Autism or autism spectrum disorder (ASD) refers to not one but various sets of conditions that may impact social skills, speech, communication and behavior in general. The Center for Disease Control estimates that 1 in 54 children in the United States of America is affected by ASD. Some theories attribute autism to pre-existing genetic conditions, while for others there may be genetic changes later in life that may make them more at risk for autism.

While there has been a lot of research dedicated to the cause and origins of autism, there is no clear answer to the question “What causes autism?”. The general consensus has been that a host of environmental and genetic factors are involved in making a person more vulnerable to autism. However, new research has found ways to isolate the environmental factors from the genetic factors, allowing science to find links between ASD and various potential environmental contributors.

Of this, heavy metal toxicity could have a close connection with autism, studies have found. The concentration of heavy metals in the body could be an indicator of whether the child could be more vulnerable to autism. The findings of the study were published in the journal Nature Communications.

Baby Teeth to Measure Heavy Metal Exposure

The study was conducted by measuring the concentration of heavy metals in a baby’s body before and after birth. This was crucial to understanding how heavy metals may impact a child while in development.

The research was conducted using lasers which analyze the growth rings under the baby’s teeth. In other words, the researchers did not need to wait for the baby’s teeth to come out to conduct the analysis. The innovative laser technology was able to allow the researchers to extract the relevant layers of dentine, which is the material that is below the tooth enamel and is present even at the prenatal stage.

The study then analyzed the levels of lead and degree of exposure to heavy metal through the child’s developmental stages. The study involved the analysis of the teeth in 32 pairs of twins. In pairs where only one twin had ASD, it was found that the concentration of lead in the body was much higher as compared to the twin who was not on the spectrum.

The findings of this research are revolutionary as often children are diagnosed with autism at the age of 3 or 4. With this research, one can determine the levels of exposure at the prenatal stage and perhaps the expecting mother can take measures to reduce the heavy metal exposure.

The study also found other correlations between ASD and heavy metals. For example, it was found that children with ASD had lower levels of zinc in the prenatal stage. But as they grew older, the zinc levels in the body increased. Similarly, children with ASD had lower levels of manganese in both pre and postnatal stages, as compared to those, not on the spectrum.

Hair Samples to Measure Heavy Metal Exposure

Similar to the study conducted by analyzing baby teeth, another study assessed hair samples in 100 children with ASD in comparison with 100 controls. The results found that the mean levels of aluminum, lead and mercury in hair samples of autistic children was significantly higher than the subjects who were not on the spectrum.

The levels of mercury, lead and aluminum were correlated with fish consumption by the mothers during pregnancy, living near areas like gas stations and using aluminum utensils and pans, respectively. The study concluded that environmental exposure to these heavy metals in developmental stages could increase the risk of autism among children.

Child Development and Heavy Metal Exposure

It is interesting to note that children and infants are more vulnerable to heavy metal exposure. They consume more food when compared to their general body weight and it has also been found that their bodies absorb metal more willingly than that of adults. This means that parents must take even more care to reduce heavy metal exposure as much as possible, keeping in mind the specific vulnerabilities of infants and children.

Heavy metal exposure has various effects on a child’s development, whether during pregnancy or in the early stages of a child’s development. Studies have found that exposure to methylmercury and lead can have an impact on a child’s cognitive abilities and also affect the development of the nervous system. Even at low levels, lead can increase a child’s risk of developing attention deficit hyperactivity disorder.

Arsenic is another heavy metal that can have serious implications for a child in the early stages of development. Prolonged exposure could increase the risk of skin and other internal cancers which may begin to show signs only as a child grows older as they have long latency periods.

Similarly, cadmium exposure could impact the lungs, kidneys and also cause intestinal damage.

Endocrine Disruption, Early Childhood and Autism

The link between heavy metals and autism is not a casually established one and does come under heavy scrutiny and controversy. Mercury exposure, for example, has been shown to have close links with autism. However, this research is still a work in progress.

There are enough fields of study, however, that are directing their attention to the fact that the “neuronal insult” characteristic of autism is not merely a result of a developmental deficiency, but can be attributed to external factors. These factors are often recognized as heavy metals and other endocrine disruptors.

Endocrine disruption is the process of the endocrine system being impacted by chemicals that interfere with its everyday functioning. The endocrine system is facilitated by the thyroid and adrenal glands which are a part of a circuit of communication and signals operating within a feedback loop. The system releases various kinds of hormones into the blood, allowing them to be transported to different parts of the body. These hormones affect mood, development, growth, metabolism, etc.

Various heavy metals can function as endocrine disruptors and hamper the chemical messaging system that the endocrine glands are running. Some of the heavy metals that are regarded as endocrine disruptors that are easily available in the environment are lead, cadmium, mercury, arsenic and uranium. All these heavy metals have an impact on the human body when present in higher concentrations.

However, disruptors like cadmium, lead and mercury can have particularly harmful effects for pregnant women and their fetuses. While heavy metals are available in the earth’s crust and the environment, the increased exposure to them is attributed to industrial setups, consumer goods, drinking water, etc. The exposure to these metals is so routine that one requires practically a complete overhauling of lifestyle to be able to avoid excessive exposure.

Preventing Heavy Metal Exposure

There are several sources of heavy metal exposure present in everyday life. While trace amounts of heavy metals like zinc, chromium, copper, etc. are beneficial for the body, heavier concentration can be very harmful.

The body can be exposed to heavy metals through various sources, from environmental to diet related. It is not easy to protect oneself from heavy metal exposure. However, the following are some of the preventive measures one can take:

  • If you work in an industrial environment or if your work involves handling heavy metals, be sure to wear the right protective equipment.
  • For pregnant mothers, it is very important to look after one’s diet. Check local fish advisory before buying fish for consumption.
  • Check the labels for all personal care and hygiene products for heavy metals in the ingredients.
  • Test any new home you are moving into for lead paint. Carry out lead abatement procedures to remove traces of lead from the air in your home.
  • Wipe your surroundings down and keep dust out, as metals often accumulate in dust. Be sure to wear a mask while dusting.

Symptoms of Heavy Metal Exposure

Often heavy metal poisoning can take place over a long period, as a result of prolonged exposure. But acute heavy metal exposure will start presenting immediate symptoms that one must not ignore. The following are some of the common symptoms of heavy metal exposure:

  • Nausea
  • Vomiting
  • Disorientation or confusion
  • Numbness
  • Coma

The symptoms of chronic heavy metal poisoning are:

  • Frequent headaches
  • Fatigue
  • Weakness
  • Constipation
  • Joint pain

Wrapping Up

Autism is a disorder that is difficult to understand and requires a lot of compassion from those living around the people on the spectrum. One of the most frustrating things about autism is that it is difficult to ascertain what causes one to be vulnerable to the disorder. There are a host of reasons that could put someone at risk of ASD but the research in the field is still limited.

New studies have found that environmental factors may play a big role in causing or making someone vulnerable to autism. Heavy metal exposure at the prenatal stage and the work of endocrine disruptors in the body can have several serious implications in early childhood and development. Further research in this area can perhaps be revolutionary to reduce the risk of autism, if not prevent the disorder.

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