Canadian Occupational Safety

14 www.thesafetymag.com/ca F E A T U R E Accessing the closest device such as an emergency shower or eyewash (ESEW) station or personal wash station as outlined in the ANSI Z358.1 standard will help limit exposure time, thus helping to reduce the penetration of the chemical into tissue cells. Case study: Emergency Shower and Eyewash Stations Taking the example of ESEW stations as a way to manage burns and irritation, there are a number of benefits — but also limitations to using water. "Water delivered through an ESEW station provides benefits such as mechanical removal, diluting and helping to cool skin or eye tissue, says Wootten. It is also important to understand that water is a simple passive rinse with limited backend effects. That is why many people who do get exposed to an registered in the Chemical Abstracts Service," Hallsworth explains. There are companies that build instruments to test for some of the common specific hazards, such as benzene or silica dust. That is why WHMIS documents are so important, because when you look at the product that you are going to use, you can see how the supplier classified the potential harm of the product and you can look at the ingredient level for the harmful ingredients, then apply a precautionary approach by either choosing not to use the product or having the correct ventilation, for example, or personal protective equipment (PPE). Burns and irritation One of the most common hazards for most workers when it comes to chemical exposure is chemical burn or irritation. A chemical burn occurs when skin or tissues (such as eyes) come into contact with an irritant or corrosive chemical. In some cases, if swallowed, it can cause burns on the tongue, esophagus and stomach tissue. "Chemical burns occur when skin or eye tissue are exposed to strong acidic or basic chemicals," says David Wootten, National Prevor Product Manager. The aggressiveness of acids and bases is determined by the pH scale of the chemical involved, which ranges from 1 to 14, he says. Strong acids can have a pH of one or less, while strong bases can have a pH of 14. Irritant group chemicals such as oxidizers, reducing agents, chelating solutions and solvents present a lesser risk of permanent injury. Wounds Canada says that every year, thousands of Canadians sustain a burn injury. Some of the most common products that can cause chemical burns include car battery acid, bleach, ammonia, denture cleaner, teeth- whitening products, pool cleaning products, oven cleaner and lye. "The first and most important step to take after exposure to an aggressive chemical is to provide mechanical removal from the surface of the skin or eye tissue," says Wootten. "While water will provide benefits to anyone who has been exposed to an aggressive agent, it won't always prevent burns and other complications from happening." David Wootten, Prevor. aggressive chemical and immediately rinse with water, still suffer serious life altering injuries." Wootten says that the limitations of water include the following: • Water can only dilute which means there is no active effect on the aggressive acidic or basic ions resulting in a very slow return to establishing a safe physiological pH on skin or eye tissue. • Water is naturally hypotonic to the human body which means that water will help diffuse the chemical deeper into tissue cells, potentially exacerbating the injury. • Accessing ESEW within 10 seconds or 55 feet is not always achievable based on many factors — most important of which are the extent of the victim's injuries; their ability to get to the ESEW equipment within 10 seconds; whether they have visual impairment, and if so, whether there is a co-worker nearby to assist them; and whether the equipment has been maintained to function properly. Based on the above, water can be seen as a "passive" rinse, while other, newer products are considered "active" rinses. "The difference between the two is that while water will provide benefits to anyone who has been exposed to an aggressive agent, it won't always prevent burns and other complications from happening. Therefore, we need to look at what we need to have happen while mechanical rinsing is occurring," he says. An active solution based on the following could improve results, says Wootten, because: • A hypertonic action prevents the ingress of the chemical and draws it back to the tissue surface. • A chelating action attracts, fixes to and absorbs the acidic or basic ions, which helps to restore the victim's skin or eye tissue's physiological pH rapidly. • It is amphoteric to opposing chemical reactions, meaning its efficacy is established on acids vs bases, oxidizers vs reducing agents, chelating agents and solvents etc. So what kind of active solutions exist currently? "Phosphate and borate buffered solutions are considered active but have limited capacity," says Wootten. "Borate buffered solutions are designed for basic chemicals but are much less efficient on acidic chemicals, and phosphate buffer

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