Are toxinsi (particularly Persistent Organic Pollutants (POPs) and Polychlorinated Biphenyls (PCBs) present in dangerous quantities in the air, water, and soil of Baguio City and are these linked to the persistent causes of morbidity in the City, particularly respiratory diseases (i.e. upper respiratory tract infection, asthma) and skin diseases (dermatitis), as well as to the persistent causes of mortality in the city such as cancer and internal organ diseases (kidney, vascular)? What are the social pathways of health risk exposure among those afflicted with the diseases?
These are the questions I raised in a presentation in my Urban Environment Management class. The topic was the nexus between Environment and Economy and the professor wanted us to identify a scenario and develop a conceptual framework demonstrating the linkage among population, resources, environment, and development.
City health data in the period 2001/2002 up to 2009/2010 showed that upper respiratory tract infection is consistently in the top ten leading causes of morbidity. In the years 2009 and 2010, dermatitis figured in the top ten list. Asthma is a cause of morbidity in 2009. In the same period, consistent in the top ten leading causes of mortality is cancer, ranked third for four consecutive years. Internal organ (kidney) diseases spiked in 2009. The health reports cited air and water pollution as well as lifestyle choices as risk factors.
The City has no data on local pollution, but on a national scale the 2005-2007 National State of the Brown Environment Report reveals that sources of water pollution came from, primarily domestic sources (e.g. septic sewage) at 33%, followed by agriculture-livestock (29%), industry (27%), and nonpoint (11%). Of the nonpoint sources, majority came from agriculture runoff (74%), followed by forest runoff (23%), and urban runoff (3%). In the same period and on the same scale, air pollutants came primarily from carbon monoxide with pollution load contribution at 50%, followed by nitrogen oxide (15%) and volatile organic compounds (15%), particulate matter (11%), and sulphur oxide (9%). The report cited “aerial spraying of pesticides” as among the causes of air pollution.
Reading through ancillary studies such as done for Manila and Batangas Bays, I learned that these waters were found to hold organic pollutants, many, such as DDT, are toxic to humans and should have been banned. Cross referencing this with the 2005-2007 National State of the Brown Environment Report showed inconsistency as when the report maintained that these internationally-banned chemicals have been locally-banned and are not in use.
Further reading of other related literature such as past articles in newspapers showed fears of excessive use by farmers of chemicals in agricultural production, the fears borne out of the lack of pesticide use monitoring by the responsible government agency.
Returning to Baguio City, the national data and trends coincide with local trends. Like the City’s population’s health status, the City’s ecosystems such as its rivers, streams, and wildlife such as birds are not exactly in the pink of health. For example, in Loakan where the City’s largest watershed is and ironically EPZA is located, streams in the area are severely polluted as could be initially observed by their color and smell. Industrial waste continue to be dumped into these, to the point that the air there, especially in the 90s into the early 2000s, reeked of sulphur, and rainwater loaded with suspicious yellowish sediment (I didn’t know about acid rain then).
Locals who resided in the area since the 40s saw the gradual loss of birds in the area until there is hardly one now. They said the birds’ “extinction” or departure is due to insectide use, hunting, deforestation (hence loss of habitat), and industrial pollution of the streams and rivers the birds depend on. They said the insect-eating birds were poisoned after eating off insects from plants sprayed with insecticides. They said with the disappearance of birds, the local ecosystem lost one natural eliminator of insects. (Incidentally, blackbirds are increasingly replacing the lost native birds in the area.)
What is done in a certain place to change the natural balance of natural resources there will affect other places, neighboring and far, through the biogeochemical cyclesii, and elements exposed to and eaten biologically accumulates and magnifies. These are the two principles in biology used to argue for the (short- and long-term) effect of toxins on humans.
In relation to the questions mentioned in an earlier paragraph there could be two biogeochemical/nutrient cycles at play:
In the nitrogen cycle (a biogeochemical cycle), overload of nitrogen from anthropogenic activities acidifies rivers, and migrating nitrogen from inorganic fertilizers, automobile gasoline, and fossil fuel combust with oxygen to produce nitrogen oxidesiii. Through chemical reaction, nitric oxides with sulfur dioxide form into sulfuric acid and nitric acid, components of acid rain. These acidic emissions are a regional phenomenon, meaning these are carried by winds across the world’s regions into localities.
In the water or hydrologic cycle (another biogeochemical cycle), in the process precipitation water molecules loaded with nitric oxides fall as acid rainiv. Through evaporation, Persistent Organic Pollutants are distributed across the world, regionally and globally, explaining in part how these chemicals accumulate in ice in the polar regions. In hotter areas, the residence time of POPs is quite short hence their transfer to the atmosphere is greater in these areas. This might be viewed as favourable for areas within the tropics however on a regional or global scale this means volatilized residues move quickly from the tropics into cooler regions. Water filtration and purification is disturbed through land use change such as covering the soil with pavement and buildings which reduces recharge of aquifers, because water can no longer penetrate the ground. Groundwater cannot cleanse itself of degradable wastes as quickly as flowing surface water does and so non-degradable wastes such as lead and arsenic remain in the water permanently.
In the phosphorous cycle, overload of phosphates from runoff of fertilizers into rivers and lakes “kill” these bodies of water by producing explosive growth of algae and cyanobacteria that in turn “kill” organisms in these bodies. Incidentally, this is why phosphorous is used in fertilizer production as it stimulates lush vegetation growth. (Not only do phosphate-induced algal growth in rivers but also in runoff winding its way out of cement and stone walls along roads, seen in the green and yellowish streaks where the water made its path.)
(In nature (without humans) there is no waste as matter or nutrients are recycled again and again. The earth came with a given supply of nutrients and to maintain this supply nature recycles these for its use. Fabulous. It is when humans enter the scene with their activities that take away too much too soon from nature before it could reproduce back sufficient supply and that create too much waste for organisms to naturally degrade and recycle that produce imbalance and a whole lot of problems. Also, imagine how the cycles and biological processes such as biomagnification play out on a global scale and one arrives at an important principle in ecology, which is interconnectedness.)
In relation to how elements find their way into human cells, the two processes below are cited:
Bioaccumulation is the mechanism of cells to selectively absorb and store a great variety of molecules, allowing cells to accumulate nutrients and essential minerals. Alternatively, cells may also absorb and store toxic substances through the same mechanism. Humans accumulate persistent toxins in their bodies from the air, water, food, and surroundings.
A 1990 study in the Philippines showed that endosulfan was the leading cause of pesticide-related acute poisoning among subsistence rice farmers and mango sprayers. In 2005 a study conducted by the Dioxin, PCBs, and Waste Working Group of the International POPs Elimination Network (IPEN) Secretariat showed that in Barangay Aguado in Cavite, free range chickens near the medical waste incinerator showed dioxin levels that exceeded the European Union limit by more than three fold. In Benguet Province, Dr. Charles Chen did a study among vegetable farmers that linked the toxic effect of female estrogen-mimicking pesticides and inorganic fertilizers on human particularly women’s reproductive health. In the scientific community, studies are being made on the effect of PCBs and POPs in “feminization” of males.
Biomagnification occurs when the toxic burden of organisms at a lower trophic or feeding level is accumulated and concentrated by a predator in a higher trophic levelv. In the figure by W. Cunningham, the chemical DDT is taken in by phytoplankton and bacteria from water or aquatic sediments. At the next feeding level, their predators, zooplankton and small fish, retain the toxins, building up higher concentrations of toxins and so carnivores – game fish, fish-eating birds, and humans – being the predator at the topmost level in the food chain finally take in very high toxin levels. There is nothing humorous therefore in a local “joke” about tilapia “fattened” with with so-called “waste” in a certain dam lake. Also with the joke about eating too many chicken that apart from having been injected with antibiotics and growth hormones are fed on fertilized food.)
Weaving these information together, I used the framework promoted by the WHO, which applies social ecology to understand environmental impacts on health. The framework is hinged on the theory that social and political contexts create social stratification which in turn determines social position (social order; rich, middle class, poor) in society. (At this point, the professor interjected that I may have to add in a person’s resistance to a disease hence the biological make up of the person. I said “right, ‘survival of the fittest’!”) Social stratification determines exposure and vulnerability (collectively, the pathways) to health risks and consequently to health outcomes. For example, looking into what social strata do majority of the afflicted with upper respiratory tract infections or cancer (in Baguio City) belong to? What are their (social, biological) vulnerabilities? And what is the pathway in their actual exposure to the disease? Ill health has serious socioeconomic impacts and these feed back into the disease causal pathway further deteriorating the individual’s health or into the context of society influencing socioeconomic development (“healthy citizens make for a productive economy”). Risk exposure is examined through the Environmental Risk Assessment methodology involving the steps, hazard identification, release assessment, exposure assessment, consequence assessment, risk estimation, dose-consequence assessment, risk characterization, risk management.
The actual research of the problem is another matter altogether.
i Some chemical compounds, according to W.Cummingham in Environmental Science: A Global Concern, are very unstable and degrade rapidly under most environmental conditions but there are more persistent substances that last for years or even centuries and because they are semi-volatile their occurrence could either be in the vapor phase or absorbed in atmospheric particles hence facilitating their transport to great distances from their source or place of use, and for which their presence is a matter of concern. These substances, also characterized by low water solubility and high lipid solubility, are classified as Persistent Organic Pollutants, and include insecticides such as dieldrin, DDT (dichloro diphenyl trichloroethane), toxaphene and chlordane, and industrial chemical products or byproducts such as polycholorinated biphenyls (PCBs), dibenzo-p-dioxins (dioxins) and dibenzo-p-furans (furans).
ii Movement of matter within or between ecosystems; caused by living organisms, geological forces, or chemical reactions.
iii A greenhouse gas three hundred times more potent than carbon dioxide.
iv Acid deposition or acid rain has a number of harmful effects such as its contribution to human respiratory diseases and leaching of toxic metals such as lead and mercury from soils and rocks into water bodies contaminating these and where these accumulate in tissues of fish which are in turn eaten by other fishes, birds or humans. Acid deposition along with other air pollutants such as ozone affect forests by leaching calcium and magnesium from soils hence depriving plants of these essential nutrients. Mountaintop forests are especially vulnerable to acid deposition because they tend to have thin soils with little buffering capacity and are bathed almost continuously in highly-acidic fog and clouds. The Cordilleras come to mind.
v The industrialization and globalization of the food system contributes to the process in new powerful ways as humans intrude into natural food webs with the introduction of chemicals. In the name of cost-efficiency and just in time supply of global demand, hamburger patties, for instance, are made in huge batches using meat trimmings from multiple carcasses. A DNA analysis by Colorado State University researchers found that the average four-ounce patty contains tissue from fifty-five separate cows and some patties had tissue from more than a thousand animals. Each of the cows, coming from various places around the globe (where the meat is cheapest), was fed and handled differently. Further to this is the lengthy use of antibiotics on livestock (which has produced through a vicious cycle new breed of resistant bacteria that in turn necessitate invention of ever powerful antibiotics). In this global food system, control of one’s food hence health has grown out of reach from the end-consumer. In supermarkets, the urban consumer is faced with a dizzying array of produce and behind each of the produce, fresh and canned or processed, local and imported, is an interesting food chain story waiting to be discovered, if consumers care to know.