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The area of Copsa Mica (Sibiu County, Romania) is well known because of its high lead concentration in the environment. A large portion of young children have been found to develop lead poisoning. We studied children ages 4-6 years. The blood lead levels were 43.89 µg/dL ± 13.61 µg/dL with an average value of 44.32 µg/dL ± 13.71 µg/dL in boys and 42.98 µg/dL ± 13.78 µg/dL in girls. Blood lead levels were measured using the Lead Care System. The lead concentration on children's hands was measured using KXRay Fluorescence (dust wipes). No correlation was found between blood lead levels and lead concentrations on children's hands. Blood lead levels were correlated with certain behaviors such as the time a child spends playing outdoors.
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CHAPTER 16
BLOOD LEAD LEVELS AND HAND LEAD
CONTAMINATION IN CHILDREN AGES 4-6
IN COPSA MICA, ROMANIA
Simona Surdu 1, Iulia Neamtiu 1, Eugen Gurzau 1, Iosif Kasler 1,
David Carpenter 2
1 Environmental Health Center, Cluj-Napoca, Romania; 2 University of Albany, New York,
NY, USA
Abstract: The area of Copsa Mica (Sibiu County, Romania) is well known because of its
high lead concentration in the environment. A large portion of young children
have been found to develop lead poisoning. We studied children ages 4-6
years. The blood lead levels were 43.89 µg/dL ± 13.61 µg/dL with an average
value of 44.32 µg/dL ± 13.71 µg/dL in boys and 42.98 µg/dL ± 13.78 µg/dL in
girls. Blood lead levels were measured using the Lead Care System. The lead
concentration on children’s hands was measured using KXRay Fluorescence
(dust wipes). No correlation was found between blood lead levels and lead
concentrations on children’s hands. Blood lead levels were correlated with
certain behaviors such as the time a child spends playing outdoors.
Key words: young children, blood lead levels, lead concentration on children’s hands,
behaviors
1. INTRODUCTION
that have been identified in some areas of Eastern Europe (Gurazau et al.,
1995a). The potentially harmful effects of exposure of young children to
relatively low levels of lead are widely recognized (Center for Disease
Control and Prevention, 1991). It has also been established that several areas
exist in Eastern Europe where children have experienced moderate to severe
© 2006 Springer. Printed in the Netherlands.
K. C. Donnelly and Leslie H. Cizmas (eds.), Environmental Health in Central and Eas
123
tern E urope,1 23-134.
Lead contamination is one of an extensive list of environmental hazards
124 Simona Surdu et al.
lead poisoning due to the presence of environmental contamination (Billig et
al., 1999). Policies and programs have been designed to reduce potential lead
exposure. New strategies such as social marketing, that are designed to
change the behaviors of the most susceptible population group, have been
reported as success “stories”(Gurzau et al., 1995b).
Much research has been conducted in recent years to study children with
moderately elevated and very high blood lead levels associated with lead
contamination (Billig et al., 1999, Gurzau et al., 1995a, 1995b). There is a
greater potential for adverse health effects from lead exposure in children
because their intake of lead per unit body weight is higher than it is for
adults. In addition, young children ingest soil and dust via hands and dirty
toys, leading to an increased intake of lead, and the physiological rate of
uptake in children is higher than it is in adults (Schwartz, 1994). Finally,
young children are more susceptible to the effects of lead exposure since
they are undergoing rapid development (Fergusson and Horwood, 1993,
Mushak, 1992, Tong and McMichael, 1999, United States Environmental
Protection Agency, 1986, World Health Organization, 1995).
Elevated lead levels continue to be a particular problem among socially
and economically deprived children. People with limited economic resources
are more likely to live in substandard housing, live near industries such as
smelters, be exposed to lead dust brought home by lead workers, and be
nutritionally deprived and therefore more susceptible (Wasserman et al.,
1992).
Debate continues over the nature, magnitude and persistence of the
adverse health effects of low-level exposure to environmental lead in
humans (Tong, 1998) though there is less debate regarding the effects of
high level exposure to environmental lead (Von Schirnding, 1999).
However, there is good evidence that intervention strategies such as social
marketing can decrease lead exposure and associated risks in very young
children (Billig et al., 1999, Gurzau et al., 1995a, 1995b). Unfortunately,
recent data show that some neuropsychological effects are largely
irreversible (Bellinger et al., 1992, Davis, 1990, Dietrich et al., 1992,
Needleman et al., 1990, Pocock et al., 1994, Ruff et al., 1993, Tong et al.,
1998), so that intervention is needed in areas highly contaminated with lead.
2. OBJECTIVES
The main objective of this study was to investigate lead exposure in
susceptible populations (children aged 4-6 years) living in the area impacted
most significantly by a heavy metal smelter in the town of Copsa Mica
(Sibiu County, Romania). Data were also collected to assess the relationship
between blood lead levels and lead levels in dust collected from children’s
125
hands, and to assess the relationship between blood lead levels and certain
risk factors in lead exposure (education, behaviors, cleaning practices etc.).
3. METHODS
To assess the lead exposure in children living near the smelter in Copsa
Mica, the following information was obtained: measurements of blood lead
levels in children recruited from Kindergarten No. 1 in Copsa Mica;
collection of dust samples from children’s hands; and collection of
information about the children’s exposure to lead from a questionnaire filled
out by each child’s parents.
A letter of recruitment was given to the parent or guardian of each child
who would potentially participate. After obtaining an informed consent, a
questionnaire was administered to the parents or guardians of all study
subjects. The questionnaire obtained information regarding potential risk
factors for lead exposure including personal characteristics (age, sex), child
residence, and traffic in the residential area and near the kindergarten.
Questions were also asked related to behaviors that are important for lead
exposure such as whether the children played with soil and put dirty toys in
their mouths. Finally, questions were included regarding socio-economic
factors such as parents’ education and family income, and questions were
asked about the parents’ occupational exposure to lead.
3.1 Laboratory techniques
The technique used to measure blood lead levels was the stripped anodic
voltametry technique which has 99% accuracy. The device used was a Lead
Care System, produced in 2000. This device is used in the USA for screening
and community risk assessment for lead exposure, and has been approved by
the Romanian Ministery of Health. Children’s hands were carefully washed,
and then capillary blood samples were collected from children’s fingers.
Hand dust samples were collected using dust wipes. Lead on dust wipes
was measured using the KX Ray Fluorescence technique. X Ray dust wipe
exposures were detected within 120 seconds, at which time the technique
sensitivity was 1 sigma (0.001 ppm) and the accuracy was 99.99%. The
device used was a K-X-ray Fluorescence 720SL, produced in 2002.
Blood Lead Levels in Children in Romania
126 Simona Surdu et al.
3.2 Statistical analyses
Statistical analyses were performed using the STATA statistical packages.
Simple 2 tests and Student’s t-test were applied for comparing variables. A
number of variables (representing the potential risk factors in lead exposure)
were entered into a stepwise linear regression multivariate estimation model,
in which each variable was assessed and was considered significant in the
model if the p value was <0.05. Variables considered to be confounders such
as age, sex, parents’ occupational exposure, and amount of traffic near the
residence and school, were kept in the model. Socioeconomic status was
based on the mothers’ education and the family’s income.
4. RESULTS
The study included 53 subjects aged 4-6 years. Sixteen (30%) of the subjects
were girls and 37 (70%) were boys. Blood lead levels were measured in 50
subjects, and lead in the dust collected from the children’s hands was
measured in 23 subjects. The parents of all 53 subjects included in the study
were asked to complete the questionnaires.
Blood lead levels in girls varied between 22.50 µg/dL and 65 µg/dL. The
mean value (±standard deviation) was 42.98 µg/dL ± 13.78 µg/dL in girls
and 44.32 µg/dL ± 13.71 µg/dL in boys. In the group of boys, the blood lead
levels varied between 15.30 µg/dL and 65 µg/dL (Table 1). The mean blood
lead levels were slightly higher in boys than in girls, although this difference
was not statistically significant.
Table 1. Distribution of blood lead levels (µg/dL) by gender.
No. of children Mean
(µg/dL)
Std. Dev. Min.
value*
Max.
value*
Girls 16 42.98 13.78 22.50 65
Boys 34 44.32 13.71 15.30 65
*Min. value and max. value, minimum and maximum values.
None of the subjects had a blood lead level <10 µg/dL. Most of the
subjects (20 children, or 58%) had blood lead levels between 35 and 60
µg/dL. Only 2 subjects had blood lead levels in the range of 10-20 µg/dL
and 5 subjects had blood lead levels >60 µg/dL (Table 2).
Lead levels in the dust collected from girls’ hands varied between 20
µg/single hand and 379.6 µg/single hand. The mean value and the standard
deviation in girls were 134.76 ± 178.05µg/single hand and 112.21 ± 168.82
µg/single hand in boys. Among boys, lead levels in the dust collected from
their hands varied between 20 µg/single hand and 511.2 µg/single hand
(Table 3). Lead concentration mean values were higher in girls as compared
127
Table 2. Subjects’ distribution by gender and category of blood lead levels.
Blood lead level
(µg/dL)
Girls (no., %)* Boys (no., %)* Total (no., %)*
10-20 0 (0.00%) 2 (5.88%) 2 (4.00%)
20-35 6 (37.50%) 8 (23.53%) 14 (28%)
35-60 9 (56.25%) 20 (58.82%) 29 (58%)
>60 1 (6.25%) 4 (11.76%) 5 (10%)
Total 16 (100%) 34 (100%) 50 (100%)
* No, number of children; %, percent of the children in that column.
Table 3. Lead concentration in dust collected from children’s hands (µg/single hand).
No. of
children
Mean
(µg/hand*)
Std. Dev. Min. Max.
Girls 6 134.76 178.05 20 379.6
Boys 17 112.21 168.82 20 511.2
*One hand per child was sampled.
Table 4. Social economic factors.
* Values are in local currency; these numbers were determined prior to the change in the
value of the local currency that took place in 2005.
**SE, standard error of the mean.
Females
Blood lead levels
Males
Blood lead levels
Risk factors
No. of
subjects
mean (SE**)
(µg/dl)
No. of
subjects
mean (SE**)
(µg/dl)
Elementary
school
Secondary
school 3 55 (8.66) 6 51.6 (14.86)
High-
school/college 12 41.05 (13.66) 28 42.76 13.22)
Mother’s
education
University 1 30 (0)
>5 millions lei* 10 39.6 (14.10) 11 47.54 11.76)
2-5 millions lei 6 48.61 (12.29) 21 42.58 (13.84)
1-2 millions lei
Monthly
income*
<1 million lei 1 65 (0)
Blood Lead Levels in Children in Romania
128 Simona Surdu et al.
with boys this time, but the difference between the mean values in boys and
girls were not statistically significant when tested using statistical t test.
There was no correlation between blood lead levels and hand dust lead
levels among either the girls or the boys. The mean blood lead concentrations
were not found to vary significantly in relation to the socio-economic risk
factors taken into consideration in this study. Table 4 presents the mean
blood lead values in relation to the mother’s educational level and family
income, stratified by the subject’s gender.
Table 5. Household and kindergarten cleaning practices and children’s blood lead levels.
Females
Blood lead levels
(µg/dL)
Males
Blood lead levels (µg/dL)
Risk factors
No. of
subjects
mean (SE*)
in µg/dL
No. of
subjects
mean (SE*)
in µg/dL
Daily 8 46.31
(14.72)
18 44.05 (14.06)
Weekly 8 39.65
(12.85)
12 46.85 (12.09)
Monthly 2 23.3 (11.31)
Rarely
Use of vacuum
cleaner in child’s
dwelling
Never 2 52.5 (3.53)
Daily 10 42.06
(15.35)
23 42.40 (14.85)
Weekly 6 44.51
(11.88)
11 48.32 (10.44)
Monthly
Rarely
Wet mopping in
child’s dwelling
Never
Daily 7 41.5 (14.83) 14 43.21 (15.52)
Weekly 3 35.16
(13.87)
4 39.55 (10.69)
Monthly
Rarely 4 53.75 (7.5) 8 48.5 (11.45)
Use of vacuum
cleaner at
kindergarten
Never 2 38.35(16.47) 6 43.6 (17.51)
Daily 15 43.64 (14) 29 42.31 (13.56)
Weekly 1 33 (0) 3 59.93 (8.60)
Monthly
Rarely 1 50 (0)
Wet mopping at
kindergarten
Never
*SE, standard error of the mean.
129
The mean blood lead concentrations were not found to vary significantly
in relation to the cleaning practices that were evaluated as potential risk
factors for lead exposure. Table 5 presents the mean blood lead values in
relation to the frequency of the most important cleaning practices (vacuum
cleaning and wet mopping the child’s living areas and kindergarten).
The comparative analysis using a statistical t-test indicated a positive and
statistically significant correlation between blood lead levels in boys and the
time spent playing outdoors while at home. The boys who played outdoors
less than 2 hours had lower blood lead levels than those who played
outdoors 2-4 hours (p = 0.028), and also had lower levels than those who
played outdoors more than 6 hours (p = 0.003). The mean value and standard
deviation for boys spending less than 2 hours outdoors was 26.48 ± 10.56 as
compared with 46.82 ± 16.83 for boys outdoors for more than 6 hours and
49.32 ± 8.88 for boys outdoors from 2 - 4 hours (Table 6).
Table 6. Children’s behaviors and blood lead levels (continued on next page).
Females
Blood lead levels
(µg/dL)
Males
Blood lead levels
(µg/dL)
No. of
subjects
mean (SE**) No. of
subjects
mean (SE**)
<2 hours 1 57.40 (0) 5 26.48 (10.56)*
2-4 hours 2 26.85 (4.45) 8 46.82 (16.83)*
4-6 hours 4 39.02 (15.72) 4 40.32 (11.36)
Time
spent/day
playing
outdoor while
the child is at
home >6 hours 9 46.72 (12.11) 17 49.32 (8.88)*
<10
minutes
5 39.58 (15.66) 6 38.75 (14.83)
10-20
minutes
5 37.96 (18.64) 15 42.41 (16.12)
20-40
minutes
5 50 (0) 12 49.01 (9.20)
Time
spent/day
playing
outdoor while
the child is at
the
kindergarten >40
minutes
1 50 (0) 1 50 (0)
*Statistically significant
**SE, standard error of the mean.
Blood Lead Levels in Children in Romania
130 Simona Surdu et al.
Table 6 (continued). Children’s behaviors and blood lead levels.
Females
Blood lead levels
(µg/dL)
Males
Blood lead levels
(µg/dL)
No. of
subjects
mean (SE**) No. of
subjects
mean (SE**)
Yes 12 43.63 (4.04) 24 46.2 (2.30)
Playing with
soil while the
child is at
home No 4 41.02 (7.50) 10 39.81 (5.77)
Yes 3 34.36 (10.31) 10 41.34 (4.69)
Playing with
soil while the
child is at
kindergarten No 13 44.96 (3.52) 24 45.56 (2.72)
Yes 13 44.69 (3.86) 22 46.85 (2.61)
Playing with
sand while
the child is at
home No 3 35.56 (7.27) 12 39.67 (4.47)
Yes 9 42.2 (4.35) 17 46.7 (2.36)
Playing with
sand while
the child is at
kindergarten No 7 43.98 (5.91) 17 41.94 (4.06)
Yes 10 41.97 (5.03) 25 45.21 (2.88)
Putting dirty
toys and dirty
fingers in the
mouth No 6 44.66 (4.25) 9 41.83 (4.00)
**SE, standard error of the mean.
The comparative analysis using statistical t-test of blood lead levels in
children with parents who were occupationally exposed to lead and the
blood lead level in children with parents who were not occupationally
exposed to lead indicated that blood lead levels were higher in girls whose
parents had no known occupational exposure to lead. In addition, the
difference between the mean blood lead levels in these two groups was
statistically significant (p = 0.045; 48.48 µg/dL ± 3.69 µg/dL as compared
with 33.81 µg/dL ± 5.22 µg/dL) (Table 7).
The results of the stepwise multivariate linear regression estimations
indicated a positive and statistically significant correlation (p = 0.04) between
blood lead levels and some potential risk factors in lead exposure that were
identified using the questionnaire. Such risk factors included spending time
outside in the Copsa Mica area and playing outdoors while the children were
at kindergarten. A negative and statistically significant correlation (p = 0.03)
was found between blood lead levels and a socioeconomic risk factor – the
mother’s level of education. Other potential risk factors in lead exposure (see
131
tables 4-7) were not found to be statistically significant in correlation to the
blood lead levels (Table 8).
Table 7. Other risk factors in lead exposure.
Females
Blood lead levels
(µg/dL)
Males Blood lead levels
(µg/dL)
Risk Factors
No. of
subjects
Mean
(SE*)
No. of
subjects
Mean
(SE*)
Less than a
car/minute 14 42.33 (3.47) 22 44.08
(2.66)
Traffic at the
child dwelling More than a
car/minute 2 47.5 (17.5) 12 44.75
(4.70)
Less than a
car/minute 13 42.9 (4.07) 29 43.57
(2.31)
Traffic at the
kindergarten More than a
car/minute 3 43.33 (6.66) 4 52.5
(11.04)
Yes 7 47.57 (4.62) 22
44.57
(3.18)
Street cleaning
at the child
dwelling No 8 38.08 (5.28) 12
43.85
(3.39)
Yes 6 33.81 (5.22) 10
43.58
(4.42)
Occupational
exposure
No 10
48.48
(3.69)** 24 44.62
(2.83)
*SE, standard error of the mean.
Table 8. Risk factors statistically significant in lead exposure estimated by stepwise
multivariate linear regression after adjusting for age, sex and other risk factors.
Blood lead level Coef. SE* t p [95% Conf.
Interval ]
Spending time outside Copsa Mica
area
10.20 4.81 2.11 0.04 0.26 20.15
Time spent playing outdoor while
the child is at the kindergarten
6.11 2.94 2.07 0.04 0.02 12.20
Mother’s education –11.30 5.06 –2.23 0.03 –21.76 –0.84
*SE, standard error of the mean.
Blood Lead Levels in Children in Romania
132 Simona Surdu et al.
5. DISCUSSION AND CONCLUSIONS
High levels of lead in the blood have been an ongoing concern because lead
is known to affect learning abilities and produce severe health problems. The
CDC (Centers for Disease Control and Prevention, 1991) defines a threshold
for the “harmful effects” level of lead at 10 micrograms per deciliter
(mg/dL) of blood. In our study the mean blood lead level for girls was 43
µg/dL, while the mean lead level in hand rinse samples was 135 µg/single
hand. In boys, the mean blood lead level was found to be 44 µg/dL, while
the mean concentration detected in hand rinse samples was 112 µg/single
hand.
This study did not observe a significant association between lead levels in
dust samples collected from children’s hands and the children’s blood lead
levels. On the other hand children’s blood lead levels were positively
correlated with the time spent playing outdoors at home and negatively
correlated with their parents’ occupational exposure.
The results of the stepwise multivariate linear regression estimations
indicated that children’s blood lead levels were positively correlated with
some risk factors in lead exposure such as spending time outside in the
Copsa Mica area and the time spent playing outdoors. It was negatively
correlated with the mother’s education level.
The small number of statistically significant correlations may be due to
the small number of subjects included in the study. That is why we intend to
enlarge the number of subjects in a subsequent stage of the study. In order to
improve results we will assure quality control for the blood lead levels
measured from capillary blood by measuring the levels in venous blood
using atomic absorption spectrometry with 5% of the blood sample,
collecting and analyzing dust samples from both hands of the subjects and
repeating the dust and soil sampling from the children’s environment.
One reason for uncertainty in this study was the methodological pitfalls
that beset many crossectional studies – exposure was only measured once
per time period. A single measure of the exposure biomarkers also provided
a limited scope to answer questions about the variation of these biomarkers
in time. Blood lead levels were measured in the capillary blood and although
we carefully washed the children’s fingers it might be possible for the blood
samples to be contaminated with lead from the skin.
Questionnaire responses were also subject to observational biases because
parents may have slightly different interpretations of the questions asked
about their children. In spite of these limitations, questionnaire based studies
in lead contaminated areas are quite common. In order to identify the major
pathways with regard to lead poisoning in the very young children, it is
necessary to evaluate attitudes and practices which may influence the
exposure to lead from environment. There are still many questions to be
133
answered including individual factors affecting susceptibility and the
relationship between lead on children’s hands and blood lead levels.
Despite potential limitations, what makes this study distinct is the novelty
of the issues it approached, especially in the East European country of
Romania where the people are just beginning to become aware of this health
problem. Further research in this field is needed. That is why we intend to
extend this study, to assess and characterize in detail the exposure to lead
through soil and dust (from outdoor and indoor environments, vegetables,
hands) and the community’s risk related to this exposure. In conclusion, this
study established that children’s blood lead levels in Copsa Mica area are
considerably high. Our knowledge of this population would indicate that
implementation of a social marketing program for risk communication and
changing of behavior related to lead contamination in the susceptible
population group (in our case, children aged 4-6 years), could decrease
exposures and thus, the risk associated with this toxin.
In addition to monitoring contaminant levels in environmental media, the
children’s blood lead levels should be measured regularly along with
indicators of lead toxicity such as IQ and growth rate. A concerted effort
should be made to reduce lead exposure because of the insidious effects it
can have on very young children.
The primary sources of blood lead are soil and household dust, but not
air. Controlling exposure to soil and dust is more difficult than reducing air
emissions and may require measures such as restricting children’s access to
soil, promoting personal hygiene practices such as requiring smelter workers
to shower and change clothes before returning to their homes and promoting
other dust control measures in houses such as frequent wet mopping.
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... Also, heavy metal exposure indicators in population living in these areas show worrying figures. The results of previous research over the past years indicate increased concentrations of lead and cadmium in children blood samples living in these regions (Bardac et al., 1999;Surdu et al., 2006). ...
... 12.7% < 20 μg/dL, 67.7% between 20 and 35 μg/dL, 19,7% between 35 and 60 μg/dL and 0% > 60 μg/dL (Niciu et al., 1998;Billig et al., 1999). Surdu et al. (2006) investigated lead exposure of children living in Copşa Micȃ. The average levels of lead in children's blood were 43.89 μg/dL ± 13.61 μg/dL (44.32 μg/dL ± 13.71 μg/dL in boys and 42.98 μg/dL ± 13.78 μg/dL in girls). ...
Article
Industrial areas affected by high and long-term heavy metal pollution have a great impact on health of the resident population. Children represent a group at high-risk with an increased susceptibility to chronic heavy metal intoxication. Our work included the assessment of attention particularities through a case-control study in pre-school and school-aged children (4–6 years and 8–11 years) from two study areas, Copşa Mică and Zlatna, compared to a non-polluted locality with no history of heavy metal pollution. Copşa Mică and Zlatna are two of the most polluted heavy metals regions in Romania due to non-ferrous metallurgy for a long period of time. Recruitment of participants was made by a random selection of an entire class for each age within the schools and kindergartens from the study areas (Copşa Mică and Zlatna) and from the non-polluted region. Interpretation of data was performed using statistical analysis (ANOVA and Student's t-test). Preschool children (4–6 years) were tested using Wechsler Preschool and Primary Scale of Intelligence (WPPSI) tests, Animal House and labyrinth samples. The results of the attention tests applied to pre-school children were lower in the study areas compared to the control group, but no statistical differences were found. The results of the attention tests applied to children aged between 8 and 11 years (Toulouse-Pieron test and Traffic light test) indicate lower average scores within the study groups from polluted areas, compared to the control group. Differences with statistically significance were registered for the 8 years age group (p = 0.037). In these areas efficient strategies and precise intervention measures are needed in order to limit or remove the heavy metal exposure and protect the human health, especially the groups exposed to a high level of risk.
... Numerous studies showed that human exposure to lead through hand-to-mouth mechanism has a significant contribution to increased blood lead level (Hwang et al., 2002; Hsu et al., 2009, Rodrigues et al., 2009 Chuang et al., 1999). Another study, this time regarding children's exposure to lead found no correlation between blood lead levels and lead concentrations on children's hands (Surdu et al., 2006). Virji et al. (2009) evaluated this pathway of lead exposure for a group of bridge painters from Massachusetts. ...
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In this study are presented the results of the investigations referring to the occupational exposure through ingestion by hand-to-mouth mechanism, investigations that are based on the assumption that the lead on hands and surfaces adjacent to the workplace (locker rooms and lunchrooms) is an important factor in estimating the oral intake of lead. Lead concentration from hands of 30 workers from all the four main car battery factory departments and contamination by the same toxic of the work adjacent areas (locker rooms and lunchrooms) were measured for two consecutively days. Sampling was performed using lead dust wipes, the lead being analyzed by X-ray fluorescence spectrometry. Averaged values of lead from workers hand ranged from 124.5 µg/sample in the section were the battery cases are produced, to 2100, 8 µg/sample in the maintenance department. Average values of lead measured from the lockers in the locker rooms ranged from 0.256 µg/cm2 to 0.611 µg/cm2 in the first day of measurements, and in the second day (after cleanliness was made after authors recommendation) were half in one of the departments (0.301 µg/cm2 ), but highest in another one (0.374 µg/cm2 ). Regarding the lunchrooms, the highest lead concentration from the tables was 0.79 µg/cm2 in the first day of measurements and 2.4 lower (0.33 µg/cm2 ) in the same place in the second day. Lead concentrations from worker’s hands were associated with lead levels from the surfaces in the locker rooms. Authors recommend the use of worker’s hands lead, locker rooms and lunchrooms surface’s lead contamination as additional/alternative indices, for screening as an assessment method for the intervention programs, the personal hygiene improvements, and for the cleanliness procedures at the workplaces. Personal hygiene and cleanliness in the workplace are the easiest and cheapest ways to reduce exposure and they represent the first step in reducing occupational exposure to lead
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In Reply.— Dr Needles raises several important points about our study. He questions the presence of a dose-effect relationship between blood lead level at age 24 months and intellectual functioning at age 10, as well as our assertion that a threshold for this relationship was not apparent. His skepticism is understandable. Our conclusions were based on three observations, not all of which we were able to include in our paper. 1) Examination of the partial regression residual plot (IQ adjusted for all covariates and blood lead level adjusted for all covariates) indicated symmetrical distribution of residuals about the regression line and similarity in the residual variances over the blood lead range.
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In Reply. —We appreciate the thoughtful comments on our article in JAMA and agree with those who urge caution in interpreting the results. Our study was the first large-scale, systematic attempt to address the consequences of intervention with moderately lead-poisoned children; it thus represents only the first step in accumulating data relevant to the issue of reversibility. The interesting Chinese study reported by Dr Rabinowitz adds to that effort.We shared Dr Ernhart's concern about the lack of relationship between blood lead levels and CIs at the initial time point. As we noted, however, both the initial effects of low to moderate levels of lead and the reversibility of those effects are likely to be part of a cumulative process, not always evident at single time points. The analyses of change, although difficult, may be the only way to investigate such dynamic processes.Ernhart rightly underscored the failure to find
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The principal environmental health issue for American children is pervasive lead poisoning from the many decades of lead contamination. Available scientific evidence cementing lead's premiere ranking is voluminous, multifaceted, and compelling. This evidence, however, requires organization into a clear and coherent body of science before it can be fully recognized or comprehended by either the scientific community or the general public and its representatives: public health officials, regulators, policy makers, and legislators. An attempt at such organization is presented and begins with the premise that there exist clear, objective criteria by which a premiere environmental health issue can be defined. A second premise is that these criteria sort themselves into three categories which cover the full spectrum of toxic contaminant-population relationships. They are: (1) economic and sociopolitical, (2) scientific and public health, and (3) societal risk assessment criteria. The first set of criteria includes economic and historical centrality, primacy of economic over public health considerations, a relatively narrow decision-making framework, and controlled flow of information on the toxicant, especially its negative impacts. The second set of criteria is also orthodox in scope: the toxicant should be indestructible, should accumulate in both the environment and the body, and should be a multimedia contaminant; it should produce toxicity in numerous organs with little impediment; toxicity should be produced with low/no threshold in huge numbers of the most vulnerable; and finally, effects should persist in the critical target organ(s). There is a third, more globally encompassing, set of criteria important for present-day requirements for risk assessment; e.g., the contaminant should produce full-spectrum population-wide as well as individual toxicity. Evidence for societal harm should be compelling. It should typify the increasing importance of the elements of preventive over clinical medicine and the substance should bring to bear the cost-benefit analysis of macro plus micro health risk. Lead exposure and toxicity is conclusively shown to meet ALL of these criteria and is the premiere environmental health threat to America's children.
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