Providing Early Warning About Workplace Hazards - Frequently Asked Questions
- What types of health hazard information triggers an alert?
- Does this information come from studying workers exposed to hazards?
- Why aren’t studies of workers used more often?
- How do you know that the results of animal tests are relevant to humans?
- How do you know who to warn?
- What effect have the HESIS health alerts had?
1. What types of health hazard information triggers an alert?
Usually it’s information which shows that a chemical or workplace exposure can cause long-term health effects such as cancer, damage to the reproductive system and nervous system, and birth defects.
2. Does this information come from studying workers exposed to hazards?
Sometimes. Studies of exposed workers showed that diesel exhaust can cause lung cancer and asthma, and that n-hexane causes nerve damage. However, most of the information for our alerts is based on the results of animal tests. For example, animal tests showed that methylene chloride used in paint stripping and perchloroethylene used in dry cleaning cause cancer. Animal studies also revealed that 1-bromopropane, a solvent used in spray adhesives and as degreasers in several industries, causes sterility, damage to the fetuses of pregnant animals, and nerve damage.
3. Why aren’t studies of workers used more often?
Long-term health damage from chemical exposures can be difficult to detect and can take a long time to show up. For example, it can take up to 30 years to develop cancer from exposure to a toxic chemical. To show that a chemical causes cancer in humans requires studying a large number of exposed people and/or a very potent cancer-causing substance. It also can be difficult to separate the effects of chemicals from other things, like smoking, that also cause cancer. Studying the effects of chemicals on human reproduction is also difficult. Many factors can contribute to sterility, spontaneous abortions and birth defects, so demonstrating the effects of chemicals that cause reproductive damage can be complicated.
4. How do you know that the results of animal tests are relevant to humans?
Many studies have looked at chemicals known to cause certain health effects in humans and compared them to the health effects caused in animals. These studies have shown that, with few exceptions, the effects on animals can be used to predict the effect on humans. Any differences between animals and humans are taken into consideration when scientists estimate the amount of a chemical that will cause health damage in humans.
5. How do you know who to warn?
When we know which industries use the chemical we want to warn about, we work with unions, trade associations and others in the industry to identify the individuals and businesses we need to reach. Unfortunately, we do not always know where a chemical is used. This is particularly true in the case of new or unregulated chemicals. California needs a system to track the use of chemicals that may pose health hazards to workers so that as new information becomes available, we can contact affected workers and employers to alert them. For more information about chemical tracking systems, see the HESIS web page Tracking Workplace Chemical Hazards.
6. What effect have the HESIS health alerts had?
In some cases, HESIS health alerts have contributed to changing how certain chemicals are used or regulated. For example, glycol ether solvents that cause reproductive damage are no longer used in the semiconductor industry and their workplace exposure limits have been reduced. Cal/OSHA’s regulation for ethylene oxide, a gas used in hospital sterilizers, is now based on cancer and reproductive damage instead of respiratory irritation. Signs near hospital sterilizers now warn workers of these long-term health effects. Following a HESIS health hazard advisory, manufacturers stopped making brake cleaners with the solvent n-hexane. Many other alerts and advisories have raised the awareness of workers and employers about new hazards; we often see increased inquiries to our program about a certain chemical hazard after issuing an alert about it.
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