Lead Concentration in Breast Milk of Nursing Mothers Living in Riyadh
1995; King Faisal Specialist Hospital and Research Centre; Volume: 15; Issue: 3 Linguagem: Inglês
10.5144/0256-4947.1995.249
ISSN0975-4466
AutoresBassam Younes, Abdul Aziz Al‐Meshari, Amal Al‐Hakeem, Saad Alsaleh, Faten Al-Zamel, Fahad Alshammari, Abdulrahman Al‐Warthan,
Tópico(s)Trace Elements in Health
ResumoOriginal ArticleLead Concentration in Breast Milk of Nursing Mothers Living in Riyadh Bassam Younes, PhD Abdul Aziz Al-Meshari, FRCOG Amal Al-Hakeem, MB Saad Al-Saleh, PhD Faten Al-Zamel, PhD Fahad Al-Shammari, and PhD Abdulrahman AlwarthanPhD Bassam Younes , Abdul Aziz Al-Meshari , Amal Al-Hakeem , Saad Al-Saleh , Faten Al-Zamel , Fahad Al-Shammari , and Abdulrahman Alwarthan Published Online:1 May 1995https://doi.org/10.5144/0256-4947.1995.249SectionsPDF ToolsAdd to favoritesDownload citationTrack citations ShareShare onFacebookTwitterLinked InRedditEmail AboutAbstractLead poisoning has proven to be one of the most difficult environmental health problems. Part of this difficulty is based on the lack of distinctive manifestations at an early phase in the process. Breast milk feeding with high lead concentration is one of the first sources of lead exposure in neonates. This study reported that lead in breast milk samples from 81% of nursing mothers varied from a low concentration of 0.318 μg/dL to a high of 2.5 μg/dL with an average of 0.768 ± 0.42 μg/dL. The high lead concentration of 2.5 μg/dL recorded in this study is similar to the average lead concentration reported by others. Lead concentration was found to be low in young mothers and higher in mothers age 36 years or more with an average of 0.515 ± 0.14 and 1.344 ± 0.65 μg/dL respectively. There were no significant differences between lead concentration in samples obtained from right or left breasts and similarly, there were no significant differences in lead concentrations in milk samples in relation to the length of period of lactation (P≥0.1). Breast milk samples obtained from mothers residing near industrial areas or highways, using copper casserole coated with white (rich in lead) inner coat and eating food material preserved for long periods in metal containers showed higher lead concentration than from those living in remote areas with reduced exposure. The diagnosis of lead poisoning required a constant awareness of its prevalence.IntroductionLead poisoning is considered to be one of the most difficult environmental health problems to control since it does not show any unique manifestation during its early stage. There are innumerable sources of lead in our environment such as paint, plumbing and water supplies from lead pipes or lead-soldered joints, dust and paint chips from older houses having lead paints, air and soil pollution from leaded gasoline, cooking in leaded pots, newsprint and many other sources.It is hard to avoid exposure to lead due to its widespread distribution in the environment. Environmental lead is absorbed either through the gastrointestinal tract or through the lungs into the blood.1 In the last twenty years, a great interest has grown regarding the accumulation of lead in the environment because many studies have found a relationship between exposure to low lead doses and neuropsychological impairment of children.2–5 Studies also show that intoxication of newborns may be caused by breast feeding with milk containing heavy metals.6 Lead levels in breast milk and blood in women from Mexico City were found to be 45.88 ± 19.88 μg/dL (in blood) and 2.47 μg/dL in breast milk.7 Mean lead concentration in Austrian women's breast milk was 3.58 ± 1.5 μg/dL.8 The concentration of lead in maternal blood, umbilical cord blood and breast milk from women who were not occupationally exposed were 7.0, 5.5 and 2.3 μg/dL respectively. These results suggest that lead freely crosses the placental barrier from mother to fetus and the transfer of this heavy metal from maternal tissues to breast milk is possible.9 It has been reported that the lead content of human milk varies during lactation.10 On the contrary, Ong9 suggested that "there is no significant change in the content of lead in breast milk during early lactation".Heavy metal (Pb, Cd, Hg) concentrations were found in the same order of magnitude in commercial infant formulas as in breast milk when the infant formulas are constituted with contaminated tap water.8 It was also reported that heavy metal (Pb) burden in infants fed with powdered formula is higher than that in infants fed on mother's milk.11 Other studies showed that breast milk of women living in heavy traffic areas had a seven-fold higher lead level compared to that of women from regions with lighter traffic.12 In Malaysian mothers, breast milk lead levels varied between urban and rural mothers. The mean lead level in urban samples was 2.53 μg/dL which was significantly higher than those of the rural samples (2.11 μg/dL).13In the Middle East, several recent reports on lead poisoning in children,14–16 including the study in Saudi Arabia,17 were an indication that lead poisoning is fairly common in this region and poses a major public health hazard. Breast milk with a high lead level is the first source of lead poisoning in the neonate. This study was undertaken to identify the lead level in breast milk of nursing mothers and correlate it with age and period of lactation.Material and MethodsMilk samples were collected from 58 nursing mothers at King Khalid University Hospital during the first postpartum week and at any time of breast feeding thereafter. The milk samples (minimum 5 mL) were collected in labeled sterile polyethylene universal bottles from the right and left breasts (separate bottles) and kept at 4°C. To eliminate the possibility of contamination, the milk was collected by self-milking into the polyethylene bottle held a slight distance from the breast nipple. Proteins were precipitated by adding a few drops of trichloroacetic acid (0.1M) to the breast milk and the aqueous fraction of the milk was separated by centrifugation at 1000 xg for 10 minutes and then lead concentration was measured by the use of the Varian Techtron atomic absorption spectrometer (model AA-1475) using dry ashing method.The aqueous fraction of milk samples (0.5 to 3 mL) were ashed in porcelain crucibles previously washed with diluted HNO3 to eliminate any possible Pb content. A muffle furnace was used for ashing the sample where the temperature was gradually increased to a final temperature of 500°C (at this temperature, ashing was completed after one hour). Samples were then cooled, diluted with 3 mL of (0.5M) HNO3 and filtered into 10 mL volumetric flasks using Whatmann filter paper (No. 41) and completed to the mark by adding 0.5M HNO3.Standard solutions (prepared from lead standard solution 1000 PPM Winlab UK) and the sample filtrates were subjected to the air-acetylene flame for atomic absorption measurements under the following conditions: Wave length 217.0 nn, Pb lamp current 5 mA, band-pass 1.0 mA, air 25.01 1/min, 5.01 1/min. Working standard solutions of lead prepared from lead standard solution 1000 PPM (Winlab UK) and the calibration graph exhibited linearity over the range 0.2 – 15 μg/mL with a correlation coefficient of 0.999. All standards and samples were read to the same accuracy and at the same time. The final results are expressed by μg/mL sample - μg/mL blank x 100 = μg/dL. Data were analyzed by using Student's t-test and level of significance was obtained by using probability table for t distribution.ResultsThe breast milk samples collected from 58 mothers were tested for lead content. Samples from 47 (81%) mothers showed lead concentration and lead was undetectable in samples collected from the remaining 11 (19%) mothers. The milk lead concentrations were compared according to age groups, Table 1 and period of lactation, Table 2. Lead concentrations in breast milk samples were found to vary from a low of 0.318 μg/dL to a high level of 2.5 μg/dL with an average (mean ± SD) 0.731 ± 0.42 μg/dL. The milk lead concentration measured in right and left breasts showed a similar level with an average 0.768 ± 0.45 and 0.693 ± 0.38 μg/dL respectively (P≥0.1).Table 1 Breast milk lead concentration in samples from 47 mothers in relation to age groups.Age groupTotal=47Average Mean ± SD μg/dLP value≤ 2040.515 ± 0.14-21–25190.777 ± 0.41≥ 0.l26–30130.697 ±0.31≥ 0.131–3530.832 ± 0.33≥ 0.1≥ 3681.315 ± 0.65≤ 0.05Table 2 Lead concentration in breast milk in relation to period of lactation.Lactation period (days)Total=47Average Mean ± SD μg/dLP value0 - 3050.651 ± 0.22≥ 0.131 - 60310.886 ± 0.53≥ 61110.626 ± 0.38The comparison within the groups is not significant (P ≥ 0.1).Table 1 demonstrates the low concentration of lead in samples obtained from mothers age 20 years or less with an average of 0.515 ± 0.14 μg/dL and close range of lead concentrations in other age groups but higher in milk samples from mothers age 36 years and more with an average of 1.344 ± 0.35 μg/dL. Lead concentration was found to be in close range in any length of period of lactation (0.626 ± 0.38 to 0.886 ± 0.53 μg/dL with P≥0.1, Table 2.The high concentration of lead in milk samples was obtained from 14 (29.8%) mothers. The lead concentration in these samples ranged from 0.97 μg/dL to 2.497 μg/dL with an average of 1.366 ± 0.498 μg/dL. This range was significantly higher in comparison to the specimens obtained from the remaining 33 (70.2%) mothers (P≤0.05).DiscussionThere are innumerable sources of lead in our environment and it is difficult to avoid exposure to lead. Studies showed that intoxication of newborns may be caused by breast feeding with milk containing lead and other heavy metals.6 In this study, 81% of the breast milk samples from nursing Saudi mothers had lead levels ranging from 0.318 to 2.50 μg/dL with an average of 0.731 ± 0.42 μg/dL. These findings represent a lower concentration of lead in breast milk from Saudi mothers in comparison to lead levels in breast milk reported by others elsewhere.6–9 However, the highest lead concentration in milk samples reported in this study is similar to the average lead level in breast milk reported by others.7,8 On the other hand, lead concentration in breast milk obtained from the right or left breast showed no significant differences as observed in this study (0.7684 ± 0.42 and 0.6926 ± 0.38 μg/dL respectively with P ≥0.1. This indicates that lead is equally deposited in milk produced by the mammary glands.The lowest lead concentration was found in milk samples obtained from mothers age 20 years or less (0.515 ± 0.14 μg/dL) and increased progressively with age and found in significantly high levels in mothers age 36 years or more (1.344 ± 0.35 μg/dL P ≤0.05). These findings can or may be attributed to the fact that young mothers have been exposed to environmental pollution for shorter time periods than older mothers. Other studies show that lead content in human milk may vary during lactation.10 On the contrary, this study showed that there is no significant change in the content of lead in breast milk during lactation (P ≥0.1, Table 2), which is similar to the observation made by Ong.9Milk samples with lead concentration of 0.97 μg/dL and above recorded in this study are considered to be high and were found only in samples from 14 (29.8%) mothers. Lead was undetectable in milk samples obtained from 11 (19%) out of 58 mothers. Living conditions, cooking utensils and eating habits were investigated and it was found in these two groups that samples with high lead concentration were obtained from mothers living close to industrial areas or highways for not less than four years. Some used copper utensils coated with a white (rich in lead) inner coat and ate acidic foods such as white cheese and pickled olives) preserved for long periods of time in large metal containers. The second group of mothers, with undetectable lead in milk samples, were found to be living quite far from industrial areas or highways. Some were also living in high traffic areas in Riyadh and using cheap utensils (aluminum casserole dishes). The observations made in this study are in support of other studies.12,13This study supports the recent reports that in the Middle East, including Saudi Arabia, lead poisoning is fairly common and poses a major public health hazard.14–17 There is no doubt that high lead concentration in breast milk is the first source of lead poisoning in neonates.In view of all the potential consequences of advanced lead intoxication, it is hardly necessary to point out the importance of an early diagnosis before morphological changes have developed. The diagnosis of lead poisoning requires a constant awareness of its prevalence. A study of lead concentration in maternal blood, cord blood, breast milk and babies' blood is suggested.ARTICLE REFERENCES:1. Cotran R, Kumar V, Robbins S. Robbins Pathologic Basis of Disease, 4th ed.WB Saunders Co Ltd, London, 1989. Google Scholar2. Centers for Disease Control. "Prevention of lead poisoning in young children" . A statement by the Center for Disease Control. Rockville, Maryland: Publications Office, Center for Environmental Health; 1985. Google Scholar3. Guidi B, Ronchi S, Ori E, et al. "Lead concentrations in breast milk of women living in urban areas compared with women living in rural areas" . Pediatr Med Chir. 1992; 14:611-6. Google Scholar4. Chisolm JJ. "The continuing hazard of lead exposure and its effects in children" . Neurotoxicol. 1984; 5:23. Google Scholar5. Schumann K. 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Yaish H, Niazi G, Soby A. "Lead poisoning among Saudi children" . Ann Saudi Med. 1993; 13:395-401. Google Scholar Previous article Next article FiguresReferencesRelatedDetails Volume 15, Issue 3May-June 1995 Metrics History Accepted23 October 1994Published online1 May 1995 AcknowledgmentWe thank Professor R. Soliman for his continuous encouragement and valuable suggestions. The technical help of Mr. Edwin Basco is highly appreciated and thanks are also due to Ms I. C. Lumanog for typing the manuscript.InformationCopyright © 1995, Annals of Saudi MedicineThis work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.PDF download
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