There's no better way to start the day than with a steaming hot cup of tea in the morning.

But experts say that your favourite teabag could be filling your cuppa with dangerous microplastics.

Although many of the UK's most popular tea brands label themselves as 'plastic free', a new analysis from Which? suggests this isn't really the case.

Of the 28 popular brands examined by the consumer champion, only four were truly plastic–free.

And it is bad news for fans of some of the nation's favourite brands, including PG Tips, Tetley, Typhoo, and Yorkshire Tea.

What's more, even some of the more premium alternatives like Teapigs, Brew Co, and Good Earth teabags harbour potentially harmful plastics.

However, fans of Dragonfly, Twinings, Hampstead, and Pukka teabags can rest easy knowing their brew is genuinely free from microplastics.

So, is your cuppa at risk? Use our interactive tool below to find out.

Historically, teabags were made with a tiny amount of oil–based plastic called polypropylene to close the edges and make sure the bag stayed sealed.

Many brands have now ditched polypropylene, but most have simply replaced it with a plant–derived bioplastic called polylactic acid (PLA).

Although PLA does break down under the right conditions, it is still a plastic and Which? says these brands shouldn't call themselves plastic–free.

More concerningly, a number of these brands also brand themselves as 'microplastics–free' - but for teabags containing PLA, this is not true.

As PLA breaks down, it releases microscopic particles of plastic, which are small enough to slip into the human bloodstream.

Some research suggests that these microplastics could be even more of a problem when PLA is placed in a hot environment, like your cup of tea.

The heat causes the particles to break down into even smaller fragments that are easier for the body to absorb and, therefore, more toxic.

That means a huge number of the UK's favourite teabag brands could be exposing their drinkers to a steady stream of microplastics.

Which? found PLA in own–brand teabags from all the major supermarkets they tested, including Aldi, Asda, Lidl, M&S, Morrisons, Sainsbury's, Tesco, and Waitrose.

Of the brands that do make truly plastic free options, some of the teabags still contained microplastics.  

While both Dragonfly and Twinings string and tag teabags were plastic–free and home compostable, the pillow bags and everyday teabags contained PLA.

Even though the brands were open about their teabags containing PLA, many branded their products as plastic–free.

For example, a Clipper spokesperson told MailOnline: 'PLA is technically classed as a plastic, but it’s plant-based and biodegradable'.

The spokesperson clarified that these tea bags were initially branded as plastic-free, but that this language has since been removed. 

Meanwhile, Tetley herbal teabags were the only teabags found to contain conventional polypropylene plastic.

This comes after a study last year revealed that a single tea bag can release billions of microplastic particles into your body.

Scientists from the Universitat Autònoma de Barcelona found that polypropylene teabags were the worst offenders, releasing approximately 1.2 billion particles per millilitre, with an average size of 136.7 nanometres.

Most of these particles were absorbed by the mucus–producing cells of the small intestine, but some can even enter the cell nucleus – the part of the cell that houses genetic material.

Worryingly, the true impact of microplastics on our long-term health remains unclear.

Previous studies have found that exposure to microplastics can cause oxidative stress, leading to cellular and tissue damage, inflammatory responses, and disruption of the gut microbiome.

Research into the effects of PLA on the human body is only just beginning, but researchers have already found some worrying data.

In animal testing, ingesting PLA was found to trigger intestinal damage, oxidative stress, and even DNA damage.

Meanwhile, further studies have shown that PLA can alter the gut microbiome and lead to metabolic disturbances in the liver.

Which? has contacted the brands for response and Daily Mail has approached Brew Tea Company, Tetley, and Clipper for further comment.