Childhood Cancer – An Environmental Wake-up Call
Cancer is the second biggest killer of children, largely because they are even more susceptible than adults to the growing number of poisons in our lives.
Childhood cancer is on the rise, and medical science says that the reason remains a mystery.
Cancer is a multifactoral disease. But, while scientists continue to focus their research on the genetic links to childhood cancer, important environmental triggers – vaccines, pesticides, food additives and electromagnetic radiation – are all but ignored.
Experts continue to decry that cancer is rare in children, yet statistics show that, after accidents, childhood cancer is the second biggest killer of children in the US (Am Fam Physician, 2000; 61: 2144-54). Government figures suggest the same is true in the UK (see National Statistics, Mortality Statistics: Child-hood, Infant and Perinatal, London: HMSO, 1999).
Just like adults, children can be prone to cancer at any site in the body. Nevertheless, two sites – bone and brain – are now particularly common. Figures show that acute lymphoblastic leukaemia (ALL) rates have risen 10 per cent in the last 15 years, while the incidence of tumours of the central nervous system are up more than 30 per cent.
Increased vulnerability
Children are many times more vulnerable to the effects of toxic insults than adults, and their response to toxic exposures can also differ markedly. A good example is the paradoxical response to phenobarbital and Ritalin seen in children vs adults. Phenobarbital, a sedative in adults, produces hyperactivity in children. On the other hand, Ritalin, used as an antihyperactive drug in children, has the opposite effect in adults.
There are many reasons for this paradoxical response (see box below). Differences in the developing infant and child affect the absorption, dose, distribution, metabolism, storage and excretion of chemicals or drugs in the body and, therefore, their toxicity (see R.J. Roberts’ overview in Similarities and Differences Between Children and Adults, Guzelian PS et al. (eds), Washington, DC: ILSI Press, 1992; 11-5).
The efficiency and availability of metabolic enzymes varies with age (Environ Health Perspect, 1995; 103 [Suppl 6]: 7-12), which can result in differences in sensitivity to the toxic effects of both drugs and environmental toxins.
But perhaps the most influential characteristic of infants and children is that they are still growing and developing. During childhood, different systems and organs develop at different rates and at different times. Growing tissue may be more sensitive to toxic insults than other tissue. Studies of exposure to cigarette smoke have shown that the risk of dying of breast cancer is greater for those who started smoking before age 16 than for those who started after age 20 (Am J Epidemiol, 1994; 139: 1001-7).
Studies of the effects of radiation also suggest an increased susceptibility in those exposed during childhood. Among survivors of the atomic bomb in Hiroshima and Nagasaki, Japan, susceptibility to leukaemia was greater for those who were under 20 when exposed compared with those who were older. Moreover, the type of leukaemia varied according to the age at exposure (Environ Health Perspect, 1995; 103 [Suppl 6]: 41-4).
Pesticides kill things
In homes, schools and gardens, in their food and water, and in the air they breathe, children are bombarded by pesticides. Despite the objections of major chemical companies, the link between pesticide exposure and childhood cancer is firmly established (Environ Health Perspect, 1997; 105: 1068-77; Am J Epidemiol, 2000; 151: 639-46; Cancer, 2000; 89: 2315-21; Eur J Cancer, 1996; 32A: 1943-8; Environ Res, 1980; 23: 257-63).
Case reports and case-control studies have linked pesticides to a wide range of malignancies, including leukaemia, non-Hodgkin’s lymphoma, neuroblastoma and Wilms’ tumour, as well as cancers of the brain, colorectum and testes (Environ Health Perspect, 1998; 106 [Suppl 3]: 893-908).
Research has shown that pesticide use in the home – to get rid of termites, flies and wasps, no-pest strips, flea collars, and garden insecticides and herbicides – has resulted in a significant increase in childhood brain cancer (Arch Environ Contam Toxicol, 1993; 24: 87-92).
In one study, the risk of childhood leukaemia increased nearly four times when pesticides were used indoors at least once a week, and more than six times when garden pesticides were used at least once a month (J Natl Cancer Inst, 1987; 79: 39-46).
Another study suggested that children living in homes with pest strips (imbedded with insecticides) had one-and-a-half to three times the risk of developing leukaemia than those living in homes without strips. Even worse, children under 14 had four times the normal risk of connective tissue tumours if their gardens are treated with pesticides or herbicides (Am J Public Health, 1995; 85: 249-52).
Shots in the dark
The efficacy and necessity of childhood vaccinations continues to be one of the more emotive subjects in medicine. While officials continue to debate the connection between behavioural and learning disorders and vaccination, other potentially deadly effects of vaccination have been shoved into the background. Indeed, how many parents have ever considered whether childhood vaccinations might also lead to childhood cancer?
Little research has been carried out in this area. One study concluded that there is no risk. However, the study population was small (less then 900 children) and not all children received the same number of vaccinations. Other flaws in the study design suggest that its results are not conclusive (Br J Cancer, 1999; 81: 175-8).
No study has looked at children who have had their full complement of vaccinations and developed cancer, and compared them with children who have had few or no jabs. In addition, none of the childhood vaccines currently in use has ever been tested for carcinogenic potential (see Physicians’ Desk Reference, 51st edn, Medical Economics Inc, 1997).
The truth is, we don’t know whether vaccines can cause cancer. But there are several sound reasons why they might. The manufacture of vaccines is a filthy process. The viruses are gathered from the excrement and bodily fluids of infected individuals. Once gathered, it is grown in a toxic medium, as disease-causing organisms cannot live in a ‘healthy’ medium (just as they cannot proliferate in a healthy body).
These are further mixed with other toxins, including formaldehyde (a carcinogen) to inactivate them, aluminium and the mercury derivative thimerosal (both carcinogens), phenol (yet another carcinogen) and antibiotics.
In addition, viruses themselves may cause cancer, and the process by which viruses are ‘inactivated’ for use in vaccines is not infallible. A well-known example of this is the simian virus 40 (SV40) that contaminated the early Salk polio vaccine. SV40 was a carcinogenic virus growing on the monkey kidneys used to culture poliovirus. It was discovered only after hundreds of thousands of individuals had been injected with it. Not only was this virus responsible for cancer in the vaccine recipients, but it was associated with DNA damage passed on through sexual contact as well as to their unborn children. Evidence of SV40 is still being found in brain tumours today (J Natl Cancer Inst, 1995; 87: 1331; Brain Pathol, 1999; 9: 33-42).
The unhealthy vitamin
Concern has also been raised as to whether injections of vitamin K given immediately after birth increase the risk of childhood cancer. In 1990, a positive association was found between the vitamin K jab and childhood leukaemia. The study involved 597 children in England and Wales born between 1968 and 1985, and diagnosed with cancer between 1969 and 1986, and a matching group of children who didn’t have cancer.
The association between overall cancer incidence and intramuscular vitamin K was small. However, there was a strong association with the incidence of leukaemia. The authors concluded that ‘. . . the risk, if any, attributable to the use of vitamin K cannot be large, but the possibility that there is some risk cannot be excluded’ (Br J Cancer, 1990; 62: 304-8).
Eight years and a great deal of debate later, the British Medical Journal devoted an entire issue to vitamin K injections and its link with cancer. An editorial likened the subject to a ‘Gordian knot’ that still awaits untying (BMJ, 1998; 316: 161-2). One of the studies found no association (BMJ, 1998; 316: 184-9), but others felt otherwise. ‘The possibility that there is some risk cannot be excluded,’ concluded one (BMJ, 1998; 316: 178-84).
A third study looking at British children who developed cancer before age 15 found no association between intramuscular vitamin K and all childhood cancers and leukaemia. But once again, there was a raised risk for leukaemia developing one to six years after birth.
The researchers concluded, ‘It is not possible, on the basis of currently published evidence, to refute the suggestion that neonatal intramuscular vitamin K administration increases the risk of early childhood leukaemia’ (BMJ, 1998; 316: 189-93). The most recent review of the vitamin K-cancer link arrived at much the same conclusion (Br J Cancer, 2002; 86: 63-9).
Are kids electric?
Evidence is also accumulating to show that living near even relatively low levels of electromagnetic field (EMF) radiation from mains electricity or powerlines can significantly raise a child’s chances of developing leukaemia. In 1979, the first major study linking such EMFs to childhood cancer was published (Am J Epidemiol, 1979; 109: 273-84).
Other studies followed, including a Swedish study of some half a million people showing that children exposed to varying levels of household EMFs had up to a fourfold greater risk of developing leukaemia (Am J Epidemiol, 1993; 138: 467-81). Others have also confirmed the EMF-cancer link (Eur J Cancer, 1995; 31A: 2035-9; Lancet, 1993; 342: 1295-6; Am J Epidemiol, 1991; 134: 923-7; Am J Epidemiol, 1988; 128: 21-38).
Most recently, however, back-to-back UK studies on electrical powerlines and cancer reached mixed conclusions. One, by Professor Denis Henshaw of Bristol University’s Human Radiation Effects Group, took 2000 field measurements and found that the toxic effects of EMFs could extend up to more than 100 yards (91 metres) on either side of powerlines.
He also suggested how EMFs could cause cancer. According to Henshaw, living near powerlines with radiation levels dozens of times the legal limit may indirectly cause cancer by increasing the concentration of carcinogenic airborne particles that are produced naturally in the soil and by local traffic pollution (Int J Radiat Biol, 1999; 75: 1505-21). This conclusion supports earlier research showing potentially toxic interactions between alternating EMFs surrounding powerlines and radioactive breakdown products of naturally occurring radon gas (Int J Radiat Biol, 1996; 69: 25-38).
However, the UK Childhood Cancer Study – an 18-year study of EMFs and 2226 cancer-stricken children matched with healthy children – did not support a link between EMF exposure and childhood cancer (Lancet, 1999; 354: 1925-31).
Nevertheless, the authors noted that the study design may have been flawed (an admission omitted from most of the media reporting). A non-relevant criterion was used, and only 2.3 per cent of the studied children fell into the higher-exposure category. Exposure was also not comparable to studies in other countries, such as North America, where the voltage is different and rates of high exposure are greater. Another study in New Zealand (Lancet, 1999; 354: 1967-8) also proved inconclusive, but had the same design flaws as the UKCCS.
Overall, we know pitifully little about the role of environmental carcinogens in childhood cancer (Environ Health Perspect, 1998; 106 [Suppl 3]: 875-80). When studies have been done, scientists have tended to hedge their bets by concluding that the effects on the general population are likely to be small. But add up all these small effects and there may be a strong case for an environmental cause for some childhood cancers.
Also, whereas scientists now believe that many adult cancers are due to lifestyle factors such as smoking, diet, occupation, and exposure to radiation and toxic chemicals, medical science has consistently failed to give the same consideration to childhood cancers.
The average age for a diagnosis of childhood cancer is six years, yet children often have more advanced cancer at first diagnosis. Only about 10 per cent of adults show evidence of spreading disease when first diagnosed compared with 80 per cent in children.
Doctors say that such late diagnosis is because the symptoms of cancer mimic so many other childhood illnesses (Am Fam Physician, 2000; 61: 2144-54). However, another viewpoint is that many medics, believing that childhood cancer is rare, may not take the symptoms seriously and may see exploratory tests for youngsters as unnecessary.
In the US, Alexander Horwin died of the most common form of brain cancer – medulloblastoma – after his parents were told repeatedly by their paediatrician that he had a ‘virus’. His parents have since made a herculean effort to raise awareness of the potential links between childhood vaccinations and cancer (log on to www.ouralexander for details).
Perhaps our children’s increased vulnerability in the face of environmental risk factors combined with the alarming increase in the incidence of childhood cancer is our wake-up call, urging us to take the unique biology of children and the damaging potential of these environmental insults even more seriously.
Where cancer is concerned, the best form of cure is prevention, and it behooves us to do whatever we can to ensure that our children have the resources to remain healthy in a toxic world.
Sidebar: Why children are at higher risk
Children differ from adults in a number of ways and these can lead to increased susceptibility to toxins. Many parts of their bodies, for example, their brain, bones and reproductive organs, are still developing:
* During this stage, they may be more susceptible to the alterations caused by toxins
* Their bodies have a less developed ability to break down toxins
* They crawl around on the floor near dust and other potentially toxic particles
* They are more likely to put things in their mouths and eat things that they shouldn’t
* They eat, drink and breathe more for their weight than do adults. This means that they take in more toxins per kilo than adults. The air intake of a resting infant, for instance, is twice that of an adult under the same conditions.
* Children’s bodies may also have less capacity to repair damage. In addition, the developing fetus is extremely sensitive to toxic chemicals. This is because the development of the body is completely dependent on the complex interactions of signalling chemicals (hormones). Disruption of these signals can permanently damage the body’s development.
Sidebar: They live to fight another cancer
One in every 250 people will be a survivor of childhood cancer. However, what kind of future can they look forward to? Studies show that childhood cancer treatment may well get rid of the original cancer, but such survivors are also more prone to cancer in other sites as adults.
One team of researchers has calculated that as many as one-third of female childhood cancer survivors develop breast cancer by the time they are 40 (N Engl J Med, 1996; 334: 745-51).
There is also evidence that children treated for one type of leukaemia go on to develop another form of the disease as adults (N Engl J Med, 1991; 325: 1682-7).
Most recently, a study based on a follow-up of 13,581 children and adolescents from 25 hospitals in the US and Canada who had survived for at least five years after treatment for leukaemia and other cancers made startling reading. Breast cancer was 16 times more common than expected and often occurred when women reached their late 20s and 30s. Bone cancer was 19 times more common than usual and thyroid cancer 11 times more common among the cancer survivors. The highest extra cancer risk was seen in children who had been treated for Hodgkin’s disease. They had an almost 8 per cent chance of new cancer during 20 years of follow-up. The researchers believe chemotherapy and radiation were largely to blame (J Natl Cancer Inst, 2001; 93: 618-29).
Chemotherapy also causes late heart problems, particularly in women (N Engl J Med, 1995; 332: 1738-43). In one study, nearly a quarter of patients treated with anthracyclines developed cardiac abnormalities years later (JAMA, 1991; 266: 1672-7). It can also cause late liver toxicity in long-term survivors of Hodgkin’s (Oncology, 1996; 53: 73-8) as well as lung cancer.
Sidebar: Suck it and see
Phthalates are a group of chemicals used in plastics, glues and inks. Research has indicated the possible negative impact of phthalate exposure on children’s health, and links with childhood cancer have not been ruled out.
Many teethers and soft toys contain phthalates, and there is evidence that these can leach out of these toys and be ingested by children. The European Commission’s Committee on Toxicity, Ecotoxicity and the Environment has concluded that there are ‘reasons for concern’ over the most common phthalates used in polyvinyl chloride (PVC) toys (ENDS Report 281, June 1998: 49).
Yet, despite being banned in several countries throughout Europe, phthalate-containing toys and teethers have not been banned in the European Union because, say EU officials, there is currently no way to tell how much of these plasticisers is leaching out of the toys.
Unfortunately, phthalates are not confined to teethers and chewy toys. Tests carried out by the UK Ministry of Agriculture, Fisheries and Food (MAFF) found phthalates in baby milk formula. MAFF’s report also noted that a 1993 UK survey of phthalate levels in fatty foods found them to be present in every sample, including meat, fish, eggs, milk and milk products (MAFF, Food Surveillance Information Sheet, Number 82: Phthalates in Food, 1996).
The phthalate diethylhexylphthalate (DEHP) may no longer be used in toys, but it is a constituent of many PVC building materials, such as PVC flooring. Researchers have found that DEHP and other phthalates are present in household dust, where it can be inhaled by both children and adults. There is evidence to suggest that the development of lung problems, including asthma, in the first two years of life is linked to exposure to plastic interior surfaces (Environ Health Perspect, 1997; 105: 972-8).
Sidebar: Protecting children from cancer risks
Protecting your children from environmental toxins requires efforts on several fronts and may even need to begin before conception. Consider the following suggestions to help keep your child healthy:
* Protection begins before birth. There is evidence that parents exposed to toxic chemicals, such as pesticides, as well as radiation have a greater risk of producing a child who develops cancer. Before conceiving, it is worthwhile for parents to consider their own environments and health. Fathers who smoke, for example, may contribute to the development of cancer in their children (J Natl Cancer Inst, 1997; 89: 238-44). Consulting groups such as Foresight (01483 427 839) may be helpful.
* Mothers should avoid X-rays. X-rays during pregnancy are usually of little value and have been associated with a 50 per cent increase in childhood leukaemia (J Natl Cancer Inst, 1962; 28: 1173-91).
* Breastfeed for as long as possible. In spite of studies showing a range of toxic chemicals in breastmilk, the general conclusion of scientists and paediatricians is that the benefits of breastfeeding, such as a possible protective effect against childhood cancer (Int J Epidemiol, 1995; 24: 27-32; Br J Cancer, 2001; 85: 1685-94), far outweigh any risks.
* Opt for oral vitamin K. Oral doses of vitamin K are not associated with cancer. In addition, colostrum and hind milk contain significant amounts of vitamin K, another good reason to breastfeed.
* Use good-quality supplements. Once your child is on solid food, supplement with important minerals such as vitamins C and E, potassium, selenium and zinc. In addition, make sure your child receives adequate doses of essential fatty acids. Hemp and sunflowerseed oils are good sources of omega-3 and omega-6 fatty acids, respectively.
* Consider alternatives to vaccination. In healthy children, mild childhood diseases are rarely dangerous. If your child is at particular risk and you wish to strengthen their resistance to disease, try homoeopathy. Evidence from 50 years ago suggests that homoeopathic prevention can be effective. If you have decided on conventional vaccination, it may be better to wait until your child is nine months or older before vaccinating. Prepare your child to receive vaccines with a course of Thuja or Bacillinum, or vitamin C.
* What are they putting in their mouths? The more organic fruits, vegetables and wholegrains your child consumes, the less the risk of ingesting harmful pesticides. However, many foods aimed at children contain other known carcinogens, such as the nitrites in cured meats (Cancer Causes Control, 1994; 5: 141-8) and the food colouring used in so many drinks and sweets. Cutting out convenience foods or being more selective about what you serve will have a substantial effect on your child’s health by removing potential carcinogens as well as boosting overall health to a level that may help your child fight off the effects of toxins.
* Avoid artificial sweeteners. The foods children eat are implicated in increased cancer rates. In one study, researchers found what they believed was a ‘promising’ connection between the artificial sweetener aspartame and increased rates of brain cancer (J Neuropathol Exp Neurol, 1996; 55: 1115-23).
* Keep kids safe from electrical gadgets. Less radiation exposure means lower cancer risk. Apart from rethinking how many gadgets you have at home and where they are placed, think seriously about your child’s bedroom environment. Babies do not need electric light and musical devices to soothe them. Children don’t need clock-radios or TVs in their rooms. Keeping your child’s room as free from domestic electrical appliances as possible means that the eight or more hours they spend sleeping each day can heal rather than harm.
* Minimise exposure to heavy metals. In particular, lead and mercury are potent neurotoxins. Left to accumulate in the body, they can cause the kind of chronic illness that may predispose to certain cancers. To minimise exposure from the water supply, install a reverse-osmosis water filter in your home. If your child needs dental filings, make sure they are composite rather than amalgam. Use lead-free paint and replace all old lead water pipes.
* Stay informed. Many environmental groups produce excellent reports on environment and child health. Friends of the Earth’s Poisoning our Children: The Dangers of Exposure to Untested and Toxic Chemicals is a good overview (www.foe.co.uk ; tel: 020 7490 1555). In the US, the Natural Resources Defence Council produces many useful publications, including Our Children at Risk, available online at www.nrdc.org.
This article first appeared in the April 2002 (volume 13 number 1) edition of What Doctors Don’t Tell You
