Earlier Findings. Morris et al. report that ambient ... of Morris et al. on hospitalizations are consistent with ... Robert D. Morris, MD, PhD, Center for. Environmental ...
Letters to the Editor
oriented economy that could provide enough jobs) should have caused the "normal" level of genocide that is endemic in that region to escalate in the way it did. Rwanda is demographically trapped in that it has exceeded its carrying capacity and the ability of its population to exchange goods and services for food and other necessities or to migrate. Indefinite food aid, in a world of falling per capita grain and mounting grain prices, can be only a temporary solution. The options before Rwanda are tragically bizarre-either continuing slaughter, starvation, and disease, or the Chinese option of 1-child families. Meanwhile, slaughter is ascribed to human rights violations, and the even more disturbing population pressure of demographic entrapment is conveniently forgotten. Much of Africa appears to be heading in the same direction.4 Malawi, where pressure on land is intense, is out of the news because it is peacefully stunting: half of its population under five years old is stunted, a quarter of them severely. Demographic entrapment is so ethically and politically disturbing that orthodox demography, public health, and United Nations agencies, particularly United Nations Children's Fund (UNICEF), maintain a political correctness so correct that the entrapment is never mentioned, and the comfortable myth of the 2-child paradigm5 is maintained. This paradigm is that, if all the unmet needs for family planning are finally met, and a two-child norm (or less) is eventually achieved, this will be demographically sufficient in that populations will ultimately stabilize without disaster. Rwanda shows how false this paradigm is. It is not cry of wolf that has dulled our anxiety, but the taboo by which we pretend that he does not exist. O Maurice King, MD The author is with the University of Leeds, United Kingdom. Requests for reprints should be sent to Maurice King, MD, One bis Rue du Tir, Geneva 1204, Switzerland.
References 1. Silver G. Editorial: beyond population statistics. Am J Public Health. 1995;85:1345-1346.
Editorial. 2. King MH, Elliott CM. UNICEF's call to greatness: an open letter to Carol Bellamy. Nat Med JIndia. 1996; in press. 3. King MH, Elliott CM. Legitimate double think. Lancet. 1993;341:669-671. 4. UN Malawi. Situation Analfysis of Poverty in Malawi. Lilongwe, Malawi: Government of Malawi; 1993.
July 1996, Vol. 86, No. 7
5. King M, Elliott C, Hellberg H, Lilford R, Martin J, Rock E. Demographic entrapment questions the 2-child paradigm. Health
PolicyPlann. 1995;10:376-383.
Silver Responds The letter from Maurice King regarding my editorial on population deserves response. I have great respect and admiration for Dr King, whose devotion to the desperately poor and sick of the developing world has inspired me and many others to address themselves to alleviating global poverty and the burden of illness. I regret that he selected an editorial comment (correct in context) to take umbrage against the entire editorial position. I would make only two statements in response. First, genocide, as we have seen in many places this century, hardly is the unique result of population pressure, and not always the end result in places where there is significant overpopulation. Hutu and Tutsi clans massacred each other in tribal warfare long before the urgency of population dynamics. Second, the theme of the editorial and of the paper by Murrow and Bryant, was a recognition of the dangers of overpopulation. In view of the unlikelihood that effective measures would be introduced sufficiently swiftly, I essayed to articulate a process whereby the perceived rationing imposed by overpopulation could be controlled. In no way was it intended to minimize the tragic consequences of overpopulation. l George Silver Contributing Editor
Ambient Carbon Monoxide and Hospitalizations for Heart Failure: Earlier Findings Morris et al. report that ambient carbon monoxide from air pollution is positively associated with hospitalizations for congestive heart failure among elderly people in seven US cities.' Schwartz, in an accompanying editorial, notes that increased risk from ambient carbon monoxide is plausible and may be associated with tens of thousands of cases per year
nationwide.2 In 1971, John Goldsmith and I studied the association, in the years 1965 to 1969, between daily mortality in Los Angeles County and certain air pollutants.3 We found a highly significant
(P < .002) association between ambient carbon monoxide and mortality. There was no association between mortality and total oxidants. We had planned several follow-up papers, including one on specific causes of death. None were published because this work was terminated in 1971 by then governor of California Ronald Reagan. However, we did conduct some analyses beyond those reported in our paper. In particular, we found that most of the excess mortality was attributable to cardiovascular disease (P < .001). The findings of Morris et al. on hospitalizations are consistent with our findings on mortality. It is well known that carbon monoxide converts some blood hemoglobin to carboxyhemoglobin, with reduction in the oxygen-carrying capacity of the blood. Even a small reduction can be a disaster for an individual who is already marginal. It is entirely plausible that ambient carbon monoxide from air pollution can increase both hospitalizations and mortality. Our study, the one by Morris, and others cited by Schwartz show that these increases are, in fact, occurring. According to Schwartz, we need more studies. Yes, we need more studies, but there is already enough evidence to indicate that we need concrete steps to reduce our exposure to the already excessive levels of this pollutant. C Alfred C. Hexter, PhD The author is a consultant in epidemiology in Kensington, Calif. Requests for reprints should be sent to Alfred C. Hexter, PhD, 58 Arlington Ave, Kensington, CA 94707.
References 1. Morris RD, Naumova EN, Munasinghe RL. Ambient air pollution and hospitalization for congestive heart failure among elderly people in seven large US cities. Am J Public
Health. 1995;85:1361-1365. 2. Schwartz J. Editorial: is carbon monoxide a risk factor for hospital admission for heart failure? Am J Public Health. 1995;85:13431345. 3. Hexter AC, Goldsmith JR. Carbon monoxide: association of community air pollution with mortality. Science. 1971;172:265-267.
Moris and Colleagues Respond We appreciate the opportunity to acknowledge the groundbreaking study by Hexter and Goldsmith investigating the association between ambient carbon monoxide and mortality in Los Angeles.' It is unfortunate that funding constraints limAmerican Journal of Public Health 1031
Letters to the Editor
ited their ability to pursue this important work, and it is disappointing that this situation has not improved in the intervening years. As Dr Hexter points out, there is an accumulating body of evidence to suggest that low levels of carbon monoxide may be harmful, particularly for people with underlying cardiac disease.1-3 These findings raise questions concerning the appropriateness of existing standards for carbon monoxide. However, it is always difficult to know when research findings should become the basis for regulatory intervention. Revising standards will be particularly difficult in light of our inability to identify a threshold for the apparent effect of carbon monoxide. As we pointed out in our article, it is possible that the observed association represents the effect of a confounder that covaries with carbon monoxide.2 The most likely time-dependent covariates are weather and other air pollutants. The low correlation of carbon monoxide with temperature suggests that weather is not a
likely confounder. Air pollutants that covary with carbon monoxide are probably vehicular pollutants. Efforts to reduce carbon monoxide may reduce these unidentified pollutants as well. Another important, unanswered question involves the extent to which the observed associations with carbon monoxide represent a "harvesting" effect. Perhaps the elevated carbon monoxide simply shifted the timing of the deaths and hospitalizations associated with carbon monoxide by a few days rather than causing hospitalizations that would have otherwise been unnecessary and advancing the time of death by months or years. The public health impact varies substantially with the extent of harvesting represented by the effects observed in these studies. An answer to this question is essential before we translate these findings into regulatory action concerning ambient carbon monoxide. Nonetheless, these studies suggest that any reduction in ambient carbon monoxide will have health benefits, and
they provide one more reason to decrease our dependence on the automobile. g Robert D. Morris, MD, PhD Elena N. Naumova, PhD Rajika L. Munasinghe, MBBS, MS The authors are with the Center for Environmental Epidemiology, Department of Family and Community Medicine, Medical College of Wisconsin, Milwaukee. Requests for reprints should be sent to Robert D. Morris, MD, PhD, Center for Environmental Epidemiology, Department of Family and Community Medicine, Medical College of Wisconsin, 8701 Watertown Plank Rd, Milwaukee, WI 53226.
References 1. Hexter AC. Carbon monoxide: association of community air pollution with mortality.
Science. 1971;172:265-267. 2. Morris RD, Naumova EN, Munasinghe RL. Ambient air pollution and hospitalization for congestive heart failure among the elderly in seven large US cities. Am J Public
Health. 1995;85:1361-1365. 3. Schwartz J, Morris RD. Cardiovascular disease and airborne particulate levels in Detroit, Michigan.AmJEpidemiol. 1995;142: 23-35.
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