1. The study examined blood and milk lead levels in lactating cows reared near various industrial activities in India. 2. The highest blood lead level was found in cows near a lead-zinc smelter, followed by a closed lead smelter and an aluminum plant. 3. The highest milk lead level was detected in cows near the lead-zinc smelter, followed by the aluminum plant and a steel mill.

1. Blood lead levels in lactating cows reared around polluted
localities; transfer of lead into milk
D. Swarup, R.C. PatraT, Ram Naresh, Puneet Kumar, Pallav Shekhar
Environmental Medicine Laboratory, Division of Medicine, Indian Veterinary Research Institute Izatnagar, 243122, U.P. India
Received 5 April 2004; accepted 1 December 2004
Available online 3 February 2005
Abstract
Lead is pervasive environmental pollutant with potential public health hazard as a contaminant of food from animal origin.
The present study examines the blood and milk lead level in animals reared in areas around different industrial activities and to
find out correlation between blood and milk lead levels in lactating cows. Blood and milk samples (n=149) were collected from
animals reared around steel processing unit (n=22), lead–zinc smelter (n=21), aluminum processing plant (n=25), rock
phosphate mining area cum phosphate fertilizer plant (n=21), coal mining areas (n=46) and closed lead but functional zinc
smelter (n=14). Samples were also collected from randomly chosen 52 lactating cows reared in non-polluted areas to serve as
controls. Significantly ( Pb0.05) higher blood lead level was recorded in animals reared around lead–zinc smelting factories
followed by closed lead but functional zinc smelter, aluminum processing unit and steel manufacturing plant, as compared to
values recorded for control animals. The highest milk lead level (0.84F0.11 Ag/ml) was detected in animals reared in the
vicinity of lead–zinc smelting unit followed by aluminum processing plant and steel processing unit. Analysis of correlation
between blood lead levels and lead excretion in milk through sorting the blood lead values into nine different ranges
irrespective of site of collection of samples (n=201) revealed significant correlation (r=0.469 at Pb0.01) between blood and
milk lead concentrations. The lactating cows with blood lead levels above 0.20 Ag/ml (Groups 5 to 9) had significantly
( Pb0.05) higher milk lead excretion than those with blood lead levels from non-detectable to 0.20 Ag/ml (Groups 1 to 4).
Pearson correlation analysis between blood and milk lead concentrations in 122 animals with blood lead V0.20 Ag/ml showed
non-significant correlation (r=0.030 at Pb0.05) but a significant correlation was observed between these two parameters with
blood lead level above N0.20 Ag/ml indicating that the excretion of lead through milk increases with the increase in blood lead
level above 0.20 Ag/ml.
D 2005 Published by Elsevier B.V.
Keywords: Lead; Blood; Milk; Cattle; Industries; Pollution
0048-9697/$ - see front matter D 2005 Published by Elsevier B.V.
doi:10.1016/j.scitotenv.2004.12.055
T Corresponding author. Tel.: +91 581 2300587; fax: +91 581 2303284.
E-mail addresses: patra@ivri.up.nic.in, rcpatral@rediffmail.com (R.C. Patra).
Science of the Total Environment 347 (2005) 106–110
www.elsevier.com/locate/scitotenv

2. 1. Introduction
Lead is a pervasive and widely distributed environ-
mental pollutant with no beneficial biological roles.
The poisoning is more common in farm ruminants,
which are considered most susceptible to the toxic
effects of lead (Radostits et al., 2000). Animals get
access to lead from soil, water, feed and fodder and
varied degree of lead poisoning have been reported in
animals reared around different polluted areas (Kott-
ferova and Korenekova, 1995; Dwivedi et al., 2001).
Higher lead levels in animals and human beings have
been reported from the various parts of the world
including India, particularly in urban localities
(Swarup et al., 2000; Dwivedi et al., 1995).
The lead level in milk from animals exposed to
environmental pollutant has serious public health
concern. A linear dose related excretion of lead from
plasma into milk was found in rats and mice after
intravenous injection and the lead concentration in
milk was approximately 100 times higher than that in
plasma 24 h after administration demonstrating a very
efficient transport of lead into milk (Hallen, 1995).
This is substantiated by the findings that rat neonates
exposed to lead via the placenta and milk had more
than 6 times greater blood and brain lead concen-
trations than neonates exposed only via placenta
(Hallen et al., 1995). Oral feeding of lead acetate at
the dose rate of 500 mg/day to limited number of
lactating cows has been reported to significantly
increase the milk lead excretion (Willet et al., 1994).
However, the level of lead in milk samples from
animals 7 months after the acute episode of lead
toxicosis was undetectable (Galey et al., 1990). This
paper reports the degree of lead residues in blood and
milk from animals reared in the vicinity of different
industrial activities.
2. Material and methods
2.1. Study site and animals
The study sites were located at various parts of
India with different industrial activities such as mining
or processing factories. Lactating cows reared and
grazing on pasture within 2 km distance of industrial
area were used for this study. The industrial units
included steel processing unit (n=22), lead–zinc
smelter (n=21), aluminum processing plant (n=25),
rock phosphate mining area cum phosphate fertilizer
plant (n=21), coal mining areas (n=46) and closed
lead and zinc (with closed lead unit) smelter (n=14).
Samples were randomly collected from 52 lactating
cows reared in non-polluted areas to serve as control.
2.2. Sampling
Both the blood and milk samples were collected
from each of the lactating cows. Blood samples were
collected in nitric acid washed heparinized glass
vials and milk samples were collected in plastic
vials. Feed and fodder provided to the cows were
collected in polythene bags for further processing in
the laboratory.
2.3. Analysis of lead in samples
The fodder samples were washed in deionized
water to remove dust and superficial contamination.
The washed fodder samples, blood and milk were wet
digested with nitric and perchloric acid mixture
(Kolmer et al., 1951). Two to three blank samples,
where biosample was substituted by deionized triple
distilled water, were run simultaneously with each
batch of the digestion. The lead concentration in
digested samples was estimated using atomic absorp-
tion spectrophotometer (Electronic Corporation of
India Limited) at the wave length of 217 nm with 6
mA current (detection limit—0.025 Ag/ml) and the
values were expressed in Ag/ml of blood or milk and
Ag/g of feed or fodder.
2.4. Analysis of data
The data was analyzed using one-way analysis of
variance to find out the statistical difference among
the mean values and the correlation between blood
and milk lead were analyzed using standard statistical
methods (Snedecor and Cochran, 1967).
3. Results
Table 1 depicts the mean (FS.E.) blood and milk
lead concentration in lactating cows reared in different
D. Swarup et al. / Science of the Total Environment 347 (2005) 106–110 107

3. polluted areas. Significantly ( Pb0.05) higher mean
blood lead level was recorded in animals reared
around lead–zinc smelter (0.756F0.069 Ag/ml) fol-
lowed by closed lead and zinc smelting unit
(0.583F0.078 Ag/ml), aluminum processing unit
(0.332F0.015 Ag/ml) and steel manufacturing plant
(0.198F0.025 Ag/ml). The lactating animals reared in
coal mining (0.139F0.014 Ag/ml) and phosphate rock
mining areas (0.144F0.018 Ag/ml) had statistically
comparable ( PN0.05) blood lead levels than those
from non-industrialized areas supposed to be free
from pollution (0.074F0.008 Ag/ml).
The highest milk lead level (0.84F0.11 Ag/ml)
was recorded in animals with the highest blood lead
level and these animals were reared in the vicinity of
lead–zinc smelter. However, the mean blood lead
level in samples from other areas with different
industrial activities was not exactly reflected in the
milk lead excretion, as the trend of significance in
blood lead levels was not similar to that of milk.
Significantly ( Pb0.05) higher milk lead level, as
compared to that of controls, was also recorded in
animals reared around aluminum processing plant
(0.652F0.020 Ag/ml) and steel processing unit
(0.501F0.037 Ag/ml). Analysis of correlation
between blood lead levels and lead excretion in
milk irrespective of site of collection of samples
(n=201) revealed significant correlation (r=0.469) at
Pb0.01. Sorting all the blood lead levels from 201
lactating cows into nine different ranges based on
blood lead concentration, 122 animals had blood
lead level (Groups 1 to 4) below 0.20 Ag/ml and the
rest 79 animals (Groups 5 to 9) had blood lead levels
above this limit. The lactating cows with blood lead
levels above 0.20 Ag/ml had significantly ( Pb0.05)
higher milk lead excretion. The lead level in milk
was relatively constant up to a blood level of 0.20
Ag/ml and increased sharply with higher blood
levels. Pearson correlation analysis between blood
and milk lead concentrations in 122 animals with
blood lead b0.20 Ag/ml showed non-significant
correlation (r=0.030 at PN0.05) but a significant
correlation was observed between these two param-
eters with blood lead level above N0.20 Ag/ml,
indicating that the excretion of lead through milk
increased with the increase in blood lead level above
0.20 Ag/ml (Table 2).
Table 1
Residues of lead in blood and milk from animals reared in industrialized areas
SI. no. Place N Blood lead (Ag/ml) Milk lead (Ag/ml)
Range MeanFS.E. Range MeanFS.E.
1 Unpolluted areas 52 0.00–0.25 0.074F0.008a
0.00–0.79 0.2523F0.028a
2 Steel manufacturing plant 22 0.00–0.41 0.198F0.025b
0.03–0.76 0.501F0.037b
3 Aluminum processing plant/thermal power plant 25 0.22–0.48 0.332F0.015c
0.44–0.88 0.652F0.020c
4 Phosphate fertilizer and mining areas 21 0.03–0.31 0.144 F0.018ab
0.05–0.53 0.255F0.030a
5 Lead–zinc smelter 21 0.17–1.22 0.756F0.069e
0.13–2.70 0.844F0.113d
6 Coal mining areas 46 0.00–0.60 0.139F0.014ab
0.07–0.79 0.344F0.024a
7 Closed lead and zinc smelter 14 0.13–0.96 0.583F.078d
0.00–0.52 0.257F0.046a
N—number of animals from which blood and milk samples were collected. Means (FS.E.) with different superscripts (a, b, c—small letters
column-wise) vary significantly at 0.05 between different places of sampling.
Table 2
Milk lead (Ag/ml) residues in respect to blood lead concentration in
lactating cows
SI. Levels in Blood lead level Milk lead level
no. Ag/ml (N) MeanFS.E. Range MeanFS.E.
1 0.0–0.05 (36) 0.020F0.003 0.02–0.79 0.302F0.033a
2 0.06–0.10 (28) 0.077F0.002 0.00–0.79 0.302F0.030a
3 0.11–0.15 (30) 0.128F0.002 0.00–0.74 0.292F0.040a
4 0.16–0.20 (28) 0.176F0.002 0.03–0.71 0.311F0.037a
5 0.21–0.30 (28) 0.248F0.004 0.03–1.18 0.503F0.047b
6 0.31–0.40 (17) 0.348F0.007 0.42–0.88 0.629F0.027b
7 0.41–0.60 (13) 0.491F0.018 0.11–1.08 0.544F0.080b
8 0.64–1.00 (16) 0.836F0.024 0.11–1.24 0.594F0.078b
9 1.06–1.22 (5) 1.132F0.036 0.13–2.70 1.092F0.429c
The lactating cows were grouped into nine different groups based
on blood lead concentrations. N—number in parenthesis indicates
the number of animals with blood lead level falling in that particular
range. Means (FS.E.) of milk lead level falling within a particular
range of blood lead level with different superscripts (a, b, c—small
letters column-wise) vary significantly at 0.05.
D. Swarup et al. / Science of the Total Environment 347 (2005) 106–110
108

4. 4. Discussion
Lead has been recognized as a major environ-
mental pollutant with diverse deleterious effects in
man and animals and does have public health
significance. Man-made activities including mining
ores and industrial activities lead to emission of this
toxic metal pollutant resulting in environmental
pollution and contamination of forages for animal
consumption. Varying degrees of lead, cadmium and
zinc poisonings have been reported in animals in the
vicinity of lead–zinc processing factories (Radostits et
al., 2000). Ward and Savage (1994) reported increased
levels of toxic heavy metal pollutants in blood and
hair from horses and alpacas exposed to traffic
emission, and the blood lead level in animals exposed
to emission ranged from 0.15 to 0.51 Ag/ml as against
control value of 0.04 to 0.18 Ag/ml. In the present
survey work, maximum mean lead level was recorded
in animals reared in the vicinity of lead–zinc process-
ing factory. Milhaund and Mehennaoui (1988)
recorded higher mean blood lead level (0.50 Ag/ml)
in dairy cattle in a farm located in the vicinity of zinc
ore processing factory and the elevated level was
attributed to contamination of the feed for animals. A
higher concentration of lead and cadmium in soil has
been recorded in a number of regions in Russia
resulting from use of phosphate fertilizer and leaded
automotive fuel emission (Shaposhnikov and Prisnyi,
2001). The present finding of higher lead levels in
animals around lead–zinc smelter followed by closed
lead cum operational zinc smelting unit, aluminum
processing factory, steel manufacturing unit might be
due to higher lead emission during these industrial
activities leading to enhanced lead intake through
contaminated fodder. This was substantiated by the
finding that the lead concentration in fodder and soil
samples collected from around the lead–zinc smelter
was 29.06F11.32 (n=7) Ag/g and 232.89F127.63
(n=2) Ag/g and from non-industrialized area was
2.08F0.22 (n=8) and 28.66F2.53 (n=3) Ag/g, respec-
tively. These finding were also supported by Radostits
et al. (2000), who mentioned that the pasture near
smelter unit carry a load of 325 Ag/g of lead.
The milk lead concentration is a potential public
health concern, particularly for growing children. Higher
lead and cadmium levels in urban cattle from India were
earlier reported from our laboratory (Dwivedi et al.,
2001). In the present study, maximum lead excretion was
recorded in animals reared around lead–zinc smelter.
However, milk from animals reared around closed lead
and zinc smelting unit did not reveal significantly
(Pb0.05) higher milk lead excretion compared to
controls, despite higher blood lead concentration than
control animals. The concentration of lead in milk
depends on the concentration of unbound lead in blood.
Chronic exposure to low levels of lead after closure of
lead smelting, and the presence of bound lead in blood
erythrocytes or albumin might be the reason of
comparatively low level of milk lead in animals reared
around this industrial activity (Humphreys, 1991).
The overall correlation between blood and milk lead
irrespective of place of collection was highly signifi-
cant (r=0.469 at Pb0.01) and Pearson correlation
above blood level of 0.20 Ag/ml was 0.252 at
Pb0.05. Palminger et al. (1991) recorded a significant
( Pb0.01) correlation (r=0.88) between blood and milk
lead concentration in experimental lead poisoning in
lactating rats. The lead excretion in milk was found to
be relatively constant up to blood levels between 0.2
and 0.3 Ag/ml and increased sharply at higher blood
lead levels in an accidental lead exposure over a period
1 to 2 days through licking of burnt storage batteries by
cows (Oskarsson et al., 1992). However, Kottferova
and Korenekova (1995) did not find any difference in
heavy metal concentrations in milk from animals in
polluted and non-polluted areas. The present finding of
higher milk lead level in animals from polluted areas
has serious public health concern and potential hazard,
if such milk is regularly consumed in quantities that
will result in a daily intake of lead more than the
maximum permissible limit.
It is concluded from the above study that contam-
ination of forages with environmental pollutant like
lead was higher around lead–zinc smelting units
followed by closed lead and zinc smelting plants
and aluminum ore handling plant, leading to higher
concentration of lead in blood and its subsequent
excretion in milk increases significantly with blood
lead concentration above 0.20 Ag/ml.
Acknowledgement
The authors gratefully acknowledge the financial
support through Competitive Grant Project provided
D. Swarup et al. / Science of the Total Environment 347 (2005) 106–110 109

5. by the National Agricultural Technological Project
under ICAR funded by World Bank and to the State
Animal Husbandry Departments for their cooperation
in collection of samples. Thanks are due to Mr.
Brijesh Tyagi for his technical assistance.
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