|ETHIDIUM BROMIDE WASTE REDUCTION|
Ethidium Bromide (EtBr) is an intercalating stain frequently used by molecular biologists for visualization of Deoxyribonucleic acid (DNA) in agarose gels. EtBr is widely used by many researchers due to its high sensitivity, rapid staining, and very inexpensive price. Unfortunately EtBr is a powerful mutagen; hence there are concerns about its use and ultimate disposal. The reduction of this hazardous substance in the wastestream may be possible with the implementation of on-site EtBr filtration systems and/or substitution of less toxic alternatives.*
State of Michigan Act 451 Part 121.
Overview of Procedure
More sensitive, less toxic alternative stains are still being researched. In the meantime, a pilot study to assess the viability of EtBr extractors for handling this waste stream is being performed. The EtBr extractor houses a specially formulated activated carbon matrix disk for the adsorption of EtBr. Each extractor is capable of filtering up to 10 liters of EtBr contaminated solution at a concentration of 0.5µg/mL.
Filters tend to clog over extended periods of time due to agarose from gels.
& Health Precautions/Personal Protective Equipment
Project Related Costs
The EtBr extractor systems cost $7.13 per unit, have a filtration capacity of 10 liters, and a 99 percent removal efficiency. An overall filtration price would be $0.71/liter. A minimum order of 72 units is required to receive the discounted price of $7.13 per unit.
The extractor units weigh 84 grams (0.168 lbs.) each. Weight difference is negligible between used and unused filters.
The figures reflect an optimum concentration of 0.5 mg/L. Concentrations used by U-M researchers are typically in the range of 0.05 to 0.1 mg/L, hence increasing the actual volume that could be filtered and lowering the cost per liter estimate.
Using the disposal information from 1996 an analysis can be made as to how much the U-M would have saved with the use of the EtBr extractors:
Current Cost of the EtBr
Disposal Cost for liquid EtBr waste: $4,510
Total Actual Disposal Cost for 1996: $4510 + $8,082.50 = $12,000
If EtBr Extractors Had Been
Purchasing Cost of Filters:
(91 filters) X (0.168 lbs./filter) = 15.3 or 16 lbs. of additional solid waste
16 lbs. + 3,233 lbs.:
(3,249 lbs.) X ($2.50/lb):
Total Cost if Filters Had Been Used:
Theoretical Cost Savings: