Risk Factors for Lead (Pb) And Cadmium (Cd) Exposure to Stunting in Toddlers: A Systematic Review
Rizky Aulia Salsabila AM1, Suhartono Suhartono2, Nurjazuli Nurjazuli3
1,2,3Department of Environmental Health, Universitas Diponegoro Semarang Indonesia
*Corresponding author: rizkyauli2@gmail.com
Received: December 1, 2022 Accepted: December 8, 2022
Abstract
Stunting is a failure in growth due to insufficient nutritional intake in toddlers. Until now, stunting is still a health problem around the world, especially in developing and low-income countries. Stunting is not only caused by one factor but from many factors that are interrelated with each other, one of which is the contribution of lead and cadmium exposure which is associated with nutrient deficiency as a risk factor for stunting in toddlers. This study was conducted to assess the risk of exposure to Lead (Pb) and Cadmium (Cd). Literature searches are carried out through the journal sites Google Scholar, Garuda, Science Direct, Proquest, Scopus, JSTOR, PubMed. Article selection is carried out with criteria including bound variables are stunting events in toddlers, free variables are exposure to lead (Pb) and cadmium (Cd), open access full text, selected articles with a publication date of not more than the last 10 years (2012-2022), in Indonesian and English. Of the 574 relevant articles, 6 main articles showe the results that exposure to lead and cadmium in toddlers come from one of the factors, it is environmental and has an impact on the incidence of stunting in toddlers, due to the nature of heavy metals that are able to inhibit food nutrition and are directly proportional to cognitive decline in children. Factors related to stunting include the environment, gender, age, economic status and education of the mother
Keywords: cadmium, lead, nutrition, stunting, toddlers
Abstrak
Stunting merupakan kegagalan dalam pertumbuhan akibat ketidakcukupan asupan gizi pada balita. Sampai saat ini stunting masih menjadi permasalahan kesehatan di seluruh dunia, terutama pada negara berkembang dan berpenghasilan rendah. Pengerdilan pada anak tidak hanya disebabkan oleh satu faktor melainkan dari banyak faktor yang saling berhubungan satu sama lain salah satunya yaitu adanya kontribusi paparan timbal dan kadmium yang dikaitkan dengan defisiensi nutrien sebagai faktor risiko stunting pada balita. Penelitian ini dilakukan untuk mengkaji resiko paparan Timbal (Pb) dan Kadmium (Cd). Pencarian literatur dilakukan melalui situs jurnal Google Schoolar, Garuda, Science Direct, Proquest, Scopus, JSTOR, PubMed.
Pemilihan artikel dilakukan dengan kriteria meliputi variabel terikat adalah kejadian stunting pada balita, variabel bebas adalah paparan Timbal (Pb) dan Cadmium (Cd) dan open access full text. Artikel yang dipilih dengan tanggal publikasi tidak lebih dari 10 tahun terakhir (2012-2022), berbahasa Indonesia dan Inggris.
Dari 574 artikel yang relevan, 6 artikel utama menunjukkan hasil bahwa paparan timbal dan kadmium pada balita yang berasal dari salah satu faktor yaitu lingkungan dan memiliki dampak terhadap kejadian stunting pada balita, hal ini disebabkan oleh sifat logam berat yang mampu menghambat nutrisi makanan dan berbanding lurus dengan penurunan kognitif pada anak. Faktor-faktor yang memiliki hubungan dengan kejadian stunting meliputi lingkungan, jenis kelamin, usia, status ekonomi dan pendidikan ibu.
Kata Kunci: balita, Cd, Pb, nutrisi, stunting
1. Introduction
Based on the SDGs target sustainable development goal, it is eliminating hunger and all forms of malnutrition by 2030 and achieving food security, the target set is to reduce stunting rates by 40% in 2025 [1]. The incidence of short toddlers or commonly known as stunting is one of the nutritional problems experienced by toddlers around the world. Children who suffer from stunting will be more susceptible to disease and when they become adults are at risk of developing degenerative diseases, besides that stunting can also affect the level of intelligence of children [2]. Based on growth standards according to WHO stunting is presented with a z-score for height for age (TB/A) less than -2 Standard Deviations (SD) [3].
Child stunting is a significant growth retardant in children, globally affecting 165 million children under the age of 5. Reporting from WHO (2016) that in 2016 as many as 5.6 million children under the age of 5 years died, with 45% of deaths caused by malnutrition [4]. In 2017 as many as 150.8 million (22.2%) of
children under five in the world experienced an increase in cases originating from Asia by 55% while more than 39% or one third lived in Africa [5]. Stunting is still a public health problem if the prevalence is 20%
or more. It can be estimated that there were as many as 162 million in 2012, if the trend of stunting in children continues, it can be estimated that there will be 127 million in 2025 [6]. Approximately 25% of children aged 5 years’ experience many delays in growth and development [3], [7]. There are several factors that cause stunting directly and indirectly. Directly including inadequate nutritional intake, maternal nutrition during pregnancy and a history of infectious diseases are at risk of causing stunting [8]. According to [9] added that the causes of stunting including poverty, socio-cultural factors, increased exposure to infectious diseases, food, and health services to the community. However, besides that there are several studies which state that stunting can be affected by the effects of exposure to environmental toxins or the entry of hazardous chemicals into the environment [3] such as lead and cadmium can be one of the risk factors for stunting in toddlers.
Lead and Cadmium are heavy metals and generally have toxic properties that can contaminate through air, food and water so that they can be distributed to parts of the human body and some others will accumulate. If this happens continuously over a long period of time, it can be harmful to humans. Lead exposure in young children has been associated with nutritional deficits and results in stunting of children [10]. The Agency for the Registration of Toxic Materials and Diseases said that lead is a heavy metal contaminant that affects stunting because it can interfere with the body's metabolism of calcium for growth that is not optimal [11]. Children are at higher risk of lead and cadmium poisoning compared to adults, this is because children often come into contact with the environment such as playing on the ground and then putting their hands in their mouths, toddlers can ingest Pb through breast milk given by their mothers, food and water contains lead [12].
Research on cadmium also reveals, that if Cd accumulates in the human body after absorption and can have a negative impact on reproduction, neurological, development, cardiovascular disease, and metabolic disorders [13]. The route of Cd exposure is through smoking, but besides that, vegetables and cereals are a source of Cd exposure in food. Other sources of exposure include emissions from industrial activities, mining, smelting, manufacturing of batteries, stabilizer pigments and alloys [14]. The assessment indicators used to determine exposure caused by lead and cadmium generally use a blood sample to further determine the absorption of heavy metals lead and cadmium. Because it is very difficult to get blood samples from children, especially infants, so as an alternative, you can use urine samples to evaluate exposure to lead and cadmium in toddlers [12]
Stunting is a health problem in toddlers that needs special attention because it can cause delays in physical growth, mental development, cognitive development, and health status in children [15]. Prevention of stunting is not only from the aspect of nutritional intake but also from the aspect of sanitation such as monitoring environmental quality. This research was conducted to assess the risk of lead and cadmium exposure to stunting in toddlers, based on articles that have been published in national and international journals.
2. Material and Methods
This research was conducted using a systematic review method of various articles. The databases used to search articles include Google Schoolar, Garuda, Science Direct, ProQuest, Scopus, JSTOR, PubMed. Articles were selected with a publication date not more than the last 10 years (2012-2022). Of the 547 relevant articles, 8 main articles met the criteria and are discussed further in this article. The articles that have been obtained will then be collected, tabulated, compared, then summarized and conclusions drawn. The article search used several keywords for Indonesian-language national journals "Pb (lead) and Cd exposure to stunting", "Stunting due to heavy metal pollution lead and Cd", "Pb (lead) on child growth",
"Cd on child growth".
The results of journal searches that have been carried out are limited to the risk factors for lead and cadmium exposure to stunting. The selection of articles began with reading the abstract and then obtained an analysis according to the criteria of 574 articles. Then reselection was carried out by reading the entire text and considering several inclusion and exclusion criteria. Inclusion criteria are stunting and exposure to Pb and Cd open access full text Indonesian language articles obtained through accredited journal sites (Google Scholar and Garuda Portal). Whereas for international journals obtained through: Scopus, Science Direct, ProQuest, JSTOR, PubMed. Exclusion criteria were stunting caused by malnutrition, articles in journal form. The inclusion criteria are stunt or growth, exposure to lead and cadmium, full text with year of publication approximately 10 years (2012-2022). Then screening was carried out to be included in the
study based on inclusion criteria, until the final number was obtained, namely 8 articles that were appropriate. This is because most of the articles did not meet the inclusion criteria.
The flowchart for selecting articles can be seen in Figure 1. Then the next step is to carry out an analysis to assess the relevance of the specified literature. The data that has been obtained from the articles is recapitulated and then displayed in the form of a synthesis matrix. Analysis is used as a narrative form.
Figure 1. Article selection flowchart
3. Results and Discussion
From the articles reviewed, it was found that the type of research used was analytic observational.
There are 5 articles with cross sectional design, and 3 cohort articles. Based on a review of the 8 selected articles, the number of samples in the study varied, starting from 27 to 1,724. From the results of a review of research articles on exposure to lead and cadmium as a risk trigger for stunting in toddlers, it was shown that several researchers state that there is a relationship between lead and cadmium exposure to stunting, but there are also those who state an inverse correlation between the concentration of lead and cadmium in the blood with high growth in toddlers.
Table 1. Research articles data No. Author &
Year of Publication
Title Destination Sample Results
1. Garcia- Villarino et al,. [16]
Exposure to metal mixtures and growth indicators at 4-5 years.
A study in the INMA- Asturias cohort
Investigated the effect of exposure to individual metals and mixtures of barium, cadmium, cobalt, lead, molybdenum, zinc and arsenic on growth indicators in children aged 4-5 years.
The method used in this research is observational, cohort. Urine samples were taken from 328 children, performing anthropometric measurements and interviews
Linear regression showed that Cd levels in urine decreased arm circumference (βadjusted = -0.44, 95% CI : -0.73, - 0.15), waist circumference (βadjusted = -1.29, 95% CI: -2.10, -0.48) and standing height (βadjusted = -1.09, 95% CI: -1.82, - 0.35). Lead was associated with reduced height (βadjusted = -0.69, 95% CI: -1.20, -0.07) and smaller head circumference Google
Scholar n
= 147
Garuda Portal
n = 5
Scopus n = 97
Science Direct n = 142
ProQuest n = 38
JSTOR n = 19
PubMed n = 126
Search for articles using the keyword n = 574
Screening of articles based on inclusions
n = 8
Inclusion criteria:
1. Full text n = 47
2. Article publications in 2012-2022 n = 41 3. Indonesian and English n = 30
4. The suitability of the dependent variable n = 23 5. The suitability of the independent variables n = 8
βadjusted = -0.29, 95% CI: -0.49, - 0.09). From BMKR it shows that there is a negative linear relationship of Cd with arm
circumference, head and height, as for lead from the results shows that lead can lower height in toddlers 2. Gleason et
al., [17]
Stunting is associated with blood lead concentration among Bangladeshi children aged 2-3 years
Identify the
relationship between lead exposure and stunting in children aged < 5 years
Observational analytic survey, Cohort. A total of 815 children participated in taking blood lead measurements.
Lead levels in blood taken from the fingertips of each child were 3.1 (1.6- 6.3) g/dL and 4.2 (1.7-7.6) g/dL, multivariable regression analysis, the possibility of stunting in children aged 20-40 months increased by 1.12 per g/dL, increased levels of Pb in the blood (OR = 1.12, 95% CI:
1.02-1.122). So that a significant
relationship was found between stunting and Pb exposure in children aged 20-40 months.
3. Gardner et al., [18]
Environmental Exposure to Metals and Children's Growth to Age 5 Years:
A Prospective Cohort Study
In this study aims to evaluate the
relationship between cadmium exposure on the weight and height of children at the age of 5 years
In the cohort study used in this study, a sample of 1,505 mother-infant pairs was sampled in rural Bangladesh
Multivariable analysis showed that the children's weight at the age of 5 years was 0.57 kg (CI:
0.88, 0.26 for high Cd exposure
compared to children exposed to low Cd exposure). cadmium is 1.6 cm (95% CI:
2.4, 0.77) this can be seen among girls than boys that is (weight = 0.67 kg, 95% CI:
0.82, 0.53) and height (-1.3 cm, 95% CI:
17.089) 4. Yang Hui
et al., [19]
Effects of lead and cadmium exposure from electronic waste on child physical growth
This study aims to determine the relationship between Pb and Cd exposure in physical changes, and bone calcium metabolism in children in the
The research analysis used was observational, namely cross sectional. The sample used was 246 children aged 3-8 years at the Kindergarten in
Blood lead levels and blood cadmium levels were 7.30 g/dL and 0.69 g/L, respectively.
Cadmium in the blood increases with age. Lead exposure in childhood affects
electronic waste treatment area.
Guiyu Village taken for blood sample testing.
growth and physical development and increases bone resorption in children.
5. Rohmawati et al., [20]
Zinc status and cadmium exposure in stunted children aged from 24 to 59 months:
a cross-sectional study
Analyzing the correlation between zinc status and cadmium exposure with the incidence of stunting in children aged 24-59 months.
The analysis used is observational, cross- sectional study. A total of 35 children aged 24-59 months, hair and urine samples were taken, spectrophotometry and interviews were conducted.
The results of the study showed that boys experienced more stunting than girls with an average HA Z-score of -2.9;
17% low birth. It was also shown that the concentration of zinc in the children's hair was 82.84 ppm and the concentration of cadmium in the urine was 2.6 g/L. there is a significant correlation between cadmium concentration and stunting (p=0.000).
6. Ilmiawati et al., [21]
Biomonitoring of mercury, cadmium, and lead exposure in Japan children: a cross sectional study
Measuring Cd, and Pb exposure in Japanese children, and to estimate food intake responsible for high body burden
The analysis used was observational with a cross- sectional study design. A total of 229 children (9-10 years) had blood and urine samples taken, spectrometry measurements and interviews.
The geometric mean of blood Cd and Pb is 0.34 lg/L and 0.96 lg/L. Urine in the blood is 0.34 lg/g. Pb and Cd exposure in children is low because there is no safety margin for Pb exposure, however, periodic
biomonitoring and potential health risk assessment should be continued in high- risk populations, especially among children.
7. Raihan et al., [22]
Examining the relationship between blood lead level and stunting, wasting and underweight-A cross- sectional study of children under 2 years of age in a
Bangladeshi slum
Assessing the relationship of lead exposure in the direction with stunting in children under the age of < 2 years
This study used an observational analysis with a cross sectional study. From the information, 729 children aged <2 years were used as samples for blood sampling, anthropometric measurements and interviews.
The results stated that as many as 39.0% of children in
Bangladesh
experienced stunting, of which 50.3% were male and 86.6%
experienced increased levels of lead in the blood with an average stunted child of 8.47 ± 3 37 g/dL and 8.10 ± 3 80 g/dL for non-stunted children. The findings show that chronic lead poisoning is significantly associated with high rates of stunting
among children in the slums of Bangladesh.
8. Leoni et al., [15]
Effect of Lead (Pb) heavy metal pollution and Urine Iodine Excretion (EIU) on the incidence of stunting in children in Surabaya
To determine the effect of lead (Pb) heavy metal pollution and urinary iodine excretion on the incidence of stunting in children aged 25- 60 months
The analytical method used was observational, cross sectional using a sample of 27 children aged 25- 60 months
Based on the lab results, it was found that there was no known lead contamination of 0.00035 mg/L (polluted .0.008).
Kruskal Wallis' results show that EIU levels have no effect on the incidence of stunting based on anthropometric standards in children.
So that there is no influence between heavy metal pollution Pb and EIU with stunting cases in children aged 25-60 months.
Table 2. Matrix synthesis of results
No The results of the study are related to Pb and Cd exposure to stunting in toddlers Source 1. Exposure to lead and
cadmium
From the results of research that has been reviewed, it was found that there is a relationship between lead and cadmium exposure to stunting incidence in toddlers
1, 2, 3, 4, 5, 7 2. Toddler age From the results of research shows that the age of toddlers has relationship
with stunting cases, this is because toddlers are more vulnerable.
1, 2, 3, 4, 5, 6, 7, 8 3. Economic status The results showed that economic status had an effect on the incidence of
stunting. Low economic status can lead to inaccessibility to the fulfillment of food with good nutrition.
1, 3, 4, 5, 7, 8 4. Parent education The results showed that parental education effects the occurrence of
stunting, especially mothers in the care of childrens.
1, 2, 3, 4, 5, 7 5. Gender The results showed that the boys sex experienced the most stunting than
female
3, 5, 7 6. Smoking habit The results showed that the smoking habits of both male and female
parents can influence the occurrence of stunting in toddlers
1, 2, 6
All over the world, children tend to be healthier and have linear growth when they are given adequate nutritional food intake. Stunting is a major cause of death in children and a burden of disease which contributes around 45% of global child deaths per year apart from infectious diseases and disabilities [23].
Children are especially vulnerable to exposure to environmental toxins. Toxic metals such as lead (Pb) and cadmium (Cd) are of public health concern. Lead can be found in foodstuffs and children's toys. Previously lead (Pb) has been described as a “multimedia pollutant” due to the many historical and current exposure pathways. Meanwhile, cadmium is found through exposure to cigarettes and agricultural activities which produce phosphate residues in soil, water and local food products. In a study it was shown that cadmium urine from 5 stunted children remained high with an average of 2.69 g/L [20]. So that it can put children at risk of stunting. Stunted children have higher levels of lead in their blood around the age of 20-40 months with an average g/dL (SD): 6.2 (5.0) - 4.6 (4.1) compared to children who are not stunted [17].
Meanwhile, exposure to cadmium when exposed to the body is feared to affect Zn absorption in the body considering Zn is a micronutrient needed to carry out immune functions so it is important in preventing the occurrence of pathogenic bacteria and if Zn deficiency in children can also cause stunting [24]. From the articles reviewed, 6 of them mentioned a relationship between exposure to lead (Pb) and cadmium (Cd) and the incidence of stunting in toddlers (Table 2. Matrix synthesis results).
Based on the 8 articles reviewed, shows that toddlers age has relationship with stunting in childrens.
This is because children are very vulnerable to malnutrition and the environment. In the research that was reviewed, it was dominated by children under 5 years old who were thought to have failed to reach their
cognitive development potential due to poor health, unclean environment, socio-economic (poverty), and malnutrition. One of the factors in the incidence of stunting is the family's economic income. From the research articles that have been reviewed, the entire article explains that the economic status in middle and low countries is one of the triggers for the increase in stunting cases. This is influenced by the education level of the parents, if the education level of the parents is high and the income is sufficient then they have the opportunity to live in a healthy environment in contrast to parents who have low income, the nutritional needs of toddlers are inadequate and the environmental conditions are less supportive and poor environmental sanitation can affect the growth and development of children [25]. Besides that, socio- economic conditions also influence the selection of various kinds of complementary foods and time when providing good and healthy food intake [26]. Low economic status results in non-fulfillment of daily nutritional intake and results in economic status having a significant effect on malnutrition [27]. Children or toddlers who come from families with low economic status have a 2 times greater risk of being stunted than children or toddlers who come from families with high economic status [28].
Stunting is closely related to the educational level of parents. Nina Rohmawati's in [20] said the education level of parents was mostly in the elementary school education category (graduated/not) by 91.4% fathers and 91.4% mothers, junior or senior high school level by 8.6%. Most work as housewives by 80%. Kelsey in [17] the research showed that 52.4% of children experienced stunting. Stunted children are less likely to have their mothers attain secondary or higher education. Stunting in toddlers must receive special attention because this can cause physical growth retardation in toddlers, a lack of ability to think, and the child's health status, in this case education and the role of parents are needed, especially mothers.
Mothers have an important role in raising children, starting from choosing food to support adequate nutritional intake to serving food to children. If the mother's education and knowledge is lacking regarding the nutritional intake given to children from an early age, they are at risk of experiencing stunting [29].
From the articles that have been reviewed on Renee's research in [18] stated that high cadmium exposure caused growth retardation in children where the children's weight at the age of 5 years was 0.57 kg (95% CI: 0.88, 026) compared to children who were exposed to low cadmium (percentile-5). The difference in height due to high cadmium exposure in children is 1.6 cm (95% CI: 2.4, 0.77). These results can also be seen especially among girls who are on average lighter, namely 0.67 kg (95% CI: 0.82, 0.53) and 1.3 cm shorter (95% CI: 1.7, 0 .89) compared to boys. Negative effects caused by exposure to cadmium in children aged 5 years between girls and boys in terms of weight and height. Mohammad's research in (2018) due to lead exposure using blood samples in children, 39.0% experienced stunting. As many as 50.3% were boys and 86, 6% had an increase in blood lead levels. The findings also show that the possibility of stunting in children is associated with chronic lead poisoning significantly by increasing stunting in children.
Research conducted by Ninna of 35 stunted children aged 24 to 59 months due to cadmium exposure showed that there were more boys with an average HA Z-score of -2.9; 17% were born with
<2500 gr (low) birth. a significant correlation was found between the concentration of cadmium and the HA score (p=0.000). Research conducted by Ninna of 35 stunted children aged 24 to 59 months due to cadmium exposure showed that there were more boys with an average HA Z-score of -2.9; 17% were born with <2500 gr (low) birth. a significant correlation was found between the concentration of cadmium and the HA score (p=0.000). Research conducted by Ninna of 35 stunted children aged 24 to 59 months due to cadmium exposure showed that there were more boys with an average HA Z-score of -2.9; 17% were born with <2500 gr (low) birth. a significant correlation was found between the concentration of cadmium and the HA score (p=0.000).
Smoking is an alternative indirect cause of stunting. In the article that has been reviewed by research conducted by [16] mothers who are pregnant and smoke, the urine Cd in the body will increase so that it is associated with a decrease in arm circumference, waist and height in children [30]. Cadmium accumulates in the body after absorption into the body so that it can cause negative effects. One of the cadmium routes is through smoking, so that pregnant women are advised not to smoke and avoid exposure to cigarette smoke because it can have a negative impact on the fetus and toddler. In the study [17] children who were exposed to smoking were fewer than those who were not exposed to smoking and found no significant association with the incidence of stunting in children. The same thing was also stated by [21] in the article.
4. Conclusion
Based on the 8 reviewed articles, it was found that 6 had a relationship between lead and cadmium exposure to the incidence of stunting in toddlers and 2 research journals stated that there was no relationship between lead and Cd exposure to stunting in toddlers. Other factors that have a significant relationship with
the incidence of stunting are toddler age, economic status, parent’s education, especially mothers, gender, and smoking habits. There needs to be further action to reduce stunting in toddlers so that they are able to grow and develop in a healthy manner like children of their age.
5. Acknowledgment
Thank you to those who have provided encouragement and helped the continuation of this review article and for the Universitas Diponegoro.
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