. That would also reduce greenhouse gas emissions. We need to change the way we do this.”

As an example, he pointed to plastic bottles - clear bottles have a recycling value five times higher than those that have been dyed, as the pigment is hard to remove. But the pigments serve no useful purpose other than perceived aesthetics. “They are there because of marketing.”

Thompson added: “You can’t ban microplastics [because they are made up of many different sources of plastics, which are broken down in oceans]. You can ban microbeads, but this should not be seen as the end of action [to tackle the problem].”

Microbeads, which are used in cosmetics and hygiene products such as toothpaste, have been found to affect the growth of fish larvae and persist in the guts of creatures, from mussels to fish, that swallow them.

“It’s not clear why we need microbeads,” said Thompson. “It’s not clear what the societal benefits are. They go straight down the plughole.”

While microbeads are a recent phenomenon, microplastics, from larger sources of litter including plastic bags and bottles, have been accumulating in the oceans for decades.

“[It comes from] 60 years of being a throwaway society,” Thompson said. Most of the plastic litter comes from single-use items, which have been inadequately disposed of and not recycled. “They have a very short lifetime in use and last a very long time in the environment.” The consequences of that accumulation “are now becoming clear”.

Alice Horton, an expert in ecotoxicology at the Centre for Ecology and Hydrology, said people should be made more aware of the effects of their consumption on our rivers and oceans, with a view to cutting down on their use and recycling more. “Small steps are important - don’t use as many plastic bags, for example,” she said.

Alastair Grant, professor of ecology at the University of East Anglia, said much more could be done to cut off the problem at its source. Once they are in waterways, some can be gathered up by mechanical means - such as the debris-catchers employed on the Thames - but this is less efficient than preventing their disposal in the first place. “It’s a question of identifying the main sources,” he said. “The most important thing is to focus on larger items, than worrying first about things like microplastics.”

Calls for governments to take action on microbeads and microplastics have intensified in recent years, as new evidence has piled up of their harmful effects. The beads have become popular in cosmetics as abrasives in skin products, such as gels, body scrubs and creams, and toothpastes.

The US has banned microbeads, and the EU is considering such a measure. The new UK government’s position is not yet clear, though a previous minister supported a ban and MPs on parliament’s environmental audit committee are holding evidence sessions with a view to policy recommendations.

However, microplastics are a longer standing problem and have received less attention, as they are more diffuse in their sources and harder to subject to a single ban. While microbeads are relatively easy to phase out, and serve little purpose, it would be impossible to ban all plastics, some of which have important uses, such as food containers.

Facebook Twitter Pinterest Microbeads in an exfoliating face scrub. Photograph: Hennell/Alamy

Evidence of the harm they do once broken down in the oceans is building up from new research. One study published in June in the peer-review journal Science found that fish larvae were changing their behaviour in response to quantities of microplastics in their environment. The larvae hoovered up the microscopic particles “like teenagers eating junk food”, the researchers said, and some in the study effectively died of starvation because they ignored real food. They also showed less response to predators, and many were eaten by larger fish.

Other research has shown the persistence of microplastics, with mussels introduced to the substances shown to swallow them and still show evidence of their persistence in their bodies even after several changes of fresh water.

Using biodegradable plastics is one way in which producers have tried to solve the problem. However, many of these only break down in certain conditions, and some of them - when mixed in with other household plastic waste, as they inevitably are - can prevent the recycling of conventional plastics. The UN’s top environment scientist told the Guardian they were “a false solution”.

The scientists called for more research on the sources of plastics, their concentrations across the world, their effects on marine life, the potential of chemicals leaching from them, and the differences among varieties of plastics that might make some more deadly than others.

“This is an emerging science,” said Thompson. “But a lack of knowledge is no reason to delay. We should be taking action on what we already know about.”