Reducing Lead Contamination in Maple Syrup Equipment

Modern maple syrup production has all but eliminated the chances of lead contamination in maple syrup. However, double checking your equipment can never hurt, no matter how modern the operation.

PHOTO: marcduf/istock

As part of a checklist, there are industry-wide practices to ensure that equipment is not unintentionally introduced to lead from the tap to bottle. Following are some places to evaluate in the sugaring process where you can double check to ensure there’s no chance of lead-contaminated maple syrup.

Types of lead

The lead in maple syrup and most types of products that are consumed is often referred to as dissolved lead.

“There are two forms that could appear,” said Timothy D. Perkins, Ph.D., research professor and director at the University of Vermont’s Proctor Maple Research Center. “One is dissolved lead, [which] you can’t see or taste or smell. You can only detect it via some type of analysis.

“The other form is particulate lead, small particles of lead, generally in maple syrup. Those would be tied up in niter. Niter is generally removed by filtering. So if the syrup is clear, which it’s required to be through filtering, then the particulate lead would be out of there and the only thing that you would be able to actually detect in a test is the dissolved component of the lead.”

The International Maple Institute has recommended guidelines to ensure filtering is effective in removing any potential “sugar sand” or niter from maple syrup. Filtering should occur at at least 185 degrees Fahrenheit and should use food grade equipment. If a plate filter is used, stainless steel or cast aluminum is recommended, while stainless steel is an acceptable material for canister pressure filters. Pumps constructed with brass or bronze alloys are not advised to filter lead from maple syrup.

How lead is commonly introduced

“Lead can be introduced into sap primarily through contact with lead containing equipment. That equipment tends to be very old types of equipment,” Perkins said. “(In) older equipment that contained lead solder or galvanized material that contained lead, the lead can be mobilized by the sap because it’s slightly acidic.”

Where can lead exposure exist?

Perkins mentions that buckets made before the 1990s are a potential source of lead contamination, along with storage tanks or evaporators manufactured prior to the 1990s.

Transition to lead-free equipment

The movement to lead-free equipment took place during the mid-1990s, as Perkins explained, when maple processing equipment manufacturers stopped using lead solder in place of lead-free solder. Manufacturing methods eventually transitioned into welding equipment, including pans and storage tanks versus soldering.

Taps and tubing

Jonas Sickler, marketing director of Syracuse, New York.-based Consumer Safety, explained that older equipment can still contain lead. Instead of using lead soldered buckets, Sickler recommends to “use plastic tubing and containers rather than metal buckets.”

When it comes to taps and tubing, Perkins explained that, “as long as producers are using tubing that is suitable for food use or potable water, then it won’t contain lead.”

The 2015 publication from the International Maple Institute explained in depth these two collection processes. The institute recommends either “aluminum, stainless steel, or food grade plastic” spiles to tap sap. Their guidelines point out that terneplate or “old tin” spiles should be specifically avoided because of the potential to introduce as much as 1,700 ppb of lead into sap.

Evaporator and pans

“Evaporators prior to the early 1990s were generally made from stainless steel, but they were soldered together with solder that was used that contained lead,” Perkins noted. “Once this problem was discovered, many manufacturers started switching to silver solder, which does not contain lead, and began experimenting with welding pans.”

Sickler described how evaporator pans containing lead can pose a serious threat of contamination during processing.

“Lead solder has (a) relatively low melting point of between 361-370 degrees Fahrenheit, and sugar melts at 366 degrees Fahrenheit.” he said. “You can see the problem there. It’s possible for your lead solder to be melting into your maple syrup while boiling it.”

The International Maple Institute notes the potential sources during the processing phase includes galvanized pans, along with lead soldered stainless steel pans, before 1994. However, Perkins said that beginning in the later part of the 1990s, virtually all pan manufacturing consisted of lead-free TIG welding methods of stainless steel.


Another potential source of lead contamination, as the International Maple Institute and Eric Feigl-Ding, an epidemiologist and nutrition scientist at Harvard School of Public Health noted, includes the source of water used.

“I think one key way to reduce lead exposure is to make sure the farming is done using lead-free water,” Feigl-Ding explained. “Lead is a heavy metal that bioaccumulates (like mercury in fish), hence groundwater and other water sources used for irrigation should be lead free. One way to check easily is [by] using U.S. Geological Service dataaggregated which has a map that is searchable by location.”

The International Maple Institute explained that water should comply with local and national water safety standards when used to clean maple processing equipment.