Endocrine-disrupting chemicals found in the urine of Danish children


Regarding the effects of exposure to potentially toxic substances on the health of the fetus and infants, researchers reported the discovery of several endocrine-disrupting chemicals in Danish infants in a recent study. international environment magazine study. More specifically, this study found that breastfeeding was associated with higher concentrations of some of these chemicals or their metabolites in infants than in those fed a mixed diet.

The study: benzophenones, bisphenols and other polychlorinated/phenols in Danish infants and their parents - including longitudinal assessments before and after the introduction of the mixed diet.  Image Credit: Prostock-studio / Shutterstock.com

Stady: Benzophenones, bisphenols and other polychlorinated/phenols in Danish infants and their parents–including longitudinal assessments before and after introduction of the mixed diet. Image Credit: Prostock-studio / Shutterstock.com

an introduction

Bisphenols and benzophenones (BPs) are two examples of phenolic and polychlorinated substances that humans are exposed to in their environment. These chemicals are commonly used in the manufacture of consumer products; Hence, they are considered everywhere.

For example, BPs filter ultraviolet (UV) rays in many consumer products, including skin creams or drapes with UV screening properties. Additionally, bisphenols, including the widely studied bisphenol A (BPA), one of the world’s most widely manufactured chemicals, are used to manufacture epoxy and polycarbonate resins in consumer products and during recycling.

Triclosan and triclocarban are antibacterial agents used in personal care and cleaning/disinfection products. Chlorophenol can be incorporated into pesticides and herbicides, with 2,5-dichlorophenol (2,5-dCP) also being used as an antiseptic.

Phenylphenols are fungicidal agents and are often used after harvest to prevent fungal growth in orchids. These chemicals can also be used in industrial or household disinfection.

Most of these chemicals undergo rapid decomposition and are eliminated via urine and/or feces, indicating that they are not persistent. However, some chemicals exhibit a pseudo-persistence, allowing them to remain in the body almost all the time due to frequent or constant ingestion, skin contact, or inhalation. This ongoing exposure is being investigated because of the potential for endocrine disruption.

In Denmark, most young people are still exposed to most of these chemicals despite current efforts to limit their use. BPA substitutes such as bisphenol S (BPS) and bisphenol F (BPF) are being produced in larger quantities and, as a result, have been widely used in Europe and the United States for the past ten years.

The current human biomonitoring study was conducted with the aim of following up on measurements of these substances in the urine and serum of parents and infants during periods of breastfeeding and mixed feeding.

This study, called TRIO, involved analyzing urine samples of more than 100 children and their parents. Paired samples of approximately 60 infants from the FOOD study during the period when they were exclusively breastfed and after exposure to a mixed diet were also included.

Results

Of the 22 substances measured in urine, 12 were in more than 50% of samples taken from parents and infants. The concentrations of excreted substances varied widely between samples.

In the TRIO study, BP-3 was present in nearly all samples from infants and parents. In addition, BPA, BPS, triclosan, and 2,4-DCP were identified in more than 75% of parental samples, and approximately 95% of infant samples except for 2,4-DCP. BP-1 was also commonly observed in all samples.

Urine samples taken from fathers had significantly higher urinary concentrations of these substances than those obtained from mothers. However, this difference disappeared when estimated daily urine excretion (DUE) values ​​were used.

The infants had DUE values ​​for BP, 4-hydroxy-benzophenone (4-BHP), BPA, BPS, Triclosan, and 2-phenylphenol that were significantly higher than those of their parents. The highest BP-3 levels were identified in some infant samples, with some patient samples reaching 20 and 40 times higher than the maximum value among parents, respectively.

Triclosan concentrations, as well as BP-1 and BP-3, were closely related to each other, indicating that they all originated from the same endogenous sources. The levels of these compounds in the infants and their mothers were also well correlated, as were the levels of 4-BHP and BPA.

Among families, greater variance in the levels of these compounds was observed than within families, as the parents showed good correlation among themselves. Other than these substances, others showed similar increases or decreases in correlation.

Thus, simultaneous exposure to several substances may occur within some families. Notably, some compounds, such as BP-1 and 4-HBP, are byproducts of BP and BP-3 metabolism and compounds used for their special properties.

In the FOOD study, seven substances, including BP, BP-1, BP-3, 4-HBP, BPA, and BPS, were present in more than 50% of urine samples in both groups. The secretion profile changed with the analysis method; However, some were higher in infants than in their parents.

After adjusting for osmolarity, BP-1, BPA, BPS, and 2,4-DCP were lower; However, 4-BHP was higher in exclusively breastfed infants.

When adjusted for body weight, exclusively breastfed infants excreted 4-BHP and triclosan in higher concentrations than when they were introduced to other foods. This may be due to inhaling chemicals from personal care or cleaning products, even those used by parents. Breast milk can be another source of these substances.

In the mixed diet group, 2,4-DCP, 2-PP and 2,5-DCP were more commonly detected. This is likely because many of these are pesticides used in growing grains, fruits, and vegetables, all of which form the basis of solid foods.

The average age of infants in the exclusively breastfed group was 2 weeks of age compared to 30 weeks in the mixed diet group. Thus, the length of exposure must be considered when assessing the urine excretion profile.

No associations were found for any substance between the two groups, with intra-individual variance much higher than interindividual differences.

Ramifications

Low levels of the chemicals are found to be excreted in the urine of both infants and parents. However, the presence of multiple endocrine-disrupting chemicals in the same samples indicates the potential for additive effects with each other, as well as with other substances in the diet or the environment in general. Most of this exposure originated from household chemicals and personal care products for parents or infants.

In general, parental exposure reflects infant exposure, although levels vary widely between adults and infants within the family. Higher average levels were found in pregnant and pre-conceptional women in several studies conducted in France, the United States and Puerto Rico. This may be due to the deliberate phase-out of these compounds over the past few years in Denmark.

Interestingly, the detection rates for triclosan were high. However, this substance is only allowed in a very small range of personal care products in Denmark and in very low concentrations.

The current study also identifies the importance of using estimated DUEs to obtain more accurate values ​​that reflect actual exposure. This method helped establish similar or higher infant exposure rates to many of these substances during exclusive breastfeeding compared to the introduction of other foods.

Journal reference:

  • Fredrickson, H., Ljubcic, M. L., Upners, E. N., et al. (2022). Benzophenones, bisphenols and other polychlorinated/phenolic substances in Danish infants and their parents–including longitudinal assessments before and after introduction of the mixed diet. international environment. doi: 10.1016/j.envint.2022.107532.



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