Maternal-fetal exposure to endocrine disruptors through the placenta in women from Panama


What is known about the subject?

Organochlorine pesticides (OPs) and polychlorinated biphenyls (PCBs) are groups of environmental chemicals that are part of the known endocrine disruptors, with the ability to mimic hormones and inducing adverse effects in exposed individuals or their offspring. Due to their toxic, persistent, and bioaccumulative properties, OPs and PCBs contribute to exposure to persistent organic pollutants (POPs), which are strictly regulated by international laws (Stockholm Convention). Historically, they were used in agriculture as pesticides, in public health for control insect vectors, and in multiple industrial processes such as electrical transformer manufacturing. The accumulation in the mother’s body and prenatal and early exposure to these environmental contaminants are related to child health and developmental issues and predispose to harmful effects in adulthood. Additionally, children are especially vulnerable to air, water, and soil contaminants as they are in the growth process and their immune system and detoxification mechanisms are not fully developed. Therefore, it is crucial that the environment in which they develop, from conception to adolescence, be protected to ensure their health.

International human biomonitoring programs for environmental exposure, such as NHANES in the United States and HBM4EU in Europe, have highlighted the widespread exposure of humans to numerous environmental chemicals. However, despite the measures taken in the Stockholm Convention on Persistent Organic Pollutants (2009), surveillance of exposure to POPs and associated diseases remains extremely limited in Latin America and other regions of the world.

What does this study add to the available literature?

Given the lack of data in Latin America, we transferred what was learned in the INMA Cohort to a maternal-infant cohort of Panamanian mothers and children (PA-MAMI), which tries to evaluate environmental exposure in early stages of development and the possible adverse impact of Environment and diet in early childhood in Panama.

Our study is pioneer in assessing the concentrations of OPs and PCBs in placenta samples from Latin American women, as well as quantifying hormone activity related due to the combined effect of POPs exhibiting estrogenic hormonal activity. The use of placenta as a biological matrix is of great relevance, as it is recognized as a valuable and readily available source of human tissue for biomonitoring chemical exposure between mother and child. Additionally, it allows for the implementation of effect biomarkers without the limitation of available tissue quantity.

The results of this study reveal that all placenta samples from Panamanian mothers analyzed were positive for at least three POP residues, with over 70% positive for at least six of them. The frequencies of quantified OPs ranged from 100% for p,p’-DDE and HCB to 30.8% for β-HCH, with the highest median concentration observed for lindane (380.0 pg/g of placenta). The detection frequency of PCBs ranged from 70.0 to 90.0%; the highest median concentration was observed for PCB 138 (17.0 pg/g of placenta), followed
by PCB 153 (16.0 pg/g of placenta). Furthermore, all placentas tested positive in the estrogenicity bioassay, highlighting that exposure to lindane was positively associated with estrogenicity, while this association was negative in the case of exposure to PCB 153. Regarding exposure predictors, higher concentrations of p,p’-DDE were associated with increased meat consumption, suggesting that animal fat is an important source of exposure to DDT metabolites.

What are the implications of the results obtained?

The data obtained in the PA-MAMI cohort study can be use as a reference for biomonitoring chemical exposure during pregnancy and its impact on offspring health in Panama and other Central American countries. They are also useful in emphasizing the need to estimate the cocktail effect of environmental contaminants, where exposure to low concentrations may result in undesirable and unsuspected combined effect when considering contaminants individually. Furthermore, these results can help the implementation of legal regulations that reduce exposure to environmental contaminants, which would help prevent possible risks to children’s health and where periodic biomonitoring would allow exploring the effectiveness of such regulations.

Reference: Iribarne-Durán LM, Castillero-Rosales I, Peinado FM, Artacho-Cordón F, Molina-Molina JM, Medianero E et al. Placental concentrations of xenoestrogenic organochlorine pesticides and polychlorinated biphenyls and assessment of their xenoestrogenicity in the PA-MAMI mother-child cohort. Environmental Research 2024; 241:117622.

Link to scientific article:

Luz María Iribarne Durán
Doctora en Medicina Clínica y Salud Pública
Nicolás Olea
Catedrático Facultad de Medicina/Facultativo Especialista Hospital Clínico
Universidad de Granada/Hospital Clínico S. Cecilio
Instituto de Investigación Biosanitaria de Granada (ibs. GRANADA)