Agro-chemicals and Chronic Kidney Disease: What needs to be doneFebruary 19, 2014, 12:00 pm
by Prof. Sunil J. Wimalawansa
A clean environment is essential for human health. Next to air, water is the most essential component required for mammalian living. Contamination of soil and water through human waste and pollution is a universal problem, but industrial waste and agricultural runoffs are serious problems, especially in urban areas. Water pollution with microbes causes noticeable diarrhoeal diseases, whereas chemical and toxic contaminations make people acutely or chronically sick and kill them silently. Chronic kidney disease (CKD) of multi-factorial origin (CKD-mfo) is one such environmentally acquired disease that is spreading outside the North Central Province (NCP).
Climate change, cultivation on sloping terrains,
and soil erosion:
The frequent high intensity and sporadic rains probably arising from climate change is increasing soil erosion secondary to deforestation and from sloping lands, especially those without adequate vegetative cover. It is easier to see a cloudy or a muddy river; it is a polluted river. It denies penetration of light to billions of aquatic organisms, causes injury to fish, carries harmful agrochemicals including excessive phosphates, and results in loss of topsoil that can take hundreds of thousands of years to reform. Moreover, these continuous soil erosions lead to major silting on reservoirs in the NCP that requiring frequent dredging which expose deploy deposited heavy metals and other toxins back into water.
Soil erosion and runoff from exposed sloping land pollutes rivers, reservoirs and ground water, and brings sickness, premature deaths, economic calamity and grief to communities that living hundreds of miles away from the sites of pollution, through no fault of them. Suffering CKD has inflicted on the people of the NCP is one such example of these environmentally harmful activities particularly in the hill-country. Overall, the damage done via pollution to socio-economic situations is enormous and it cannot be measured in financial terms. Vegetative cover should be present on all sloping lands throughout 365 days of the year. This is the right of those living and those yet to be born. Sri Lanka must get its policies right and the fundamental right of people to have access to clean water and be healthy should be safeguarded.
Negative environmental issues using excessive agrochemicals:
There is no doubt that the excessive use of chemical fertiliser and other toxic agrochemicals is not healthy to the ecosystem, environment, or human beings. Farm soils and water in reservoirs are saturated with chemicals now, particularly with phosphates, due to excessive use of phosphate-fertilisers. These unnatural soil and water conditions and the excessive use of agrochemicals are causing significant environmental damage, leading to unintended consequences including decreases of agricultural output (Figure 1). Despite these, many farmers continue to use excessive amounts of fertiliser and other toxic agrochemicals: pesticides and herbicides, with the false expectation of higher crop yield.
The overuse or abuse of artificial fertiliser and other agrochemicals is common among the farmers in Sri Lanka. These have deepened during the past two-decades. Both agrochemicals and petro-chemicals are not only potential sources of environmental pollution but also probable causes of CKD-mfo.
Meanwhile, in the future, large-scale projects such as Mahaweli, with objective of settling people, should critically be evaluated before being launched to minimise their long-term, negative human and environmental consequences. The main beneficiaries of these projects unfortunately have become dependent on unsustainable fertiliser subsidy, as experienced. Currently, approximately 3.5% of the governmental budget is spent on agro-subsidies (close to 50 billion rupees, annually). Considering the major health issues affecting the NCP and spreading to other areas in Sri Lanka secondary in part due to the overuse of fertilisers, a gradual reduction of 10% per years of this expenditure is appropriate.
In addition to polluting the environment, farmers are not using adequate protective gear (in most case none) to protect themselves from toxic agrochemicals (Figure 2), they are exposing themselves to high concentrations of toxic chemicals. These chemicals get into human bodies through the skin, via inhalation, and through the gastrointestinal tract.
Irrigations, agriculture and animal husbandry:
Currently, the development of water resources to maximise the cultivable areas and increase crop output from the irrigated agriculture is measured only on conventional economic terms. However, maximising these returns come at the expense of long-term un-sustainability, environmental damage, and consequent ill health of humans and animals. Exposure to environmental hazards affects not only human but also animals. In this regard, cows ingest high amount of heavy metals and toxins which may end up in milk and in meat. Therefore the industry and the responsible government authorities must work together to establish a unified method of testing milk and meat samples on a regular basis to assure suitability for humans consumption.
Ancient irrigation and agricultural systems produced rice over the past few centuries using environmentally healthy irrigated conditions. It also used multi-cropping, organically grown nourishing food varieties, varied landscapes such as under the canopy of natural forests, Chena cultivations, and wetlands in an environmentally sustainable manner. These also provide healthy bio-diverse spaces for livestock. We need to re-adopt these environmentally healthy agricultural systems not only to improve the environment, but also to increase the long-term agricultural output and better health of all living beings.
Fertiliser use in the country:
Drinking water, food consumption, environmental changes and exposure to agrochemicals are common not only in the NCP but also elsewhere in the country. None of the postulated pollutants alone explains the observed differences of CKD-mfo disease prevalence in the NCP versus elsewhere in the country. Considering these, it is unlikely that any of these lone is a candidate for the current epidemic of CKD-mfo.
Overuse of fertiliser in Sri Lanka:
Sri Lanka is the highest user of phosphate fertilisers and certain other toxic agrochemicals in South East Asia. Currently, Sri Lankan farmers use around 600,000 tons of solid-fertilisers and 250,000 tons of liquid-fertilisers annually (info: department of agriculture; DoA).
http://data.worldbank.org/indicator/AG.CON.FERT.ZS). These include approximately 300,000 tons of urea, 120,000 tons of triple super phosphates, 150,000 tons of muriate of potash, 50,000 tons of ammonium sulphate, and 50,000 tons of Eppawela apatite. Fertiliser use in three largest provinces is as follows; NCP, 130,000 ha; NWP, 96,000 ha; and Eastern province, 100,000 ha.
Per-hectare basis, it is estimated that NCP farmers are using four to five times and their counterparts in the Nuwara-Eliya district use up to ten times more than the recommended amounts of phosphate fertiliser. The key reasons for the overuse of agrochemicals are illustrated in Figure 4.
Phosphate fertilisers are either water-soluble or water insoluble. Examples of water-soluble phosphate fertilisers are triple superphosphate (mono calcium phosphate, commonly referred to as TSP) and relatively water insoluble rock phosphates (calcium fluo-apatite and calcium hydroxy apatite; as present in Eppawela deposit); single super phosphates, referred as, SSP.
Phosphate SSP is used for longer-term crops, such as tea, rubber, and coconut, whereas TSP is used for relatively fast-growing crops, such as rice, maize, chilli, onion, potato, and other vegetables. However, both types of phosphates are known to contain heavy metals among others, cadmium, and arsenic. In addition, recent reports suggest that TSP phosphate fertilisers distributed to farmers also contain small amounts of other heavy metals, including uranium.
Due to the insolubility in water, these phosphate complexes have to be acid solubilised first, prior to generation of SSPs. Equation for this chemical reaction is provided below:
[Ca10F2(P04)6 + 7H2S04 + 3H20 = 3Ca(H2P04)2.H20 + 7CaS04 + HF].
Irrespective of the type of phosphate, the excess fertiliser applied to soil will leach out into surface water runoffs and to groundwater, eventually leading into major rivers, water diversions, and to reservoirs. This is particularly a problem with reference to the excessive fertiliser use in the hill-country, where eventually fertiliser is drained via river Mahaweli into Rajarata. In addition, similar consequences like in the NCP are likely to manifest in the Sabaragamuwa and the Southern regions that drains via the river Walawe; particularly in the Udawalawe region. In contrast, excess fertiliser that is draining into Kelani Ganga and Kalu Ganga, flow directly into the sea. These pollutants not only affect the fauna and flora in the rivers but also the marine life and all life forms in the canals and reservoirs, disrupting the eco-equilibrium.
Phosphate fertiliser–soil poisoning:
Due to the overuse of imported, perhaps contaminated, triple super phosphates (TSP) and the local SSP chemical fertilisers that are distributed with subsidies, Sri Lankan farm soils are over-saturated with phosphate (not with potassium as some claimed). However, despite this, since early 2013, the agriculture department promoting locally produced high SSP–‘phosphate’ fertilisers. Runoffs draining to reservoirs are also having excess nitrates.
When the farm soils are saturated with phosphate, there is no rationale to flood the soils with extra phosphates by using TSP or SSP. Therefore, considering the current excessive phosphate levels in farm soil and high reservoir water phosphate levels in the NCP, the recent initiative to locally produce and market single super phosphate (SSP) seems short-sighted.
Under the current farm soil conditions, fertilisers should contain the minimum and not the maximum allowable of amounts of phosphates.
There is much to be done to educate farmers and improve their awareness of toxic agrochemicals, soil conditions, and the consequences of environmental pollution. In this regard, the DoA needs to take the lead in rectifying these. DoA should use its network of extension officers that scattered throughout the country for this awareness campaign providing a unified, effective, simple message.
In general, most phosphate deposits and consequently, phosphate fertilisers are naturally contaminated with heavy metals. Chemically, phosphate molecules can be replaced by arsenate or cadmium, so these heavy metals tends to accumulate with phosphate ions, because of their similar chemical behaviour.
Verities of imported TSP-phosphate fertilisers contain between 30 to 50 ppm of arsenic and 8 to 12 ppm of cadmium (but some consignments are known to contain even higher amounts). Meanwhile, the phosphate deposits from Eppawela also contain between 10 to 25 ppm arsenic and 3 to 8 ppm cadmium.
Both excess nitrates and phosphates decrease the levels of oxygen dissolved in water in reservoirs. In addition, excessive amounts of both these components in water in reservoirs promote the growth of unusual algae; some of these may be potentially harmfully to both fauna and flora, and perhaps, humans. This ecological imbalance are already affecting the environment and, all life forms in the area.
What should be done?
Some of the recently introduced pesticides such as neonicotinoids incorporates into plants and corps and thus, directly contaminate the food chain. Spraying of fruits, vegetables, and grains before and after harvesting with chemicals and preservatives including carbofurans and anthracols are harmful to humans, and must be stopped.
What is necessary is an effective truly grass root-level, disease-preventative programme, prevention of environment pollution and establishing a long-term surveillance programme across all affected regions.
In addition, organisations concerned with the plights of people in Rajarata should take the lead by using the media to convey the CKD-mfo prevention message and the need to protect the environment in a more effective manner.
(The writer is a professor of medicine)
Last Updated Mar 30 2017 | 09:26 pm