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Ingestion of Non-food items as a potential source of lead poisoning among pregnant women
Pica is described as the craving and subsequent purposive consumption of non-food substances for more than one month. Among the most prominent forms of pica in this study is geophagia, the intentional ingestion of earths or soils.30 While this practice is prominent in countries of the African region, it has been observed in other regions as well as in nationalities which have immigrated to the developed countries.8,31 Observations of women ingesting surface soil, particularly from anthills, have been noted in urban areas as well in Botswana and this is consistent with studies elsewhere.
32 In a related New York study women were likely to purchase such soils from areas where they were reared that was brought by visiting relatives. 33 In Kenya, more than half of pregnant women practice geophagy.34 Our results show a similar pattern where approximately, 55% of women ingested different types of soils ranging from clays to termite mounds during their first trimester of pregnancy. Ingestion of paint was less of a problem and this is consistent with Shannon’s findings where she reports more women engaging in geophagia compared to paint ingestion.7 Soil and dust have been identified as dominant pathways for human lead exposure and that these pose a
greater risk than lead-based paint to children who engage in hand-to-mouth and pica behavior.35 In a literature review of 25 years, Shannon (2003) identified pregnant women who experienced severe lead poisoning as a result of ingestion of soil, clay or pottery.7 Reported adverse health effects as a result of geophagia during pregnancy include hypokalemic quadriparesis as well as death.7,36 It is more concerning that pregnant women in this study have engaged in other forms of pica such sucking heads of match sticks, chewing pencil (likely to be painted with lead containing paint), ingesting paint chips from peeling wall paints and furniture paint, bone-meal and chalk. While paint-chips, chalk and bone-meal ingestion during pregnancy have been reported by other studies.37-39 Studies of women chewing pencil have not been reported. This type of practice has generally been reported in children ingesting pencil paint that contains lead. 40 A study carried out in South Africa by Okonkwo (2004) identified pencils painted with lead paint.41 Pencil chewing as a pica habit by pregnant women in this study therefore presents a potential lead exposure source. Ingestion of matches by pregnant women has been reported in other studies, however, these were burnt matches women habitually ingested.39 In this study, pregnant women sucked the heads of unused matches. While it is not established if such a practice can predispose women to lead exposure, matches has previously contained lead pyrophorus from roasted lead tartrate and the modern matches has a variety of chemicals which may present harm if ingested such as ammonium phosphate, borax, paraffin, potassium chlorate, sulphur, zinc oxide, glass powder and many other substances.
Use of nonconventional skin treatment solutions
Used brake fluid was reported to treat psoriasis, ringworm and applied on wounds including open wounds. Car lubricants, known to contain lead and its derivatives such as lead naphthenate were used. 43,44 Lead has been determined from various used and unused oils ranging from 4.6 to 928ppm lead.43 Such oils include gear oils, brake washing oil, lockhead brake oils, tyre cleaners and many other used motor oils. In their study, among autoworkers, Claussen and Rastogi (1977) concluded that inadequate protection of workers might allow organic lead to be taken up by the body through direct skin contact.43 Cutaneous application of lead naphthenate solution has been found to produce chronic lead toxicity in rats.45 This therefore places women who apply oils such as brake on their skin, including on open wounds, at a much greater risk for lead exposure. It is not understood why women engage in using car lubricants for treatment of skin infections of conditions. However lubricants containing lead naphthenate have been used elsewhere for cleaning hands in auto workshops for their apparent effectiveness in removing carbon particles due to their apparent detergent content.45 Of major concern is that in studies of auto workers who used car oils for cleaning hands, high blood-lead levels have been observed (mean 57.4μg/dL) yet the workers were not aware of the risks from such practices.45 In other non-human studies car oils have been identified as an important cause of lead toxicity for cattle in countries such as Australia where cattle drank it. 46 Auto oils are also used in South Africa as an acaricide even though there has been no report of lead poisoning as a result of such practice by small scale farmers.47 This study reveals that while the use of brake fluid is prevalent in all age groups, women aged 20-24 years are at a significantly higher risk of using brake fluid compared to other women. These women may not be aware of the hazards presented by using brake fluid and exposure at such a young age might present lifelong lead exposure source for them and generations to come. Light brown shoe polish was used as a ―cosmetic‖ for smoothing and vanishing skin. This is a new phenomenon identified by this study. Shoe polish contains high concentrations of solvents and the solvents contained in shoe polish, just like lead, cause adverse effects on the central nervous system which may result with brain damage.48,49 Other effects of solvents from shoe polish similar to those caused by lead found in animal studies include anemia and embryo-toxic effects such as significant reduction in fetus weight.50 While solvents in shoe polish may not be a direct exposure source of lead in pregnancy, the solvent concentrations in it need to be taken into consideration as potentially powerful confounding factors in lead studies. The prevalence of torch batteries used for the treatment of ringworm and other skin conditions was low (8%) compared to that of brake fluid (30%) and shoe polish (18%), but it is yet another new finding by this study. While it is not known how these women identified torch batteries as a treatment option for ringworm and found it effective, it is suspected that its effectiveness stems from the high zinc content in dry cell batteries. Studies that have characterized dry cell batteries have found large amounts zinc in dry cell batteries. In one study the total amount of zinc per AA alkaline household battery was 3418 mg.51 The same study however reported total lead in one battery to be 1.2 mg.51 Even though lead concentrations in dry cell batteries are reported in trace amounts and the levels may even fall within the recommended standards, the application of contents of dry cell batteries on skin cannot be ignored because dry cell batteries contain other hazardous substances such as arsenic, cadmium and mercury. 51,52 On the other hand one may also argue that the standards were not set with the application of dry cell battery contents on human skin. This practice therefore, may still pose yet another new exposure source for lead not only for pregnant women, but for children and other adults who have been observed using dry cell batteries for treatment of ringworm in Botswana. This argument is supported by a body of literature which confirms that there is no threshold for lead toxicity.
Chapter 1 General Introduction
1.1 Lead Sources, Uses and Impact in the Environment
1.2 Lead Use in Botswana
1.3 Lead Toxicity
1.4 Lead Exposure and Women’s Health- A Challenge for Developing Nations
1.5 Study Rationale
1.6 Research Question
1.7 Aims
1.8 Thesis Structure and Outline
1.9 References
Chapter 2 Uncommon Sources of Lead Poisoning: An Emerging Public Health Threat with Life-long Implications- A Systematic Review of Literature
2.1 Abstract
2.2 Introduction
2.3 Methods
2.4 Results
2.5 Discussions
2.6 Limitations
2.7 Conclusions
2.8 References
Chapter 3 Prevalence and Predictors of Risk Behaviours and Practices for Lead Exposure during the First Trimester of Pregnancy in the Central District, Botswana
3.1 Abstract
3.2 Introduction
3.3 Methods
3.4 Ethical Approval
3.5 Results
3.6 Discussion
3.7 Limitations
3.8 Conclusions and policy implications
3.9 References
Chapter 4 Potential Environmental Sources of Lead Exposure to Pregnant Women in the Serowe Palapye District, Botswana
4.1 Abstract
4.2 Introduction
4.3 Materials and Methods
4.4 Results
4.5 Discussion
4.6 Limitations
4.7 Conclusions
4.8 References
Chapter 5 Levels of Lead across pregnancy in women in major and small villages in the Central District Council, Botswana
5.1 Abstract
5.2 Introduction
5.3 Possible lead exposure sources in Botswana
5.4 Materials and methods
5.5 Results
5.5.1Socioeconomic and demographic characteristics of participants
5.6 Discussion
5.7 Limitations
5.8 Conclusions
5.9 References
Chapter 6 A Model for Assessing Lead Exposure during Pregnancy and After Delivery
6.1 Abstract
6.2 Introduction
6.3 Purpose of tool
6.4 Methods
6.5 Results
6.6 Discussions
6.7 Limitations
6.8 Conclusion
6.9 References
Chapter 7 Developing a Screening Tool for Assessing Lead Exposure Level During Pregnancy and After Delivery
7.1 Introduction
7.2 The Clinical Assessment Tool Guideline
7.3 Policy Brief Pretesting and Validation
7.4 Focus Group discussion- Awareness booklet
7.5 Strength of the research and deliverables
7.6 Major Recommendations
7.7 Study Limitations
7.8 Conclusions
7.9 References
Chapter 8 General Discussions and Conclusions
8.1 Overview
8.2 Strengths and Limitations
8.3 General Recommendations
8.4 Directions for the future
