In the first installment of this series, you learned why incorporating an environmental management system as part of a broader business plan is becoming an essential part of running any company. Here the discussion continues with a look at on-press cleaning materials and practices with a focus on identifying VOC risks.
Not all harms are equal
It’s good news that safety professionals review chemicals and identify risks to human health. Increasingly we find that solvents which were once thought of as safe are now labeled harmful. It is, of course, a good thing that we are alerted to these risks. But the law of unintended consequences has meant that this increased use of harmful labeling has sometimes increased the potential harm to screen printers and to the environment.
Health and Safety professionals know the basic equation for risk to human health: risk=hazard x exposure. Water, for example, has a very low hazard, but if the exposure is high (e.g., you are dropped into the middle of the Pacific Ocean) then the risk (drowning) is high. Similarly, tetrodotoxin is a very powerful neurotoxin found in Japanese puffer fish. The hazard is very high, but if the fish is prepared by trained professionals, the exposure is very low so the risk is also very low. One of the authors is living proof of this, having eaten this delicacy a number of times.
So let’s apply this to screen printing. A printer has to make a decision. There are two cleaning solvent blends. One has a hazard warning on the label and the other, costing the same, is hazard warning label free and works just as well. The choice is easy—go for the product with no hazard warning label. Now try the choice again. Two solvents have the same hazard classification, but one is more expensive than the other. The choice seems obvious—go for the low-cost product. But this is where the professionals need to do their calculation. The hazard might be the same, but what about the exposure? If the cheaper product is 10 times more volatile than the more expensive one, then the exposure will probably be 10 times higher. And because the volatile product is going up the printer’s nose rather than staying on the screen to do the cleaning, there’s an increased waste.
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