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LOGGED TO DEATH: THE IMPACTS OF THE TROPICAL TIMBER INDUSTRY ON HUMAN HEALTH
By Simon Counsell
The human health aspects of the tropical logging industry are usually overlooked. However, there is growing evidence that the human health costs of rainforest logging are significant, if difficult to estimate fully. This paper suggests that, at best, the tropical logging industry, and those that advocate its continuance and expansion, are directly undermining the achievement of Millennium Development Goal 6, which seeks to reduce suffering from diseases including malaria and HIV-AIDS.
Malaria
The relationship between the incidence of malaria and modification of tropical forests has long been appreciated. Several governments, including those of Uganda and Guyana have recognised the relationship between loss of, and damage to, their forests and the incidence of malaria. A recent study in the Peruvian Amazon has shown that the incidence of malaria vectors, Anopheles darlingi, increased more than 200-fold in deforested areas compared with intact rainforest (Vittor and Patz 2006). The increase in mosquito populations appears to be due to the availability of standing water suitable for reproduction. This is often caused by ponding of streams and rivers through road and skidder-track construction, blocking of watercourses by erosion and logging debris, deep ruts and gullies caused by heavy equipment and lorries, as well as stagnant pools occurring in and around logging camps. Clearance of overhead vegetation can also cause a reduction in the acidity of surface water, thus creating better conditions for anopheles mosquitoes to breed (Patz 2000).
HIV-AIDS
There is evidence that HIV-AIDS may have originally been transmitted to humans via bushmeat, and subsequent adaptation, of Simian Immunodeficiency Disease (SIV), which is present in various sub-species of chimpanzee in West-Central Africa 's forests 1 . This indicates the danger of proximity of humans to such sources of disease, but there is also growing evidence of the role of commercial logging in the spread of HIV-AIDS.
Logging concessions, in Africa and elsewhere, create conditions in which sexually-transmitted diseases are likely to proliferate: high concentrations of mostly male manual workers, often migratory and without their families, enjoying regular cash income, located in remote areas where levels of wealth amongst the local female population is often also very low. One recent study in Cameroon , carried out in a village where a sawmill and logging camp is located and two nearby villages, has shown that nearly one quarter of women aged 25- 34 were infected with HIV (compared to an 8.3% infection rate for this gender-cohort in Cameroon 's East Province as a whole) (Laurent et al 2004). In a context in which loggers had relatively high salaries (US$60 to US$530 per month), sexual networks were extensive and complex. An estimated 40 female sex workers were permanently living in the logging camp. In addition, around 100 women from towns or neighbouring villages visited the camp once a fortnight at the time of salary distribution, to trade or offer paid sex. This would be a fairly typical scenario for most logging operations across the Congo Basin .
In addition to the introduction of HIV into remote forest areas, it is likely that logging camps also serve as a nexus for infection, with the disease being spread out along log extraction and transportation routes by truck drivers – though this aspect has not yet been the subject of specific study.
Outside Africa , the only other reports of a relationship between the forest industry and HIV-AIDS have come from Burma where, according to Global Witness (2003), logging and an associated influx of migrant workers in Kachin state has led to an increase in social problems including prostitution, HIVAIDS and drug abuse.
Other diseases
The full range of diseases likely to be promoted by the combined effects of forest habitat change and new settlement has not been fully documented. However, as noted in a Harvard Medical School study, 'the majority of important vectors of human and animal diseases [are] found in the rich biodiverse tropical rain forest ecosystems, woodland savannahs, and the edges of these ecosystems' (Chivian 2002).
The proximity of humans to such vectors encourages their adaptation to human hosts, especially when alternative hosts in the form of large mammals become locally scarce (Chivian 2002). The killing of bushmeat by logging workers, their dependents, and other people attracted along logging roads, to supplement their usually meagre incomes, is only adding to this problem.
Much of what has been noted above concerning malaria is also true of dengue and dengue hemorrhagic fever; any environmental or cultural changes encouraging the proliferation of mosquitoes is likely to promote the spread of dengue if the disease is present in the area or in those traversed by logging industry workers (Gratz 1999). A study in South America reveals the links between the human invasion of forests and exposure to diseases including yellow fever, and rabies transmitted by vampire bats (Brandling-Bennett and Francisco Pinheiro 1996).
Conclusions and recommendations
There is strong evidence that industrialscale logging operations in tropical forests are closely linked to the spread of a range of serious, often fatal diseases, especially malaria and HIV-AIDS. In addition, there are good reasons to fear that further new diseases will emerge from forest areas undergoing modification, both because of environmental change as well as the proximity of larger numbers of humans to disease vectors. This strongly suggests that the promotion of commercial logging in tropical forests runs directly counter to Millennium Development Goal 6, which aims to combat HIV/AIDS, malaria and other diseases.
To a certain extent, these problems could be mitigated through improved health-care provision and screening. However, in other cases, it is difficult to see what steps can be taken in practice, as the causes for the spread of disease are fundamentally related to the nature of tropical logging. Therefore, the hidden human health costs associated with tropical logging concessions should be assessed and internalised within the calculations of national governments and international agencies that promote the expansion of industrial logging in the tropics, and compared with the net economic value of alternative forms of forest management.
Footnotes: 1 http://www.med.harvard.edu/chge/biobrief.html
References
Further information:
Simon Counsell, Director
The Rainforest Foundation
Email: simonc@rainforestuk.com
Note: This article has been adapted from a longeressay, which can be obtained on request from the author.