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Public Health in a Changing

Environment

Bert Brunekreef, PhDProfessor of Environmental Epidemiology

Institute for Risk Assessment Sciences

Public Health in a Changing Environment

Ladies and gentlemen,

Its my privilege today to offer you anniversary entertainment, and I will do so bytelling you a few stories about public health in a changing environment. Let me startwith one that most of you are familiar with, smoking in public places. We have knownsince the early nineteen fifties that smoking causes lung cancer. We have knownsince the early nineteen eighties that inhaling somebody elses smoke is also bad foryou.

Then in 2008, smoking was finally banned in bars and restaurants, to the relief ofmany non-smokers and to the disappointment of a small but vocal minority ofsmokers and journalists.As the example shows, changing the environment for the benefit of public healthtakes time, and can be politically highly charged.After such changes have been implemented, it is important to document the healthbenefits. Smoking bans lead to abrupt and large reductions in exposure to tobacco

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smoke, which turns them into fairly unique natural experiments. Investigators havetaken advantage of this, and have shown that yes, there are measurable benefits.These do not only apply to bar and restaurant workers, but also to the visitors.

Scotland: Smoking Ban17% reduction

UK: No Smoking Ban4% reduction

NEJM2008

In Scotland, smoking has been prohibited in all indoor public places since March2006. Hospital admissions for Acute Coronary Syndrome decreased since then by17%, compared to a decrease of just 4% in England where a smoking ban had notyet been introduced. (1).

I have shown this example as an illustration of the links between epidemiology andpublic health, the theme of this Dies Natalis. Public health is concerned with thehealth of the community as a whole. It is shaped by the combined individual healthexperience of all members of the community. Epidemiology is the science of publichealth. We test hypotheses about causes of disease. We investigate whether newmedications are better than existing ones. We study side effects once newmedications have entered the market. We look at interactions between animal andhuman health, and we study effects of dietary, occupational and environmentalexposures on human health.

MedicineScience

Veterinary Medicine

Julius

Center

Pharmaco-epidemiology

Veterinaryepidemiology

IRAS

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All of these are active areas of research at the Utrecht University. Epidemiology hasbecome a focus area thanks to the excellent work of many colleagues working inthree different faculties. The Julius Centre at the Medical School has a high visibilityin clinical epidemiology. The Faculty of Science harbours a strong programme inpharmaco-epidemiology. The Faculty of Veterinary Medicine has an excellent

veterinary epidemiology unit, and my own Institute for Risk Assessment Sciences issponsored by all three Faculties just mentioned.

Source:RIVM

There are many ways to measure public health. I will concentrate on a few keyindicators, life expectancy and healthy life expectancy. Life expectancy has increasedenormously over the last century in many parts of the world. This is the result of

better living conditions, and advances in medical care and treatment.

A life expectancy of 80 at birth does not mean that everyone lives to 80, and no onelives beyond that age. Survival curves show how a population gradually dies withincreasing age, and life expectancy at birth is simply the mean of all individualattained ages. Healthy life expectancy is the number of years lived without disease ordisability, and it can equally be represented in a survival curve as in this graph. Onecould say that the aim of public health interventions and medical treatment is toincrease life expectancy. Also, the aim is to compress morbidity, so that the healthylife expectancy becomes more and more equal to life expectancy itself. So ideally,were trying to make everyone live until 85 or 90 or so, but without serious morbidity

and disability until almost the very end.

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World Health Report 2008

There is a relationship between the Gross Domestic Product of a country and the lifeexpectancy of its population. For the highest income countries with GDPs above25,000 U$ or so, the range in life expectancies is rather narrow, from more than 75 toless than 85 years. At the low end of the GDP scale, however, the variation is huge,showing that some poor countries are doing much better in fostering public healththan others. The distribution of income and opportunities within countries has beenshown over and over again to be a major determinant of life expectancy.

Life expectancy in the Netherlands

varies 6-7 years by level of education

Source:RIVM

Even in a fairly egalitarian country like ours, there is a six or seven year gap in lifeexpectancy between those with high and low education (3). Various factors havebeen shown to be related to differences in life expectancy as well as healthy lifeexpectancy. These include access to healthy foods, smoking and life long learning.There are environmental determinants as well: in England, the differences in lifeexpectancy related to social disparity were found to be much smaller in areas with alot of green space compared to areas without green space (4). This provides clues tohow we can manipulate our environment to further improve public health.

Let me now turn to the environment and to changes in our environment relevant forpublic health.

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Vedi Napoli,

e pui Muori

2008 Wastecollection crisis

in Naples

The environment changes, it changes us, and we change our environment too. Formost of us, the environment we live in is almost entirely manmade. We spend 95% ofour time indoors, not outdoors. The climate we create indoors is often very differentfrom conditions outside. The water we drink is purified, the waste we produce iscarried away, and the food we eat is processed to the extent that our ancestorswould not recognize it as something they could possibly eat. We dont think aboutthese luxuries much, but with the exception of housing, these are all achievements of

the last 50 to 200 years or so.Its only when services break down, such as waste collection in Naples last year, thatwe realise we need to count our blessings more than we do.

Gas crisis in Bulgaria, Winter 2009

Similar examples are not hard to come by. When transport of natural gas to EasternEurope was interrupted this winter, many people were unable to heat their homes,and reverted to burning dirty fuels increasing air pollution.

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As they say, you dont miss your water till your well runs dry. This is only human, andnot something unique to our generation.

Of the great sewer that runsbelow, Londoners know, as arule, nothing; though theRegistrar-General could tellthem that its existence hasadded some 20 years to theirchance of life

The Times of London, 1891

The great sewer system of London was built in the second half of the 19thcentury.When its chief engineer, Sir Joseph Bazalgette died in 1891, the London Times ranan obituary which said:.Of the great sewer that runs below Londoners know, as a rule, nothing; though

the Registrar-General could tell them that its existence has added some 20 years totheir chance of life

One could argue about whether a single sewer can increase your life expectancy by20 years, but the quote does show a keen awareness of the link between livingconditions and public health. Interestingly, the decision to build the sewers was madebecause of a unique event, the Great Stink of 1858. The summer of 1858 was veryhot, and the river Thames stank to high heaven. The Houses of Parliament arelocated right next to the Thames and for weeks on end, neither lords nor commonscould escape the horrible stench from the river. This finally convinced them thatsomething needed to be done. Then as now, decision making in public health ishelped along by a highly visible crisis or two.

http://ehs.sph.berkeley.edu/krsmith

Indoor biomass smoke in Guatemala

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Having some sort of shelter is a near universal achievement of human beingseverywhere. We build shelters to keep us warm, and to protect ourselves and ourbelongings from a hostile outside world. Inside, we light coal and biomass fires forheating and cooking.

Almost half of the world population is still exposed to very high concentrations ofsmoke from these fires, above all in rural areas. An estimated 1.5 million women andyoung children die every year because of this. If these people had access to it, theywould use cleaner fuels and live in homes with chimneys. Health is closely linked towealth, and indoor air pollution is just one example of how this works.

http://www.newscenter.philips.com

An improved wood stove

It does not necessarily cost a lot of money to clean up the indoor environment,though. There are now encouraging examples of clean but still affordable technologywhich greatly reduces indoor air pollution. Epidemiological studies are showing thehealth benefits of introducing clean technology in China where coal smoke is themain culprit (5) and also in Guatemala where wood smoke is the problem (6).

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Indoor pollution from biomass and coal fires is largely confined to rural areas indeveloping countries, but that does not necessarily mean that urbanisation is alwaysa cure. Rapid urbanisation in developing countries has now created an underclass ofabout one billion people who live in slums with very little access to clean fuels, cleanwater and safe food. Jonas Bendiksen has made a moving book showing what its

like to live in a slum (7). We have a long way to go before the slum dogsof this worldare provided with the basic amenities which we have learned to take for granted.

Big and Smallalong theOld Canal

We heat and cool our homes for health and comfort, and a large amount of energy isgenerated worldwide for this. Heating costs money, and a few centuries ago, peoplewho could afford it would build two homes along the old canal here in Utrecht: a small

one for the winter because that was more economical to heat; and a large one for thesummer. The servants would live in the small house in summer and in the big, coldhouse in winter. A clear example of the relationship between wealth and healthyliving conditions.

For centuries, heating meant burning coal or wood, and the resulting smoke has longbeen recognized as a form of unhealthy outdoor air pollution. Complaints about coalsmoke go back several centuries in London, for example.

Monet, Houses of Parliament, London, 1905

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In the early 1900s, Monet made several paintings of the Houses of Parliament,capturing what in retrospect was heavy air pollution. There was a keen awarenessamong many in London that something needed to be done, but for a long timeauthorities were unwilling to tell Londoners to get rid of the open coal fires they loved

so much. An editorial published in 1925 in The Lancet went as far as to say that itmay require the death from fog of three cabinet ministersbefore any action is taken.

London,December 1952

And then in December of 1952, 4,000 ordinaryLondoners died in just one weekwhen stagnating weather conditions prevented the coal smoke from dissipating. Airpollution increased to extreme levels. Conditions were hard to imagine. Theatre playshad to be cancelled because even indoors, the smoke was so thick that audiencescould not see the stage. A doctor was called to a nearby patient but utterly lost hisway in his own neighbourhood. He finally found his way back to his own home, andthen called Mr. Hunter, one of his patients who was blind. The good Mr. Hunter cameover, and guided the doctor to his other patient after all, he was used to finding hisway around London without being able to see.

Since the London Smog of 1952, there have been enormous improvements in airpollution in the developed world. Nevertheless, we have learned over the last two

decades that fine particles and ozone are still of concern.

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Utrecht

Decrease in life expectancy due toanthropogenic fine particles (IIASA)

Exposure to manmade fine particles is estimated to reduce life expectancy in Europeby nine months on average and by more than one year in more heavily pollutedplaces like Holland. Air pollution nowadays is very much a function of populationdensity, and thats why The Netherlands gradually has become a hot spot in mapslike this.One year of life expectancy may not seem much in view of the average lifeexpectancy of 80 or so years. However, it is more than the mortality and disabilityeffects of all traffic accidents combined, and its the same order of magnitude as theestimated effects of the obesity epidemic. So it is clearly important to establish how

robust this estimate is, and to show that reduction of air pollution increases lifeexpectancy.

NEJM2009

Life expectancy increases in the US are

associated with decreases in air pollution

A recent study from the US suggests that this is actually the case: the investigatorsfound that life expectancy over a period of 20 years increased most in areas that had

experienced the largest decreases in air pollution (8). (Moreover, the magnitude ofthe change was exactly as predicted from earlier observational studies (9).) This is

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another example of how epidemiology takes advantage of changes in theenvironment to study the effects on public health.

You must have the impression by now that epidemiology is all about studying whats

bad for public health. But thats not quite true. I do admit that studies are most oftenprompted by some sort of public health problem, but scientifically, it is equallyinteresting to find out why some of us do not get sick.

A Bavarian farm

Slide courtesy Erika von Mutius

An example is the finding that children who grow up on traditional farms developfewer allergies than their urban counterparts. Its not completely clear why this is so,but high exposure to various microbial components on the farm is one explanation.Now we cant all go back to living on the farm, so investigators are trying to squeezethe farm environment into pills called probiotics. Results of trials have been mixed sofar, but one interesting study suggests that probiotics may prevent allergy especiallyin children born by caesarean section (10). The idea is that such children are bornsterile, and have more difficulty developing a protective gut flora early in life.

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Source: IPCC 2007

When we discuss a changing environment, it is inevitable to talk about climatechange. Climate change raises many concerns, as temperatures are projected toincrease by up to several degrees centigrade over the next century. We think that atleast part of the warming is due to manmade emissions of greenhouse gases.Climate change may affect public health in many ways. Climate change makes oursummers warmer, and our winters less cold. Both hot and cold weather kill people so an increase in heat waves not necessarily will lead to more annual deaths as theremay be fewer cold related deaths.

Cold weather kills far more peoplein the UK than heat waves do

Annual deaths from HEAT Annual deaths from COLD

In fact, analyses from the United Kingdom show many more cold related deaths inwinter than heat related deaths in summer. Climate change in the UK is alreadyreducing cold related deaths, without actually increasing heat related mortality (11).In Canada, which is much colder in winter than the UK, this is paradoxically not so;and this is because Canadian homes are much better in shielding you from the cold

than the British are (12).

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Heat waves do not kill young and healthy people; they kill subjects who are old, frailand alone. After the dramatic events in France during the heat wave of 2003, anemergency warning system was developed. When another heat wave struck in 2006,the emergency warning system was estimated to have reduced the number of deathsby more than 60% (13). But the key question is: how many months or years will the

vulnerable subjects live on after theyve been saved from the heat wave?

ERJ 2009

Heat related mortality has

increased in Stockholm

An interesting study from Stockholm provides a few clues. Stockholm is not knownfor having hot weather in summer, but even there, more people die on warmer days.

Interestingly, the effect of warm weather on mortality seems to have increased in thelast fifteen years. Since the early nineteen nineties, elderly Swedes have increasinglyreceived influenza vaccinations at the beginning of the winter season. It now lookslike this vaccination programme serves to increase the pool of susceptible subjectslikely to die from hot weather the next summer (14). Similarly, effective programmesreducing immediate heat wave effects on mortality will increase the pool ofsusceptible subjects likely to die from influenza and other infections the next winterseason.

The Grim Reaper.

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The story is a familiar one: the Grim Reaperwill get you eventually, and saving youfrom one cause of death today will set you up to die from another one tomorrow. Thisis more generally true for all causes of death: the demise of infections as leadingcause of death one hundred years ago set the scene for cardiovascular disease and

cancer to become dominant. And the recent successes in reducing cardiovasculardeaths have now propelled cancer in our country to become the major cause ofdeath.

Other health risks associated with climate change for this country include a changingdistribution of vector borne diseases; more food and waterborne diseases because ofthe warmer temperatures; a prolonged pollen season which may be bad news for hayfever patients; and more dust mite allergy because dust mites do better in mildwinters than in cold ones (15). But here we already encounter a possible interaction:the way we build and operate houses is also changing, and in our own investigationsof dust mite allergens in homes over the last twenty years we have been unable to

see an increase (16, 17). The projected sea level changes are not large enough togive us wet feet in the next century. But this may be very different for other low lyingareas in the world which do not have the sea defences we have erected after thedevastating 1953 flood. Worldwide, global warming is expected to seriouslyaggravate public health consequences of poverty such as access to safe food andwater.

Source: IPCC 2007

Temperature variations overthe last 800,000 years

It is important to realise that climate change has been the rule, not the exception onplanet earth. Long term climate records have been pieced together by geologists, icecore investigators, ocean scientists and archaeologists. This evidence shows thathuman civilisation developed in the last 12,000 years or so when the climate wasrelatively warm and stable. For much of the last 800,000 years, the climate was muchcolder, dominated by prolonged periods of glaciation which made much of thenorthern lands on this earth uninhabitable. The linein the graph shows that the warmtemperatures were having now are really exceptional. In all likelihood, dramaticclimate change will be upon us again in the deep future. Some of this is related toregular variations in the earth orbit around the sun, and in the position of its axis; not

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much we can do about that. But some of it is related to ice sheets which may or maynot melt, ocean currents which may or may not change, and volcanoes which may ormay not erupt. Evidence quoted by the IPCC suggests that the next ice age is stillsome 30,000 years away a very long time, but in geologic terms just a split second.

Some scientists have looked at the records from the deep past, and into the deepfuture and it makes for interesting reading. Three examples are the Dutch book TheHuman Measure by geologist Salomon Kroonenberg (18), The Long Summer byarchaeologist Brian Fagan (19) and The Long Thaw by David Archer whos an

ocean scientist (20). All describe the same evidence base of ice ages which comeand go, sea levels that changed by more than a hundred meters, and CO2levelswhich were twenty times higher than today in the deep past. But their outlook israther different. Kroonenberg suggests that we need to adapt to climate changerather than trying to avoid it; our distant ancestors have survived the previous iceage, and we should be better capable to handle the next one. In fact, he comparesthe current warm period to a terminal patient, whose life expectancycan be extendeda bit by pumping CO2into the air. His reasoning is that manmade global warmingmay make the next ice age less cold. Thats what Archer suggests as well but hisconcern is that sea levels will rise so much that at least 10% of the earth population

will be displaced already in the next few centuries, creating widespread potential forconflict over scarce resources. Sharp and immediate reductions in greenhouse gasemissions are needed to avoid these and other adverse effects of global warming.Apart from the technical and political challenges associated with this, there is also animportant dilemma here. A few billion people still live in extreme poverty, and a lot ofenergy will be needed to create living conditions which will allow them to lead healthyand productive lives. In the process, greenhouse gas emissions are likely to go uprather than down in the near future.

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Worldwide CO2 emissions are accelerating

PNAS 2007

Indeed, in recent years, CO2 emissions have been accelerating rather than slowingdown. If it took us fifty years to do something about a minor issue such as smoking inpublic places, we should perhaps not be too optimistic that we can seriously take onclimate change in a much shorter period of time.

JECH 2009

So what does this all mean for those of us working in Epidemiology and PublicHealth? Is climate change, as some suggest, the White Horseof the Apocalypse,spreading disease everywhere (21)? Or is it something more familiar, affecting publichealth by changing the distribution of natural resources in ways that we have seenbefore?Time will tell, and I am sure that future generations of epidemiologists will have a veryinteresting time studying the effects of these and other changes in the environment

on public health.

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PRSM 1965

In the meantime, the prospect of dramatic environmental change should not stop usfrom developing and advocating ways to improve public health on our lonely planet. Iwould therefore like to end with a quote from Sir Bradford Hills famous 1965 paperon Environment and Disease (22):

All scientific work is incomplete - whether it be observational or experimental. Allscientific work is liable to be upset or modified by advancing knowledge. That doesnot confer upon us a freedom to ignore the knowledge we already have, or topostpone the action that it appears to demand at a given time. Who knows, askedRobert Browning, but the world may end tonight? True, but on available evidence

most of us make ready to commute on the 8.30 next day.

Thank you for your attention!

With that, and with the view from my office window, I would like to thank you for your

attention!

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References

1. Pell JP, Haw S, Cobbe S, Newby DE, Pell AC, Fischbacher C, et al. Smoke-free legislation and hospitalizations for acute coronary syndrome. N Engl J Med.2008 Jul 31;359(5):482-91.

2. Jagger C, Gillies C, Moscone F, Cambois E, Van Oyen H, Nusselder W, et al.Inequalities in healthy life years in the 25 countries of the European Union in 2005: across-national meta-regression analysis. Lancet. 2008 Dec 20;372(9656):2124-31.3. RIVM. http://www.rivm.nl/vtv/object_document/o8676n41258.html (accessedMarch 6, 2009). 2009.4. Mitchell R, Popham F. Effect of exposure to natural environment on healthinequalities: an observational population study. Lancet. 2008 Nov 8;372(9650):1655-60.5. Shen M, Chapman RS, Vermeulen R, Tian L, Zheng T, Chen BE, et al. Coaluse, stove improvement, and adult pneumonia mortality in xuanwei, china: aretrospective cohort study. Environ Health Perspect. 2009 Feb;117(2):261-6.

6. McCracken JP, Smith KR, Diaz A, Mittleman MA, Schwartz J. Chimney stoveintervention to reduce long-term wood smoke exposure lowers blood pressure amongGuatemalan women. Environ Health Perspect. 2007 Jul;115(7):996-1001.7. Bendiksen J. The Places we Live. New York: Aperture Foundation; 2008.8. Pope CA, 3rd, Ezzati M, Dockery DW. Fine-particulate air pollution and lifeexpectancy in the United States. N Engl J Med. 2009 Jan 22;360(4):376-86.9. Brunekreef B. Air pollution and life expectancy: is there a relation? OccupEnviron Med. 1997 Nov;54(11):781-4.10. Kuitunen M, Kukkonen K, Juntunen-Backman K, Korpela R, Poussa T, TuureT, et al. Probiotics prevent IgE-associated allergy until age 5 years in cesarean-delivered children but not in the total cohort. J Allergy Clin Immunol. 2009Feb;123(2):335-41.11. Kovats S.http://www.dh.gov.uk/en/Publicationsandstatistics/Publications/PublicationsPolicyAndGuidance/DH_080702 (accessed March 6, 2009). 2008.12. Doyon B, Belanger D, Gosselin P. The potential impact of climate change onannual and seasonal mortality for three cities in Quebec, Canada. Int J Health Geogr.2008;7:23.13. Fouillet A, Rey G, Wagner V, Laaidi K, Empereur-Bissonnet P, Le Tertre A, etal. Has the impact of heat waves on mortality changed in France since the Europeanheat wave of summer 2003? A study of the 2006 heat wave. Int J Epidemiol. 2008

Apr;37(2):309-17.14. Rocklov J, Forsberg B, Meister K. Winter mortality modifies the heat-mortalityassociation the following summer. Eur Respir J. 2009 Feb;33(2):245-51.15. Huynen MMTE, de Hollander AEM, Martens P, Mackenbach JP. Mondialemilieuveranderingen en volksgezondheid: stand van de kennishttp://www.erasmusmc.nl/5663/135857/933005/080318_Mondiale.Definitief.pdf.Bilthoven: RIVM; 2008.16. Brunekreef B, van Strien R, Pronk A, Oldenwening M, de Jongste JC, Wijga A,et al. La mano de DIOS...was the PIAMA intervention study intervened upon?Allergy. 2005 Aug;60(8):1083-6.17. Antens CJ, Oldenwening M, Vos A, Gehring U, Smit HA, Aalberse RC, et al.

Repeated measurements of mite and pet allergen levels in house dust over a timeperiod of 8 years. Clin Exper Allergy 2006 Dec;36(12):1525-31.

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18. Kroonenberg S. De menselijke maat - de aarde over tienduizend jaar.Amsterdam: Atlas; 2008.19. Fagan B. The long summer - how climate changed civilization. New York:Basic Books; 2004.

20. Archer D. The long thaw - how humans are changing the next 100,000 yearsof earth's climate. Princeton: Princeton University Press; 2009.21. Jensen GK. Taking the reins of the white horse of climate change. J EpidemiolCommunity Health 2009 63(4):269-70.22. Hill AB. The environment and disease: association or causation? Proc R SocMed 1965 May 58:295-300