What’s the most dangerous place in your wastewater treatment plant? Headworks. Biosolids area. Electrical panels. 

Think again. It could be your laboratory. While one of the most regulated places within a wastewater treatment plant, the laboratory can be an accident waiting to happen, according to Rick Mealy and George Bowman who are part of a team of chemists who handle the auditing of the 270 wastewater plant laboratories in Wisconsin. 

There is no lack of instruction and advice on lab safety. Every operator association publishes lists and handbooks on laboratory hazards and safety tips. OSHA dedicates more than 15 pages to lab safety procedures.

Still, the safety message can’t be overemphasized. 

Mealy and Bowman put safe laboratory practice in simple and specific terms, based on their experience visiting treatment plants around the state. Here are their “Top 15 Lab Safety Concerns”: 

1. Lack of fume hoods. Shocking, but true. Even in new laboratories, it’s not unusual that fume hoods are missing. 

2. Improper use of fume hoods. Solids ovens and other equipment should not be placed in the fume hoods; they belong under canopies or vented to snorkel vents. If equipment must be located in a hood, the device should be raised properly to ensure adequate airflow so the hood works properly. When using unvented ovens, whatever is in the sample is in the vapors and can be inhaled. 

3. Using concentrated acids needlessly. Some labs are using 50 percent hydrochloric acid to rinse glassware for phosphorus testing when 10 percent is more than adequate and in many cases, 1 percent is sufficient. Overuse creates dangerous and unnecessary fumes. 

4. Use of mercury thermometers in the lab, especially in TSS ovens. Up to a third of labs have at least one mercury thermometer. What happens when someone shoves a tray too fast into an oven and shears the thermometer? 

5. Old ovens and furnaces with crumbly flaking asbestos lining. It’s a major health hazard, and can result in a lawsuit against your community. 

6. Failure to wear safety glasses. Personal protection is a major concern in wastewater plant labs, and it’s one of the easiest problems to solve. Every bacterial, viral or fungal infection passes through the treatment plant. Many labs don’t require any eye protection even when the operator/analyst wears contact lenses. That’s a big problem. First hand, we’ve seen individuals that had to be hospitalized from contact with acids, reagents and samples. 

7. Soaking pipettes and phosphorus glassware in acid baths in an unvented area. It’s a safety hazard and the bath tends to get contaminated easily after repeated use, actually increasing contamination in the phosphorus test. It’s also a major source of corrosion in labs, and the operators are breathing those fumes.

8. Using hydrochloric acid (HCl) and bleach to clean BOD bottles. When labs wash bottles in bleach alone (no detergent) and then follow with HCl, the residual bleach in the sink mixed with the HCl will release enough chlorine gas to kill.

9. Rinsing glassware with HCl in sinks that are not vented. This is a major safety concern, not to mention another source of corrosion in the laboratory. At least one sink should be vented with a slot vent.

10. Preparing dilute acids in the lab from concentrated sulfuric acid (H2SO4) and HCl. This is a problem for those labs that don’t have a fume hood or those that have a fume hood but cannot use it because it’s filled with equipment like ovens. Why make up acids and take risks when you can buy them already diluted? Vendors sell 10 percent HCl for cleaning (phosphorus-free) and dilute acids that can be used for preserving samples. We recommend 5N or at the most 11N H2SO4 for preserving samples. They’re cheap.

11. Not having MSDSs on-site and not understanding the hazards of handling some chemicals. An example is the chromate indicator used for chloride titrations. It’s a carcinogen, but most labs don’t know that, and many handle the stuff without gloves. (While on the subject, most labs simply dump reacted samples/vials down the sink. Do you know what chemicals are used in those processes?)

12. Storing acid and bases in the same cabinet. There will be some storage of oxidizers in close proximity to reducers in laboratories. However, violent reactions can occur when these opposites are spilled or mixed.

13. Storing reagents (acids, bases, etc.) above eye level, which increases the chances of dangerous spills to the face.

14. Labs should consider using mechanical pipettes and disposable tips to reduce the number of volumetric pipettes needed. This also reduces the amount of acid handling required since fewer pipettes need to be rinsed with HCl for P testing. One variable volume mechanical pipette (1-10 mL) can eliminate six or seven glass pipettes. People still get cut during washing of glass pipettes, and that’s an invitation for some microbial pathogen to enter the bloodstream.

15. Occasionally, and unfortunately, mouth pipetting is still a problem.

In short, say Mealy and Bowman, it’s the simple, routine tasks that often are the most dangerous. Don’t take anything for granted and think before you act.