CADMIUM: The 1st Class Carcinogen Served Unknowingly on Dinner Tables

iweatherman-food

Fig: A sumptuous selection of food. Food is the major pathway of build-up of carcinogenic Cadmium in our bodies (Picture from flickr.com/creativecommons)

Food especially the high fatty type always draws people closer. However, there has been an increased interest in the cultivation and consumption of healthier foods in our age due to the prevalence of lifestyle diseases. A number of people have resorted to avoiding meaty diets in order to have healthier and more vibrant lifestyle. It is however becoming increasingly clear in the scientific community that some instances of lifestyle diseases such as cancer are as a result not of the kind of diet we have but the kind of soils the plants grow on.Plants take up nutrients from the soil for growth.  However some other substances present in the soil mimic the behaviour of nutrients but have no biological significance and end up being absorbed by crops. One such kind of a substance is the rarely known Cadmium.

Cadmium is a metallic element found in the earth’s crust. Together with Lead, Mercury, Chromium and Arsenic (also known as the big five), it forms a group of highly notorious,  persistent,  top-notch and non-biodegradable pollutants generally found in the environment commonly referred to as Toxic Heavy Metals.  Cadmium is rare but quite evenly distributed on the surface of the earth mostly associated with zinc or phosphate related rocks. It is therefore present in very small amounts in agricultural soils all over the world. Even though it is not as abundant as Iron or Potassium, it has no biological significance in the body which makes it a toxic element to humans. Some heavy metals like Lead and Mercury are in the same toxic category as Cadmium. However, what sets Cadmium in a class of its own is that it is readily absorbed by some agricultural crops. What is even more stunning is that these crops such as green leafy vegetables, potatoes, some cereals, rice and even tobacco are not affected by the accumulation of Cadmium in their tissues. This makes the element available for storage in plant parts which form sources of food for humans such as the roots and tubers, leaves and even the stem. Because of its accumulation in food crops, cadmium becomes very mobile in the food chain ending up in our diets and accumulating in our bodies since it has no use biologically. This build-up of cadmium can take place over a very long time before its toxic effects are noted. According to the Centre for Diseases Control, the reduction of Cadmium in the body to half its quantity may take place after 10-30 years if no additional Cadmium is taken up (which is rarely the case).  Therefore a diet composed of food high in Cadmium levels may lead to its bio-accumulation in the body.

Cadmium has been classified adversely by several Cancer research institutes with the International Agency for Research on Cancer (IARC) which is a department of the WHO and The American Cancer Society categorizing it as  a first class carcinogen. What this means is that there is a very high likelihood of developing either lung or prostate cancer as a result of accumulation of even small amounts of Cadmium in the body. Cadmium causes cancer by damaging the DNA or inhibiting its repair. The interference with the self repair process of DNA is known to cause mutations (DNA faults) which may lead to the over- expression of certain genes which are responsible for cell multiplication or the suppression of others responsible for healthy cell destruction. It also has been known to cause the release of very toxic substances also called Reactive Oxygen Species (ROS) as a result of DNA breakdown. Cadmium is also known to be a deadly kidney toxin. It inflicts injury to the kidney tissues which more often than not leads to kidney failure. It is also known to accumulate around the liver.

SOURCES OF CADMIUM IN OUR ENVIRONMENT

Phosphate fertilizers

Phosphate fertilizers such as DAP and TSP are used in planting of agricultural crops. Phosphate fertilizers are produced from phosphate rocks called hydroxyappatite which usually contains trace levels of Cadmium. The removal of these trace amounts of Cadmium is very hard without compromising the standard of the fertilizers or may be too expensive. Therefore quite some amount Cadmium finds its way into the soils and by extension crops through fertilization.

judson-reid-maize-and-buckwheat

Fig: Well fertilized corn field. Cadmium enters our food chain through phosphate fertilizers (Picture by flickr.com/creativecommons)

Plastic stabilizers

A substance known as Cadmium Stearate is used as a plastic stabilizer in the manufacture of plastics. This is a substance added to the plastic material to make it more resistance to temperature and pressure thereby boosting its durability. Such trace amounts of Cadmium can be released into foods stored in such kinds of plastics or even in the air when these plastics are burnt.

Industrial Processes

Several kind of industrial processes release Cadmium into the environment. Nickel/Cadmium battery plants may release effluents rich in Cadmium into the nearby sewers; Zinc ores might release traces of Cadmium into the environment during smelting processes; and some electroplating processes may also lead to the release of cadmium into the soil and water around the industries. Some industrial processes involving high temperature may also release traces of Cadmium Oxide into the atmosphere.

Waste

The amount of toxic heavy metals contained in waste material is considerably high. This is because these materials are not biodegradable thus end up being released from a source to an accumulator called a sink and on many occasions,  the vicious cycle is continuous with no end in sight.  Some of the important waste sources are such as incinerators, burning rubbish, sewage and industrial waste.

AKA_Eutrophication

Fig: Wastewater. Cadmium and other toxic heavy metals are re-introduced into the environment through human and animal waste (picture through flickr.com/creativecommons)

Natural Activities

Natural occurrences such as volcanoes can release some traces of heavy metals like Cadmium into the atmosphere and even onto soils. This is however less of an occurrence.

CADMIUM EXPOSURE ROUTES

Food

Food perhaps is the most potent exposure route especially to an unsuspecting population. Crops grown on soils even with trace amounts of Cadmium lead to the accumulation of the element in the crops and later on in the food sources. Continuous consumption of such foods by an unsuspecting population will expose them to a build-up of the toxin leading to medical complications. Also, livestock which are exposed to pasture grown on cadmium contaminated soils may lead to the accumulation of the substance in their kidneys and livers leading to its transfer to the meat consumers up the food chain.

Pollution

Burning rubbish can be one of the most subtle modes of exposure to Cadmium. Plastics which have been stabilized by Cadmium compounds can end up releasing cadmium in the atmosphere in the form of Cadmium Oxide which is known to be a very potent carcinogen when inhaled. Human and animal wastes are also very key sources of cadmium which is being excreted after being bio-accumulated in the body for a long time.

Tobacco Smoking

The tobacco leaves are known to be very conducive hosts for cadmium. This means that tobacco smokers face a double risk of Cadmium toxicity through smoking and even through food.

PRACTICAL STEPS TO REDUCE CADMIUM TOXICITY

Buying Vegetables from reputable sources

Since Cadmium accumulates more readily in leafy vegetables, it is essential to be careful when purchasing and consuming them. Vegetables grown near rubbish dumpsites and sewer lines have a greater risk of Cadmium accumulation. It is important to ensure that the vegetable sources one is consuming are from a hygienic environment in order to mitigate against heavy metal contamination.

Washing Vegetables thoroughly

It is important to wash vegetables thoroughly before cooking them in order to remove traces of Cadmium if possible. A good practice is washing the vegetables three times in clean water. Also ensure to wash one’s own hands during and after washing the vegetables.

Eating a balance diet

The dependence on one form of food might lead to over exposure to considerable Cadmium levels. Leafy vegetables, potatoes, some meats like beef and some cereals like maize have been known to accumulate considerably higher levels of Cadmium compared to other crops. In order to reduce the risk of exposure, it is essential to diversify one’s diet to include fruits, pulses etc. Also foods rich in vitamins E and C found in colored foods like fruits are known anti oxidants which reduce the toxicity of Cadmium in the body.

 

References and further reading

https://www.ncbi.nlm.nih.gov › NCBI › Literature › PubMed Central (PMC)

www.efsa.europa.eu/sites/default/files/scientific_output/files/main…/980.pdf

http://www.cfs.gov.hk › Programme Areas › Risk Assessment in Food Safety

 

https://www.atsdr.cdc.gov/phs/phs.asp?id=46&tid=15

 

https://monographs.iarc.fr/ENG/Monographs/vol100C/mono100C-8.pdf

 

http://www.cdc.gov › NIOSH Publications & Products › Publication Types

http://pressroom.cancer.org/releases?item=245

Advertisements

PAHs: The Indiscriminate and Silent Carcinogens among us

SONY DSC
SONY DSC

Fig: Burning of garbage can be one of the most potent and common sources of Polycyclic Aromatic Hydrocarbons (Photo by Mark Williams courtesy of flickr.com/creativecommons).

Ever enjoyed a sumptuous meal of roasted meat? It is a delicious and sumptuous delicacy loaded with cancer- causing potential due to the presence of polycyclic aromatic hydrocarbons (PAHs).  Polycyclic Aromatic Hydrocarbons (PAHs) are a class of organic chemical compounds found generally everywhere in the environment. They are polycyclic derivatives of the Benzene ring (a six- carbon hexagonal compound which is cyclic in nature). Some of the most popular PAHs include naphthalene (used in disinfection in toilets) and phenanthrene.  They are usually found in the environment as a result of incomplete combustion of fuel from vehicle engines, incinerators, fossil fuels, forest fires, tobacco smoke and also high temperature cooking of foods such as meat and vegetables.

The International Association for Research on Cancer has classified a number of PAHs as carcinogens or potentially carcinogenic including naphthalene derivatives such as naphthylamines and pyrene derivatives such as benzo-pyrene. PAHs can be inhaled through the air or ingested through foods. They are not completely metabolized in the human body ending up as very reactive species capable of causing mutating changes in the DNA structure resulting into conditions such as cancer. PAHs have been known to be culpable of stomach, skin, lung and liver cancers. Due to their prevalence in everyday life, it is essential to appreciate the routes of exposure to them in order to find ways of minimizing their effects in our lives:

AIR POLLUTION

This is the most common way through which PAH exposure takes place. Populations living in urban areas or on the road sides have a high likelihood of exposure to PAHs due to the incomplete combustion of diesel in vehicle exhausts. Many vehicles emit a high amount of PAHs from their exhausts resulting into air pollution and exposing the population around to cancerous risks. Also, forest fires and the usage of fossil fuels such as charcoal for cooking may expose many people especially in the developing nations to higher risks of cancer due to exposure to PAHs. Populations living near industries, especially those using fossil fuels like coal, may also be exposed to high PAHs levels in the environment.

francesco falciani

Fig: Air pollution from industries. A major source of PAHs in urban areas (photo by Francesco Falciani through flickr.com/creativecommons)

DIET

Foods such as meats cooked under very high temperatures can result in the formation of several forms of PAHs. When foods are cooked over a low and regulated heat, the disintegration of the organic bonds in the food is gradual resulting into much more tender and healthier foods as opposed to when they are cooked under extremely high heat which results into incomplete breakdown of the chemical bonds in the foods producing some PAHs. Smoked or roasted foods are very big carriers of PAHs and if ingested regularly may increase the chances of development of several kinds of cancers.

marilyn acosta

Fig: Roasted meat on a grill. High temperature cooking methods such as roasting may end up elevating the levels of PAHs in foods leading to more instances of Cancer (Photo by Maryline Acosta through flickr.com/creativecommons)

TOBACCO SMOKING

Tobacco is composed of a cocktail of PAHs. It also contains other cancer causing substances such as Cadmium and benzene derivatives therefore making it one of the most potent causes of cancer of the lungs. Secondary smokers are also at the risk of interacting with the PAHs from tobacco which could result into cancer.

Polycyclic Aromatic Hydrocarbons are very potent carcinogens due to their metabolism in the body. They are usually completely broken down by some animals but are not fully metabolized in Humans leading to the formation of very reactive intermediates in the process. These reactive intermediates can alter the structure of DNA through bonding or transferring of important DNA bases leading to gene mutation and ultimately cancer. Some of the well known potentially cancer-causing PAHs include naphthalene and pyrene derivatives. Some enzymes have however been known to deter the cancer causing effects of these PAHs in a number of cases thus suppressing the occurrence of cancer.

PAHs are environmental pollutants which should be of concern at the local and national level. Monitoring of the levels of PAHs requires the usage of techniques such as liquid chromatography and mass spectrometry. These instruments could be stationed government environmental or quality control labs.

References and further reading

https://www.epa.gov/sites/production/files/2014-03/documents/pahs_factsheet_cdc_2013.pdf

https://www.dhs.wisconsin.gov/chemical/pah.htm

http://www.idph.state.il.us/envhealth/factsheets/polycyclicaromatichydrocarbons.htm

https://nepis.epa.gov/Exe/ZyNET.exe/30003UP9.TXT?ZyActionD=ZyDocument&Client=EPA&Index=1991+Thru+1994&Docs=&Query=&Time=&EndTime=&SearchMethod=1&TocRestrict=n&Toc=&TocEntry=&QField=&QFieldYear=&QFieldMonth=&QFieldDay=&IntQFieldOp=0&ExtQFieldOp=0&XmlQuery=&File=D%3A%5Czyfiles%5CIndex%20Data%5C91thru94%5CTxt%5C00000002%5C30003UP9.txt&User=ANONYMOUS&Password=anonymous&SortMethod=h%7C-&MaximumDocuments=1&FuzzyDegree=0&ImageQuality=r75g8/r75g8/x150y150g16/i425&Display=hpfr&DefSeekPage=x&SearchBack=ZyActionL&Back=ZyActionS&BackDesc=Results%20page&MaximumPages=1&ZyEntry=1&SeekPage=x&ZyPURL

https://uk-air.defra.gov.uk/networks/network-info?view=pah

https://en.wikipedia.org/wiki/Polycyclic_aromatic_hydrocarbon

AFLATOXINS: A Cancerous Battalion hidden in Food

Aspergillus fungi twin and twin trading cdc

Fig: A microscopic view of the Aspergillus fungus (Photo by Twin and Twin Trading/ CDC through flickr.com/creativecommons)

Aflatoxins are poisonous chemicals released by a special kind of fungi called the Aspergillus species. These fungi dwell in dry foodstuffs such as maize, peanuts and groundnuts. Aflatoxins can also be found in livestock milk after the animals feed on pasture infected by these fungi. Aflatoxins have been known to cause liver cancer if ingested over time. Since maize and peanuts are staple foods in many parts of the African continent, there is a need to mitigate against Aflatoxin contamination of these foodstuffs to avoid a growing Cancer epidemic.

Aflatoxins are produced by two kinds of fungi called Aspergillus parasiticus and Aspergillus flavus. These fungi can be found in dry foodstuffs such as maize, peanuts, legumes, cereals and even in groundnuts. There are four major types of Aflatoxins produced which include B1, B2, G1 and G2 types. Aflatoxin B1 (AfB1) is the most potent type which has been classified by the International Agency for  Research on Cancer as a class 1 carcinogen. Aflatoxins can also occur in milk if the livestock feed on feeds that have been infested by the Aspergillus species fungi. They are metabolized and then converted to a different but potent form of Aflatoxins called either AfM1 or AfM2.

Intl Instut of Tropical Agric

Fig: Maize Infected by Aspergillus Fungi (Photo by International Institute of Tropical Agriculture through flickr.com/creativecommons)

Since the Aspergillus fungi grow on maize and peanuts, the likelihood of great exposure to aflatoxin poisoning exists for those populations which rely on maize and peanuts as major food sources. This puts many populations in the developing nations at risk of aflatoxin poisoning. In order to avoid the possibility of exposure, it is advisable to purchase foodstuffs like maize meal and peanuts from reputable retail outlets. Also, before purchasing, observe for signs like discoloration, mold or shriveling of nuts and maize. Storage of these foodstuffs must be in cool and dry conditions to avoid such contamination. It must be noted that Aflatoxins are extremely hard to remove due to the prevalence of fungi in many foodstuffs. Good food storage especially in cool and dry conditions is essential in reducing the possibility of aflatoxin poisoning. 

Aflatoxins have a variety of health effects in the body. Aflatoxicosis is a condition resulting from the poisoning of the human body due to the ingestion of Aflatoxins which may result into death. They can also be taken in the body through breathe especially by farmers or farm workers in fungi infested areas. Liver Cancer is the major ailment brought about by ingesting of Aflatoxins. Aflatoxins are also known as DNA mutating agents (substances that cause an alteration of the DNA pattern) which are some of the major causes of cancer in humans. The most potent of the Aflatoxins in its carcinogenicity is tge B1 type. 

The concentration of Aflatoxins in food stuffs can be determined using a technique called liquid chromatography. In this procedure, a portion of the foodstuffs is reacted with an organic liquid capable of dissolving the Aflatoxins from the foodstuffs. This aflatoxin solution is then subjected to a chromatographic column which detects its presence in solution and even quantifies it’s concentration in mg or ng/L. other more modern methods of aflatoxin quantification include the use of a High Performance liquid Chromatography and Enzyme Linked Immuno- Sorbent Assay or ELISA.

Aflatoxin contamination can be mitigated against by the use of substances that bind to the Aflatoxins thereby reducing their bio-availability in the body. Silicates (Sands) such as zeolites, montmorillonite and various clays have been used in reacting with Aflatoxins in cattle feeds. They are able to reduce their bio-availability thus reducing their toxicity to the animals’ bodies.

References and further reading/

http://poisonousplants.ansci.cornell.edu/toxicagents/aflatoxin/aflatoxin.html

https://www.cancer.gov/about-cancer/causes-prevention/risk/substances/aflatoxins

https://ec.europa.eu/food/safety/chemical_safety/contaminants/catalogue/aflatoxins_en

https://medlineplus.gov/ency/article/002429.htm

http://ajcn.nutrition.org/content/80/5/1106.full

SUSTAINABLE AGRICULTURE: In an age of Unsustainable Food Prices

1195791077_bacff0506d_z

Fig: A collection of peppers (Photo by Jay and Mellisa Malouin through flickr.com/creativecommons)

Today, many nations in the developing world are taking the hit from elevated food prices. This is even in the midst of availability of food during bumper harvest seasons. In Sub-Saharan Africa and more specifically in nations like Kenya, where over 50% of the population lives below the United Nations poverty line coupled with an ultra high unemployment rate, the cost of food has been a greater problem than the availability of food. Natural occurrences (triggered by careless man-made effects) like drought and famine have brought about the worse-case scenario involving access to food for the most vulnerable in the society and the lack of government goodwill to implement measures to cushion these deadly effects on their populations.

High food prices is however not an issue that can be approached in an isolated manner. There are conditions that lead to the build-up of the hellish situations the most vulnerable in the society go through when it comes to accessing food at an affordable cost.

TH LAND ISSUE

Land being an instrument of production is very vital in the production of food. In nations like Kenya, the land tenure system can be communal based, individually owned or owned by the state or any of its agents like the County governments on behalf of its people. However, the mismanagement of the agricultural sector and the lack of confidence in the land ownership system in Kenya has led to the overuse of land as a speculative tool rather than a tool of agricultural production. Areas that once teemed with cash crops have now been converted into real estate neighborhoods attracting very high prices. On the other hand, some small-scale farmers who have struggled for long to eke out a living from their agricultural activities have ended up selling or leasing out their parcels of land. The advent of  industrial farming, where huge multinationals and nations like Saudi Arabia, Kuwait and China lease huge parcels of land from African nations, has brought a ray of hope in the area of food production however it is still yet to be seen whether it is a sustainable venture. This is because this kind of land use arrangement has a very adverse effect on the ecosystem due to the over-use of farm inputs such as pesticides, fertilizers and an over-reliance on mono-cropping which will lead to an increase in instances of pests and diseases. Implementation of land reforms and promotion of local farmers cooperatives for small and medium scale farmers in nations like Kenya holds the promising key to unlocking the full sustainable agricultural potential of producing food at an affordable cost.

COST OF FARM INPUTS

In nations like Kenya, a few individuals with strong political connections have a lion’s share control of the fertilizer sector. Worse still, there is not even one known and acknowledged fertilizer manufacturing plant in the nation which prides itself as having an agricultural- based economy. Food prices will always soar as long as the fertilizer trade is controlled by an oligopoly bent on making the maximum profits from the pockets of poor and impoverished farmers. It is also interesting to note that these same fertilizer oligopolies run large industrialized farms through their proxies thereby subsidizing the costs of fertilizers to themselves but doing the opposite to the peasant farmers. Food prices are also pushed up by the use of expensive pesticides many of which are used very ineffectively such as by spraying indiscriminately leading to wanton destruction of and ecosystem hindering future agricultural production.

URBANIZATION

Urbanization plays a very important role in the increment of food prices. Because of the need to get employment, many rural folk choose to migrate to urban centers in order to look for opportunities of employment. However, if not successful, many of them end up living in squalor in informal settlements. Whereas they might have been able to produce some food at home for consumption, they are now reduced to buying food from the markets thereby increasing the demand but reducing the supply of the same. Increased urbanization without looking for alternatives to feed the growing urban population might lead to increased food prices.

References and Further Reading

https://www.theguardian.com/environment/2008/nov/22/food-biofuels

www.springer.com/cda/content/document/cda…/9789400705180-c2.pdf?SGWID

http://www.ucsusa.org/food_and_agriculture/our-failing-food-system/industrial-agriculture/hidden-costs-of-industrial.html#.WL0UBtJ97IU

https://www.nap.edu/read/12832/chapter/12#522

http://www.fao.org/organicag/oa-faq/oa-faq5/en/

http://www.sciencedirect.com/science/article/pii/S0306919212001285

https://www.theguardian.com/business/2013/jul/21/philip-clarke-tesco-farmers-interview-jay-rayner

http://rstb.royalsocietypublishing.org/content/365/1554/2809

http://pubs.iied.org/pdfs/G03114.pdf

SUSTAINABLE AGRICULTURE: The Role of Nanotechnology in Water Management and Disease Control

luciana-christante

Fig: A Titanium Dioxide Nano-particle seen through a Scanning Electron Microscope (Photo by Luciana Christante- flickr.com/creativecommons)

Water management is a very important aspect of commercial farming. Water pollution and the climate change crisis have significantly reduced the available fresh water resources making it necessary to redeem the already existing polluted reserves for profitable farming. Water pollution has a very damaging effect on agriculture. This is because agriculture consumes a huge amount of the fresh water reserves thus competing with other priorities such as domestic and aesthetic usage.

WATER POLLUTANT REMOVAL

Nanotechnology plays a very key role in the removal of pollutants from water to make it safe for domestic and agricultural usage. Some of the significant (though not exhaustive) areas in this regard are very briefly highlighted below:

Treatment of water salinity

Water salinity is the presence of salts in the water. Whereas some salts are useful in agriculture e.g. Calcium, Magnesium and Potassium salts some others especially the salts of Sodium are very detrimental to agriculture leading to high soil salinity and crop failure. Some technologies such as reverse osmosis have been tried and tested successfully, have prohibitive costs especially to the local farmer. One of the areas of progress in nanotechnology is in the field of thin film membranes for filtration of these metallic ions (5). These membranes are usually formed out of nano materials called zeolites which are embedded in a polymer matrix for removal of specific salts like those of Sodium. These zeolites can be ‘fine-tuned’ to scavenge specifically for these ions in water in order to render it usable for agriculture. These Thin Film Membranes have been known to remove over 99% of salts in water when used effectively.

Removal of Pesticides

Pesticides pose a very real threat to the existence of fresh and potable water in many areas of the world. Poor agricultural practices have led to dramatic levels of toxicity in fresh water leading to death of aquatic life. Pesticide removal is one of the areas where active research is taking place due to the level of toxicity of some of these farm chemicals. Another emerging area of interest in substances called ‘endocrine disruptors’ some of which are pesticide- related and have an adverse effect on the hormonal system of humans. One of the most formidable ways to neutralize pesticides in water is by the use of Titanium Dioxide or TiO2, also known as titania (6). Titania nanoparticles use their surface and the presence of Ultra-Violet rays from the sun to deactivate these toxic compounds in water rendering it useful for agriculture and domestic use.

tio2-luciana-christante

Fig: Titanium Dioxide Surface seen through a Scanning Electron Microscope. (Photo by Luciana Christante- flickr.com/creativecommons)

Removal of Pathogens

The introduction of pathogens or harmful microorganisms into fresh water systems takes place at specific points in the water system. This may be through open defecation in water ways, discharge of untreated sewage effluents at specific points or even the disposal of contaminated material in water. Harmful microorganisms are known to cause diseases in humans but could also infiltrate into the crops through irrigation and infect them with deadly diseases. Silver nanoparticles and carbon Nanotubes (4) are known to have a deadly effect on many of these microorganisms and can therefore be used to treat water before its employment in agricultural or domestic use.

Nutrient removal

Nutrients are agricultural substances that are beneficial for the growth of crops. They include Nitrogen, Phosphorus and Potassium. The presence of nutrients in water is as a result of over fertilization and especially the use of phosphate fertilizers. These polluted waters might not affect agriculture directly but may cause the development of algae in surrounding water bodies and wetlands which might lead to them drying up and affecting the surrounding ecosystem negatively. These nutrients such as Phosphates and Nitrates can be removed from the water using natural adsorbent materials such as zeolites (2). Upon removal from the wastewater, the nutrients can then be recycled back to the farm and employed as fertilizer to the crops.

IRRIGATION

Nanotechnology can play a very vital role in irrigation systems. Drip irrigation system is highly dependent on pressure which drives the system and ensures adequate water supply to each crop for the required duration of time. Sometimes however, the pressure of water being supplied to specific crops is altered due to certain reasons such as the relief or clogging due to salinity. Pressure sensors on the drip lines can be employed especially in precision farming to ensure that the pressure used to supply water to all crops is equalized to reduce instances of over watering and under watering of some crops. Zinc Oxide nano-particles are known to function as ultra sensitive pressure sensors (3). This is because of their characteristic of responding electrically to any small changes in pressure. This makes them ideal  for detection of small water pressure fluctuations using an electrical or electronic read-out which might lead to poor irrigation.

luciana-christante-zno

Fig: Zinc Oxide Nanoparticles as seen under a Scanning Electron Microscope. (Photo by Luciana Christante- flickr.com/creativecommons)

PESTICIDE DELIVERY

Pesticide delivery in agriculture has always relied on the traditional spraying methods. These methods utilize huge amounts of pesticides, harm the environment and endanger the lives of the workers transferring a huge cost to the farmers leading to hiking of food prices. Nanotechnology has opened up research frontiers in the field of smart pesticide delivery. Here, there is targeted delivery of pesticides to specific regions of the plants that need them and at the required doses (1). Nano materials called fullerenes (carbon structures shaped like a soccer ball) are able to ‘cage in’ the pesticide particles and improve its solubility in plant cell fluid delivering it to the required region promptly. This method also guarantees slow release of the pesticide particles in the crop system to ensure complete eradication of the infection. Another frontier of research is in the usage of natural polymer nano particles such as cellulose in pesticide delivery since they are biodegradable and won’t linger in the crop system after successful action.

References

  1. Mohamed Ragaei and Al-kazafy Hassan Sabry. NANOTECHNOLOGY FOR INSECT PEST CONTROL. International Journal of Science, Environment ISSN 2278-3687 (O) and Technology, Vol. 3, No 2, 2014, 528 – 545

 

  1. S. Bolan a,*, L. Wong b , D.C. Adriano. Nutrient removal from farm effluents. Bioresource Technology 94 (2004) 251–260.

 

  1. Patel, P. MIT Tech Review (2007)- https://www.technologyreview.com/Nanotech/18266/

 

  1. Xiaolei Qu, Pedro J.J. Alvarez, Qilin Li. Applications of nanotechnology in water and wastewater treatment. water r e s e arch 4 7 ( 2 0 1 3 ) 3 9 3 1 -3 9 4 6

 

  1. Lind, M.L., Ghosh, A.K., Jawor, A., Huang, X.F., Hou, W., Yang, Y., Hoek, E.M.V., 2009a. Influence of zeolite crystal size on zeolite-polyamide thin film nanocomposite membranes. Langmuir 25 (17), 10139e10145.

 

6. Nadia Aïcha Laoufi, Fatiha Bentahar. Pesticide removal from water suspension by UV/TiO2 process: a parametric study. Desalination and Water Treatment Vol 52, 2014 Issue 10-12.

SUSTAINABLE AGRICULTURE: Tackling Water Scarcity

2009 World Water Day: Effects of Water Scarcity

Fig: Parched and highly saline Soil (Courtesy of United Nations Photos through flickr.com/creativecommons)

Water is an important factor in agricultural production. According to the Food and Agricultural Organization, water usage in agriculture accounts for around 90% of the fresh water resources in Africa. Realities such as global warming leading to climate change have further altered the weather patterns in many places around the world leading to an increase in desertification and drought. This has led to an increase in hunger especially in many developing nations around the world.

A new approach to the management of water for agriculture involves the measurement of the food production per drop of water. This is a popular strategy used in agriculture land management where the food production is linked to the acreage. The efficient utilization of water resources for agriculture can be approached from various angles by a farmer desiring to use sustainable practices for food production (Adapted from the Food and Agricultural Organization {FAO}):

PRECISION AGRICULTURE

Precision agriculture or Precision Ag can be defined as the practice of utilization of plant specific information such as soil, water and nutrition requirements, seed sowing positions and vulnerability to different pests in order to identify the best locations and seed intensity necessary for cultivating specific crops for maximum yields.  In many cases, instruments such as GPS scanners are employed to scan for the soil moisture, nutrient levels, pH among other parameters to determine the desired locations for specific crops. The crop water requirements can be determined specifically together with their fluctuations during wet and dry spells for volume specific delivery to the crops. Also, the specific crop nutrients can be ascertained for crop nutrition purposes. More efficient irrigation methods such as drip irrigation which is more crop specific as opposed to flooding methods can help us preserve water in agriculture. Precision Ag is a potentially formidable mode of agriculture for the future to help us in tackling global challenges such as water scarcity.

CLIMATE CHANGE

Farm activities such as irrigation, ploughing, transportation and post-harvest processing are usually powered by fossil- based fuels. These sources of fuel are known to increase the amount of carbon dioxide in the atmosphere (carbon footprint) leading to the increase in the global surface temperatures due to the ability of carbon dioxide to trap heat from the sun. This in turn leads to an alteration of the global weather resulting into more instances of continental drought and famine.  An intentional and renewed focus towards renewable energy sources such as solar energy could mitigate against such adverse effects albeit in small ways. This is despite the fact that the greatest contributors to global warming are large industrialized economies like the US and China which are hostile towards international Climate Change agreements such as the Rio or Paris Pacts. Farmer mobilization however is still an important strategy to use in succeeding on this front. The ease of applicability of renewable energy especially solar power in activities such as drip irrigation management is great since farming is an outdoor activity.

un-photo

Fig: Water scarcity in an African Community (Courtesy of the United Nation Photos through flickr.com/creativecommons)

POLLUTION PREVENTION

Water pollution is an endemic problem worldwide. Substances such as pesticides, industrial chemicals, heavy metals, sediments, harmful micro-organisms human and industrial waste and pharmaceuticals among others are known to render water unusable for domestic purposes and agriculture. Water pollution prevention strategies might involve safe domestic disposal of pharmaceuticals; safe disposal of domestic waste water; limited or no usage of pesticides; and discouraging of practices such as open defecation in fresh water resources such as rivers and lakes. Also, new technologies for water purification are needed to treat water and render it useful for agriculture.

ALTERNATIVE WATER SOURCES

Since water is a scarce commodity in the globe today, there is a need to find and establish several water sources a farmer could use to extract it. One of the most important reservoirs of water especially during the rainy season is the soil. However, unsustainable practices such as over-fertilization lead to the increase in soil salinity and soil compaction resulting into most of the rainwater being drained as run off.  Practices such as mulching, conservation tillage and growing cover crops will lead to retention of the soil structure resulting into higher water retention by the soil boosting crop performance. These water conservation methods can be employed together with irrigation to conserve make more water available for farmers.

MULTIPLE USES OF WATER

Farm water could be utilized for more than one activity in order to maximize the usage. Farm wastewater can find uses in other areas where it could be utilized profitably instead of discarding it. A good example is in hydroponics farming where water from the fish pond is utilized for fertigation (fertilization through irrigation) of the crops.

CROP PROTECTION

Crop protection strategies involve development of intervention methods which ensure good crop performance even in the midst of stresses such as pests, diseases and water scarcity. Drought resistant crops are an important step in the right direction in mitigating the effects of climate change and drought. In Kenya, the Katumani maize, which is a drought resistant crop produced by intensive cross breeding has performed very well in water stressed regions. According to the John Hopkins Water Magazine, scientists are exploiting the possibilities of assessing the individual DNAs of specific crop species in order to determine the performance of their hybrids under stressed conditions such as water scarcity.

References

http://www.fao.org/3/a-i6459e.pdf

http://water.jhu.edu/index.php/magazine/agriculturemeeting-the-water-challenge

FAO Aquastat, 2005, World Resource and Earthscan “Water for food, water for life” Institute

2030 Water Resources Group; Charting our Water Future, Economic framework to inform decision-making; Dec 2009; http://www.2030waterresourcesgroup.com/water_full

http://stud.epsilon.slu.se/7257/1/khan_t_h_140909.pdf

http://www.water.ox.ac.uk/120416conference/6-falkenmark.pdf

http://rsta.royalsocietypublishing.org/content/371/2002/20120410

SUSTAINABLE AGRICULTURE: Integrated Pest Management

parthiban-m

Fig: A feeding locust (Courtesy of Parthiban M through flickr.com/creativecommons)

Pest control presents one of the most formidable challenges to food security. The emergence of chemical resistant pests and infections has led many agricultural and chemical companies coming up with newer and more potent pesticides to control these emerging pests. However the use and over use of pesticides presents a very key environmental challenge today. Organo-chlorine pesticides such as DDT, dieldrin and methoxychlor have been known to persist in the environment for tens of years depositing in fatty tissues of domestic animals rendering their meat inedible. More potent and recently formulated pesticides such as Organo phosphates possess a high level of neuro toxicity not only towards the pests of concern but also towards humans. The excessive utilization of these pesticides in modern day agriculture has therefore presented a challenge about their sustainability due to their environmental toxicity which has led to pollution of water sources, a loss in biodiversity and rising cases of cancer and respiratory diseases.

Integrated Pest Management (IPM) is a smart practice applied in sustainable agriculture which entails using pesticides to the minimum in the control of pests. IPM as it is called emphasizes on the identification of the pests of concern, monitoring their damaging effects, employing preventative measures, using environmentally acceptable control methods and then assessing the impacts of these control methods (Adapted from the US Environmental Protection Agency & University of California, Agriculture and Natural Resources Dept.). For our scenario, we shall use the whitefly which is a common pest in many crops as a case study.

IDENTIFICATION

This is the first step in carrying out an IPM strategy on possible crop pests. It entails the identification of the pest’s habitat; scouting out for its presence; and understanding its life cycle. This step requires keenness and engagement in researching on the life cycle of the pest and talking to other farmers who have succeeded in the same area cultivating your crop of interest. In our case study, one could scout for the presence of whiteflies on the crops by shaking the stems and the leaves and checking out for their eggs on the lower side of the leaves. A farmer could also check out resources about the life cycle of the whiteflies, its habitat, its breeding cycles and multiplication. Identification helps the farmer to understand the pest of concern in order to take pest- specific action in the future.

MONITORING

This involves scouting for the possible damage the pests have done to your crops and checking on their possible multiplication in order to decide whether the pests warrant your attention and make a decision for the best management strategy. One could check on the physiological conditions of the plants (the stem, leaves, fruit production etc.) in order to see if the pest damage has become of economic concern. In our case study, white flies are known to pierce the leaves and suck them dry of fluid. One can check on the rate of leaf desiccation and make a decision about the significance focusing on the pest in order to avert crop failure.

fao-emergencies

Fig: IPM involves robust identification of the pests. Farmers from Guatemala investigate their maize crops for possible pest infestation (Courtesy of FAO Emergencies through flickr.com/creativecommons)

PREVENTION

Preventative steps are best taken after fully understanding the pest and before cultivation of the crop of concern. It is therefore essential that the farmer is able to understand the first two steps above from another experienced farmer in order to forge his/ her preventative strategies. Some of the possible preventative strategies may include using disease- resistant seed varieties, creating a hostile environment for the pest to thrive or creation of barriers for the pest to access the crops. Whiteflies are known to thrive in conditions of high temperature. One of the strategies could be to plant the crops in a greenhouse and control the temperatures to prevent their multiplication. Also, the green house will form a good preventative barrier for the pests when trying to access the crops. Preventative strategies do not involve any chemical, biological or chemical interventions but only an adjustment of the already set conditions to create hostility for the pests to thrive.

CONTROL

Control methods are modes of intervention a farmer may put in place to prevent the pests from getting out of hand and doing maximum damage. In IPM, the control measures need to take into concern the well-being of the community around the farm and also the environment.

Biological Control: Biological control entails the employment of natural enemies of the pests in order to control their numbers. Insects such a beetles and ladybirds are known to be able to control the multiplication of other pests. Biological control can involve the introduction of a new species which has not existed before, the boosting of an already existing species of predator insects or a maintenance of an already existing adequate number of predator species for adequate pest control. For the case of the white flies, some of their natural enemies include the big-eyed bug, the lace wings and the pirate bugs.

Chemical Control: This mode of control involves the usage of pest- specific pesticides or naturally extracted pesticides like pyrethrins. The emphasis is on the reduction of damage to the environment and on people. Instead of spraying the pesticides randomly, they can be employed in bait situations to target the pests specifically. This is to minimize the effects of these pesticides on other useful organisms. For whiteflies, their preferred positions is at the underside of the leaves. So pesticides can be chosen which have the ability to act specifically on the underside of the leaves for maximum control and less collateral damage.

Mechanical or Physical methods: This involves the creation of barriers, usage of sticky trap hangings or even practices like soil steam sterilization to kill the pests. Growing crops in enclosures such as greenhouses creates useful barriers for some pests which target crops. Whiteflies are known to be attracted to bright colors. So the employment of yellow sticky traps around the farm will reduce their numbers considerably.Also using reflective mulch can repel pests like whiteflies from the underside of the leaves. 

Cultural Methods: These involve the alteration of farming practices in order to provide a hostile environment for the pests to thrive. For example watering methods such as sprinkling or over head can watering could provide conducive environments for the emergence of weeds. These could be replaced by other methods such as drip irrigation.

ASSESSMENT

Assessment of the impact of the control methods in the control of pests and the effect to the environment is important. This can be attained by observing the numbers of the pests and noting their reduction, evaluating the crop recovery and performance after the interventions, evaluating the collateral damage of chemical interventions such as the physiological effects on the crops or the destruction of other useful organisms.

The IPM strategy of farm pest management offers two major advantages: reduced agricultural input costs due to the reduction of spending on excessive pesticides; and promoting environmental safety by the use of methods that are friendly to the environment.

References

https://www.epa.gov/managing-pests-schools/introduction-integrated-pest-management

http://www2.ipm.ucanr.edu/WhatIsIPM/

http://www.fao.org/agriculture/crops/thematic-sitemap/theme/pests/ipm/en/

http://npic.orst.edu/pest/ipm.html

https://nysipm.cornell.edu/

http://ipm.ucanr.edu/PMG/PESTNOTES/pn7401.html

 

Further Reading

www.ipm.msu.edu/

http://extension.psu.edu/pests/ipm/what-is-ipm

www.epa.nsw.gov.au/pesticides/integratedpestmgmt.html