**5. Monitoring of pesticides residues in yam**

All over the world, there are concerns about pesticide residues resulting from the use of pesticides on crops [67]. For this reason, governments and especially in the EU allow pesticides to enter their respective countries as long as they are used in line with the law and the guidelines controlling their use.

In Ghana, public concerns are high about the use of pesticides by Ghanaian farmers and its attendant food safety and human health issues. This has led to the conduct of pesticides residue monitoring studies to assess the levels of pesticides in various food items. In a study by Asiedu [68] to determine pesticides residues in lettuce, garden egg, pineapple, and mango in three regions of Ghana, it was found that some market fruits and vegetables contained different types of pesticides of which chlorpyrifos (an organophosphate) and cypermethrin (a synthetic pyrethroid) were the most common ones. In a study by Bempah & Donkor [69] to assess the concentration of pesticides residues in fruits and vegetables from selected markets in Kumasi in the Ashanti region, it was found that 19% of the samples contained pesticides residues above the maximum residue level (MRL) with the health risk analysis further revealing that the pesticides endrin had exceeded the reference dose in vegetables, thereby suggesting a great potential for systematic poisoning in children that are considered as the most vulnerable population subgroup.

There is limited literature on pesticides residues in yam in contrast to other root and tuber crops in developing countries [70, 71]. This is partly because the crop is grown and consumed mostly in the developing world where there is limited scientific expertise and resources to set residue limits and to monitor them. In a study of Adeyeye and Osibanjo [70], 55% of yam samples from Nigerian markets were contaminated with one or more organochlorine pesticides (aldrin, dieldrin, HCH, and

### *State of the Art of Yam Production DOI: http://dx.doi.org/10.5772/intechopen.106504*

DDT). In a monitoring program by the "UK pesticides residue committee," to check whether pesticides residues in food and drink are above the maximum residue levels (MRLs), it was found that yam was among the food commodities with pesticides residues exceeding the MRLs [72]. Out of the 52 yam samples analyzed, 9 samples contained residues at or below the MRL, 11 samples contained residues above the MRL, and 13 samples contained more than one residue. The report observed further that as in previous years relatively high numbers of samples with residues over the MRL were found in the specialty vegetables, okra and yam. The yam samples used in this monitoring study originated from Ghana, Brazil, and Jordan. The samples from Ghana had residue levels of 0.2–0.3 mg/kg carbendazim (MRL = 0.1 mg/kg) and 0.4 mg/kg tebuconazole (MRL = 0.02 mg/kg). Since MRLs are not safety limits, risk assessment were carried out with the monitoring results which showed that the residues found in the yam will be unlikely to have adverse effects on health [72]. Similarly, in the studies of Wumbei et al. [73, 74] to investigate pesticides residues


#### **Table 5.**

*Estimated daily intake of fenpropimorph and fenitrothion through deterministic exposure assessment and corresponding ADIs. Adopted from Wumbei et al. [32, 74, 75].*

in yam, 12 pesticides, including five insecticides (cadusafos, fenitrothion, imidacloprid, profenofos, and propoxur), four fungicides (carbendazim, fenpropimorph, metalaxyl, and propiconazole), and three herbicides (bentazone, glyphosate, and pendimethalin) were detected. However, when consumption risk assessment was carried out, it was revealed that there was no risk of dietary intake of these pesticides in yam under the deterministic approach (**Table 5**) and simple distribution approach (**Table 6**), but there was intake risk in about 10% of the study population to fenpropimorph and fenitrothion under the probabilistic (upper bound scenario) approach (**Table 7**) [75].


#### **Table 6.**

*Estimated daily intake of cadusafos, carbendazim, glyphosate, imidacloprid, metalaxyl, pendimethalin, profenofos, propiconazole, and propoxur through simple distribution and corresponding ADIs. Adopted from Wumbei et al. [32, 74, 75].*


#### **Table 7.**

*Estimated daily intake of fenpropimorph and fenitrothion through probabilistic exposure assessment. Adopted from Wumbei et al. [32, 74, 75].*

*Advances in Root Vegetables Research*
