In the gestational period, each stage of fetal development is critical. This entire (normally) 40-week duration is when major organs such as the brain, heart, and lungs form, leaving the fetus in a very fragile state. Teratogens (such as alcohol, drugs, chemicals, viruses, etc) are agents that can cause incipient deficits to the undeveloped child and can result in lasting physical, mental, and behavioral impairments that manifest in early childhood. Endocrine disruptor chemicals (EDCs) are some of the most dangerous teratogens that are not only present in the environment but are being used in everyday items such as plastic, clothing, electronics, food, drinking water, toys, and more. EDCs are exogenous elements that interfere with many parts of a woman’s endocrine system.
These chemicals are able to simulate thyroid hormones, androgens, and estrogens which tend to overload the body with excess hormones or may even stop the production of some. Due to their precise binding capabilities to cell receptors, these chemicals are able to block the correct, autogenous hormones from binding. During pregnancy, this causes an imbalance of hormones which can pose an immediate threat to early fetal development, as the mother provides everything that the unborn child requires. As a consequence, these disruptions in early formation can cause a number of complications such as changes in gene expression, physical and mental impediment, as well as diseases later in life such as cancer, obesity, early menarche, and other neurodevelopment disorders. Although not directly exposed to the chemicals, developing embryos can be endangered through the placenta and umbilical cord, which in turn can inhibit or alter important growth cycles. In order to investigate this further, the types of sciences that will be used are epidemiology as well as chemistry. As per their namesake, EDCs have always been seen in a negative way.
However, certain EDCs such as pesticides, bisphenol A (BPA) and dichloro diphenyl trichloroethane (DDT), are needed to make fundamental goods. These chemicals are how many countries grow crops, produce usable plastic, manufacture cars, create medical devices, and more. Some epidemiologists and chemists have performed clinical experiments proving that EDCs are used in the environment in small doses, and therefore do not have tremendously adverse consequences on the majority of the United States’ population, including pregnant women. These chemicals are continuously tested and have clearly been shown to be safe enough to embed into ordinary, household items. However, there have also been numerous studies done by their colleagues who have gathered evidence and revealed that these chemicals, although monitored by the government, generate adverse effects on fetal development, consequently affecting the postnatal maturation as well. When pregnant women are exposed to endocrine disrupting chemicals, it can cause adverse effects on early fetal development and therefore lead to neurocognitive and behavioral advancement difficulties such as decreased mental development scores, disobedient and hyperactive behavior, as well as anxiety and depression in children ranging from birth to 9 years old. Hundreds and thousands of EDCs are used all over the country. Not only are these compounds found in mundane items, but they also slyly creep into and become concentrated in food and water that is being consumed by millions of Americans each day.
As a matter of fact, a scientific study performed by Benotti, et al. (2009), revealed that EDCs were detected in drinking water in various states across the United States of America. By testing tap, source, and finished drinking water (all treated and acceptable for public consumption) samples in 19 states, they found that at least 34 of the 51 toxic chemicals that were being tested were detected in at least one sample of water. The fact that chemicals such as atrazine, estrone, diethylhexyl phthalate, and more are not only being used in goods but also embed themselves into basic essentials like drinking water expands the concern of the potential effect of these compounds, especially on highly susceptible pregnant women. In a study done by Harley, et al. (2013), a group of 601 pregnant women (some of which were ruled out due to certain circumstances) living in Salinas Valley, California. Spot urine samples were collected from the mothers during around 13 and 26 weeks of gestation. Urine samples from the group of 292 children were collected at 5 years old. The assessment of child behavior was done by self-report through mothers and teachers at age 7 and then by direct assessment at age 9. Through the Behavior Assessment System for Children 2 (BASC-2), measuring depression, somatization, and anxiety, as well as the Conners’ ADHD/DSM-IV Scales (CADS), measuring hyperactivity, Harley et al. (2013) concluded that 98% of the children (245/250) possessed appreciable BPA concentrations. In girls, higher BPA concentrations were associated with lower behavioral scores and presented the internalizing of problems, depressive and withdrawn behavior, as well as anxiety. In boys, higher BPA concentrations showed rule-breaking behaviors, thought problems, externalizing and internalizing behaviors, somatic complaints, and depressed/anxious symptoms.
Although boys were more statistically significant and consistent, this study clearly shows data illustrating the alarming effects of endocrine disrupting chemicals that pregnant women, as well as children, are exposed to throughout their lives. A resultant comparison study in 2015 by Roen et al. (2015) was performed to examine the prenatal and early childhood exposure to EDCs and how they affect behavioral patterns in children. The data was collected from African American and Dominican mothers throughout pregnancy and their children (250 children; 135 girls and 115 boys) in the inner city of New York. The amount of the EDC bisphenol A (BPA) was measured in the prenatal period by the mothers’ urine samples in the third trimester and during subsequent years by spot urine samples from the children (aged 3 to 5).
The mother and child’s background and environmental circumstances such as gestational age, maternal education and intelligence, quality of home and prenatal environment, tobacco smoke exposure, and more were monitored throughout this experiment as well. Once the children reached the ages of 7 and 9, Roen et al. used The Child Behavioral Checklist (CBCL) evaluation to asses overall development of behavior. The CBCL (available in Spanish and English) evaluates 8 syndrome scales: attention problems, internalizing problems, rule-breaking behavior, somatic complaints, thought problems, anxious/depressed, withdrawn/depressed and social problems. The results determined that higher prenatal concentrations on BPA in girls were correlated to lower behavioral symptoms, relating to withdrawn/depressed signs as well as internalizing problems. In boys, high BPA concentrations were associated with increased behavioral symptoms, meaning that they had problems with rule-breaking behavior, though processing, aggressive behavior, somatic complaints, anxious/depressed signs, and externalizing behavior. A comparable empirical study conducted by Stewart et al. (2008) was executed to measure prenatal exposure to the EDC group, polychlorinated biphenyls (PCB).
Once the concentrations were determined, the IQ of the 9-year-old children was tested to observe a correlation between the two. The subjects consisted of 156 children from Oswego, New York who were tested during the prenatal period and then at 9 years of age. Once the data was collected from prenatal placental tissue and then near the child’s 9th birthday, an IQ test was taken. Other factors such as socioeconomic status, nutrition, neonatal risk factors, cigarette/alcohol use, and home life environment were measured as well. By using the Wechsler Intelligence Scale for Children, third edition (WISC-III), categories including: Information, Similarities, Arithmetic, Vocabulary, and Comprehension subtests, Picture Completion, Coding, Picture Arrangement, Block Design, Object Assembly subtests, and many more, the Stewert et al. (2008) were able to measure IQ and varying levels of cognitive, verbal and nonverbal functioning. The results and conclusions of this study showed that for each 1-ng/g increase in the concentration of PBCs in the placental tissue, each child had a drop of 4 points in their Verbal IQ as well as a subsequent drop of 3 points on a Full-Scale IQ test. Likewise, a study produced by Doherty et al. (2017) aimed to measure the urine concentrations of pregnant women in order to identify the exposure to nine phthalate metabolites in an urban environment and the consequential mental development results. The subjects of this study were 404 pregnant women in the New York City area and, at around 24 months of age, their children.
After gathering information about the women’s lifestyle and personal background, Doherty et al. (2017) gathered spot urine samples from the mother’s during a prenatal visit around 25 to 40 weeks into pregnancy. Once these were collected, they began to test them for the phthalate metabolites: mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), monobenzyl phthalate (MBzP), mono(2-ethylhexyl) phthalate (MEHP), mono(2-ethyl-5-carboxypentyl) phthalate (MECPP), mono-n-butyl phthalate (MnBP), monoethyl phthalate (MEP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono-isobutyl phthalate (MiBP), and mono(3-carboxypropyl) phthalate (MCPP). Upon 22-42 months of age, the eligible 258 children were administered the Bayley Scales of Infant Development, Second Edition (BSID-II) in their preferred language which provided scores from the Psychomotor Development (PDI) and Mental Development Index (MDI). The PDI assesses fine and gross motor skills, while the MDI assesses problem-solving, habituation, classification, social skills, early number concepts, generalizations, memory, and vocalizations. The results depicted that concentrations of the endocrine disrupting chemicals MnBP, MiBP, and MCPP were associated with a 2 to 2. 5 point decrease in the MDI scores, specifically among girls. Once again, this reiterates the fact that prenatal exposure to these endocrine disrupting chemicals can truly unknowingly impact a child in serious ways.
Similar to the Doherty et al. (2017) study, the focus of another study was to find out if is the prenatal exposure to Polybrominated diphenyl ethers (PBDEs), a widely used flame retardant, adversely affected neurodevelopment. Executed by Herbstman et al. (2010), the sample size contained 329 mothers who delivered their children in one of three hospitals in Manhattan, New York. The maternal blood was collected the day after birth and the child’s blood was collected during delivery via the umbilical cord. After separating the plasma from the red blood cells, the samples were then sent to analyze for evidence of PBDE concentration as well any contaminations. The collections of these concentrations in the umbilical cord blood were then used as an indicator of fetal exposure during the gestational period. When the children were around 12, 24, and 36 months old, the BSID-II was given and once again, provided scores from the PDI and MDI. Once these scores were captured, the Wechsler Preschool and Primary Scale of Intelligence, Revised Edition (WPPSI-R) was given to the children when they were around 48 and 72 months old. This test measured cognitive growth through nonverbal and verbal tests. Although some children’s primary languages were not English, the developmental exams were adjusted according to their language (such as Chinese and Yiddish) or maternal translation was utilized.
After examining blood concentrations and intelligence test outcomes, Herbstman et al. (2010) were able to come to the conclusion that children who had lower mental and physical test scores at the ages of 12 to 72 months ended up have higher fetal blood concentrations of PBDEs. Children who were in the lower 80% of the exposure scales had much higher scores on each test. If slow neurocognitive development is caught around this time, it is possible for children to enroll in guidance programs that are implemented across the United States. However, many of these deficits go undetected and therefore cause mental and physical problems that affect the child in all aspects of life. Endocrine disrupting chemicals are not something that people think about on a frequent basis, consequently, it is something that silently threatens pregnant mothers and their unborn babies. Fetal exposure to EDCs, which can happen via the umbilical cord and/or the placenta, can be linked to reduced mental competency, assessed by official standardized psychological examinations.
Equally as important, there has also been evidence connecting fetal EDC vulnerability and hyperactive and disobedient behavior among young school children. This also leads to children developing serious mental concerns as depression and anxiety. Although this may be true, there is also an abundance of conflicting information on this subject. Governmental agencies such as the Environmental Protection Agency has stated that they do in fact monitor any potentially harmful EDCs and make sure they are dispersed through the environment in low doses. In addition, epidemiologists and chemists have conducted studies that have proven to support this assurance, explaining that these low doses are satisfactory and will most likely not harm the citizens inhabiting the area. Despite the various studies and data collected, there is very convincing and more recent evidence deeming EDC exposure to be very harmful to a newly developing child in the womb. Due to the nature of the subject and target population, women and children, it is hard to gather patients who will voluntarily subject and expose themselves to repetitive testing. Therefore, further research should be conducted within regions of not just urban, but suburban and rural living areas. Being able to connect this data to other elements such as race and gender is equally as important in this day and age.
