Slow poison that is the local grinding machines

Some weeks back, I went to grind pepper in a commercial grinding center. While the woman was busy grinding and blending the pepper together, I could not help but think about the possible contaminants that would get into the blended pepper as a result of the machine being used. The grinding machine consists of two essential parts:

  • An electric motor
  • Fabricated metal

The fabricated metal is connected to the electric motor using a belt. As the motor rotates, the belt drives the grinding plate of the fabricated metal and any content in between the grinding plates gets pulverized and is collected at a converging point using a container.


The local grinding machine as we have it in Nigeria

In other words, the commercial grinder works by using two opposing grinding plates with one being rotated by a belt connected to an electric motor while the other just serves as a pivot. The frictional force between the two grinding plates is primarily responsible for the grinding. Looking at the setup, there is no way some quantities of metals will not get into substances being ground.

With this thought on my mind, I decided to do a bit of an online search to see if someone in the scientific world has been inquisitive enough to conduct proper research in trying to see if there is indeed contamination by heavy metals as a result of the grinding setup.

I really do not have the knowledge of how widely distributed the grinding setup is beyond the shores of Nigeria. One thing I am sure of is that it is very common here in Nigeria. Hence, it did not come to me as a surprise when the first relevant paper I saw was published in 2017 by a group of Nigerians.

In their work, the researchers investigated the heavy metal contents of soup condiments ground by the so-called grinding machines. Two grinding machines of different ages were used to grind the soup condiments and the heavy metal contents of the soups were analyzed using standard methods. Results were compared between the two grinding machines.

Results showed that the soups from the two grinding machines both had the presence of lead and cadmium with the soup grounded by the older machine having as much as 300% heavy metal as those grounded by the not-so-old machine.

In another research carried out in 2017, also by Nigerians, grounded millets using domestic grinders were assessed for the presence of metallic contaminants. The millets were grounded in different forms and each form was found to contain a certain level of metallic contaminants with the wet form having the highest level of contaminants and the dry form having the lowest.

I could actually go on and on with published investigations confirming that, truly, certain levels of metallic contaminants get into foods grounded using the popular local grinding machine. Unfortunately, nothing has been done by the government or the concerned authority to regulate the use of these machines. Apparently, the metallic elements that make up the fabricated metal for grinding vary and this also influences the amount and type of metallic contaminants that will get into foods.

The effects that heavy metals have on the body system are terrible. The only thing is that these effects do not manifest immediately until the metals accumulate and get to a certain threshold concentration in the body system.

The sad thing is that while someone like me can decide to stop grinding using this machine, many others will not, even if you tell them the likely consequences of continuously patronizing such an avenue. In addition, it is not like there are viable alternatives. The only alternative would be to use an electric grinder and that would limit the quantity of materials that can be grounded at once.


Grinding machine in operation

Final Words

Grinding food materials using the local grinding machine as we know it in Nigeria results in heavy metal contamination of foods. These contaminants accumulate in minute quantities until a threshold concentration that elicits symptoms in individuals is reached. The best thing would be to stay away from the local grinding machine as much as possible or, if you must use one, be sure that the fabricated metal part is a relatively new one as this would limit the amount of contaminants.

Thank you for reading.

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