In this last article on the series of chemicals and health, we explore the links between chemicals and the brain, or our neurological health, particularly in the younger generation.

Whereas there is much data on xeno-oestrogens (environmental oestrogens) implicated in causing infertility, immune disorders and cancer, there is relatively little on the effects of these chemicals on learning and behavioural disorders.

However, as I started to pull the threads together, a picture began to form with the thyroid gland taking the central role. The thyroid is an endocrine gland (produces hormones) and, like the sex glands (ovaries and testes) and the adrenals, is a major target of the endocrine-disrupting synthetic chemicals.

We know that maternal thyroid hormones are critical for foetal brain development. Maternal hypothyroidism (in the majority of cases due simple iodine deficiency) leads to mental retardation in the offspring and is the biggest risk factor for mental retardation world-wide. Maternal thyroid hormones oversee the development and migration of foetal nerve cells to appropriate areas of the brain. The critical age-window for brain development is from conception to 2 years of age; but if this is disturbed, the damage is permanent.

How synthetic chemicals such as the PCBs, dioxins and organochlorines (DDT and its by-products) exert their effects on thyroid metabolism is incompletely understood, but some authors suggest that they may block hormonal action by getting to the hormonal receptor first. A hormone has to “dock” at a receptor in the cell; if the docking space is already taken up by a “mimic” then the true hormone cannot exert any influence and hence the hormonal action is blocked. Other authors suggest that chemicals compete for transport on the carrier protein which normally transports thyroid hormone to brain cells.

Currently, thyroid disorders are now diagnosed in 10% of the female population in the USA with endocrinologists estimating this figure likely to be nearer 25%. Reports from Canada, Saudi Arabia and Ireland indicate similar increases.¹ It is also estimated that in the US 5-10% of children suffer from hyperactivity as well as from impaired concentration and fine motor skills and are unable to cope with stress. Is there a connection?

Clinically, there most certainly is; and scientifically, well we may be waiting years before the research is done, and even then it may not be released until common consensus demands an explanation.  However existing data on animal experiments and human studies does confirm these links,  even if they’re not scientifically proved yet.

The best place to start is the study conducted in the early 1980’s on children born to mothers who ate fish from the heavily contaminated Great Lakes, USA, six years prior to and during pregnancy. The Great Lakes were heavily contaminated with PCBs and synthetic chemicals from industrial pollution. Physical deformities, sexual reproductive abnormalities and enlarged thyroid glands were already noted in the fish and the herring gulls that fed from the lakes. The study revealed that the offspring from mothers who had eaten fish from the Great Lakes only 2-3 times a month in the 6 years prior to pregnancy were of lower birth weight, had smaller head circumference, had weak reflexes and impaired cognitive function. The children later scored poorly in intelligence, verbal and memory tests compared to the children of non-fish eating mothers.

A second study of 866 infants found correlative evidence between the levels of PCBs in breast milk and neurological development of offspring. Children born to mothers with high levels of PCBs in their breast milk had weaker reflexes and displayed poor gross and fine motor coordination. A further epidemiological study conducted during 1985-1992 looked at children born to Taiwanese women who in 1979 had consumed cooking oil contaminated with PCBs.  It was found that these children exhibited permanent impairment of motor skills and mental abilities, and also suffered behavioural problems. 

Animal experiments on mice, rats and monkeys provide striking parallels. They show that low dose PCB exposure not only produces learning deficits, motor impairment and hyper-reactivity (inability to deal with stress) in the offspring, but also transgenerational effects where the same impairments are exposed in the second generation, even though no PCBs were administered after the initial breast-feeding period of the first generation. ²

More culprits…..

Scientific proof demands the testing of an isolated, chemically defined substance whose mode of action can be linked to a specific mechanical dysfunction – one causative agent, one effect. However the thyroid story isn’t that simple as there are a few more culprits in the equation that we need to take into account:

§        Fluoride, chlorine and bromine (all three commonly found in our water supplies; bromine also found in pesticides and dough conditioners) target the thyroid gland and, being more chemically reactive than iodine, displace iodine and cause its excretion. Fluoride was once prescribed by doctors in hospitals and clinics to slow down an overactive thyroid used as an anti-thyroid medication prescribed by doctors in hospitals and clinics to slow down an overactive thyroid.³ Nazi concentration camps also used fluoridated water to suppress the will and motivation of their prisoners.

§        If you are hypothyroid, then the isoflavones from foods such as soy products will inhibit thyroid production further. Your natural oestrogens will do the same which is why we may see goitre (enlarged thyroid) developing during pregnancy in some women. Do the xeno-oestrogens found in pesticides, plastics and detergents also inhibit thyroid hormone production in the same way?

§        The enzyme in the liver which converts thyroid hormone to its active form is selenium dependent. Selenium deficiency will inhibit this conversion, and mercury (found in fungicides and our water supplies) cripples the enzyme; both these factors may lead to hypothyroidism.

§        The damage that radioactive fallout of radioactive iodine-131 from nuclear power plants cannot be underestimated. If you have an iodine deficiency, your body will greedily take up iodine-131. It targets the thyroid, the breasts, salivary glands, testicles and ovaries where it quickly breaks down releasing destructive gamma radiation to the nearby tissues. There is no safe dosage of gamma radiation inside cells. ⁴

What can we do?

§        Reduce your exposure to chemicals – both agricultural and those sourced through municipal drinking water.  If you are on mains water, the only effective method of removing fluoride is through reverse osmosis or distillation. Carbon block filters remove chlorine and bromine.

§        You may add a daily dose of 3-5g of kelp. The best source is Icelandic kelp.

§        If you grow your own vegetables, then fertilize with seaweeds. The root crops will be richer in iodine than leafy vegetables. Garlic may also be a good source of iodine.

§        Remember that corticosteroids and the sex hormones, as found in the oral contraceptive pill, HRT, and the “natural bio-identical” sex hormones, inhibit thyroid production

§        Note that aspirin and anticoagulant drugs also increase iodine excretion – so you may need to increase your iodine intake if you take them.

§        Vegetarians may be more prone to iodine deficiency, as animal blood is a natural source of thyroid hormones. Populations that historically suffered endemic goitre would ensure plenty of black pudding (blood sausage) in their diet!

§        And for those in Queensland – join the campaign to stop the fluoridation of your water

§        Read the following articles from the internet – they are a good resource

Ryan Drum PhD:  “Environmental Origins of Thyroid Disease: Parts 1 and 2”  http://www.ryandrum.com/

Drs. Richard and Karilee Shames on the Thyroid/Fluoride Linkage: “Fluoride: A Bad Idea Whose Time Has Passed”  http://www.thyroid-info.com/articles/shamesfluoride.htm

1.      http://www.ryandrum.com/

2.      Colborn T, Dumanoski D and Myers P. Our Stolen Future  ISBN 0 349 10878 1; 1997

3.      http://www.thyroid-info.com/articles/shamesfluoride.htm

4.      http://www.ryandrum.com/thyroidpart2.htm