News and analysis · Nouvelles et analyses

CMAJ 1999;161:237-9

• Smog advisories help Ontarians cope with increased pollution
• Surgical microscope gives virtual 3D view
• High praise indeed for CMAJ
• Helping musicians to keep hearing the high notes
• Getting paid not to teach too costly for New York hospitals
• Pulse: Canada's greying population
• Feds dole out $47 million for research
• Sprouts linked to illness
• Shortage of primary care doctors in US
• Research Update
  • No, electromagnetic fields don't cause cancer
  • Yes, magnetic fields do cause cancer

A trio of smog advisory health messages will help patients weather the dog days of summer. Developed by the Ontario Medical Association (OMA), the 1-page advisories are aimed at smog-sensitive people, children, and people working and exercising outdoors (see www.oma.org). In Ontario, smog causes respiratory difficulties for about 7% of the population and triggers about 1800 premature deaths annually.

"These are the first comprehensive, province-wide documents of their type," says Dr. Ted Boadway, executive director of the OMA Health Policy Department. The messages, which focus on raising awareness and reducing exposure, are part of the OMA's 4-part plan to reduce ground level ozone levels (see www.oma.org/phealth/ground.htm).

The advisories couldn't have come at a more opportune time in Ontario. In the past year, sulphur emissions have increased by 40%, primarily because of an increase in the use of coal-fired electricity after several nuclear power plants were shut down. "[The increase] is shocking in the face of knowing what it's doing and knowing you can't fix it," says Boadway.

The advisories came on the heels of the federal government's decision to reduce the level of sulphur in fuel by more than 90%. Current national levels are about 350 parts per million (500 ppm in Ontario) but in June the federal government said oil refineries must reduce the rate to 30 ppm by January 2005. The US Environmental Protection Agency told its refiners to make the same reduction by 2004.

The OMA was one of many lobby groups, including the CMA and 130 municipalities across Canada, that were urging Ottawa to slash emissions. — Barbara Sibbald, CMAJ

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A new surgical microscope uses virtual reality to help surgeons see beneath the surface. With the binocular microscope, stereo images are superimposed, layer by layer, to provide a 3D image of the structures beneath the surface. The stereo-augmented reality-display microscope, developed by radiologists and scientists at the University College of London in England, also has an infrared tracking system to ensure that the virtual image exactly matches the part of the patient under the microscope.

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Do doctors care about books? This is precisely the question posed in a recent editorial in The Lancet (1999;353:1719). In a brief overview of book review sections in major journals such as The New England Journal of Medicine, The Annals of Internal Medicine, JAMA and BMJ, The Lancet editorial concluded that, "present company necessarily being excluded," top honours should go to the Canadian Medical Association Journal and the editor of its review section — The Left Atrium — Anne Marie Todkill.

According to the editorial: "She has created a cushioned corner for all those who desire the company of words and who wish to escape the dutiful brutalities of other worthy periodicals."

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The waiting room of the Centre for Health Promotion looks like the audition room for a symphony orchestra or a rock and roll group. The centre, which specializes in helping musicians, encourages its clients to bring their instruments to their appointment. They play for Dr. John Chong and Prof. Marshall Chasin, not for applause, but to ascertain what physical price they are paying for their love of music.

Chong's training as a concert pianist provided him with firsthand knowledge of the physical toll that playing music can take on the body. Chasin's expertise in audiology, combined with his love and appreciation of music, made him the ideal audiologist for the centre, which opened in Hamilton in 1986. A second centre recently opened in Toronto.

Hearing loss is one of the biggest problems, with 90% of musicians experiencing some sort of hearing loss, according to Chasin. And many of these people don't seek medical attention until the damage is so severe that it impedes their ability as a musician.

Rock musicians tend to lose their hearing due to the sheer volume of noise. Statistically, classical musicians are at an equal or greater risk of hearing loss. The reasons vary from the number of hours they practise to where they sit in the orchestra. Hearing loss can even be related to whether musicians like the music they play.

To prevent loss, Chong and Chasin offer hearing protection designed with musicians in mind. What makes these protective devices unique is that they reduce sound levels by 15, 20 or 30 decibels but the sound waves remain intact, even the high notes that cause the greatest damage. The fact that the integrity of the music remains is vital in convincing musicians to wear hearing protection. In the past, they complained that the bass line and the high notes were lost when hearing protection was worn.

Chasin hopes that with the innovations taking place in hearing protection, younger musicians will respect the potential for hearing loss and take preventive measures. — © Peter Wilton, Toronto

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Despite handsome government bonuses to cut residency programs and thereby stem physician oversupply, New York State hospitals are finding they can't do without the low-cost, high-volume services of their young doctors-in-training.

Two years after signing on to the federal program, similar to one that paid farmers not to grow crops, more than half of the 49 hospitals in the Medicare Graduate Medical Education Demonstration Project have dropped out. Their complaint: replacing residents earning US$50 000 and working 80-hour weeks, with fully qualified specialists earning US$150 000 and working only 40 hours, was a losing proposition — even with the federal government kicking in its subsidies.

As Kenneth Raske, president of the Greater New York Hospital Association (GNYHA) said in a published report: "It became clear how indispensable the residents are to providing high-quality care on a day-in, day-out basis." It was the GNYHA, backed up by the state's 2 powerful senators, that first thought up the plan (see CMAJ 1997;157;1263-4).

Federal Medicare pays hospitals up to US$100 000 per year for each resident trained, and after paying their salaries (about US$50 000), hospitals can pocket the rest. Under the demonstration project, Medicare continued to pay hospitals even for the residency slots that were cut, so long as they reduced the total number of slots by as much as 20% to 25%. The plan was expected to result in up to 400 fewer residency positions in New York in the first year alone.

Though devised initially for New York, which trains some 15% of the nation's doctors, the plan was to extend the program to other states if it was successful. One major teaching centre that signed on to the program found the first year's experience cost the hospital US$1.5 million. Administrators quickly backtracked and restored the 40 resident positions they had cut.

When they signed on, the hospitals anticipated some significant changes in the supply-demand equation. They expected patient populations to decline, thus reducing the need for residents, and they felt Medicare reimbursements to hospitals to train doctors would surely be cut given federal balanced-budget imperatives. That would have reduced their incentive to employ residents. Neither change happened. Medicare budget cuts were only slight, and although average lengths of stay have dropped, the number of admissions rose and so the demand for residents' labour intensified. — © Milan Korcok, Florida

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The 1998 report from Canada's auditor general predicts that baby boomers will begin retiring around 2010 and the number of seniors will increase sharply in Canada over the subsequent 2 decades. The number of Canadians older than 65 will grow from 3.6 million today to 5 million by 2011, and then climb to 9 million by 2031.

Not only will the proportion of elderly Canadians almost double from the current 12% to 22% by 2031, the "dependency ratio" will also double. This means that the ratio of the population 65 and over to the population aged 20-64 is projected to climb from 20% today to more than 38% by 2031. Any increase in fertility rates will not affect the labour force for at least 20 years, and even a doubling of current immigration levels will have only a marginal effect on the dependency ratio.

Per capita public spending on health care for those 65 and over is almost 5 times greater than for the rest the population, and it jumps significantly for the very elderly (aged 80 and over). That latter group is expected to quadruple in size over the next 45 years.

According to the auditor general, the changing demographics could mean that government spending on social security and health care could rise from the 1996 level of 11.6% to between 14.7% and 20.7% of the gross domestic product by 2031 (see Table).

This column was written by Lynda Buske, Chief, Physician Resources Information Planning, CMA. Readers may send potential research topics to Patrick Sullivan (sullip@cma.ca; 613 731-8610 or 800 663-7336, x2126; fax 613 565-2382).

   | Other Pulse articles / Autres chroniques Médicogramme |

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The federal government has doled out more than half of the $82.5 million it committed to health research in the 1999 budget. So far, $47 million will be spent on research initiatives across Canada over the next 3 years.

Ottawa says the following measures will increase the level of support in several areas of health research and help in the transition to the Canadian Institutes of Health Research (CIHR):

• 109 new operating grants and 57 personnel awards ($34 million);
• $2 million per year for 3 years available in Saskatchewan, Manitoba, Nova Scotia and Newfoundland under the Regional Partnership Program;
• $1.9 million Challenge Partnership Program with health charities;
• $3-million CIHR Opportunity Fund;
• $2.1 million for new clinical trials; and
• 6 new health services research awards.

Dr. Henry Friesen, president of the Medical Research Council of Canada, said the new funding "is a solid first step in the transformation of the MRC to the CIHR." The CIHR is be in place by 2000. Details of the newly funded projects are available at www.mrc.gc.ca in the "What's New" section.

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Crunchy sprouted seeds and beans have been linked to outbreaks of Salmonella- and Escherichia coli-related illness around the world. In Canada and the US, alfalfa sprouts are suspected as the culprit, while in Japan radish sprouts are being blamed; in Europe, white bean sprouts are suspected. The bacteria apparently lodge in tiny seed cracks and are difficult to eliminate. They can multiply during sprouting in warm, humid conditions.

Health Canada says public health officials are working with industry to establish safer growing methods, but in the meantime the federal government is warning consumers about the risk of eating uncooked sprouts. Proper cooking kills the bacteria.

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US medical students are being urged to consider careers as primary care physicians in the face of worsening shortages. The move comes after the percentage of graduating seniors entering primary care residencies decreased for the first time in a decade. The Council of Graduate Medical Education recommends a ratio of 50% primary care doctors and 50% specialists. In 1997/98 too few generalist residents began training — 7% less than the recommended target. The American Medical Student Association is holding National Primary Care Week at every medical school in late September to promote primary care as a career.

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No, electromagnetic fields don't cause cancer

The most comprehensive study to date of electric and magnetic field exposure (EMF) and childhood leukemia has concluded that there is no increased risk of leukemia in children exposed to EMF (Am J Epidemiol 1999;9:831-41.) The 10-year study, involving almost 800 children from 5 Canadian provinces, was led by Dr. Mary McBride, an epidemiologist at the British Columbia Cancer Agency.

The case­control study included 399 children with a diagnosis of leukemia (88% had acute lymphocytic leukemia), and the same number of control children matched with the case children for age, area and sex. The children were all from BC, Alberta, Saskatchewan, Manitoba and Quebec. The control group was randomly selected and considered representative of children without leukemia. The size of the study was a key strength, says McBride.

The study was the first in the world to monitor children's personal EMF exposure, through a specially designed backpack containing a meter that continuously measured and recorded EMF levels. The children wore the backpack for 48 hours except while sleeping and bathing. Parents wrote down the children's activities during the 48-hour period in a diary. As well, 24-hour measurements of EMF in the children's bedrooms were carried out. Researchers were also interested in the children's history of exposure to EMF, so perimeter measurements of EMF around all homes the children had lived in were recorded. Wire codes (power line configurations) on power poles adjacent to the children's residences were recorded, and researchers looked at the distance to power lines and magnetic fields in all of the children's residences throughout their lifetime.

In contrast to earlier studies, which suggested a relationship between certain power line configurations and increased risk of leukemia, this study "presents considerable evidence against such a relationship," says McBride.

Some previous studies have shown a higher incidence of leukemia in children who have moved frequently. In McBride's study, the mobility factor was controlled for in the analysis. — Heather Kent, Vancouver

Exposure to magnetic fields is associated with an increased risk of childhood leukemia, especially in children exposed before birth or in the first 2 years of life, those with a diagnosis of leukemia at less than 6 years of age, and those with acute lymphoblastic leukemia, according to a case­control study of children in southern Ontario (Int J Cancer 1999;82:161-70, Cancer Causes Control 1999;10:233-43).

The results conflict with those of the recent BC Cancer Agency study (see above), which found no increased risk of leukemia associated with electric and magnetic fields. "The studies were planned similarly," explains Dr. Lois Green, the principal author, who is with the Department of Public Health Sciences at the University of Toronto. However, there were some differences in the methodology and analysis that could account for the divergent findings.

A total of 201 children with leukemia were matched with 406 controls, and magnetic field exposure was estimated using wire codes in their homes and measured using point-in-time or "spot" measurements inside and outside the homes. Previous homes were also examined. The researchers found that when they analysed these data by age at diagnosis and "time windows" of exposure (prenatal, first 2 years of life, up to 2 years before diagnosis and during 2 years before diagnosis), the associations emerged. Magnetic fields of 0.15 µT or more on the outside perimeter of the house were associated with more than a threefold increase in leukemia risk. Green says that the magnetic field strength in the upper quartile of exposure is "by no means unusual" in homes in southern Ontario.

In a separate analysis, 88 of the children with leukemia and 133 of the controls were also outfitted with personal monitoring devices. This analysis showed that higher levels of exposure to magnetic fields, as measured by the monitors, were associated with 4½ times the risk of leukemia, and confirmed the increased risk in children under 6 and for acute lymphoblastic leukemia.

This analysis also looked at electric fields, which, unlike magnetic fields, were associated with a decreased leukemia risk. Both analyses showed no association between living close to high-tension power lines and leukemia risk overall.

Green says that one of the strengths of the study was the use of personal monitors. "There is a lot of spatial and temporal variation in magnetic fields in residential environments. We felt therefore that the monitor on the child would best capture the variability of exposure."

Originally, Green and her colleagues hypothesized that exposure to magnetic fields in the 2 years before leukemia diagnosis might act as a "promoter" of the disease. However, the findings are more consistent with the theory that exposure during prenatal and early developmental stages is the critical factor.

The study was funded by Ontario Hydro, which has not commented on the results. — C.J. Brown, CMAJ

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