Amjad Hazim Al-Naemi * MBChB; Msc, Aliaa Rajih Al-Khateeb * MBChB; Msc
Basma Yousif Fattohi ** MBChB; Msc, Muna Muneer Ahmed *** MBChB; Msc
Asmaa Ahmad Al-Jawadi **** MBChB; DPH; PhD****

* Assistant lecturer, Dept. of Biochemistry, College of Medicine, University of Mosul, Mosul, Iraq.
** Assistant lecturer, Dept. of Community Medicine, College of Medicine, University of Mosul, Mosul, Iraq.
*** Lecturer, Dept. of Community Medicine, College of Medicine, University of Mosul, Mosul, Iraq.
Prof. and Head of Dept. of Community Medicine, College of Medicine, University of Mosul, Mosul, Iraq.

Address correspondence to:

Amjad Hazim Al- Naemi, MBChB; MSc
Assistant Lecturer, Dept of Biochemistry
College of Medicine
University of Mosul
Mosul, Iraq
E- Mail amjadhazim@yahoo.com
..........................................................................................................................

Key words: Blood lead level, childbearing age, environmental predictors.
..........................................................................................................................

Lead is an ancient metal. Because of its malleability and low melting point, humans have used lead since prehistoric times to make statues, jewellery, water pipes and drinking vessels. The quantity of lead used since 1940 surpasses the total used in all previous centuries. This heavy recent use reflects industrial applications as well as the use of lead as a fuel additive. In the mid-1970s, nearly 200,000 tons of lead were consumed annually in gasoline in USA (1). Virtually all of this lead was emitted into the environment from vehicles in a fine particulate form and caused widespread contamination of air, dust, soil, drinking water and food crops (2).

Although USA and the European Union have banned lead as an additive to consumer fuel for road-going vehicles, in some instances leaded petrol is still permitted for off-road uses such as in farming equipment, marine engines and airplanes. Lead continues to be used in petrol in many countries because it is a relatively inexpensive method for boosting octane. As of 2004, leaded petrol was still being sold in Indonesia, the Middle East, the former Soviet-Republic, Cuba, parts of South America, and nearly all of Africa (3).

Thus, due to excessive use of lead in industry and automobile fuel, human beings have been, and are constantly being, exposed to it. This exposure adversely affects the functions of several organ systems including cardiovascular, renal, nervous, hemopoietic, endocrine and skeletal systems (4, 5).
In women, lead at high doses can be toxic to reproductive functions. Clinical reports, most of them from the first half of the 20th century, describe an increased incidence in spontaneous abortion among female lead workers as well as in the wives of male lead workers. Low level maternal lead exposure may increase the risk of spontaneous abortion (6). Since the placenta does not offer any restrictive barrier to the transfer of lead from maternal blood to the fetal blood, the developing fetus may be exposed to the adverse effects of lead (7). The difficult problem in the reproductive toxicity of lead is the finding that lead may cause neurological damage to the fetus at blood levels as low as 5- 10 µg/dl (8). This problem is further compounded by the fact that under the metabolic stress of pregnancy, lead may be mobilized from bony stores of the mother to enter her blood and thus the fetal circulation (9).

In Iraq there were several studies performed about BLL which covered different community groups with high risk of exposure, such as traffic police men, car services station workers, battery repairers, petroleum station workers, electrical generator workers, and printing industry workers (10- 12). However, no study was conducted to cover population with assumed low exposure, particularly females of childbearing age. Thus, the purpose of this work was to evaluate the BLL among a sample of married non-pregnant females of childbearing age in Mosul city, and to investigate the possible association of certain risk factors.

Prior to data collection final approval was obtained from Ninevah Health Office to conduct the study. Al- Hadbaa primary health care training center was the focal point of this study. It is situated on the right side of Mosul city, near Mosul Medical College. It was established in September 1989 and nominated as a training center by WHO in 1997. It serves a wide catchment area of 60,390 population of various socio- economic and educational strata.

The unit of the present study was a healthy non-pregnant mother (age 15-49 years) who came to the center for vaccination of any of her children, and who had lived in Mosul city for more than three years. The chosen mothers were included by systematic sampling randomization in which every third mother was taken. This process yielded 306 non- pregnant mothers at childbearing age, all of whom were assessed during a one month period (July 2006). All women were asked to participate in the study and none of them refused. They were interviewed by one of the investigators who was well-trained about the method of interview. This was carried out via especially designed questionnaire form containing information about socio-demographic characteristics and some risk factors of lead exposure (e.g. traffic density at their residence, occupation, education, occupation of the husband, smoking exposure (passive-active), age of the building they live, and use of kohl).

Blood lead level was measured using Lead Care Blood Testing System and Lead Care Blood Lead Test Kits purchased from (ESA, Inc., USA). This system relies on electrochemistry and a sensor to detect lead in the whole blood where the kit is specific for quantitative measurement of lead in fresh whole blood specimens only. A sufficient whole blood sample was obtained from a skin-puncture using a finger stick. The lateral side of the middle finger was used. The puncture side was properly wiped clean with alcohol wipes already supplied with the system. A special heparinized capillary tube that allows collecting exactly (50 µl) of whole blood was used. The accuracy and precision of the test depended on accurately measuring a 50 µl blood sample. For each test, the exact 50 µl whole blood sample was dispensed from the capillary tube into the treatment reagent tube using special plungers. Mixtures in the treatment in reagent tubes were kept refrigerated until analyzed for BLL in weekly batches. Analyses were made at the Environmental Health Unit in Mosul Medical College.

The performance of the Lead Care System was checked on each batch run using appropriate quality control materials, i.e. both high and low known readings lead standards by Lead Care as well. Results obtained on control samples were within the expected range.

Data were analyzed with a statistical package for social sciences (SPSS) software for windows. Chi-square test, odds ratio, and 95 % confidence limit interval were used to find the presence or absence of statistical association between certain proposed risk factors and high BLL. Stepwise logistic regression analysis was also used aiming to identify risk factors (independent variables) that may predict development of high BLL (dependent variables) among the study sample. Student t- test was performed to indicate the presence of a significant difference between the mean values of the two subsets of study population (BLL = 10 µg/dl and < = 10 µg/dl) (13).

Table (1) depicts the socio-demographic characteristics of study population by BLL in µg/dl. Out of 306 women in the childbearing age examined 24 (8.5%) had BLL of = 10 µg/dl. Overall the mean BLL (± SD) was 5.26± 3.33 µg/dl with a range of (1.5- 32.5) µg/dl.

The mean BLL for the high-risk group (i.e. those had BLL = 10µg/dl) was 14.90± 4.72 µg/dl while that of the low risk group (i.e. those who had BLL < 10µg/dl) was (4.44± 1.27) µg/dl with a highly significant difference (p= 0.000).

Although the high-risk women seemed to be younger than the low-risk group, however, no significant difference is reported between the mean ages of the two groups. No significant association is found between any of the variables shown in the table and BLL, except frequent use of kohl.

Almost two thirds of women (70.8%) who had BLL = 10µg/dl reported frequent use of this cosmetic material. Those women were 2 times more prone to develop BLL =10µg/dl (OR= 2.46, p= 0.05, 95% CI= 1.02- 5.96).

Table (2) compares distribution of potential risk housing characteristics between study women: those with BLL = 10µg/dl and those with BLL < 10µg/dl. A highly significant association is found between all housing characteristics that carried potential risk and BLL with a (p-value) varied from (0.028- 0.000). Old buildings showed an operational risk for the development of BLL = 10µg/dl (OR= 13.56, p= 0.000, 95% CI= 5.05- 36.4) which is the highest risk. Peeling and chipping of paint carried a highly significant risk (OR= 9.59, p =0.000, 95% CI= 3.40- 27.03) too.

Location of the household near to an electricity generator increased the risk in a highly significant way (OR= 5.19, p= 0.004, 95% CI= 1.71- 15.75). To a lesser extent but still significant was the location near a fuel station (OR= 6.46, p=0.028, 95% CI=1.77- 23.59) and near a major road (OR= 5.33, p= 0.006, 95% CI= 1.63- 17.46). Having more than one of the above-mentioned characteristics related to the household location also carried a highly significant risk (OR= 5.60, p= 0.002, 95% CI= 1.86- 16.90).

Table (3) presents a stepwise logistic regression model for the predictors of high BLL among the study sample. Elevated BLL was associated with location of the household (p= 0.002, Exp (B) = 6.820), age of the household (p= 0.004; Exp (B) = 6.791), and presence of peeling and chipping paint (p= 0.006, Exp (B) = 6.253).

The characteristics of the women with the highest BLL, two women were identified; one with a BLL of 32.5 µg/dl, who was almost 48 years old, while the other was 35 years old with a BLL of 29.2 µg/dl. The only risk factors consistently identified for the two women were living in an old house (> 20 years of age) and having heavy chipping and peeling paints. One of the households was near a big electricity generator and the other was near a main road.

Mosul is a densely populated city. It is the second largest city in Iraq situated 400 km north of Baghdad, the capital. Mosul as with other cities in Iraq, is facing several environmental health problems with an increased burden from environmental lead pollution. This pollution may come from various sources such as old cars, electricity generators, which are widely distributed in the city, and the presence of a large number of old houses. This can be translated into increased BLL in the general population (14).

Poor pregnancy outcomes like intrauterine growth retardation, prematurity and high maternal mortality, are common in this part of the world (15). It is worth noting that female in the childbearing age form about (20%) of the population in Mosul city. So it is important to determine the BLL among this sector, where the prevention of adverse effects of high BLL, namely fetal lead encephalopathy, requires that BLL(s) of prospective mothers be kept below 10µg/dl not only during pregnancy but also in the years preceeding conception (16).

The sample of the present study was selected from non-pregnant mothers (age 15-49 years) who attended Al- Hadbaa primary health care training center for vaccination of any of her children. This center has a wide catchment area mostly of moderate and low socio-economic status. These women are more likely to have high BLL because of increased environmental and occupational lead exposure, where almost 40% are living in old houses with peeling and chipping paint (46.2%), while just more than 40% of the husbands are employed in lead trades.

The present study revealed that the point prevalence of BLL = 10µg/dl was (8.5%) among the examined women. Blood lead level in Iraq is not routinely measured in any health facility, therefore; there are limited data about the prevalence of high BLL either in the general population or in the disadvantaged groups like women in childbearing age and children under five years of age. A number of studies with almost a small sample size have reported occupational exposure in the country (10- 12).

The mean BLL reported in this study was 5.26± 3.33 µg/dl with a range of (1.5- 32.5 µg/dl), which is very much lower than that reported in the Al-Nori study carried out in 2002 (27.54± 5.87 µg/dl) (10). The mean BLL reported by the Al-Nori study was for 100 healthy male subjects with minimal or no risk of exposure to a polluted atmosphere. This discrepancy could be explained by three hypotheses: (1) BLL is a reflection of the lead that gets accumulated in the bone after about 30 days (17-18). (2) The sample of the current study covered females of childbearing age while the sample of Al-Nori (14) study includes males. In our community females have lower environmental exposure since they have lower mobility outside the home. (3) Al- Nori (14) in his work used atomic absorption spectrophotometry which is probably more sensitive than the method used in the present study. Hence, a further study is recommended to compare the validity of Lead Care Blood Testing System versus atomic absorption spectrophotometry particularly when they are used in survey studies.
A screening for BLL(s) was carried out in Basrah which is also a large city with high population density situated about 500 km south of Baghdad. A higher mean BLL was reported by this study (11.26± 3.46) µg/dl, which covered all age groups of both genders and it was (10.10± 2.96) µg/dl for females. This difference is probably due to a different sample size (n= 602 individuals) which were randomly selected from people attending 17 PHCC(s) with a wide age range (9- 79 years) (17).
Some sporadic studies in Pakistan have indicated that the BLL(s) in the general population were much above safety levels (i.e. 10 µg/dl) recommended by the center for Disease Control and Prevention (CDC). Mean BLL(s) were reported to be 18.8 µg/dl in children in Rawalpindi (18) and 34.4, 31.8, 29.9 and 38.2 µg/dl in males, females, soldiers, and children respectively from Karachi (19).

Much lower figures were reported in the USA findings of the National Health and Nutrition Examination Surveys (NHANES). This survey indicated that BLL(s) continued to decrease in all age groups and racial/ethnic populations. During 1999-2002, the overall prevalence of elevated BLL(s) was 0.7% and it was 0.3% for females aged 20-59 years of all racial/ethnic groups, however, it is higher among the black, non- Hispanic (0.5%), a decrease of 68% from 2.2 in the 1991-1994 survey. This survey also showed that the geometric mean BLL(s) declined significantly (p= 0.05) from the 1991-1994 survey period in all populations and subpopulations. Among females aged 20-59 it was 1.7 µg/dl in the survey of 1991-1995 to be 1.2 µg/dl in that of 1999-2002, a higher figure was reported among the black non-Hispanics (1.4 µg/dl) (20).

The findings in this report indicate that BLL (s) continue to decline in the USA and may be in all of the similar highly developed countries. This decline in BLL(s) has resulted from coordinated intensive efforts at the national, state and local levels beginning with efforts to remove lead from gasoline, food cans and residential paint products (20).

Although there is much concern about risk factors of high BLL(s) in Mosul, there is no study conducted to determine the presence or absence of association of certain well documented factors and high BLL in the general population and certain disadvantaged groups namely women in the childbearing age and children under five years of age.

Unlike many environmental health problems, lead contamination is often found at home, in paint, house dust, drinking water and soil. Worldwide, six categories of products account for most cases of lead exposure: gasoline additives, food can soldering, lead-based paints, ceramic glazes, drinking water systems and folk remedies (21).

The results of this study showed that maternal age and job, husband job, and smoking carried no risk association for high BLL(s). On the other hand frequent use of kohl as a cosmetic on eyes carried a significant risk (OR= 2.46, p= 0.05). Unfortunately the stepwise logistic regression model used in this study did not reinforce this risk significance. Kohl or surma is a topical agent applied around the eyes and is used in Asian and Arabic countries; they are available as a fine powder or heavy crystals of lead sulfide (21). An analytical study found that the concentration of lead of different types of this substance available in Pakistan ranged from 0.03% to 81.37 % (22). Given that more than half (58.2%) of the mothers in the present study were exposed to this hazardous substance, it is believed that educating mothers about the potential hazards of kohl could discourage application to their eyes.
There is a wide agreement on the importance of old buildings and presence of peeling and chipping paint as a risk factor for high BLL. This is clearly shown in the present study, where women living in old houses with chipping paint are at a great risk for the development of high BLL (p= 0.000) in both instances. Romien in Mexico City mentioned that lead-based paint and pigments that contain lead chromate are frequently used in this city. The proportion of lead can reach 50% for exterior lead-based paint. Although this product is not water soluble, it is soluble in acid liquids, and therefore lead may be released into the environment (dust and water) (23). Also, the dissociation of lead chromates by gastric acid can be responsible for the bioavailability of the lead contained in the ingested dust or soil contaminated by leaded paint (24). Workers and home-owners involved in the rehabilitation of old buildings are at risk of lead poisoning and for bringing lead-containing dust home to their families (21).
In the present study the risk significance of these two household characteristics is further strengthened by using stepwise logistic regression model of analysis with a significance value of 0.004 and 0.006 for age of the household and presence of peeling and chipping paint, respectively. The present work showed that location of the household near a major road, electricity generators, fuel station either alone or a combination of two or all of these characteristics carried a significant risk showed by OR and p-value. This association is furthermore approved by the stepwise logistic regression model with a (p value) of 0.002.

In Iraq, the number of automobiles increases yearly where the majority of these cars are second hand. Thus the increasing number of cars and rising gasoline consumption resulted in a wide dissemination of lead in the environment, in addition to the large number of electrical generators that are haphazardly distributed all over the city. Besides gasoline and diesel fuel used by cars, electricity generators and buses is imported from different sources and most probably they are leaded ones.
No data are available estimating the amount of gasoline and diesel fuel consumed every day in Mosul city and the annual amount of deposited lead in the environment from combustion of leaded gasoline and other sources of airborne lead in Mosul city which are battery repair shops, local paint factories and lead smelters. Inhalation or ingestion of dust and soil contaminated with lead can play an important role in the total lead body burden in children (23). Similar conclusion may be applied on females in childbearing age.

Methodological Issues
There are certain limitations to this study that merit discussion. This study is a cross sectional design. Habits and exposure may differ by season and socio-economic status especially among females of childbearing age affecting BLL(s). The study sample size did not provide enough statistical power to identify factors associated with elevated BLL(s), which is the result of our limited funds and due to the difficult security situations. Also the present study did not probe deeply the habits and customs related to lead exposure.

The BLL(s) observed in the population of the present study indicate that lead exposure is an important public health problem in Mosul city. The major predictors of high BLL were the location of the household in relation to traffic density and home exposure i.e. age of the household and presence of chipping paint.

Preventive strategies must be conducted to provide a lead-free environment in the city. These strategies should be based mainly on either decreasing the percentage of lead content in leaded gasoline or completely prohibiting its use since it is the primary source of lead pollution in the environment. The population of Mosul is largely unaware of the hazards and health consequences of lead exposure, and they therefore lack prevention strategies. Prenatal screening for lead exposure may include a five-item questionnaire and management focused on removal of the lead source. Further research is badly needed to evaluate the BLL(s) among other disadvantaged groups i.e. children under five, and its contributory factors.

1. National Academy of Sciences. Lead: air-borne lead in perspective. Washington, DC: National Academy Press, 1972.
2. Brody DJ, Pirkle JL, Kramer RA, Flegal KM, Matte TD, Gunter EW, Paschal DC. Blood lead levels in the US population: Phase I of the third National Health and Nutrition Examination Survey. JAMA 1994; 272: 277- 83.
3. Gordon B, Mackay R, Rehfuess E. Inheriting the world: The Atlas of Children's Health and the Environment. Brighton, US: WHO, 2004.
4. Schwartz J. Lead, blood pressure and cardiovascular disease in men. Arch Environ Health 1995; 50: 31- 7.
5. Goyer RA. Nutrition and metal toxicity. Am J Clin Nutr 1995; 61: S 646- 50.
6. Borja- Aburto VH, Hertz- Picciotto I, Lopez MR, Farias P, Rios C, Blanco J. Blood lead levels measured prospective and risk of spontaneous abortion. Am J Epidemiol 1999; 150: 590- 97.
7. Rahman A, Hakeem A. Blood lead levels during pregnancy and pregnancy outcome in Karachi women. J- Pak- Med- Assoc 2003; 53(11): 529-33.
8. Moline MJ, Landrigan JP. Metals and Related Compounds: Lead. In: Rosenstock L, Cullen MR, Brodkin CA, Redlich CA. Textbook of Clinical Occupational and Environmental Medicine. 2nd. Ed. NY: Elservier Saunders, 2005: 967-976.
9. Gomaa A, Hu H, Bellinger D, Schwartz J, Tsaih SW, Gonzalez- Cossio T, Schnaas L, Peterson K, Aro a, Hernandez- Avila M. Maternal bone lead as an independent risk factor for toxicity: a prospective study. Pediatrics 2002; 110: 110- 118.
10. Al- Tamimi D. The adverse health effects of direct and indirect exposure to lead among battery factory workers. J comm Med 1990; 3(2): 103- 110.
11. Hikmet J, Al- Timimi D, Al- Ajzan J, Al- Ghabban S. Lead absorption in printing workers. J Fac Med Baghdad 1991; 33(1): 101- 112.
12. Hikmet J, Dhia JA, Saad IA, Qasim IV. Lead absorption in petrol filling station workers in Baghdad city. J Fac Med Baghdad 1987; 29(1): 95- 102.
13. Thompson WD. Statistical analysis of case- control studies. Epidemiological Review 1994; 16(1): 33- 50.
14. Al- Nori MK. Levels of some trace elements and related biochemicals in different groups. M.Sc. Thesis, Mosul University 2002; 41.
15. Al- Ridhawany Hajer HE. Epidemiological surveillance for maternal and neonatal health in Mosul city. M.Sc. Thesis, Mosul University 2003: 9- 51.
16. Landrigan PJ. Toxicity of lead at low dose. Br J Ind Med 1989; 46: 593- 96.
17. Al- Naama LM, Hassan MK, Nadum J. Screening for blood lead levels in Basrah. A paper presented in the International Environmental Health Conference, Amman, Jordan, September 12- 22, 2005.
18. Hafeez A, Malik QU. Blood lead levels in preschool children in Rawal pindi. J Pak Med Assoc 1996; 46: 272- 74.
19. Manser WWT, Lalani R, Haider S. Trace elements studies on Karachi population. Pt V: Blood lead levels in normal healthy adults and grammer school children. J Pak Med Assoc 1990; 40: 150- 54.
20. MMWR (weekly). Blood lead levels in United States, 1999- 2000. May 27, 2005; 154(20): 513- 16.
21. Markowitz M. Lead poisoning. Pediatrics in Review 2000; 21(10): 327- 335.
22. Haq I, Khan C. Hazards of traditional eye- cosmetic surma. J Pak Med Assoc 1982; 1: 7- 8.
23. Romieu I, Palazuelous E, Avila MH, Rios C, Munoz I, Jimenz C, Cahero G. Sources of lead exposure in Mexico city. Environ Health Perspect 1994; 102: 384- 389.
24. Hammond BP. Metabolism of lead. In: Lead absorption in children. Management, clinical and environmental aspects, Baltimore: Urban and Schwarzenberg 1982; 11- 19.