|Year : 2014 | Volume
| Issue : 2 | Page : 69-73
Inter-relations between habitual abortion and lead levels in venous blood, abortuses, and drinking water in Egyptian women
Arwa A Abuelfadl1, Ahmed M.E. Ossman2, Mohamed A.T. El-Sharawy2, Tarek Elnimr3
1 Department of Forensic Medicine and Clinical Toxicology, Tanta University, Tanta, Egypt
2 Department of Obstetrics and Gynecology, Faculty of Medicine, Tanta University, Tanta, Egypt
3 Department of Physics, Faculty of Science, Tanta University, Tanta, Egypt
|Date of Submission||07-Apr-2014|
|Date of Acceptance||17-Apr-2014|
|Date of Web Publication||31-Jul-2014|
Ahmed M.E. Ossman
Department of Obstetrics and Gynecology, Faculty of Medicine, Tanta University, El Gish Street, Tanta 31211
In Egypt, one of the main sources of lead exposure is a network of lead pipes used for water supply. Adverse effects of high lead exposure are well known. Many studies have focused on the health effects of low blood lead levels after sharp decline of its exposure levels. Currently, there is a growing concern about threats posed on pregnancy outcomes among women with low to moderate blood lead levels.
Aim of the work
This study was conducted to evaluate the role of contaminated water as one source of multifactorial lead exposure chain, and to be acquainted if the currently observed lead levels are associated with increased risk of spontaneous abortion in pregnant women in Egypt.
Patients and Methods
This study was conducted at Obstetrics and Gynecology Department, Tanta University Hospital from January to September 2012. The participants were 26 pregnant female with history of habitual abortion in early pregnancy (8-14 weeks) who presented by dilated cervix with bleeding, non-pulsating fetal node on ultrasound, and/or decreasing beta-HCG level.
The results of this study revealed significant positive correlations between drinking-water lead with both blood lead and abortus lead levels in cases of abortion. Each woman with unexplained spontaneous abortion should be subjected to blood lead estimation. Primary prevention by removing lead from the environment is the only pathway to avoid threats posed on pregnancy outcome since there is no effective remedy to remove lead from the body at levels below 30 μg/dl.
Keywords: abortus, drinking water, habitual abortion, lead, pregnancy
|How to cite this article:|
Abuelfadl AA, Ossman AM, El-Sharawy MA, Elnimr T. Inter-relations between habitual abortion and lead levels in venous blood, abortuses, and drinking water in Egyptian women. Tanta Med J 2014;42:69-73
|How to cite this URL:|
Abuelfadl AA, Ossman AM, El-Sharawy MA, Elnimr T. Inter-relations between habitual abortion and lead levels in venous blood, abortuses, and drinking water in Egyptian women. Tanta Med J [serial online] 2014 [cited 2020 Nov 30];42:69-73. Available from: http://www.tdj.eg.net/text.asp?2014/42/2/69/137808
| Introduction|| |
In Egypt, one of the main environmental sources of lead exposure is leaded gasoline, which contains 0.2-0.4 g/l as tetraethyl lead. Leaded paints, which include inorganic lead compounds of more than 40% by weight, are still in common use. For instance, industries including cement, chemicals, fertilizers, iron, steel, nonferrous metallurgy (lead and zinc), asbestos, and electric power, in addition to other minor sources (e.g. printing and smelting), dispose of their wastes into the river Nile and its brushwood. Furthermore, another important source is the outdated network of lead pipes used for water supply, together with use of the manual water pump. The officially allowed water lead level in Egypt is 0.1 mg/l, which is double the level recommended by the WHO .
Adverse effects of high lead exposure on the nervous system, hematopoietic, renal, and reproductive systems are well known. In the early part of this century, reports described increases in spontaneous abortions, stillbirths, premature births, and neonatal deaths in pregnant women exposed to high lead levels compared with unexposed mothers .
Barr et al.  considered the maternal-fetal unit as a fragile, complex functioning system, especially during early gestation when the embryo may be most susceptible to environmental stressors. Different fetal biochemical pathways render the fetus highly susceptible to teratogens at low exposure levels that do not harm the mother [3,4].
After a sharp decline of lead exposure levels in the past decades, many studies have focused on the health effects of low blood lead levels. Adverse health effects have been reported at the 'acceptable' blood lead levels (≤10 mg/dl). Currently, there is growing concern about threats to pregnancy outcomes at levels lower than the international guidelines, and a significant increase in miscarriage risk, even among women with low-to-moderate blood lead levels, has been reported .
Experimental evidence supports the effects of lead on the female reproductive function. Serum progesterone, hypothalamic gonadotropin-releasing hormone, and somatostatin were reduced in different experiments . Degeneration of ovarian follicles together with teratogenicity was demonstrated in other reports .
Regarding low serum lead levels, which were encountered in the general population in many urban areas of the world, some research work revealed its association with spontaneous abortions [7,8]; however, other studies failed to show such an association [9-11].
In light of the inconclusive evidence from previous reports, this study was conducted to evaluate whether the currently observed lead levels are associated with increased risk of spontaneous abortion in pregnant women in Egypt, and to evaluate the role of contaminated water as one source in the multifactorial lead exposure chain.
| Participants and methods|| |
The study was approved by our local ethics committee. Prior to the commencement of the study, written informed consent was obtained from each participant after receiving detailed information concerning the procedure and aims of this research work.
This study was conducted at the Obstetrics and Gynecology Department, Tanta University Hospital, from January 2012 to September 2012. The participants were 26 pregnant women with a history of habitual abortion during early stages of pregnancy (8-14 weeks) who presented with a dilated cervix with bleeding, nonpulsating fetal node on ultrasound, and/or decreasing b-HCG levels.
The inclusion criteria were a history of at least two unexplained miscarriages in the first trimester and age range of 22-34 years. The exclusion criteria included a history of consanguinity (exclude chromosomal abnormality), the presence of general or local causes for habitual abortion (e.g. uterine anatomical or pathological abnormalities, infectious causes of abortion or trauma), alcohol consumption, smoking, immunological diseases (systemic lupus erythematosus and antiphospholipid syndrome), and chronic diseases (diabetes mellitus, hypertension, bronchial asthma, and renal and hepatic disorders). Serum Ca was measured in all cases to exclude hypocalcemic cases.
The control group included 25 age-matched pregnant female volunteers who attended the outpatient clinic for routine antenatal care. Volunteer patients were apparently healthy with no history of previous systemic disease or abortion and had passed the first trimester.
All participants were asked to complete a face-to-face questionnaire, which included standard demographic data (age, residence, occupation) as well as lifestyle (smoking and alcohol consumption) and lead exposure risk factors (using kohl and/or lead-glazed ceramics, old housing, and lead pipes).
Blood sample collection
All participants contributed to the study with a single blood donation. Venous blood samples (˜5 ml) were drawn from each participant into heparinized tubes. Samples were coded and processed within 2 h. One gram from abortuses (the products of conception) was put in a clean flask. Both blood and abortuses were kept at 4°C until assay. Each participant was asked to provide a sample of 20 ml of her drinking water for lead level assay.
Digestion of blood, water, and abortus samples was performed by the wet method of digestion. To each sample 10 ml of concentrated nitric acid and 2.5 ml of concentrated perchloric acid were added. Each sample was boiled and heated to dryness, cooled and dissolved in distilled water and concentrated HCl (10 : 1), and finally brought to a volume of 25 ml .
Lead levels were determined according to the method prescribed in Selvaraju et al.  using Inductively Coupled Plasma Optical Emission Spectrometry (Thermo Scientific, Cambridge, UK) in the Biomedical Research Laboratory, Faculty of Science, Tanta University .
Data were expressed as mean ± SD and compared using Student's t-test (to compare two groups). The χ2 -test was used for qualitative data (frequency and proportion). Correlation coefficiency was used to test the association between variables. Results were considered significant when P values were less than 0.05. The statistical package for the social sciences (SPSS, version 16; SPSS Inc., Chicago, Illinois, USA) for Windows software package was used.
| Results|| |
[Table 1] shows the sociodemographic characteristics and lead exposure risk factors of the studied groups. According to the information obtained from the questionnaire, both cases and control participants were found to have comparable demographic characteristics, lifestyle, and lead exposure risk factors.
[Table 2] shows that no significant difference was observed in the drinking-water lead levels in patients experiencing spontaneous abortion compared with control pregnant women. At the same time, blood lead levels were significantly elevated in patients experiencing abortion when compared with controls. The lead level in the abortus was estimated to be 5.30 ± 0.33 mg/g.
|Table 1 Sociodemographic characteristics and lead exposure risk factors of abortion cases and control participants|
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|Table 2 Student's t-test of lead levels in blood, drinking water, and abortus in abortion and control participants|
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[Table 3] revealed significant positive correlations between drinking-water lead with both blood lead and abortus lead levels in cases of abortion. Furthermore, there was significant positive correlation between blood lead level and abortus lead level in the aborted patients [Table 3].
|Table 3 Pearson's correlation coeffi cient for lead levels in blood and abortus with age and drinking-water lead levels in cases of abortion|
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| Discussion|| |
The results of the current study revealed nonsignificant differences in demographic characteristics, lifestyle, and lead exposure risk factors among abortion cases and control participants. According to Olsen and Skov  the controls should be taken from the same population at risk and matched with cases so that any exposure occurs in both groups uniformly. Consequently, different risk factors shown in [Table 1] were discussed in details in previous studies both outsid and inside Egypt [2,15].
It was found that the blood lead level was significantly elevated in patients experiencing abortion when compared with controls, which was in accordance with the results of several research works [2, 5, 15]. In other studies, the odds ratio for spontaneous abortion was determined to be 1.8 for every 5 mg/dl increase in blood lead. Elevation in chromosomal aberration rate, preconceptional effects on gametogenesis, disturbed hormonal balance required to maintain pregnancy, and direct teratogenic effects on the fetus could be considered suggested mechanisms to explain lead-induced abortion. In addition, different fetal biochemical pathways make the fetus highly susceptible to teratogens, typically at low exposure levels that do not harm the mother [2, 4, 16].
Over 99% of blood lead is erythrocyte bound and cannot pass to the fetus. Therefore, plasma lead reflects the toxicologically active fraction of lead in blood  Interindividual factors, such as polymorphisms in the d-aminolevulinic acid dehydratase genes involved in partitioning of lead, will influence the plasma/blood lead ratio .
Subsequently, if some women are exposed to lead during pregnancy, their erythrocyte lead binding capacity will determine how much lead remains free in plasma and potentially reaches the fetus. In view of these observations, it seems reasonable to expect an insignificant difference in drinking-water lead levels between abortion cases and control participants.
Evidence suggests that, during pregnancy, in addition to ambient exposure, stores of lead deposited in bone over the lifetime is a potential endogenous source that can be mobilized and that contribute to increasing blood lead levels [19,20]. This is particularly true in women who smoke  or in women whose calcium intake is low . If the mother takes insufficient calcium during pregnancy, a higher demineralization rate is expected, leading to the higher mobilization of lead from the bones.
In addition, WHO  reported altered lead absorption in atypical physiological states, particularly anemia and calcium deficiency. As iron and calcium can compete with lead for active transport into the blood, lead uptake is greater when other minerals are not present. This explains why women equally exposed to lead show different blood lead levels. Endogenous lead mobilization from bones into blood during pregnancy was reported by Al-Saleh et al. . This mechanism is related to the calcium status; hence, insufficient calcium intake during pregnancy will lead to more demineralization and mobilization of lead from the bones.
In the present study, both blood lead and abortus lead levels showed positive correlations with drinking-water lead in cases of abortion. This comes in line with several previous studies, which revealed significant elevations in blood lead levels with different ways and levels of environmental exposure [2, 25, 26]. The demonstrated significant positive correlation between blood lead level and abortus lead level in this study as well as in other studies could be mainly related to intrauterine or transplacental transfer [26,27].
Cases of abortion in this study showed blood lead level less than 30 μg/dl. According to Needleman , there is no effective remedy to remove lead from the body at this level, rendering treatment ineffective. Therefore, it is reasonable to keep environmental exposure as low as possible. In view of the fact that environmental exposure effects on pregnancy outcome have no thresholds, the only meaningful response is primary prevention: removing lead from the environment [28,29].
| Conclusion|| |
This study points to considering blood lead levels that do not harm mothers as a cause for unexplained spontaneous abortion. It is recommended to estimate plasma and plasma/blood lead in each mother suffering from unexplained spontaneous abortion, and keeping environmental exposures as low as possible. Primary prevention by removing lead from the environment will help reduce exposure risks on pregnancy outcome.
| Acknowledgements|| |
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[Table 1], [Table 2], [Table 3]