“In addition to the multidose vaccines containing thimerosal discussed above, some companies offer a 0.5 mg/L single dose, pre-filled syringe vaccine. Some of these products are labeled “preservative- or thimerosal-free”. Preservative-free products may contain trace amounts (less than or equal to 1 microgram/0.5 mL dose) because thimerosal was used during the manufacturing process. The term preservative- or thimerosal-free can be utilized if the manufacturer further purified the product, leaving only trace amounts (less than or equal to 1 microgram/0.5 mL) per dose. Even at this level, calculations indicate mercury would exceed the TCLP standard; therefore these vaccines, if deemed unusable, should be managed as hazardous waste as well.”
Source: http://www.iaomt.org/news/files/files372/Thimerosal%20-%20South%20Dakota%20Waste%20Mgmt%20Guidelines.pdf
