Chemicals can be dangerous. Chemicals can ignite. Chemicals can explode. They can corrode pipes, poison fish and damage trees and other plants.
Chemicals can also harm the health of human beings. This isn’t a new story. Lead poisoning in ship builders was documented 2000 years ago. For hundreds of years, people have known the arsenic is a poison, that mercury damages the nervous system and that coal and cotton dust cause lung disease.
But there are some dramatic changes in our scientific understanding of how chemicals can harm us. We used to think that “the dose made the poison.” Occupational safety and health was built around the concept that we could protect people by keeping their exposure under a certain number (permissible exposure limits (PELs) or recommended exposure limit (RELs). Now we know that it’s not just the dose that matters.
New science had taught us that levels of chemical exposure that were once considered safe can actually be quite dangerous. We are learning, for example, that there are no safe levels of lead exposure for children – every bit does some damage to a child’s brain and nervous system. The new idea of small amounts of chemical exposure doing big amounts of damage to our health and development is especially true for the chemicals called endocrine disruptors which can cause harm at very low doses.
New science has also taught us that there are many different factors that affect how we respond to chemicals. These include dose but also include:
- Timing of exposure
- Duration of exposure
- Previous chemical exposures
- State of health
- Genetic makeup
- Individual metabolism
- Environmental and economic factors
- Route of exposure
Most occupational health rules were written based on the old understanding that every chemical had a “safe” level of exposure. That way of thinking about our chemicals problem leads to solutions that lower the levels of exposure below that “safe” threshold through personal protection equipment like masks and gloves and engineering controls like ventilation hoods.
These are solutions at the bottom of the hierarchy of controls. ChemHAT was designed to let us ask and answer a different question. Instead of what engineering controls and personal protective equipment do I need to lower the levels of exposure to a “safe” level, ChemHAT is being designed to answer the question, “Is there a way to get this job done without using dangerous chemicals? We know from stories of substitution and elimination that already exist, that the answer can be yes.