Health effects of fertilisers and pesticides: A critique

A report entitled “Health effects of fertilizers and pesticides” has been submitted to the authorities on 22, October, 2021 by Dr. S. H. Munasinghe of the Ministry of Health. The report may be read at: https://dh-web.org/place.names/posts/MinistryOfHealthReviewAgroChem2021.pdf

We believe that Dr. Munasinghe has attempted a very fair and competent evaluation of the situation, especially in boldly stating that there is as yet no direct link between Kidney disease and agrochemicals. However, what he can say may be constrained by government policy. As independent scientists, we present more wide-ranging comments on the Ministry document below.

In particular, the Health Ministry Review (HMR) nowhere mentions how the use of agrochemicals increased harvests and cut down the worst of all diseases, namely, MALNUTRITION. It boosted life expectancy from 48 years in the 1950s to 80 years today, and reduced infant mortality to near zero.

1. The HMR cites Ekanayake et al (2009), and Chandrjith et al (2009) to state that there are traces of heavy metals and metalloids in the agrochemicals used in Sri Lanka.

Records reveal that nearly 3.5 million premature, non-communicable disease deaths, for example, in 2017, were from stroke, ischemic heart disease, chronic obstructive pulmonary disease, lung cancer, respiratory infections, and diabetes.

Records reveal that nearly 3.5 million premature, non-communicable disease deaths, for example, in 2017, were from stroke, ischemic heart disease, chronic obstructive pulmonary disease, lung cancer, respiratory infections, and diabetes.

Indeed, we know the amounts of trace metals or contaminants in conventional agrochemicals, while this is usually unknown with organic fertilizers although, in effect, they add MORE contaminants, as shown in item 5.

Sri Lankan standards

Sri Lanka uses a standard requiring that only fertilisers containing 5 mg of Cadmium (Cd) per kg of fertilizer be imported to Sri Lanka. In contrast, Canada allows 889 mg of Cd/kg of fertiliser as being safe.

No other country has such a ludicrously small value for the cutoff “standard” for cadmium. May be all agrochemicals that enter the country become “substandard”. Hence importers have to “facilitate” the approval of all agrochemicals using “kickbacks”!

Even with agrochemicals 10 times more polluted than the Sri Lankan standard, simple calculations show that changes in concentrations of toxins in the soil (e.g., a hectare ploughed to 20 cm plough-blade depth, with 100 -200 kg of the fertilizer/ha) are undetectably small.

2. HMR cites Weggler et al (2004) to state that “contaminated” fertilizers used since the green revolution may have increased heavy metals and metalloids in the soil and ground water aquifers.

The HMR statement is incorrect, and does not follow the latest research on Cadmium accumulation in soils. See the journal EG&H, i.e., “Environmental Geochemistry and Health, volume 40, pages 2739–2759 (2018). In EG&H it is shown that the heavy-metal accumulation in soils due to agriculture is minuscule. Even if 10 times more contaminated fertilizer were used in Sri Lanka for a century, it would have little impact, especially given the ambient concentrations of cadmium in the soil (see EG&H).

3. In its 4th paragraph the HMR refers to Perera et al (2021) and states that “Sri Lankan scientists have reported that paddy soils in the Mahaweli Development areas (most of the CKDu endemic areas) are polluted with toxic metals”

This reference is to the Hindawi Journal of Chemistry, vol. 2021, Article ID 6627254 | https://doi.org/10.1155/2021/6627254. Hindawi is an Egyptian publisher once considered predatory that improved its practices a bit. The paper by Perera et al contain fallacious references and indicates the uncritical peer review used.

Nevertheless, the main thrust of the article is the very opposite of the HMR position.

We quote from Perera et al (2021):

“Mean concentrations of heavy metals/metalloids such as Mn, Co, As, Cd, Pb, Cu, Zn, and Fe in drinking water of CKDu endemic areas were far below Sri Lankan water quality standards (permissible limits)”.

Nevertheless, in Sec. 3.3 Perera et al say

“Sri Lankan scientists reported that paddy soils in Mahaweli development areas (most of the CKDu endemic areas) are polluted with potentially toxic metals, and paddy soils in Sri Lanka are highly modified by artificial fertilizer applications [35].

However, Ref .[35] has little to do with Sri Lanka and refers to metal toxins in Vineyards in Sauo Paulo, Brazil !

Perera et al (2021) say:

“urea which is commonly used in paddy cultivation as well as other cultivation in Sri Lanka has contained toxic metals such as Cd, As, Cr, Pb, Zn, and Cu in noticeable amounts. Apart from that, potash and triple superphosphate that are applied in the paddy cultivation also have contained significant amounts of … toxic metals except Cd and As. Furthermore, the risk of accumulation of toxic metals is augmented due to the limitless application of fertilizers in paddy cultivation”.

These arguments have no merit as the chemical analyses the authors give are for the total amounts of these elements, but NOT for the bio-available amounts.

Only the bio-available amounts must be considered for health risk assessment. Furthermore, the presence of large amounts of Zn has the effect of counteracting the toxic activity of any bio-available cadmium (see EG&H).

Perera et al themselves say even in the Abstract that the water (in contact with these soils) contains metal toxins only at very safe levels. Thus, the water soluble (i.e., in effect bio-available) heavy metals in the soil are negligible. So, the agrochemicals have not created a health hazard and this is confirmed by the biomass of micro-organisms, earthworms etc., found in these soils, though not measured by Perera et al or the Health Ministry.

When soils are ploughed, egrets and other birds flock to eat the abundant earthworms and other soil micro-organisms exposed by the ploughing process. This too shows that the soils are not toxic.

Perera et al (2021) say that “risk of accumulation is augmented due to the limitless application of fertilizers in paddy cultivation”. This is seen to be false by simple calculations (e.g., see EG&H, volume 40, pages 2739–2759) where the added toxins, the amounts carried away by run off etc., are taken into account in mass-balance and toxin-accumulation equations. Such calculations show that the cadmium (or arsenic) concentration increment in the soil by agriculture is completely negligible compared to what is naturally present in the soil.

Perera et al uncritically cite Jayasumana et al in the “Journal of Natural Science Research (JNSR)”, a predatory journal (i.e, a “for-profit” journal not supported by a learned society and unconcerned by factual correctness). In JNSR, Jayasumana, Paranagama and Amarasinghe fallaciously state that soils do not naturally contain As, Cd and such toxins, and that they are of agricultural origin! They seem to believe that the cadmium concentration in the soil must increase with depth if the source of cadmium is from “nature”! That soils are formed by the weathering of rocks in the top soil exposed to air appears unknown to these authors! Recently, at a TV programme titled “Pasa and Wasa” (Soil and Toxins”) a pediatrician turned agriculture advisor to the President also attempted to argue that top soil has more heavy metals as a result of fertilizer application, and was ridiculed by the participating soil experts!

4. From page 3 up to almost the end of page 5 of the MHR, Dr. Munasinghe now ASSUMES that there are unsafe levels of metal toxins and proceeds to list the adverse health effects of them, even though Perera et al showed that bioavailable heavy metals were far below WHO thresholds.

However, the MHR signed by Dr. Munasinghe CORRECTLY says that “it is unlikely that low-level exposure to agrochemicals has an impact on the development of CKDu”.

5. The report fails to address the presence of metal toxin pollutants in organic fertilizers. Plants accumulate metal toxins, and products like straw, or cow dung may contain hundreds of times as much cadmium as the soil. So, if such straw, land or sea weed etc., are used in composting, the resulting compost will also be correspondingly higher in metal toxins.

While a kilogram of Eppawala rock phosphate contains 20-30 mg of Arsenic (Gunwardhana 1987), a kilogram of organic fertiliser may contain only 2 mg of as per kg. However, only about 50 kg/ha of rock phosphate are usually used in most crops whereas about 5 tonnes of organic fertiliser need be added to meet the phosphate requirement. So the total arsenic from the organic fertiliser is 10,000 mg per hectare, while that from mineral fertiliser is only 1000 -1,500 mg per hectare!

6. On page 11 the MHR by Dr. Munasinghe gives 7 recommendations. We cannot understand the logic of the recommendation “subsidize organic fertilizer”. No fertiliser should be subsidized. They should be used strictly as dictated by a chemical analysis of the soil.

Composting for Organic fertiliser produces large amounts of methane, CO2, and reactive nitrogenous compounds that are greenhouse gases that Sri Lanka is committed to cut down.

MHR fails to note that if agriculture were to become totally “organic”, there will be a crop loss of 20-30% with serious repercussions to both the farmer and the consumer, and then malnutrition, the worst disease of all, will return with harvests typical of the 1940s!

7. The HMR notes that urea contains heavy metals/metalloids. This is true for nano-urea as well. All nano- fertilzers pose a great danger to health. (see https://island.lk/human-health-and-nano-fertilisers-where-is-the-safety-clothing/).

Conclusion

In conclusion, there is overwhelming evidence that consumption of water from dug wells in high ground containing hard water and fluoride is the cause of the kidney disease, and people consuming water of rivers, streams, reservoir or wells in the planes do not contaminate the disease. There is no clear evidence linking agrochemicals or heavy metals and CKDu. Regrettably, the government has failed to accept this fact, and the President and ministers continue to blame agrochemicals in their public speeches in regard to CKDu! No politician utters a word about ambient air pollution, which records reveal, caused 3.5 million premature, non-communicable disease- deaths, globally in 2017, for example, from stroke, ischemic heart disease, chronic obstructive pulmonary disease, lung cancer, respiratory infections, and diabetes. We urge the health authorities to provide more discreet advice than done in the report to them and the government at large on this matter.