Substances which have been found to be particularly harmful are lead (which is stored in the mother's bones), cigarette smoke, alcohol, mercury (a neurological toxicant consumed through fish), carbon dioxide, and ionizing radiation. These two conditions can lead to a large range of defects that can affect the fetus physically, cognitively, neurodevelopmentally, and can cause neurobehavioral deficits. These changes are dependent on severity of alcohol use and the timing during gestation. The physical characteristics of FAS could include facial abnormalities, growth deficit, and dysfunction of central nervous system development. Even more so behavioral and emotional differences are also very common in patients with FAS.
Tobacco smoke Fetal exposure to
prenatal tobacco smoke may experience a wide range of behavioral, neurological, and physical difficulties. Adverse effects include stillbirth, placental disruption, prematurity, lower mean birth weight, physical birth defects (cleft palate etc.), decrements in lung function, increased risk of infant mortality. Methylmercury, a worldwide contaminant of seafood and freshwater fish, is known to produce adverse nervous system effects, especially during brain development. Eating fish is the main source of mercury exposure in humans and some fish may contain enough mercury to harm the developing nervous system of an embryo or fetus, sometimes leading to learning disabilities. Mercury is present in many types of fish, but it is mostly found in certain large fish. One well-documented case of widespread mercury ingestion and subsequent fetal development complication took place in the 1950s in Minamata Bay, Japan. Used by a nearby industrial plant in the manufacture of plastics,
methyl mercury was discharged into the waters of Minamata Bay, where it went on to be ingested regularly by many villagers who used the fish living in the bay as a dietary staple. Soon, many of the inhabitants who had been consuming the mercury-laden meat began experiencing negative effects from ingesting the toxin; however, the mercury especially impacted pregnant women and their fetuses, resulting in a high rate of miscarriage. Surviving infants exposed to mercury in-utero had extremely high rates of physical and intellectual disabilities, as well as physical abnormalities from exposure in the womb during key stages in fetal physical development. The United States
Food and Drug Administration and the
Environmental Protection Agency advise pregnant women not to eat swordfish, shark, king mackerel and tilefish and limit consumption of albacore tuna to 6 ounces or less a week. Mercury exposure in pregnancy may also cause limb defects.
Cadmium Cadmium is a heavy metal that the United States Environmental Protection Agency classifies as a probable human carcinogen. People are often exposed to cadmium through various industrial and agricultural sources, and diet is considered the primary exposure method. The heavy metal has been shown to cause damage to the kidneys, bones, and neurological systems. Cadmium can also pose health risks to the fetus, some of which may be lifelong, as it interferes with placental function and fetal development. Although studies show that relatively low levels of cadmium exposure can affect pregnancy outcomes, more studies must be done to confirm these effects, establish updated exposure limitation guidelines, and explore ways to decrease exposure, particularly during pregnancy.
Dioxin Dioxins and dioxin-like compounds persists in the environment for a long time and are widespread, so all people have some amount of dioxins in the body. Intrauterine exposure to dioxins and dioxin-like compounds have been associated with subtle developmental changes on the fetus. Effects on the child later in life include changes in liver function, thyroid hormone levels,
white blood cell levels, and decreased performance in tests of learning and intelligence.
Air pollution Air pollution can negatively affect a pregnancy resulting in higher rates of preterm births, growth restriction, and heart and lung problems in the infant. Compounds such as carbon monoxide,
sulfur dioxide and nitrogen dioxide all have the potential to cause serious damage when inhaled by an expecting mother. Low birth weight, preterm birth, intrauterine growth retardation, and congenital abnormalities have all been found to be associated with fetal exposure to air pollution. Although pollution can be found virtually everywhere, there are specific sources that have been known to release toxic substances and should be avoided if possible by those who wish to remain relatively free of toxins. These substances include, but are not limited to: steel mills, waste/water treatment plants, sewage incinerators, automotive fabrication plants, oil refineries, and chemical manufacturing plants.
Particulate matter (PM) consist of a mixture of particle pollutants that remain in the air, and vary be region. These particles are very small, ranging from PM10 to PM2.5, which can easily enter the lungs. Particulate matter has been shown to be associated with acute cardio-respiratory morbidity and mortality. Intrauterine growth has been shown to be affected by particulate matter, leading to unhealthy outcomes for fetal development such as poor or slow fetal growth, and increasing fetal morbidity and mortality. A study from 2012 found that exposures to PM2.5 differed by race/ethnicity, age, as well as socioeconomic status, leading to certain populations experiencing greater negative health outcomes due to environmental pollution, especially relating to
particulate matter.
Pesticides Pesticides are created for the specific purpose of causing harm (to insects, rodents, and other pests), pesticides have the potential to cause serious damages to a developing fetus, should they be introduced into the fetal environment. Studies have shown that pesticides, particularly fungicides, have shown up in analyses of an infant's
cord blood, proving that such toxins are indeed transferred into the baby's body. Overall, the two pesticides most frequently detected in cord blood are
diethyltoluamide (DEET) and
vinclozolin (a fungicide). A
systematic review of neurodevelopmental effects of prenatal and postnatal organophosphate pesticide exposure was done in 2014. The review found that "Most of the studies evaluating prenatal exposure observed a negative effect on mental development and an increase in attention problems in preschool and school children." In 2017, a study looked at the possible effects of agricultural pesticides in over 500,000 births in a largely agricultural region of California and compared their findings to birth outcomes in other less agriculturally dominated California areas. Overall, they found that pesticide exposure increased adverse birth outcomes by 5–9%, but only among those mothers exposed to the highest quantities of pesticides.
Benzenes Benzene exposure in mothers has been linked to fetal brain defects especially neural tube defects. Benzene can be found in cleaning products, glue or adhesives, paint thinners or strippers, exhaust, gasoline fumes, and tobacco smoke. In one study,
BTEX (benzene, toluene, ethylbenzene, xylenes) exposure during the first trimester of pregnancy has been clearly indicating negative association with biparietal brain diameter between 20 and 32 weeks of pregnancy. Women with high exposure to toluene had three to five times the miscarriage rate of those with low exposure, and women with occupational benzene exposure have been shown to have an increased rate of miscarriages. Paternal occupational exposure to toluene and formaldehyde has also been linked to miscarriage in their partners. Normal development is highly controlled by hormones, and disruption by man made chemicals can permanently change the course of development. Ambient ozone has been negatively associated with sperm concentration in men, chemicals associated with UOG operations (e.g., benzene, toluene, formaldehyde, ethylene glycol and ozone) have been associated with negative impacts on semen quality, particularly reduced sperm counts. A 2011 study found a relationship between Neural Tube Defects and maternal exposure to benzene, a compound associated with natural gas extraction. The study found that mothers living in Texas
census tracts with higher ambient benzene levels were more likely to have offspring with neural tube defects, such as
spina bifida, than mothers living in areas with lower benzene levels.
Other • Heat and noise have also been found to have significant effects on development. ==Avoiding relevant environmental toxins in pregnancy==