According to the Oxford Dictionary of Proverbs, the oldest written version of the saying “what you don’t know can’t hurt you” comes from 1576, in Petit Palace by G. Pettie. “So long as I know it not, it hurteth mee not.” And although this may be true in some circumstances, it is certainly not the case in matters of health and safety.
Not knowing that something toxic is present at the site can be lethal. The same can be said of toxins and contaminants in our environment. If we don’t know they are there, we may not protect ourselves against them. More frequently on construction sites, especially in urban areas or past industrial facilities, environmental studies done in advance of construction are looking at a very small and finite list of contaminants commonly referred to as priority pollutants. The priority pollutants are a subset of "toxic pollutants" as defined in the Clean Water Act (USA). These 126 pollutants were assigned a high priority for development of water quality criteria and effluent limitation guidelines because they are frequently found in wastewater but it is not a comprehensive list and since the 1970s many new industrialized chemicals have been developed and are now present in our environment. The list focused on those chemicals that were frequently found in wastewater and contained toxic properties. The list did not include toxic chemicals that were not found in wastewater but may represent a hazard in the soils or to people exposed by direct contact.
Current practice today involves developing health and safety plans based on chemicals known to exist at a site usually as a result of site characterization studies using the EPA’s priority pollutant list as basis for determining what is on the site. This can lead to missing important and toxic contaminants that present a real threat to construction workers and the surrounding public if not properly managed. Perhaps the most common contaminant overlooked in this process is asbestos. Asbestos was widely used in United States after World War II in many products. It can often be found in building materials such as floor tiles, transite piping, insulation, wall board or as mastic on bricks. As buildings were demolished or damaged by fire it was common practice to use the waste as fill material or left in place and graded into the surrounding area.
Critical to establishing what chemicals/contaminants might be present at a site is having a solid understanding of historic land uses. Much of the information may already be available in environmental study reports prepared at the time of a property transfer or in advance of site development activities to determine environmental liabilities; however, even with this information, oftentimes, the environmental consultants will only rely on the priority pollutant list analyses to determine what if any contamination exists at the site from historical operations. This can lead to missing important contaminants in the subsurface. In order to avoid this problem, a careful review of chemical usage at the facility should be done, though even this may lead to missing compounds of concern. Another tool is to request the analytical laboratory to provide the gas chromatograph print out so that it can be viewed for unidentified compounds. Many laboratories will provide a list of tentatively identified compounds if requested. This is particularly important when working on a site with a long history of chemical usage or industrial operations using a wide-variety of chemicals.
Even in a well characterized site there can be surprises, so the safety officer should be alert to worker exposures. If workers complain of headaches, skin rashes, coughs or nausea these symptoms may be related to environmental exposures to unknown contaminants or known contaminants at higher than expected concentrations. Sometimes just the exposure of air or the introduction of new chemicals can cause a reaction releasing chemicals into the environment.
Vigilance is key and knowing what you don’t know will help you prepare for the unknown. If you have any questions about the hazards you are encountering at your project contact us...we can help!