Introduction
Day 3 on the lead up to World Cancer Day, we have decided to touch on a substance named Styrene. In this article, we aim to discuss the key health effects caused by exposure to the substance, leading to possible increased rates of cancer found in humans.
Introduction to Styrene
Styrene, also referred to as Ethenylbenzene, Vinylbenzene, and Phenylethene, is an organic compound. This substance is derived from Benzene and is a colourless or sometimes light yellow flammable liquid that evaporates readily.
Those who have worked with Styrene within the working environment will recognise the presence of this substance by its sweet smell. Although, higher concentrations have been known to have a less pleasant odour.
Styrene is mainly used in the production of plastics, resins and synthetic rubbers and is known as the precursor to polystyrene and several copolymers.
Where Would We Find Styrene?
Styrene is produced in industrial quantities from benzene and ethylene. The main use of styrene is in the production of plastics, resins and synthetic rubbers for commercial and domestic uses. Some of the most common plastics and resins produced using styrene including polystyrene and acrylonitrile-butadiene-styrene (ABS), styrene-acrylonitrile (SAN) resin and styrene-butadiene rubber (SBR).
Plastics and rubbers such as these have many commercial and domestic uses including containers for foodstuffs, packaging, synthetic marble, flooring, disposable tableware and moulded furniture.
Styrene is also a known product for the production of Glass Reinforced Plastics (GRP) which, is commonplace in the caravan, motorhome and boat building industries.
What are the Health Effects of Styrene?
Styrene may cause mild irritation to the skin along with moderate to severe irritation of the eyes with inhalation of this substance recognised as having the ability to cause irritation of the nose and throat.
Symptoms including coughing and wheezing may also follow significant exposure. Exposure to larger amounts of styrene may lead to headache, nausea, vomiting, weakness, tiredness, dizziness, confusion and clumsy or unsteady motion.
The short-term exposure effects are considered to be an irritation to the eyes, skin and respiratory tract, effects on the central nervous system. At higher concentrations, exposure has been known to result in unconsciousness.
Long-term or repeated exposure may have effects on the central nervous system. There has also been an associative link relating to enhanced hearing damage caused by exposure to noise.
Following exposure to any chemical, the adverse health effects you may encounter will depend on several factors including the amount to which you are exposed; referred to as the dose, how you are exposed and toxicokinetics – that being how the substance enters, travels, transforms and exits your body.
Cancer Risks Explained
The International Agency for Research on Cancer (IARC) has classified Styrene as Group 2A - Probably carcinogenic to humans.
Styrene is classified as a probable human carcinogen based on limited evidence of carcinogenicity from studies in humans and sufficient evidence of carcinogenicity from studies in experimental animals.
Styrene and the primary metabolite styrene-7,8-oxide are considered to be genotoxic and carcinogenic. Long-term chemical carcinogenesis bioassays showed that styrene caused lung cancers in several strains of mice and mammary cancers in rats with styrene-7,8-oxide found to cause tumours of the fore-stomach in rats and mice and of the liver in mice.
Subsequent epidemiological studies found styrene workers had increased mortality or incidences of lymphohematopoietic cancers (leukaemia or lymphoma or all), with suggestive evidence for pancreatic and oesophageal tumours. No adequate human studies are available for styrene-7,8-oxide although this is the primary and active epoxide metabolite of styrene. Both are genotoxic and form DNA adducts in humans. (Styrene exposure and risk of cancer; July 2011).
How to Assess Control Measures
In this article, instead of talking you through how you can control the substance, we decided to cover the subject of assessing exposure and quantifying risks, evaluating the possible methods. Below is a brief discussion on how you can assess the suitability and effectiveness of existing control measures.
COSHH Risk Assessment
A COSHH Risk Assessment allows the responsible people to evaluate the risk associated with the hazard in question. In this case, that would be Styrene. An assessment of the processes carried out in which Styrene would be used, can be viewed, assessed and broken down into stages. From this, key data can be obtained to highlight the need to improve on inefficiencies in the process leading to elevated exposure which could be controlled better by implementing safer systems of work.
Thorough Examination and Testing of Local Exhaust Ventilation Systems (LEVS)
Existing controls, such as LEV systems should undergo a thorough examination and test within a 14 month period as a minimum standard. Due to the carcinogenic effects associated with Styrene, it would be recommended that more frequent testing is carried out however.
A thorough examination and test of the LEV systems would highlight inefficiencies and allow for improvements to be recognised and implemented.
Workplace Air Monitoring
Air monitoring is a great way of measuring workplace exposures to airborne substances. A sampling pump or passive diffuser can be personally worn by an operative, to which sampling of the air is carried out to measure personal exposures during specific tasks or activities.
Air monitoring is carried out in line with occupational hygiene standards and approved sampling methods are adhered to. These sampling methods have been approved by international bodies such as the HSE, NIOSH, OSHA and more.
Biological Monitoring
Exposures to Styrene (and other substances) can be measured by biological monitoring. Biological monitoring is a method of measuring exposure to hazardous substances by sampling blood, urine, skin, hair amongst other bodily fluids. In the case of Styrene exposures, the exposed operative's urine is measured to detect Mandelic acid with methyl hippuric acid - a metabolite of Styrene.
Other Information
All assessments should be carried out by a COMPETENT occupational hygiene professional who can conduct the assessments in line with occupational hygiene standards and methods of determination.
This applies to most substances. Exposures can be quantified and control measures can be assessed using appropriate testing methods, qualitative and quantitative assessments.
Workplace Scientifics can offer you any support needed to help you assess and quantify the risk associated with exposures to hazardous substances.
For help managing your COSHH requirements, please don't hesitate to contact us today for free advice.
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