You know that smell! Styrene is a common and unmistakable smell in the world of composites – the can of Bondo, the mixing of primer, or maybe it’s all day every-day at work. A vast majority of the composite parts built worldwide are made from fiberglass and polyester resin – and with polyester resin comes styrene. It can be up to 1/3 of a general purpose laminating resin by weight!
Concentrations
Nobody really likes the smell – it makes you think “this can’t be healthy!” – and you’re probably right. The thing about styrene is that you can smell it way before it starts to get really bad for you. Your nose can detect just a few parts per million (ppm) of styrene in the air you breathe / smell. That means that just one or two units of mass out of a million – one or two millionths – of the air can be styrene and that’s enough to notice. It still means that there are thousands of styrene molecules in a square foot of air – but there are a really really big number of oxygen, nitrogen (and other stuff) molecules!
So you can smell it at low concentrations and it’s not really a health risk, but you can also smell it at higher concentrations when it becomes one. The problem is that it’s hard to tell how much you’re dealing with. In the US, the OSHA maximum recommended 8-hour weighted average exposure is 50ppm. The legal limit is a weighted-average exposure of 100ppm over an 8 hour shift. The maximum peak concentration is 600ppm over 5 minutes. This is the measurement method explained.
Measuring
So when you’re laminating and you lean over that mold and it stings your eyes – how bad is that? Well it’s probably north of 300ppm if it causes eye or respiratory irritation. This isn’t good! But the problem is that there’s no easy way to measure styrene in the air without some tools.
The simplest are small glass tubes called “gas detector tubes” or similar. They are small glass tubes filled with a reactive agent that changes color when exposed to the chemical to be measured. A small hand pump pulls a specific volume of air into the tube and the reaction works its way up the tube changing the color of the contents until it runs out of whatever its measuring and stops. There are numbers on the tube reading off the approximate concentration of the chemical measured. The setup is relatively affordable and gives fast measurements.
What does it do to your brain?
Overexposure to styrene can effect your central nervous system (your brain and brainy nerve stuff) and it doesn’t do good things. Balance problems, drowsiness, slowed reaction time, lack of focus and headaches are all common symptoms of overexposure. Feeling “foggy” and incoherent, a little drunken-like – these are very common over the short term. Your body breaks down styrene pretty fast and it comes out in urine within a day.
The long term effect of over-exposure are not well understood. Because it is hard to measure real people over long periods of time, scientists sometimes measure effects on animals. Studies have shown hearing loss and liver damage in animals – not sure what kind of animals – but that’s not appealing. And in rats specifically – “impaired learning” and “sperm damage.”
Cancer
According to the Agency for Toxic Substances and Disease Registry:
“The Department of Health and Human Services (DHHS), National Toxicology Program (NTP) listed styrene as “reasonably anticipated to be a human carcinogen” in the Report on Carcinogens, Twelfth Edition, released on June 10, 2011.”
and:
“The International Agency for Research on Cancer (IARC) has determined that styrene is a possible carcinogen.”
That doesn’t sound good. Even though there is no scientific “smoking gun” on styrene and cancer, it is still worth an abundance of caution.
Protection
The two best options for protection are good ventilation and organic vapor respirators. Styrene is heavier than air, so if you are working down in a mold, the concentration of styrene will be very high because it doesn’t want to float up and out. Using fans to circulate air will help clear low-lying areas of really intense concentrations. Spray booth fans and exhaust systems are a really good idea and should be run continuously when open molding is going on.
Respirators with activated charcoal filters will remove most of the styrene from the air you’re breathing. If your filter cartridges are replaced regularly you should never smell any styrene when you have the respirator on. Make sure to keep respirators stored in closed containers and remove the cartridges and stored in a sealed bag – or whatever the manufacturer says to do!
A little more on respirators here: RESPIRATORS AND BREATHING SAFELY
Conclusions
So wear that respirator! Styrene is not as scary as many chemicals used in the composites industry, but it is very common and exposure can be continuous. Make sure to protect yourself and if you ever feel symptoms of exposure, go get some fresh air and come back with your respirator. Styrene may not be super bad for you – but it isn’t good!