Effect of Kaolin Consumption on Serum Heavy Metal Levels of Pregnant Women

Abstract

Geophagy is the consumption of earth materials across several cultures in many continents. For various reasons, consumption of kaolin is common among pregnant women in Nigeria. This earth material is known to contain heavy metals. This study was carried out to determine the effect of kaolin consumption on some heavy metal levels in pregnant women attending antenatal clinic in a Teaching Hospital in the south east Nigeria. A total of eighty pregnant women recruited for this study were grouped as follows; Group 1, (30 geophagic pregnant women within the first trimester). Group 2 (30 geophagic pregnant women within the second trimester) and Group 3 (20 non-geophagic pregnant women that served as control) Subjects in Groups 1 and 2 were subdivided into three based on the quantity of kaolin consumed per week, Group A (100 g/week), group B (150 g/week) and group C (200 g/week). Preliminary analysis of the heavy metal contents of kaolin was carried out. After two weeks of kaolin consumption, the serum levels of lead, arsenic, cadmium and mercury of the subjects were determined. The mean concentrations of lead (0.347 ± 0.12), arsenic (0.354 ± 0.15), cadmium (0.209 ± 0.11) and mercury (0.029 ± 0.02) in the kaolin exceeded the maximum permissible concentrations in food. The concentration of lead increased significantly (p < 0.05) in the first and second trimester pregnant women on 150 and 200 g of kaolin per week. There was a significant (p < 0.05) increase in the concentration of arsenic and cadmium in the second trimester women who consumed 200 g of kaolin per week. These results indicate that unregulated consumption of kaolin in pregnancy increases the serum level of the heavy metals and may be a risk factor for lead toxicity with its attendant complications in the infants.

Geophagia: Benefits and potential toxicity to human—A review

“…Cadmium (Cd) and Hg were observed to bio-accumulate in the liver ( 92 ). Similarly, serum levels of Pb and varying concentrations of other heavy metals have been found ( 93 , 94 ), confirming that toxic heavy metals can be absorbed during toxic clay consumption. Ekosse et al ( 43 ) inferred limited health threats in a study in which they observed low bioavailability of heavy metals in gastrointestinal tract simulation.…”

Geophagic practice in Mashau Village, Limpopo Province, South Africa

“…Msoffe et al (2019) indicated that pregnant women in Tanzania and their babies are potentially exposed to toxic levels of As, Al, Ba, Cd, Ni, and Pb. The practice of geophagia during pregnancy is also associated high serum level of the heavy metals, as shown in a study conducted in Nigeria among geophagic pregnant women (Akah et al, 2020). Zeigbo et al (2020) also showed that geophagia may predispose pregnant women to gestational diabetes, electrolytes imbalance and reduced intestinal enzymes activities.…”

“…Ingestion of soils rich in high amounts of Fe could be harmful to pregnant women and their unborn child (Abrahams et al, 2006). Carmichael et al (2003) and Akah et al (2020) also stated that the practice of geophagia during pregnancy could be a risk factor for lead toxicity in infants. Gundacker et al (2017) reported that soils ingested by pregnant women in some parts Democratic Republic of Congo contained substantial amount of lead, which could lead to prenatal lead exposure.…”

Kaolin Consumption Affects Serum Electrolytes, Glucose and Amylase Levels of Pregnant Women

“…The effect of unregulated and continuous kaolin consumption in pregnancy may manifest as gestational diabetes and its associated complications. The mechanism by which kaolin elevates plasma glucose is not known, however, previous findings revealed that some heavy metals were elevated in pregnant women on kaolin [20]. Heavy metals especially lead and arsenic had demonstrated inhibitory activities on insulin and were capable of inactivating over 200 enzymes [21].…”

“…Though, clinical relevance of low serum amylase is poorly understood, animal and cellular studies regarding the relationship with endocrine and exocrine pancreas have shown that insulin secretion affected the basal and stimulatory amylase secretion via islet of acinar axis, and there was negative association between serum amylase and heavy metals [26]. High concentration of some heavy metals in geophargic pregnant women has been documented [20], and in biological systems heavy metals have been reported to inactivate enzymes, and affect cellular organelles and components [27].…”