Study exposes tobacco smoke's alarming impact on breast milk, elevating toxic elements

By Dr. Chinta SidharthanNov 27 2023Reviewed by Susha Cheriyedath, M.Sc.

In a recent study published in the journal Scientific Reports, researchers investigated the levels of toxic micro-elements and elements between breast milk samples from non-smoking women and those who were exposed to second-hand tobacco smoke or smoked tobacco during their pregnancy or lactation.

Study: The effects of active and passive smoking on selected trace element levels in human milk. Image Credit: Image Point Fr / Shutterstock

Background

Breast milk has a vital role in infants' health, not just in growth and development during the first half-year of life but also in establishing immunity against various pathogens and diseases, such as allergies, and against respiratory and autoimmune diseases. Breast milk is also essential for establishing a healthy intestinal flora, which further strengthens the infant's immunity. Recent studies have also shown that the quality of breast milk also plays a significant role in intellectual development, reducing iron deficiency, and in childhood obesity.

However, the quality of breast milk is dependent on the health and nutrition of the mother, and studies have found toxic elements, such as heavy metals, in human milk, which can cause potentially lethal health problems for the infant. Excessive levels of cadmium, lead, arsenic, mercury, manganese, chromium, and cobalt have been found in breast milk. Tobacco smoke is known to contain over 5,000 harmful compounds and carcinogens, and active or passive exposure to tobacco smoke can influence the quality of breast milk in lactating mothers.

About the study

In the present study, the researchers conducted a cross-sectional analysis of lactating women who were registered in various health centers in the urban areas of Kermanshah, Iran. The study included all healthy women who had an uncomplicated pregnancy, had given birth, and were breastfeeding their first child. Women with multiple children, as well as those with chronic autoimmune or cardiac diseases or residing in areas with high pollution levels, were excluded.

Studies have shown that human milk is one of the main routes through which trace elements are excreted from the mother's body and can be a biological indicator. Moreover, exposure to tobacco smoke through smoking or second-hand smoke exposure can influence the breast milk composition. Research also indicates that infants who are breastfed by mothers who smoke have a higher likelihood of developing colic, sleep disorders, upper respiratory tract infections, allergies, cardiac rhythm disorders, and even sudden infant death syndrome.

However, despite the current understanding that the risks of exposure to second-hand smoke are comparable with those of active smoking, research on the effects of passive and active smoking on breast milk quality is lacking. The researchers, therefore, investigated breast milk samples to evaluate the levels of six micro-elements and six elements that could be potentially toxic to the health of the mother and the infant.

The participating women were classified into non-smokers, active smokers, and passive smokers. While the participants in the three groups differed significantly in factors such as occupation, education, age, cosmetics usage, and fruit consumption, their consumption of milk, salt, fast food, vegetables, oil, and potatoes was not substantially different. Breast milk samples were collected and analyzed using inductively coupled plasma mass spectrometry to measure the concentrations of manganese, magnesium, cobalt, iron, zinc, copper, arsenic, chromium, cadmium, nickel, mercury, and lead.

Results

The findings showed that active and passive exposure to tobacco smoke can cause the accumulation of potentially toxic elements in breast milk, severely endangering the health and life of the infant. The concentrations of trace elements such as mercury, cadmium, lead, and arsenic were significantly higher in the breast milk samples from women with active or passive tobacco smoke exposure as compared to women who were non-smokers. The concentrations of manganese and magnesium were higher in the breast milk samples from passive smokers than those from active smokers.

Cadmium exposure is of serious concern as it impacts the metabolism of micronutrients such as magnesium, copper, zinc, and iron, which are critical for the development of the infant. Cadmium can be absorbed from contaminated soil through crops and enter the body through smoked tobacco or food. However, recent studies indicate that a substantial amount of cadmium exposure is through smoking, with cadmium concentrations in breast milk showing a significant increase with an increase in cigarette smoking.

The study also discussed the various ways in which exposure to other toxic elements, such as mercury and lead, has increased in recent times and is linked to tobacco smoking. The researchers also explained some of the potential mechanisms through which these elements could negatively impact the health and development of the fetus.

Conclusions

Overall, the findings indicated that active and passive exposure to smoke in pregnant or lactating women results in higher and potentially toxic concentrations of mercury, cadmium, lead, and arsenic. Furthermore, passive exposure through second-hand smoke was found to increase the concentrations of magnesium and manganese in breast milk as compared to active tobacco smoking. While it is already known that tobacco smoking is harmful, these results also highlight the far-reaching consequences of smoke exposure in pregnant and lactating mothers.