Magda Havas, B.Sc., Ph.D.

Environmental & Resource Studies and Science Education

Trent University, Peterborough, Ontario, Canada, K9J 7B8

Phone:  (705) 748-1232, FAX:  (705) 748-1569, e-mail mhavas@trentu.ca

 

 

 

The comments below are my response to Dr. Peter Valberg's oral testimony presented at the public hearing held on March 22, 2001 regarding the Southeast Metro Transmission Line.

 

I have three points to make:

 

Point #1:  Epidemiological studies of childhood leukemia. 

 

Dr. Valberg repeatedly refers to one study conducted by Linet (1997) that showed no significant increased risk of childhood leukemia associated with wire codes (a surrogate measurement for magnetic field exposure).  To use this study as though it were the norm is misleading.

 

I reviewed this study, along with all of the childhood epidemiological studies available up until 1998 (see attached Table 17).  Five studies based their results on wire codes.  Of these five studies one study (Fulton et al. 1980) did not exceed the 2 mG associated with childhood cancer and hence the insignificant odds ratio was expected.  Of the remaining 4 studies only Linet's produced an odds ratio below 1.  The rest were above 1.  Interestingly this is the study to which Dr. Valberg consistently refers when he attempts to show that epidemiological studies are inconsistent or that they show no association. 

 

The other study that Dr. Valberg claims showed no significant association between childhood leukemia and exposure to power lines was conducted in the UK (which he attributed to Sir Richard Doll).  In this more recent study very few children were exposed to magnetic fields above 4 mG (which is what the study used as the critical value).  Yet, even this study states that there is a slight increased risk that might result in a doubling of deaths from childhood leukemia in the UK. 

 

All of the meta-analyses that have been conducted show a small but significant increased risk of children who live near power lines developing leukemia.   The fact is that the degree of consistency among epidemiological studies is remarkable considering that we have an imperfect estimate of magnetic field exposure. 

 

 

Point #2:  Re:  Studies with laboratory animals and cancer promotion.

 

Dr. Valberg states that there is no evidence from laboratory studies with live animals showing cancer promotion.  This statement is FALSE.

 

The National Institute of Environmental Health Science (NIEHS) and the National Research Council (NRC) reviewed in vivo studies with laboratory animals.  Standard protocol for laboratory bioassays for electromagnetic fields does not exist hence the studies referred to were conducted for different periods of time, at different exposure, using different strains of laboratory animals.  I simply sorted the bioassay data based on magnetic fields for mammary cancer in rats.  The results showed that magnetic fields between 1 and 1000 mG [note the units used in Table 23 are in micro tesla and 1 uT is the same as 10 mG] were generally harmful (black boxes).  They promoted cancer by increasing incidence, number or size of tumors or by shortening the latency period.   Magnetic fields above 1000 mG (100 uT) appeared to be beneficial (hatched boxes).  Although this is contrary to what one might expect (namely that lower fields are harmful while higher electromagnetic fields are beneficial).  However, one possible explanation is that very high magnetic fields inhibit cancers cells just as very high levels of radiation kill cancer cells and are used in cancer therapy. 

 

 

Point #3:  Three-legged stool.

 

Dr. Valberg comments that EMF research is like a three-legged stool and all three legs have to be in place for the stool to be stable.  I agree with this statement.

 

One leg is epidemiology and this now indicates a clear association between EMF exposure and childhood leukemias (refer to my written testimony). 

 

The second leg is in vivo testing (laboratory tests with live animals) and the example above based on many studies indicates that magnetic fields promote at least one type of cancer, mammary cancer in rats. 

 

The third leg is in vitro studies (laboratory tests with cells and tissues) and Dr. Martin Blank's oral testimony clearly indicates that enzyme activity and stress protein production in cells are affected at magnetic fields below 20 mG and in some cases at 5 and 10 mG.  These effects occur at lower magnetic fields (5 to 20 mG) than those produced by the existing transmission line (30 to 130 mG). 

 

From my vantage point we have very powerful scientific evidence that magnetic fields are harmful to living organisms (especially young children).  In other words we have a stable three-legged stool. 

 

 

Final Comments

 

The decision that you will ultimately make regarding this power line will have consequence beyond your three municipalities.  Many communities are facing similar challenges and what your communities does will be noted.  From a health perspective it would be heartening to point to an example of a planning decision that seriously considered effects on public health now and in the future.