Plastic Waste: Ecological and Human Health Impacts

Plastic waste is a growing concern and the drivers behind

it look set to continue. Although recently there has been

a slight decrease in plastic production, this is unlikely to be

maintained. Plastic is a highly useful material and its applications

are expected to increase as more new products and plastics are

developed to meet demands. The increased use and production

of plastic in developing and emerging countries is a particular

concern, as the sophistication of their waste management

infrastructure may not be developing at an appropriate

rate to deal with their increasing levels of plastic waste.

 

 

Management of waste in the EU has been improving in terms

of recycling and energy recovery, but there is still much

to be done. At the heart of the problem is one of plastic’s

most valued properties: its durability. Combined with the

throwaway culture that has grown up around plastic products,

this means that we are using materials that are designed to

last, but for short-term purposes

 

 

 

The state of plastic waste is notoriously hard to measure. It

is estimated that in 2008 EU-27, Norway and Switzerland

produced about 24.9 megatonnes of plastic waste (Mudgal

et al., 2011) but its distribution is difficult to ascertain. This is

especially so in the marine environment where the constant

movement of the oceans, both horizontally on the surface

and vertically within the water column, make it difficult

to develop an accurate picture. Since the discovery of the

Northern Pacific Garbage Patch, research has explored

the gyres as areas of plastic waste accumulation, as well

as beaches and river estuaries. There are a number of

methods used to survey marine litter and currently there

are initiatives to harmonise these. Several standardised

surveillance guidelines have been developed, for example,

those produced by the Oslo Paris Convention for Protection

of the Marine Environment of the North-East Atlantic (OSPAR)

and the United Nations Environmental Programme (UNEP)

 

 

 

On land, there are few figures on the level of plastic waste

and there is a need for more information on sources and

possible pathways into the environment. There has been

increasing concern about the presence of microplastics, which

are generally defined as plastic fragments less than 5mm in

size. These are produced either from the weathering of larger

plastics or deposited directly as pre-consumer plastic or

from use in abrasives, such as those used in some cosmetics.

Microplastics are particularly difficult to monitor and they

may also have more influential impacts than larger plastics

 

 

 

The impacts of plastic waste on our health and the environment

are only just becoming apparent. Most of our knowledge is

around plastic waste in the marine environment, although

there is research that indicates that plastic waste in landfill

and in badly managed recycling systems could be having 

an impact, mainly from the chemicals contained in plastic.

 

 

 

In the marine environment, the most well documented impacts

are entanglement and ingestion by wildlife. Other lesser-

known effects are the alteration of habitats and the transport

of alien species. Perhaps one of the most difficult impacts

to fully understand, but also potentially one of the most

concerning, is the impact of chemicals associated with plastic

waste. There are several chemicals within plastic material itself

that have been added to give it certain properties such as

Bisphenol A, phthalates and flame retardants. These all have

known negative effects on human and animal health, mainly

affecting the endocrine system. There are also toxic monomers,

which have been linked to cancer and reproductive problems.

The actual role of plastic waste in causing these health impacts

is uncertain. This is partly because it is not clear what level of

exposure is caused by plastic waste, and partly because the

mechanisms by which the chemicals from plastic may have

an impact on humans and animals are not fully established.

The most likely pathway is through ingestion, after which

chemicals could bioaccumulate up the food chain, meaning

that those at the top could be exposed to greater levels of

chemicals.

 

 

 

Plastic waste also has the ability to attract contaminants, such

as persistent organic pollutants (POPs). This is particularly so

in the marine environment since many of these contaminants

are hydrophobic, which means they do not mix or bind with

water. Again, the role of plastic waste in the impact of these

toxic chemicals is unclear. Plastic could potentially transport

these chemicals to otherwise clean environments and, when

ingested by wildlife, plastic could cause the transfer of chemicals

into the organism’s system. However, in some conditions

plastic could potentially act as a sink for contaminants,

making them less available to wildlife, particularly if they are

buried on the seafloor. With their large surface area-to-volume

ratio, microplastics may have the capacity to make chemicals

more available to wildlife and the environment in comparison

to larger sized plastics. However, once ingested, microplastics

may pass through the digestive system more quickly than

larger plastics, potentially providing less opportunity for

chemicals to be absorbed into the circulatory system.

Although plastic waste may not always cause detectable

harm or death as an isolated factor, when combined with

other impacts, such as uncontrolled fishing or oil spills, it may

contribute cumulatively to serious impacts. These sub-lethal

effects are difficult to monitor, but are nonetheless important

to recognise. Research has indicated that some species or

developmental stages are more vulnerable to ingestion of plastic

waste and the toxic effects of the chemicals associated with it