1. Nitrate contamination in
vegetables grown in
Punjab: An imminent
human health risk
 Muhammad Mubashir, Saeed A.
Malik,Tariq M. Ansari and
 Aleem A. Khan

2. All living systems need nitrogen for the production of complex
organic molecules, such as proteins, nucleic acids, vitamins,
hormones and enzymes. Due to the intense use of synthetic
nitrogen fertilizers and livestock manure in modern day
agriculture, food (particularly vegetables) and drinking water may
contain higher concentrations of nitrate than in the past. The
mean intake of nitrate per person in Europe is about 50-140 mg/day
and in the US about 40-100 mg/day. In the proximal small intestine,
nitrate is rapidly and almost completely absorbed (bio-availability
at least 92%). In humans, approximately, 25% of the nitrate
ingested is secreted in saliva, where some 20% (about 5-8% of the
nitrate intake) is converted to nitrite by commensal bacteria. The
nitrite so formed is then absorbed primarily in the small intestine
(Bartikiavichiute et al., 1991).
Nitrogen is a vitally important plant nutrient, the supply of which
can be controlled by man. Plants primarily in the form of nitrates
absorb it through smaller amount of other forms can be absorbed
including the ammonium N using the energy provided by
photosynthesis. When nitrogen supplies are adequate and
conditions are favorable for growth. Proteins are formed from the
manufactured carbohydrates when plants are deficient in nitrogen.
They become stunted and yellow in appearance (Bernstein, 1964).

3. Researchers have studied the link between nitrate rich fruit and
vegetable and gullet cancer which claims the lives of more than
30,000 people in the UK every year in reported cases of cancer,
which affects the three times, as many men, as women have treble
in the last 20 years (Barker et al., 1979).
Elevated levels of nitrate in drinking water and eatable plants have
the negative impact on human health (Niecko et al., 2001).
Nitrates have also been linked to miscarriages in women and an
increased risk of non-Hodgkin’s lymphoma (Jasa et al., 1988) and
bladder and ovarian cancers (Townsend et al., 2003; Ward et al.,
2005).
Nitrate had been found to react with amines and amides to form
nitrosamines and nitrosamides, which have been found to induce
cancer in rodents. There is no other group of carcinogens known
that have the ability to induce such a wide variety of tumors in
organs, ranging from lung, oral, brain, skin, leukemia, and bladder
(Tannehill et al., 1996).
During an epidemiological survey, a high percentage (41%) of
goiter was prevalent among the children aged 6-14 years in the
villages with nitrate contamination (Gatseva et al., 1998).

4. Collection & Analysis of vegetable samples
Vegetable samples were taken from selected sites and were
immediately transported to laboratory in proper leather labeled
paper bags that allow for transpiration; this reduces the possibility
of rooting.
Summer and winter vegetables were collected from all 35 districts
in Punjab, Pakistan.
In each district, a sum of nine, market based and agricultural fields
were selected to collect seasonal vegetable samples for nitrate
assessment.
The samples include, Carrot, Eggplant, Okra, Onion, Potato,
Radish, Spinach, Squash, Tomato, and Turnip.
Total number of vegetable samples = 35 x 9 x 2 = 630
Multivariate statistics were performed as, mean and standard
error of mean, Analysis of variance, Repeated analysis and Duncan
multiple range test (DMRT).

5. Research Rationale and Hypothesis.
Nitrate contamination is a growing concern with the initiatives
following green revolution in agricultural development. The fast
growing world human population means more and more food
required, in a scenario of frequently changing global climate
pattern and weather regimes. In order to cope with the prolific
demand for food, in the wake of global warming phenomena, has
put great burden on the present agricultural practices to enhance
crop yield per acre. There is dire and ever growing demand to get
multiple crops from the same patch of land and with high crop
yielding ratio.
The bioecological system is unable to provide ample organic
based fertilizers to cope with the prolific food demand of the world
population, which almost approaching 7 billion people, as we talk,
hence requires to supplement the use of chemical fertilizers to
tackle the issue. Consequently, the application of nitrogen
fertilizers is on the inexhaustible increase. There have been a few
studies done on assessment of the use of nitrogen and its
probable effects on human health, in particular, and on the
biodiversity and bioecological systems, in general.
Thereby, a study was designed to assess the nitrates levels, in
vegetables being grown and sold in different markets.

7. Nitrate
Concentrati
on(ppm) In
Winter
Vegetables
Of Punjab
Province
0
2 0 0 0
4 0 0 0
6 0 0 0
8 0 0 0
0
500
1000
1500
2 0 0 0
2 50 0
0
500
1000
1500
2 0 0 0
0
2 0 0
4 0 0
6 0 0
8 0 0
10 0 0
12 0 0
0
200
400
600
800
1000
1200
1400
0
1000
2 0 0 0
3 0 0 0
4 0 0 0
5 0 0 0
6 0 0 0
7 0 0 0 Radish
Turnip
Potato
Carrot
D. Spinich
H. Spinich
B.Pur B.Nagr
Rykhn Dgkhn
Layh M.garh
R.pur F.abad
Jhang Nkana
T.T.sing G.wala
Gujrat H.abad
Mbdin Nr.wal
S.kot Kasur
Lahore Okara
Sh.pura K.wal
Lodhran Multan
Pakpat S.wal
Vehari Attock
Ck.wal Jehlum
R.pindi Bakhar
Khushab M.wali
Sargodha

9. Conclusion.
The population of Pakistan is expanding
at the rate of more than 3% per annum
necessitating demand for more food and
subsequent increase in the use of
fertilizers. There is a need for proper
education of the framers regarding the
judicious use of fertilizers and they must
be made aware of the detrimental
effects, before using such fertilizers (a)
whether there is any deficiency in the
soil and (b) the requirement of the crop
to be raised.

10. Precautions and Preventions.
Nitrate-nitrogen accumulates from sunset to sunrise and is reduced from
sunrise until late in day. Effective control of the nitrate-nitrogen content of
vegetable products can be achieved simply by adjusting the time of harvest
at the afternoon hours. The temperature effects the nitrate accumulation
because it affects the processes of absorption, translocation and
assimilation and varies from species to species (Wiebe, 1993; Nedwell,
1994).
Vegetables are the primary dietary source of nitrate; however, when they
are taken with vitamin C and other nitrosation inhibitors (Bartsch and
Frank, 1996) and, therefore, high intakes may not result in high rates of
formation of N-nitroso compounds.
Leafy green vegetables and some root crops assimilate nitrate naturally.
Fertilizer applied in excess may result in the accumulation of large amount
of nitrate in some vegetables. Eating these vegetables contribute to the
daily ingest of nitrate.