Agriculture Reference
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common acceptable standard of 1 10 3 100 g 1 wet weight) were recorded on
all irrigated lettuce including those irrigated with piped water.
Apart from lettuce from Accra that was stream-water irrigated, higher
levels of FC contamination were recorded in the rainy season than in the dry
season. The difference was significant (P < 0 : 05) only in the cases of well- and
stream-water irrigated vegetables from Kumasi (Amoah et al, 2005). The
results also showed that in 80-90 per cent of the weeks' produce sampled in
Accra and Kumasi, there was no significant difference in the FC counts of
samples analysed from the farm gate to the markets and final retail points.
Helminth eggs
Helminth eggs, including those of Ascaris lumbricoides, Hymenolepis
diminuta, T. trichuris, F. hepatica and Strongyloides larvae, were counted on
lettuce samples at the different entry points. The helminth egg population
ranged from one to six eggs 100 g 1 wet weight. In the majority of cases,
significantly higher levels (P < 0 : 05) were recorded in lettuce that was
irrigated with polluted water than those from piped water irrigated sources.
However, mean helminth egg population on lettuce from the same original
stock and irrigation water source did not show any significant difference from
field to market (see Table 6.4).
The study revealed that the contamination of lettuce with pathogenic
micro-organisms does not significantly increase through post-harvest handling
and marketing, in contrast to earlier work (Armar-Klemesu et al, 1998). These
results were unexpected because of the alarmingly unhygienic conditions on
market sites, which are related to washing habits, display and handling of
food and the availability of sanitation infrastructure. Only 31 per cent of the
Table 6.4 Helminth egg contamination at different entry points along
the production-consumption pathway
Mean helminth egg concentration
(100 g 1 wet weight)
City
Irrigation water source
Farm
Wholesale market
Retail
4 a
5 a
4 a
Kumasi
Well
6 b
5 a
5 a
Stream
2 c
2 b
1 b
Piped water
6 a
6 a
5 a
Accra
Drain
4 b
3 b
4 ab
Stream
3 b
2 b
3 b
Piped water
Mean numbers represent the mean of all the different types of eggs, as well as Strongyloides
larvae (n ΒΌ 15 for each irrigation water source). Eggs were rounded to the nearest whole
number.
The same letters indicate no significant difference in column numbers between water
sources for each city (P > 0:05). For differences between farm, wholesale market and retail,
see Figure 6.3.
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