health

Starting at conception, the developing embryo is susceptible to many factors
that affect development. Birth defects also can be caused by environmental
factors, either alone or together with faulty genes. Environmental
factors include the environment in the mother’s uterus, or womb, and the
possible influence of poisons in the earth’s environment. Following are
some common types of serious brain defects and their possible causes:

• Anencephaly. This fatal defect occurs when the neural tube fails to
  close during early development, and the child is born with a missing
  brain or only the parts that control processes such as breathing.
  Although the exact cause is not known, the condition has been
  linked to the nutrition of the mother and lower than normal levels
  of the B vitamin folic acid; pollution is also suspected.
  
• Spina bifida. In this disorder the failure of the neural tube to close
  properly causes an opening in the spinal cord and spinal column.
  This birth defect is one of the most common involving the nervous
  system and may be related to folic acid deficiency.
  
• Cerebral palsy. Cerebral palsy causes damage to the motor control
  centers of the young developing brain and can occur during
  pregnancy (about 75%), during childbirth (about 5%), or after birth
  (about 15%) up to about age three. However, about 80 percent of
  causes are unknown but may be traced to infection, malnutrition,
  and head trauma.

During the first weeks of embryonic development, exposure to toxins
may disrupt the development of the offspring and cause serious birth
defects. Certain agents may have a teratogenic effect on the embryo. The
word “teratogen” literally means “giving rise to monsters.” There are several
known teratogens:

• Alcohol. Women who consume excessive amounts of alcohol during
  the early stages of pregnancy risk having babies with fetal alcohol
  syndrome (FAS). Children with this disorder may have various
  defects in growth, facial appearance, and mental ability.
  
• Tobacco. Nicotine from cigarette smoke in the mother’s bloodstream
  is passed to the developing fetus and causes a variety of
  problems, including low birth weight, birth defects, and sudden infant death syndrome (SIDS). Also, smoking causes the oxygen
  level of the mother to fall causing a condition called fetal hypoxia,
  which may damage the developing fetus.
• Medications and street drugs. Illegal drugs such as amphetamines,
  cocaine, and heroin may damage the developing central nervous
  system of the fetus and lead to birth defects. Even prescription and
  over-the- counter drugs can affect the fetus. Thalidomide was prescribed
  to pregnant women to combat morning sickness, and the
  drug caused babies to be born with defective limbs. Accutane, a
  medication given for severe acne, was linked to birth defects.

Environmental hazards may act as teratogens. Exposure to chemicals
or other toxins in the environment may contribute to birth defects.
Pregnant women should avoid weed killers, insecticides, and even certain
household cleaning agents. An increase in birth defects has occurred after
atomic bomb attacks, bomb tests, and use of certain munitions, such as
the following:

• Atomic bomb blasts. Extensive lab tests have shown that human
  DNA exposed to radiation may break apart and rejoin in patterns differing
  from the original forms, causing mutations. Stages of embryonic
  development are sensitive to radiation. In Nagasaki and Hiroshima,
  where the United States dropped the atom bomb in World War II,
  the probability of severe mental retardation is strongly associated with
  the degree to which the mother was exposed to radiation. Women
  exposed during the third and fourth months had children with deformities
  such as facial clefts or too many fingers and toes; interestingly,
  embryos in other stages of development did not exhibit deformities.
  In the late 1950s studies of IQ tests showed survivors lost approximately
  five points and performed at a decreased level in school.
  
• Dioxin or agent orange. Agent orange was designed to defoliate
  the jungle, thus destroying coverage to Vietcong guerrilla soldiers
  in the Vietnam conflict. The virulent poison killed the rainforest
  and then got into the food chain, which led to a number of birth
  deformities. In Vietnam, some 150,000 children with birth defects
  can be traced to the parents’ exposure to Agent Orange or to consuming
  dioxin in contaminated food and water.
  
• U-238 or DU. Depleted uranium (DU) or U-238 is a toxic, heavy
  metal byproduct that is used in munitions, ballasts for airplanes,
  tank armor, and other products. Since 1991 cancer rates in Iraq
  have risen tenfold, and the number of birth defects has multiplied
  fivefold. Internalized DU has been found to induce DNA damage
  and cancerous lesions in cells that make up bones in the body.
  
• Bombing practice in Vieques. Since 1941 Vieques in Puerto Rico
  has been used by the U.S. Navy for target practice. When a DU
  round is fired, 60 percent of its mass ends up as microscopic aerosol
  particles in the air, which can be carried to other areas. Breathing the material can cause a host of problems, including possible birth
  defects. The United States is not the only country to use DU munitions;
  18 countries including Israel, Saudi Arabia, Turkey, and
  Taiwan have bought them.