|LEAD Action News Volume
13 Number 4, June 2013, ISSN 1324-6011
Incorporating Lead Aware Times ( ISSN 1440-4966) and Lead Advisory Service News (ISSN 1440-0561)
The Journal of The LEAD (Lead Education and Abatement Design) Group Inc.
Editorial Team: Elizabeth O’Brien, Zac Gethin-Damon, Hitesh Lohani, Shristi Lohani and David Ratcliffe
Planning For A Healthy Baby - Chapter 7 from the book
By Belinda Barnes & Suzanne Gail Bradley, Foresight Association UK, circa 1996
Reprinted with kind permission. See http://www.foresight-preconception.org.uk/ for more excellent information on the topic of pre-conception health.
Problems in the Twentieth Century: Toxic Metals
INFORMATION TO HELP YOU
SAFEGUARD YOUR BABY BY
All trace elements can be toxic if consumed in sufficient quantities. However, the term 'toxic metals' generally denotes 'those elements not recognised as having an essential function and known to have well documented deleterious effects'. 1 It is these on which we focus in this chapter.
Although man has been utilising many of them for hundreds of years, in this century their use has escalated as new processes, purposes and products have been developed. As a result, we now have more widespread pollution than ever before, with concomitant problems. Even though we know there are adverse effects of lead ingestion and inhalation, we are still reluctant to change to unleaded petrol. We are aware of the dangers of cadmium, highlighted in discussions on high soil levels, yet we overlook the major sources: cigarette smoking and refined flours. Dentists have been aware of the dangers of mercury for many years, but still use mercury-containing amalgams. We are now being told that aluminium may be a factor in Alzheimer's Disease - yet we know that patients in mental hospitals imbibe large amounts of tea which contains high levels of aluminium! It would seem prudent to assume that aluminium is toxic, until we know otherwise. At the least, this would not harm anyone, and at the best, it could save many from hospitalisation, if it is true. A major shift needs to take place from the assumption that a substance is safe until it is proven otherwise, to the position that it is dangerous until proven safe!
There is also a dearth of studies which look at more than one element, even though it is known that there is a continual interaction between many of them. Fortunately, the work of Bryce-Smith and Ward, among others, is remedying this, though such research is difficult and expensive. 2
In this chapter, we examine the data on lead, cadmium, mercury, aluminium, copper and some other elements on which there has been less research. Since all chemicals interact in the body, we pay special attention to the studies which cover more than one metal, especially lead and cadmium, before explaining how the body can be detoxified.
The single most researched chemical, lead has been known to be toxic to animals and humans for centuries. Despite this, its use has increased dramatically, especially in the last 40 years, so that it is now impossible to escape ingesting or inhaling it. It comes mainly from the atmosphere, polluted by exhaust fumes from lead in petrol and from food, especially that grown in soils polluted by lead from petrol, and unlined cans. 3,4 A London GP warned against eating food grown in London. 5 Water which has coursed though old lead piping, or through lead-glazed earthenware mains, or through modern copper piping where the joins of the pipes have been formed with lead-containing alloys, is also a major source for many people. Cigarette smoking can increase lead uptake by 25 per cent, partly because of the way it interacts with other substances, and also from the lead arsenate used as an insecticide for tobacco. 6,7 Occupational exposure can be a hazard, as lead is used in a number of industries. 8,9 High rates of infertility, miscarriage, stillbirth, congenital abnormalities including macrocephaly, convulsions, early deaths and chromosomal alterations have been reported. 10,11 Children are at greater risk than adults, because they ingest more and have immature bodies. But lead can also cross the placenta, and so affect the fetus. The younger the child, the greater the risk, since lead affects the brain and the greatest brain development occurs before and in the first few year after birth. 12
Animal research suggests that nutritional status may be a factor in lead absorption. Diets low in calcium, iron, zinc and manganese may actually enhance lead uptake. However, one study suggests that cow's milk may increase absorption, since, although high in calcium, it is low in other trace minerals such as iron. 13 The fact that lead can be removed from the body by nutrients further supports the idea that nutritional status is important. (See below.)
There is, as yet, no agreement on safety levels. Some researchers say that no level can be assumed to be safe, while the government sets limits for industry and the environment which are lowered from time to time as more is revealed about its toxicity. 14 There are no agreed ways to measure levels, which adds to the problem. Blood lead levels are not reliable, as the lead is passed from the blood to other tissues, especially bones, quite quickly. Hair analysis, though accepted as a reliable guide, is not widely available. (See Chapter 4.)
But, regardless of the arguments, there is no longer any doubt that levels which do not manifest symptoms of 'classical' poisoning may have subtle effects on the body. Chronic 'low' level lead exposure is implicated as a significant causative or contributory factor in a wide range of conditions, including cardiovascular disease, renal and metabolic disease, immune dysfunction, and a multiplicity of vague symptoms, such as lethargy, depression, muscle aches and pains, frequent infections, cancer, developmental abnormalities and learning, behavioural and central nervous system dysfunction. 15, 16 Lead interferes with the normal functioning of many trace elements, especially by inhibiting zinc dependent enzymes, making its effects widespread. 17 Other enzyme systems are also vulnerable. High childhood blood levels and smaller stature have been shown to be highly correlated. 18
Lead and the next generation
Lead can affect both male and female reproductive abilities. Men exposed to high levels in their work have been found to be at risk of low sperm count, with more sperm likely to be misshapen and less mobile. 19, 20 In women, its capacity for inducing abortions has long been known – it was used around the turn of the century with, sometimes, blindness and brain damage in surviving babies. It was also this property that ensured that women were not being employed to work with lead. 21 One reason it may be abortifacient lies in its tendency to accumulate in the placenta. 22
Research in the 70s has linked high lead levels with stillbirth. In 1977, a study of placental lead levels showed that there were greater amounts in the placentas of malformed stillbirths and neonatal deaths compared with normal births surviving longer than a week. 23 In the same year, two other researchers reported higher levels of lead (and cadmium – see below) in stillbirths, using rib and pre-ossified cartilage for the analyses. They concluded: ‘Although some levels were low, others were so high as to raise suspicion that they were aetiologically connected to the death of the fetus.’ 24 (This paper also cites useful references on animal research into the teratogenic effects of lead.) Multi-element studies involving lead are discussed below.
The relationship between lead exposure and utero and congenital abnormalities has already been mentioned. (See above.) Needleman and his colleagues have found it to be associated ‘in a dose-related fashion with an increased risk for minor anomalies’. 25
Prenatal exposure can result in lead intoxication in the newborn. In one report, an infant exposed in the eighth month in utero was delivered normally and found to have no detectable neurologic abnormality. However, testing at the age of 13 months showed she was functioning cognitively at the level of an 8-12-month child. 26 Another study measured the level of lead in umbilical cord blood at birth. Subsequent mental developmental testing at the ages 6 months and 12 months showed that the higher the level of lead the lower the test scores. At neither age were scores related to current blood lead levels. The researchers concluded: ‘Prenatal exposure to lead levels relatively common among urban populations appear to be associated with less favourable development through the first year of life.’ 27 A further study by the same researcher, which concerned ‘Longitudinal analyses of prenatal and postnatal lead exposure and early cognitive development’, concluded that: ‘It appears that the fetus may be adversely affected at blood leadconcentrations well below 25 µg/dl, the level currently defined by the Center for Disease Control as the highest acceptable level for young children’. 28 [PAGE 85]
Research by Drs McConnell and Berry of the University of Birmingham gives us a clue as to why this should happen. They found that in rats lead tends to derange the development of the brain in a special way. If you think of the brain as a computer, then at birth, although all the parts are there, they have not all been connected. This happens over childhood, with the greater number being ‘wired up’ in early infancy. The lead stopped much of the ‘wiring’ and may well have meant some wrong connections being made. Other studies have shown that other parts of the brain closely involved with learning processes are also susceptible to damage by lead. 29
Animal research with monkeys has confirmed that learning abilities are affected. In one study, monkeys in their first year of life showed no physical signs of toxicity, but all the lead-treated ones showed performance deficits on reversal learning tasks. The effects are not the result of delayed maturation, as the researchers report that ‘… Data currently being collected in this laboratory indicate that the deficit can be observed at least three years beyond final lead dosing. It therefore appears likely that this deficit represents a relatively permanent characteristic of the chronically lead-poisoned monkey’. 30
The most widely quoted study on the effects of lead on children is that done by Needleman and his colleagues. They showed that at levels below those which are considered to produce symptoms of toxicity, the performance of children in the classroom was adversely affected. A wide range of behaviours was examined, including distractibility, persistence, dependence, organisational ability, hyperactivity, impulsiveness, frustration, day dreaming, ability to follow, and overall functioning, and it was found the higher lead level, the poorer the performance in every measure. 31 Other studies have also indicated the negative effects of lead on learning abilities and classroom behaviour. 32-35
Decreased hand-eye coordination and shortened reaction times, as well as physical effects, were seen in 45 adolescents and young adults with hair levels considered to be normal, with problems starting at levels as low as 10 ppm (parts per million). Most laboratories class up to 15 ppm as ‘normal’. 36 (What this may mean for the acquisition of practical job skills and driving abilities has yet to be considered!)
A number of other studies have also suggested a link between hyperactivity and raised lead levels. 37-38 One looked at 13 children with no apparent cause for their hyperactivity and found that their behaviour improved when the lead was removed with lead-chelating medication. 39 A Danish study linked high levels with minimal cerebral disfunction (MCD) – learning disabilities are often linked with hyperactivity or MCD. 40
Cadmium is now a common pollutant which is highly dangerous to man as it accumulates in the kidneys and liver slowly, unless nutritional measures are taken to remove it or reduce absorption. It particularly builds up in people deficient of Vitamins C, D, B6, zinc, manganese, copper, selenium and/or calcium. 41 The main sources are cigarette smoking and processed foods, since in the refining of flour, the zinc in the germ and bran is removed leaving a high cadmium to zinc ratio. It is found in water, especially where impure zinc has been used in galvanising of the mains and pipes, through which soft water flows. 42 It is also widely used in manufacturing industries, including those concerned with paint, batteries, television sets and fertilisers. 43 It also comes from shellfish from polluted waters and galvanised containers 44 and coal burning. 45
It is known to be embryotoxic in animals. Cleft palate and/or lip, other facial malformations and limb defects have been reported in a number of species. 46 Testicular and ovarian necrosis, and renal disorders are also found. 47 It has been found to impair reproduction in mice. 48 Cadmium accumulates in the placenta, causing placental necrosis if large amounts are given. 49 It also crosses the placenta. 50 Pregnant animals have developed toxaemia, an observation which has led one expert to wonder if ‘one might suspect that toxaemia in humans may be due to excess cadmium and/or a lack of the nutrients that counteract the effect of cadmium’. 51
In humans it has been associated with proteinuria 52 (protein in the urine) as well as low birth weight and small head circumference. (See below.)
The importance of zinc in counteracting the effects of cadmium has been demonstrated in animal research on the effects of cadmium on the testes. Pretreatment with zinc can abolish some of the adverse effects, though it does not reverse others. 53 When cadmium is injected subcutaneously into female rats it produces marked changes in the ovaries, the adverse effects increasing over time, although the ovaries do return to normal eventually. 54
Mercury has long been recognised as a poison. The ‘Mad Hatter’ of Alice in Wonderland was often a reality, as mercury was widely used in the millinery trade. The damage it can cause to he fetus was highlighted in the Japanese tragedy of Minamata, in which 23 children were born with cerebral palsy-like symptoms, varying from mild spasticity to severe mental retardation, blindness, chronic seizures and death. 55, 56 Their mothers, free from symptoms themselves, had been exposed to Mercury while pregnant. Mercury is readily passed through the placenta and fetal blood often contains concentrations 20 per cent greater than the maternal blood. Fetal brain tissue brain tissue may be four times higher than the mother’s braintissue. 57 Adults and older children were also affected, with a total of 46 dying. [PAGE 87]
There are three basic forms, elemental, non-organic and organic. The elemental and non-organic forms tend to be slowly absorbed and readily excreted, unlike the organic forms, which are easily absorbed and slow to be eliminated. Thus, the main dangers lie in the latter, especially methyl mercury, although there are conditions linked to elemental mercury. These include psychological disturbances, oral cavity disorders, gastro-intestinal, cardiovascular, neurologic, respiratory, Immunological and endocrine effects. In severe cases there are hallucinations and manic-depression. Organic Mercury exposure is linked to psychological symptoms which develop into paralysis, vision, speech and hearing problems, loss of memory, uncoordination, renal damage and general central nervous system dysfunctions. Eventually coma and death can occur. 58
Metallic Mercury vapour has been reported to affect men exposed to it in a serious way for prospective parents. In one study of nine men exposed after an accident, all complained of a loss of libido, lasting in some cases up to eight years. One reported temporary impotence for 18 months. 59
Animal work by Dr Joan Spyker suggests that the adverse effects may be long-term. Mice exposed in utero did not appear outwardly different from controls until they were about 18 months old (middle-aged). The experimental mice then contracted severe infections, implying an immune system impaired prenatally. They lost all pretence of normalcy, ageing quickly and prematurely. Only extensive investigation, magnifying the brain tissues 48,000 times, showed slight damage to the individual cells – yet this slight damage was responsible for their problems. Dr Spyker points out that the victims of Minamata are deteriorating just as the animal model predicted. 60
The main sources of mercury are pesticides and fungicides (see chapter 11), fish, industrial processes and dental fillings. The larger the fish, the greater the concentration, with tuna fish being the most likely source in the UK. 61 Freshwater fish can also be contaminated if the river has been polluted with factory effluent, or water run off fields that have been subjected to mercury-containing agrochemicals. It is found in slimicides, used in paper manufacture to stop the growth of slime moulds. 62 If your hair level is high, it would be wise to have your water checked.
The major current controversy around the dangers of mercury concerns mercury-containing amalgams in dentistry. 63, 64 Dentists have been aware of mercury poisoning for many years –indeed, 147 years ago the American Society of Dental Surgeons was opposed to such amalgams. (They were overruled by their members, many of whom must later have suffered from toxic effects!) 65 Sweden has now banned mercury in dental work on pregnant women as a prelude to a total ban.
It appears that some large marine mammals ingest high levels of selenium, which detoxifies mercury, especially if taken with Vitamin E. 66
Aluminium is easily absorbed, accumulating in the arteries. It is now linked with Alzheimers Disease, though scientists are quick to point out that there is no conclusive proof. However, it is known that aluminium can destroy many vitamins as it readily binds with other substances. It weakens the lining of the gut. It inhibits fluoride and phosphorus metabolism, resulting in mineral loss from the body over a long period. Excessive amounts can lead to constipation, colic, excessive perspiration, loss of appetite, nausea, skin problems and fatigue. Adverse affects associated with the body’s attempts to cleanse itself, in which aluminium salts are found in small quantities in the blood, include paralysis and areas of numbness, with fatty degeneration of the kidney and liver, as well as symptoms of gastrointestinal inflammation. 67 Thus it can seriously compromise nutritional status. It has been linked with kidney problems in babies, with the researchers concluding that formula feed should be aluminium-free for neonates and infants with reduced kidney function. 68 (Why not for all, we ask?) It has been associated with behavioural problems and autism. 69 Mice fed large doses had no symptoms, but the next three generations of offspring had growth defects. 70
The major sources include antacids, antiperspirants and food additives, especially an anti-caking agent found in milk substitutes. 71, 72 In some places, aluminium flocculants are added to the water, so you should have your water tested to at the tap if your hair level is high. Aluminium saucepans and other cooking utensils impart some metal if they are in contact with the food. Leafy vegetables, rhubarb, apple and other acid fruits are especially problematic. Pressure cookers are worse than ordinary pans. Kettles and aluminium teapots are potent sources, particularly if the tea is allowed to stand for a long time. Work at University College, Cardiff, suggests that our major food source of aluminium is tea, since the tea plant thrives on alum soils, so it is fed with alum. (Think of all that tea drunk in psychiatric hospitals!) Foil-wrapped foods, such as meats, fish, poultry and pies made in foil saucers are other sources. Foil-wrapped fats and acid foods are the worst.
The contraceptive pill and copper coil can both cause copper levels in the body to rise. (See Chapter 9.) Excess levels may be embryotoxic or teratogenic. 73 They are certainly known to produce behavioural symptoms, such as uncontrollable rages, 74 and are linked with toxaemia. 75 Copper levels rise naturally during pregnancy, so if a woman conceives with a raised level, she is at risk of overloading her body. This could lead to postpartum depression. 76 Raised levels are associated with low levels of zinc and manganese, both of which are known to cause birth defects. (See Chapter 5.)
Other sources of copper may be the drinking water in areas where water is soft and acid, or where it has been heated through an Ascot heater. Always fill the kettle from the cold tap. If you have been using a filter for two weeks and seen the white contents of the filter change to bluish green, you have a significant amount of copper in your water. You should continue to filter, changing the cartridge regularly.
Copper kettles, pans and jewellery are also sources. There may be external contamination of hair from Henna dyes and rinses, and in swimming-pool water where the water has been treated with a copper-containing algicide. For an accurate reading, you should cease the contamination for six weeks before having another hair mineral analysis.
Animal tests have brought arsenic, lithium and selenium under suspicion as embryotoxic or teratogenic. 77 Arsenic has also been found to act as a transplacental carcinogen. 78 A study among workers in Sweden has implicated arsenic in decreased birth weight and an increased rate of spontaneous abortion, but the design of the study was poor so the results are subject to debate. Depending on when it is administered it is said it can cause neural tube defects, agenesis and renal problems. 79
As far back as 1969, it was reported that ‘Cadmium teratogenicity is dramatically augmented by lead when they are administered concurrently’. 80 Lead and cadmium often occur together. Their concentrations in hair and blood show strong positive correlations and their overt symptoms of toxicity are not unalike. These similarities have lead some researchers to the view that ‘It is possible that some of the deleterious effects attributed to lead in correlational studies may instead be due to cadmium’. 81 They conducted a study on hair cadmium and lead levels in relation to cognitive functioning in children, in which the results showed that hair cadmium and lead were significantly correlated with intelligence tests and school achievement, but not with motor impairment scores. Statistical analysis suggested that ‘cadmium has a stronger effect on verbal IQ than does lead and that lead has a stronger effect on performance IQ than does cadmium’. 82
A few years before this, Professor Bryce-Smith and his colleagues, aware of the inadequacies of single element studies, had reviewed the levels of four elements: lead, cadmium, zinc and calcium in stillbirths’ bones and cartilage. They found that cadmium concentrates in the stillbirths were ten times greater than the levels normally found in human bone. Lead levels were also raised. Low calcium and zinc were sometimes associated with these marked elevations. 83 (See also lead above for reference to this study.)
Given the results of these, and many other studies, showing that lead and cadmium can have adverse effects on the fetus and older children, could they also cause problems for the neonate? Research has shown that they do! [PAGE 90]
Spurred on by the results of the four element study, a much larger project was done by Professor Bryce-Smith and his colleagues. This major study has taken a number of years to complete, revealing much of interest throughout. In an interim report in 1981, Professor Bryce-Smith said that for all the elements being studied (at that time, 36), the levels of fetal and maternal blood were about the same. Only in lead levels was there a difference, with the fetal level about 95 per cent of the maternal. He went on to explain the significance of this: “This means that the placenta passes all elements, both nutrients and toxins, to the fetus from the maternal circulation with little or no selectivity or filtering defect. We can see no evidence for a significant barrier to protect the fetus from inorganic toxins such as mercury, arsenic and antimony; and there is only a slight, but significant (p=0.01) barrier in the case of lead for normal births only.’ 84 Having begun by analysing nine tissues, including maternal and fetal (umbilical) cord whole blood and serum, amniotic fluid, placenta, and scalp hair from the mother and neonate, later on they decided that the placental element levels showed the clearest correlations with indices of fetal development for supposedly ‘normal’ births. Thus it was with this tissue that they continued the investigation.
In the first written report on the final 37 elements studied, the researchers observed highly significant negative relationships between placental cadmium and lead levels, and birth weight, head circumference and placental weight. The smaller the birth weight, head circumference and placental weight was, the higher the levels of cadmium and lead. There was a statistically significant positive correlation between placental cadmium and lead levels where birth weights were less than 3,000 g. For higher birth weights, the correlation, though still positive, was not significant. Placental zinc showed significant positive relationships with birth weights up to 3,000 g and head circumference of less than 34 cm, i.e. the lower the zinc level, the lower the birth weight and the smaller the head circumference.
With respect to other elements, there was ‘a weak positive correlation between placental iron and head circumference, and stronger but negative correlations for chlorine, vanadium, and lanthanum’. However, placental levels of iron did not correlate with birth weight, nor were the iron levels or birth weights significantly raised in those mothers receiving iron supplements. Indeed, the results in iron and zinc led the researchers to suggest that more emphasis should be paid to zinc supplements than to iron.
The final point made in the paper states that ‘In cases of cadmium, lead and zinc, biological, neurobehavioural, and biosocial studies in which the levels of all three elements are measured may prove more informative than those involving single elements’. 85 [PAGE 91]
Much the same conclusion was reached by the researchers who conducted further investigations into lead, cadmium and cognitive functioning. Looking at the protective effects of zinc and calcium against toxic metals, they found that higher zinc levels seemed to protect against the effects of cadmium, while calcium did the same against lead. They concluded: ‘The results suggest that the effects of heavy metal pollutants on cognitive function cannot adequately be assessed without concurrently evaluating the status of essential nutrients with which these toxins are known to interact metabolically.’ 86
Detoxifying the body
The preferred method for detoxification must, undoubtedly, be nutritional, since it does not have the same potential for adverse side effects as drugs. (There is a drug called EDTA which can be used in acute poisoning, though it is not to be recommended.) It binds the elements to it so they are removed from the body along with the EDTA. However, it removes essential minerals as well, so the doctor needs to check to see if you are not short of calcium, magnesium and other nutrients. Alternatively, penicillamine may be given. The following is a guide to the nutrients and foods that are helpful in removing toxic metals.
Vitamin C and zinc supplements were used successfully in reducing blood lead levels of psychiatric outpatients in one study. The treatment was also found to lower blood copper levels. Subjects included some hyperactive children. 87 Vitamin C has also been shown to lower cadmium levels in birds. 88
Calcium helps prevent absorption, as well as removing lead from the tissues. Vitamin D is necessary for calcium metabolism and to help displace lead from the bones. Vitamin B1, taken with a B-complex, provides protection against lead damage. Lecithin can also help in protection, while Vitamin A helps to activate the enzymes needed for detoxification. Trace elements, in addition to zinc, which are protective include chromium and manganese. Garlimac tablets are often used but they need to be combined with manganese to preserve the levels of manganese. In the diet, peas, lentils and beans act as detoxifiers. Algin, found in seaweeds, attracts lead to it in the gut and carries it out of the body. Yoghurt, garlic, onions, bananas and fruits such as apples and pears which contain pectin (especially the pips) help to reduce absorption, as well as detoxifying.89 Vitamin [?] may also reduce lead poisoning. 90 Manganese and selenium are also useful in detoxification.
It has also been found that sunlight can help remove toxic metals in animal studies. 91 [PAGE 92]
CHECKLIST FOR REDUCING TOXIC METAL LEVELS IN THE BODY.
system lead poisoning |
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