Plastic items take up to a thousand years to decompose. Even when they do decompose, they carry on polluting as they release toxins into the soil and water. Plastics can be deadly to animals and birds, and can also pollute the soil and damage our health.

Effect on Marine & Bird Life

An estimated 8 million metric tonnes of plastic enter the ocean each year according to a 2015 study carried out by the NCEAS Marine Debris Working Group at UC Santa Barbara. Plastic items can look like food to marine life and seabirds, who often ingest them.

One study conducted by North Highland College UHI on seabirds in Northern Europe found that 74% of the birds studied had ingested plastic.

The level of plastics ingested by seabirds is thought to be even higher in other parts of the world, particularly the southern Indian, Pacific and Atlantic oceans (source).

Researchers from CSIRO and Imperial College London estimated that around 99% of seabirds will be ingesting plastic by 2050 (source).

The BBC’s Blue Planet II series, broadcast in 2017, made people more aware of the extent of the damage plastic usage is doing to the marine environment.

Ingesting plastic can cause marine life and birds to die as a result of intestinal injury or starvation caused by plastic limiting the storage capacity of the stomach.

Effect on Human Health

Ingesting plastic via fish

If we consume fish, we are consuming some of the plastic they have ingested. A 2018 study on deep-water fish in the Northwest Atlantic carried out by the National University of Ireland Galway found that 73% of fish had plastic in their guts.

Most of the fish we eat in the UK comes from the Northwest Atlantic, so this isn’t good news for our health.

Effect on hormones

We are also exposed to plastics in our everyday life. One of the most harmful plastics is bisphenol A (BPA).

BPA is often used in water bottles and food containers, and can leech into food and drink and be ingested. It’s an endocrine disruptor, which means it affects hormone levels, disrupting ovulation and puberty and affecting the balance between oestrogen and testosterone.

Studies such as this one suggest that the hormone-disrupting effects of plastics such as BPA may be to blame for falling rates of male fertility.

A 2005 study carried out in the USA found BPA in 95% of human urine samples, and it can be reasonably assumed that BPA levels will be similar in the UK.

It’s almost impossible to completely avoid BPA, but BPA-free food containers and bottles are becoming more popular.

There’s still a limited amount of research available into the effects of many plastics, so just because a particular plastic hasn’t been proven to be harmful this doesn’t mean it’s safe.

According to this study, some BPA-free plastic products actually released more oestrogenic chemicals than products containing BPA.


Microplastics are tiny pieces of plastic that measure less than 5 mm in diameter. They are found in various materials including many cosmetics and synthetic clothes.

When cosmetics are washed off or synthetic clothes are put in the laundry, microplastics enter the water supply, and can then be ingested in tap water.

Microplastics also enter the oceans through various sources including road runoff, wastewater treatment systems and wind transfer.

They are then ingested by fish, and are therefore present in most of the fish we consume. Microplastics are also present in table salt.

They can also end up in the sewage system and then become part of fertiliser used on fields. Once the fertiliser dries out, it can be picked up by the wind and then breathed in by humans.

This means we are both ingesting and inhaling microplastics. There hasn’t been enough research to know what effects microplastics have on humans yet, but it’s unlikely they are good for us.