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.
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).