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).