High lead contamination of animal foods pre-dispose the Ugandan population to cancer

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Wednesday, 12 September 2018

Inorganic compounds are such a key part of our ecosystem, it is difficult to define human history without making a key reference to them.

This is because some are required by the body for physiological purposes, while some are crucial for the commercial and technological industry. Among the former are zinc (Zn), iron (Fe) and copper (Cu), which are required for key detoxification, enzymatic and body function.


Cows in Uganda. © Fanny Schertzer

These compounds are important to the body in micro amounts, since an excess of them can lead to significant tissue death and predispose one to cancer. In developing countries, irrational usage of agricultural and industrial chemicals has led to severe environmental pollution with inorganic compounds such that these have managed to enter the food chain.

Currently, lead (Pb) has been shown to be a major contaminant in roast beef in Uganda and the absence of proactive legislation and enforcement implies that the public is continuously exposed to multiple carcinogenic compounds in foods, which would easily be monitored by the local national regulatory authorities.

Weak food safety

Unfortunately, there are no efforts being taken to screen foods, probably due to a weak food safety industry in Uganda, as is common with most developing countries.

In this particular study, we assessed the levels of major inorganic compounds in beef and milk of cattle origin (since this is the major source of animal protein in several African countries), calculated the estimated daily intake (EDI = amount of metal eaten by a person from the foods), the incremental lifetime cancer risk (ILCR = risk of developing cancer by eating the foods over a 70 year period) and the hazard index (HI = risk of developing other non-cancer related illness).

It was important for us to estimate the ILCR and HI, since foods eaten contain all the pollutants, and the sum would offer a clear picture of the synergistic health hazard in the public, i.e. in children and adults.

In a majority of developing countries, a lot of emphasis has been placed on microbial load and food hygienic assessment, ignoring the impact played by organic and inorganic compounds. This situation would probably be created by the limited infrastructure or technical support in several developing countries, and this is worsened by the privatisation of several agricultural agencies leading to limited or no routine information on food safety screening being offered by the government to the public.

In the current study, we showed that inorganic compounds in milk and beef were highest in the order of Zn > Fe > Pb > Cu and Zn > Pb > Fe > Cu respectively. These findings seem to suggest that zinc is highest in milk and beef, however, emphasis was placed on the EDI and the tolerable allowable levels (TAL) in humans by using the United States Environmental Protection Agency (US EPA), since this was important in defining what is healthy and carcinogenic to the body.

Low quality of milk and beef in Uganda

After making comparisons, we discovered that all the other compounds are present in very minute concentrations (not enough for the body), showing that the milk and beef quality in Uganda was low. Very high Pb concentrations above the TAL call for a need to access sources of Pb contamination on a majority of farms in Uganda where these animals graze.

In developing countries, the absence of robust national food safety regulatory centres implies that a majority of findings like these hardly capture the attention of the regulatory authorities. Findings in the study would help the public make a better decision whenever they decide to consume dairy products of Ugandan origin. 

Cancer risk was measured against Pb and Zn, from which the study showed that beef and milk are not safe for both children and adults due to very high Pb concentrations. Sources of Pb in the environment would have to be investigated as it seems that livestock products on the Ugandan market, would be vehicles for Pb contamination to the general population, thus creating a lot of strain on the healthcare systems and increasing the incidence of cancer within the Ugandan population. 

The authors believe that the establishment of national food safety and toxicological screening centres would help the government offer robust information to the public and prospective investors in the livestock value addition chain.

Information on the study can be found online 

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