For example, a majority use unclean water for irrigation leading to introduction of heavy metals and microbial pathogens into crops.

Similarly, some farmers use chemical fertilisers, herbicides, pesticides and fungicides without following the manufacturer's recommendation or having clear information about the active ingredients, disposal or even the pre-harvest interval (PHI).

"At the production level, poor site selection, like growing crops along sewer lines and roadsides, leads to contamination of food with pathogenic micro-organisms, automotive fumes and heavy metals such as lead," says Brian Ogwang an agronomist at Naro.

"Use of herbicides, pesticides and fungicides without due regard to PHI, recommended quantities and disposal methods also pose a threat to food safety."

At this stage, food handlers who do not observe hygiene may introduce pathogens whereas the water used to clean the produce may introduce micro-organisms such as E. coli or Salmonella sp.