Exposure to certain phthalates in the womb is associated with a slight earlier onset of puberty
A study published in Environmental Research provides new evidence on the possible effects of these endocrine disruptors on sexual development
A joint study by the Granada Biosanitary Research Institute (ibs.GRANADA) and the Barcelona Institute for Global Health (ISGlobal), a center promoted by the ”la Caixa” Foundation, has provided new evidence on the ability of phthalates to interfere with sexual development. The results of this research published in the magazine Environmental Research show that exposure to certain phthalates in the womb is associated with a slightly increased risk of having started puberty in boys and girls between 7 and 10 years of age.
Phthalates are chemical compounds used as plasticizers and as fragrance retainers in a wide range of consumer products. They are used, for example, in the manufacture of PVC and are present in construction materials, cosmetics, plastic toys or food containers, among others. Is about endocrine disruptors which in previous studies have been associated with a number of detrimental effects on reproductive health such as urogenital malformations, decreased sperm quality, low testosterone levels, placental/umbilical dysfunction, premature birth, low birth weight, ovarian failure or endometriosis, among others.
In studies vitro and with animals phthalates have shown antiandrogenic activity, that is, ability to inhibit the effects of male sex hormones. Under this hypothesis, the scientific team set out to evaluate the possible influence of these compounds on pubertal development in boys and girls. To do this, they chose to examine exposure to these compounds in the antenatal stage, since it is in this phase when the adrenal and gonadal axes that control the onset and progress of puberty develop.
The study included the participation of 788 boys and girls of the cohorts of INMA project en Guipuzcoa, Sabadell and Valencia. Prenatal exposure to phthalates was assessed using maternal urine samples collected during pregnancy. Later, when the boys and girls were between 7 and 10 years old, the state of sexual maturation was evaluated of each participant through a questionnaire aimed at parents, from which boys and girls were classified into five stages of development: 1) pre-puberty, 2) early puberty, 3) middle puberty, 4) advanced puberty and 5) post-puberty. The body mass index of boys and girls was also taken into account since obesity plays an important role in pubertal development.
The analyzes revealed that the phthalates studied were present in more than 99% of the urine samples collected in pregnancy. The results varied depending on the compound examined, the sex and the body mass index of the participants. However, it was observed that higher exposure to certain phthalates in the womb was associated with a slightly increased risk of having started puberty. These results were more evident in boys with normal weight and in girls with overweight or obesity.
Specifically, prenatal exposure to DEHP o di(2-ethylhexyl) phthalate, a substance used to make plastics more flexible, was associated with increased risk of onset of puberty in both boys and girls. prenatal exposure to DEHP, DEP (diethyl phthalate) and dnBP (dibutyl phthalate) was associated with advancement of puberty in boys of normal weight. In contrast, prenatal exposure to BBzP (benzyl butyl phthalate) and al DINCH® (di-isononyl cyclohexanes-1,2-dicarboxylate) was associated with delayed puberty only in boys who are overweight or obese. For girls, prenatal exposure to DiBP (diisobutylphthalate), al dnBP and DINCH® was associated with a slight early puberty in those who were overweight or obese.
The observed associations occurred with some of the phthalates studied individually, although not with the mix of all phthalates as a whole.
"We cannot say that phthalates are associated with precocious puberty understood as clinical pathology, since we did not evaluate at what moment this process began in each participant. What is evidence is that the age of puberty has advanced in recent decades and our results suggest that phthalates could be one of the factors involved," he says. Carmen Freire, group researcher A15-Basic and Clinical Oncology from ibs.GRANADA and first author of the study.
“Our results in children are somewhat surprising, since due to the antiandrogenic activity of phthalates, they would have been expected to interfere with the development of puberty in the opposite direction, that is, by delaying it. However, determining the effects of this type of compound is very complex, since they are usually multifactorial and exposure never occurs in isolation, but in conjunction with a whole series of substances and environmental factors," he explains. Maribel Casas, ISGlobal researcher and last author of the study.
Currently, it is considered It is normal for puberty to begin at age 8 in girls and age 9 in boys.. Among the factors that are related to the age of onset of puberty is obesity, although there are others such as environmental exposures or stress.
Reference
Carmen Freire, Francesca Castiello, Maria-Jose Lopez-Espinosa, Andrea Beneito, Aitana Lertxundi, Alba Jimeno-Romero, Martine Vrijheid, Maribel Casas, Association of prenatal phthalate exposure with pubertal development in Spanish boys and girls, Environmental Research, Volume 213, 2022, 113606, ISSN 0013-9351, https://doi.org/10.1016/j.envres.2022.113606