Vizag gas leak: How styrene affects humans, animals

Exposure to 20 parts per million of styrene over eight years of working around styrene increases reaction time in subjects

By Akshit Sangomla
Published: Thursday 07 May 2020

A gas leak in Andhra Pradesh’s Visakhapatnam has killed eight people and reportedly led to the hospitalisation of more than a thousand. The leak occurred early morning May 7, 2020 at a private plastic making plant owned by LG Polymers Pvt Ltd, a part of South Korean conglomerate LG Corp. 

The gas was confirmed to be styrene or vinyl benzene by RK Meena, the district commissioner of police.

It is used in the production of polystyrene plastics and resins. These materials are subsequently used in food packaging, rubber, plastic, insulation, fiberglass, pipes and automobile parts. It is also known as PVC gas (polyvinyl chloride), as it is used in the production of PVC.

Styrene is the 20th most-used chemical in the world, according to the World Health Organization. The chemical can be found in air, water and soil once released into the environment. It is broken down in air in 1-2 days, while it evaporates from soil and shallow water surfaces.

It is broken down by micro-organisms if it reaches soil.

It can enter the human body through breathing, eating food and contact through skin. Once it enters the human body, styrene takes a few days to break down into other chemicals and pass through urine.

It is the most harmful in its most basic form as a monomer (a single unit of styrene), according to the Agency for Toxic Substances and Disease Registry (ATSDR) of the Centers for Disease Control and Prevention, the United States.

When humans are exposed to styrene, it causes eye irritation and gastro-intestinal effects. It also impacts the outer layer of tissues in the skin causing erosion and bleeding in the short term. Long-term effects include central nervous system dysfunction, depression, hearing loss and peripheral neuropathy (a numb feeling in the hands and feet).

Exposure to 20 parts per million of styrene over eight years of working around the chemical increases reaction time in subjects, something that may be a cause for automobile accidents, noted a study published in journal Environmental Health Perspectives in 2005.

It also leads to an increase in the colour confusion index that may lead to colour blindness.

Animal studies show they are more sensitive to styrene exposure and suffer greater effects. “The styrene concentrations that cause these effects are more than a thousand times higher than the levels normally found in the environment,” ATSDR pointed out.

This means the gas leak that occurred in Visakhapatnam is a major one. The International Agency for Research on Cancer (IARC) has determined that styrene is a possible carcinogen and can cause cancer under long exposure.

Several epidemiological studies suggest there may be an association between styrene exposure and an increased risk of leukaemia and lymphoma, according to the US’ Environment Protection Agency (EPA).

The EPA also suggested that “human studies are inconclusive on the reproductive and developmental effects of styrene”.

Several studies did not report an increase in developmental effects in women who worked in the plastics industry, while an increased frequency of spontaneous abortions and decreased frequency of births were reported in another study, the EPA noted.

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