AND ON FIELD PRODUCE CROPS

Contaminant: Virus
Contaminant: Insecticides
Contaminant: Herbicides
Contaminant: Nitrates
Contaminant: Bacteria
Contaminant: Algaecides
Contaminant: Protozoans & Parasites
Contaminant: Minerals
Contaminant: Volatile organic chemicals
Contaminant: Radioactive
Contaminant: Drugs and Food Chemicals


The purpose of this section is to describe the contaminants that can be found in irrigation water used in field agriculture. Salad Greenhouse removes these contaminants to low or undetectable levels with a series of water treatments. The goal is to purify water for irrigation.


Fresh produce and vegetables can carry with them: billions of infective viruses and bacteria, parasite eggs, cysts and larvae; sewage residue; agricultural runoff, insecticides, herbicides, and assorted poisons and contaminants that are threats to health.

Inspections for disease causing contaminants on produce are often low to nil because of manpower and budget restraints. Produce is eaten at one's own risk. The contaminants are invisible. Eating imported produce grown under unknown conditions may do more harm than good.

The amounts of contaminants on imported produce are increasing because the demand for produce is up, and California is declining in its ability to supply the market. California food wholesalers now import produce and sell it mixed with California produce under a California brand. This is an example of what can happen in other countries as well where branding fogs the origin.

In countries other than the U.S. and Canada, irrigation can be grossly polluted because there can be no regulations or enforcement for herbicides, pesticides, and soil or air quality. Irrigation water can carry sewage, parasites, and pollutants and is applied to crops untreated and raw. The more water is recycled, the more contaminants are added. The dollar return is of prime importance and the nutrition or purity of the crop is secondary. It is calculated that the average person in the U.S. and Canada consumes over 10 lbs. of insecticides and herbicides every year. Many of these are proven carcinogens.

Food contaminants are delivered to vegetable and produce crops in the field by:

1. Sewage and polluted water: used for stream and spray irrigation.
2. Human and animal feces: deliberately spread on fields for fertilizer; dropped by wild and domestic animals.
3. Handlers and equipment: pickers spreading the contaminants among crops
4. Soil: polluted soil growing polluted crops
5. Herbicides, pesticides, fungicides, algaecides
6. Air pollution: what is in the air lands on the ground to be absorbed by crops

Cooking, washing and soaking produce before eating are some ways to reduce the exposure to contaminants in produce. Illness or disease from eating contaminated produce can best be prevented by: a) eating produce that has been grown under pure conditions, b) knowing the grower and his practices. Knowing the grower is often impossible - except for Salad Greenhouse.

SG produce is grown in clean conditions and is pollution free when harvested. Irrigation water is filtered to a pure state before it is introduced into the system.

The following is a brief look at the contaminants found in raw irrigation water and soil. When eaten with plants they can cause diseases. Plants will take up bacteria and viruses through their roots and can’t be washed off. Other contaminants can be absorbed by the leaves, as well as embedding on the surfaces. 

Contaminant: Virus


Infectious hepatitis'A'
20 to 40 day incubation; caused by virus through food water or close contact; hepatitis can also be caused by liver flukes and cysts

Infectious hepatitis B

60 --> 160 day incubation; through blood or sera transfer, needles, surgical tools; early symptoms of both = brief skin rash, general weakness and fatigue, chilliness nausea, vomiting, and itching; liver becomes tender and liver and spleen may become enlarged; jaundice or yellowing of skin appears in second stage and reaches maximum in 1 week and then subsides; may be weak for some time; relapses may lead to chronic hepatitis and scarring of liver (cirrhosis); - toxic hepatitis = hepatitis that may appear within a few hours of ingesting a toxic substance ie: alcohol, carbon tet, phosphorous, arsenic, poisonous mushrooms
- acute yellow atrophy of liver = infection or toxic materials; rapid reduction in size of liver, + extensive damage to liver cells, jaundice develops quickly which leads to sleepiness, and coma; death is usual from lack of liver function.

20 million people died in 1918 epidemic

Japanese encephalitis
Inflammation of brain; headache, fever, drowsiness,double vision, coma, or tremors

Contaminant: Insecticides

Cumulative in amounts and types in foods---- 180 different pesticides found on produce---- constant background effect----DDT still around as a residue and legal outside Can. and US---- between 1970 and 1987 the number of harmful insect species immune to one or more pesticides have more than doubled from 224 to 500---- the only justification for pesticide use is cheap food, but at what price---- there is a pesticide 'treadmill' trying to catch the superbugs---- pesticides work the same as nerve gas by disrupting the functions of the nervous system ie. inhibiting the enzyme in the neural synapses which leads to confusion, blurred vision, diarrhea, weakness, paralysis, coma, and death in humans---- estimated that 2,500,000 people a year die directly from pesticide use----use a space suit when applying; there is inadequate listing, testing and regulation---- We may be rushing headlong into an agricultural and medical dark age that existed before the discovery of insecticides and antibiotics, ie resistant microorganisms and insects---- soil bacteria have developed that feed on the insecticides---- a super beetle has developed from the Colorado potato beetle----many strains of salmonella are now drug resistant----insects and disease are the symptoms of a failing crop, not the cause of it----Avadex and Carbine do not degrade; Carbine with 1 cut can lead to death in 3 days; Carbine not on market but being used; Avadex remains in applicators system for 3 days and causes sickness----Mexican produce has DDT residue, and empty DDT drums are evident in fields----Pesticides are designed to alter or kill living organisms, and they are deliberately brought into contact with food sources----Black market vegetables from Mexico contain DDT and are sold as California produce----There are 900 registered pesticides that are now believed to cause adverse reactions---- Since 1945 45,000 different pesticide formulations with 600 active ingredients have entered the global market and testing is poor---- So far the EPA has only been able to provide assurances of safety for 37active ingredients---- Parathion is deadly but used by the ton on Mexican fruit----Phosvel used in Honduras turns victims into zombies---- Pesticide tonnage has tripled in the past 2 decades in Costa Rica, 50 years ago there were 6 companies selling pesticides, now there is 160 and many of the pesticides are being sold there because of bans in the U.S., especially Shell and Dow; Costa Rica has the highest incidence of child leukemia in the world; this is part of the 'circle of poison'---- In May 1986 the U.S. became a food importing nation for the first time since 1959---- 6% of the vegetables, and 25% of the fruits are imported from Mexico, Chile, Brazil, Argentina, Philippines, and others where there are no restrictions on pesticides; neonicotonoids are linked to bee die off

                                                        Various symptoms of
                                                        Pesticide Poisoning

DDT (bbiu)                                        cancers
Diazinon                                            confusion
*Dieldrin (bbiu)                                  paralysis
Dimethoate (bbiu)                              weakness
*DBCP                                               sight sensitivity
*Endrin (bbiu)                                    swelling & rashes
Endosulphan                                      open ulcers
*Ethylene dibromide                           hyperactivity
*Ethyl Parathion (bbiu)                       slurred speach
Carbaryl                                            breathing problems
*Chlordane                                        diarrhea
Chlordecone                                       dizziness
*Chlordimeform                                  death
Kelthane (bbiu)                                   allergy magnification
Avadex excema
Aldecarb asthma
Methathion (bbiu)
Trifluralin (bbiu)
* 2,4,5,-T

(bbiu) banned but in use
* The 'Dirty Dozen: Together these compounds cause most of the pesticide deaths and much of the pesticide damage that pesticides cause every year

Contaminant: Herbicides

Phenoxy herbicides
2,4-D (Killex, Weed n Feed) Registered 1946 as chemical warfare defoliant; agent; major component of Agent Orange; WHO & NRC report a strong association between cancers and phenoxy herbicides (2,4-D) immune system problems; large areas of South Vietnam were defoliated with 2,4-D and genetic problems are still being felt a generation later; Swedish gov't banned 2,4-D in 1989; in 2014 the USDA is considering giving permission for GMO seeds that are 2,4-D resistant enabling Dow Chemical to spray 2,4-D on US fields; 

Others in the News
- atrazine made by Syngenta is used for corn fields and is reported to be destroying insects and birds, now in US water tables; hormone disruptor and possible carcinogen, no one knows, but banned in Europe
- superweeds are now emerging that are resistant to Monsanto Roundup and Roundup suspected in bee die off

genetic defects
concentration loss
kidney ailments
memory loss
mental disturbance

Contaminant: Nitrates

Convert to nitrosamines in the digestive system and are carcinogens causing stomach and colon cancer.

Contaminant: Bacteria

Bacteria are now known to be absorbed by the plant roots to become embedded in the plant tissues while the plant is growing. Washing will not remove these bacteria.

Salmonellosis includes infection by any of 2000 types of salmonellae bacteria. Source: from ingestion of contaminated food or drink. Spread by flies

S. enterica; Enteric fever
Incubation 10 to 12 days: some mildly ill for 1 to 2 wks, others 4 to 6 wks; some cases die in a few days

Salmonella typhosa; (Typhoid fever)
Three phases
a. gradual onset of malaise, headache, sore throat and finally pea soup diarrhea, nose bleed
b. rose spots on trunk, abdominal distention and tenderness
c. slow (step ladder) rise of fever to maximum and slow decline to normal

S. schottmuelleri
; Enteric fevers; as above but shorter (1 to 3 weeks)
S. hirschfeldii; Enteric fevers; as above but shorter (1 to 3 weeks)
S. paratyphi; Enteric fevers; as above but shorter (1 to 3 weeks)

S. choleraesuis; Salmonella Gastroenteritis
Incubation 8-48 hours after contaminated food or drink; symptoms: fever and chills, nausea, vomiting, cramping, abdominal pain and diarrhea which may be bloody lasting 3-5 days with low mortality: bacteremia (bacteria in blood, which is otherwise sterile) may occur with localization in some bones or joints

Salmonella; Bacteremia
Prolonged or recurrent fevers accompanied bacteremia (bacteria in blood); bacteria may settle in any tissue causing complications such as kidney infection, pneumonia, and arthritis

Vibrio comma; Cholera
Cause: human feces contamination of water or contact with an infected person; bacteria (short comma shape) liberate a toxin which produces profuse vomiting and diarrhea; great loss of fluid; voluminous diarrhea, stool is liquid, grey, and without fecal odor; rapid dehydration; gaunt and thirsty, widespread muscle cramps from loss of salts: recovery is with water and salts; antibiotics questionable; strict sanitation & isolation; vaccine is available for 3 to 6 mos. Protection; tropical water is swarming; tea drinking and stir fry saves many; in 1991 a cholera epidemic spread to South and Central America and Mexico; cases have been reported in the U.S.

Shigella; Bacillary Dysentery
Common disease; Most dangerous and found in Orient; develops rapidly, violent often bloody diarrhea, fever, chills, cramps, nausea, vomiting; 5 or more bowel movements per hour common during first day + severe dehydration; treatment: intravenous sodium and potassium salts + chloromycetin antibiotic will relieve symptoms in 2-3 days then recovery within a week. Milder infections 2 -3 days; not ordinarily fatal except in undernourished people or in poor condition; recently, a rise in resistance to multiple antibiotics.

E. coli; Coliform Group; Gastroenteritis
Severe cramps and diarrhea; the variety O157 is found in cattle intestines and contaminates groundwater supplies. It is a virulent form of E. coli causing bloody diarrhea and sometimes death.

Leptospirosa; Leptospiroses Swamp fever
A group of diseases caused by strains of corkscrew - shaped microbes which are found in the bodies of rats, dogs, cattle and pigs, which contaminate ponds, swamps, lakes, and sloughs with their urine. The disease is worldwide and incidence is higher than usually supposed. In various parts of the world the diseases are named with respect to the type of exposure leading to infection. For example, cane field fever, mud fever, swamp fever, and swineherd's disease. Many infections have followed bathing in contaminated water. It is an occupational hazard among sewer workers, slaughterhouse workers, rice planters and farmers. Organisms are thought to enter through small breaks in the skin, or through the eyes and nose, or ingested with contaminated water or food.

These microbes can be sprayed onto crops, or introduced to crops in stream irrigation. Symptoms (in the mild form of the disease): a) fever of 39-40, chills, abdominal pain, severe headache, muscle pain especially in the calf muscles.
b) immune phase begins after the absence of fever. A recurrence of symptoms is seen as in the first phase with the onset of meningitis. Illness usually lasts 3-40 days and complete recovery is the rule. Symptoms (severe form): impaired kidney and liver function, abnormal mental status, hypotension, and a 5%-10% mortality rate.
Prevention: Antibiotics are sometimes effective but also disappointing. Other measures are eliminating the rat and other animal carriers.

Contaminant: Algaecides

Contaminant: Protozoans & Parasites

Cryptosporidium; Coccidiosis
Intestinal infection usually accompanied by diarrhea and abdominal discomfort up to 4 wks. Its associated with fatigue, flatulence, and marked weight loss. Incubation period is 7-11 days. It is rarely life threatening except for those with immune system problems. Hard shelled cysts; protects them from chlorine treatment.

Giardia lamblia; Gastrointestinal
Protozoan infection of the upper small intestine caused by the flagellate G. lambia. The parasite occurs worldwide. It can reach a prevalence of 15-20% in children of developing countries. In the U.S., Canada, and Europe it is considered the most common protozoan pathogen.The cyst form is contagious and is not affected by gastric juices. Humans are the main carriers but dogs, cats, and beavers have been implicated. Transmission is by fecal contamination of food and water, person to person contact, and food and farm workers. Multiple infections are possible in households, and outbreaks occur in day cares, and mental institutions as a result of contaminated water supplies. Campers who drink from lakes and streams, and travelers to Mexico and other countries are susceptible. The cyst form can be sprayed onto crops with irrigation sprayers, or introduced to the soil with stream irrigation. When on the soil they can be wind blown onto crops or be placed onto crops by harvesting, handling and distribution of the crop.

Balantidium coli; Balantidiasis
B. coli is a large, ciliated intestinal protozoan found worldwide, but particularly in the tropics. Infection results from the ingestion of cysts passed in the stools of humans or swine, the reservoir host. These feces are often used as fertilizer and find their way onto crops. The cysts are ingested and hatch in the intestine. They invade the large bowel causing abscesses and ulcerations. Many infections are asymptomatic and probably need not be treated. Symptoms are chronic recurrent diarrhea, alternating with constipation is most common, but severe dysentery with bloody mucoid stools, tenesmus (a straining but unsuccessful effort to defecate) and blockage may occur intermittently.

Toxoplasmidium gondii; Toxoplasmosis
An intracellular protozoan is found world wide in humans and in many species of animals and birds. Human infection results from the eating of cysts (oocysts) found in soil deposited in cat feces. Cats roam in produce fields looking for mice. The cysts find their way onto produce by being blown by the wind or during harvest handling. Symptoms: fever, malaise, headache, stiff neck, sore throat, rash confusion, enlarged liver.

Endamoeba hystolytica; Amoebic Dysentery Infection of the Large Colon.
This infection is present worldwide but most prevalent in subtropical and tropical areas where rates of infection may exceed 40% under conditions of crowding, poor sanitation, and poor nutrition. It is estimated that there are 50-100 million cases of invasive amebiasis and up to 100,000 deaths worldwide. 24 million people in U.S. are probably infected with hystolytica; in temperate areas, amebiasis tends to be asymptomatic or a mild chronic infection; more common in tropics; outside body it exists as a cyst; in this form resists drying and freezing and is easily transported on produce; when in the gut, the wall of cyst is shed and the larvae burrows into the intestinal wall; new cysts form in lower intestine and pass out via infected feces which then contaminate more water or food. Carriers of the cysts also include flies and other arthropods, farm workers, and food handlers. Where human excrement is used as fertilizer it is often a source of water contamination which finds its way onto crops.

It is logical that food and produce infected with amebic cysts can be brought into households and be transmitted to, and among family members through the common handling and eating of produce and the food touched during preparation. Person to person contact is also important in transmission, therefore all household members of the infected person and sexual partner should have their stools examined.

Symptoms: Most infected people are 'carriers' and have no symptoms; some cases have mild indigestion and fever; severe cases have diarrhea over period of 3 to 4 days + weakness, cramps, & vomiting; attacks may disappear and recur at regular intervals; severe cases may be fatal
a) mild to moderate colitis (inflammation of the colon): recurrent diarrhea and abdominal cramps, sometimes alternating with constipation, and mucus may be present,
b) severe colitis: semiformed to liquid stools streaked with blood and mucus; fever, colic, prostration. In fulminate (developing suddenly and severely) cases trophozoites invade the colon wall and produce characteristic flask shaped ulcers; bowel perforation, local abscess, or generalized peritonitis may result; this can occur anywhere in the large bowel.
c) hepatic amebiasis; due to the amoeba being carried to the liver; fever, enlarged liver, local tenderness; hepatic abscesses range from a few millimeters to 15 cm or larger.
Prevention requires the identification of carriers, safe water supplies, sanitary disposal of human feces, adequate cooking of foods, protection of food from fly contamination; and washing hands after defecation, and before handling produce, or eating, or preparing foods. In the case of produce growing, handling, and shipping, it is almost impossible to keep track of these requirements.

It is advised to avoid foods that can't be cooked or peeled if one is eating produce in areas where the produce is grown - Mexico for example. Water supplies can be boiled (briefly) or treated with iodine (0.5 ml tincture of iodine per liter for 20 min. or longer if the water is cold). Disinfection dips for produce and vegetables are not advised and no drug is safe or effective as a preventative. In the cyst form the bug can resist gastric juices. However, in Mexico it is sometimes advised to dip produce in a 10% bleach solution (1 part bleach to 10 parts water) or 1% formaldehyde solution. This is little comfort to those who eat imported produce that is covered with amebic cysts and don't know it..
It can be treated with various medications including diodoquine, oxytetracycline, and carbarsone.

Naegleria fowleri
; Primary Amebic Meningoencephalitis
Resembles bacterial meningitis and is rapidly fatal. Early symptoms include headache, fever, lethargy often associated rhinitis (inflamed nose) and pharyngitis (inflamed throat). Vomiting, disorientation, and other signs of PAM develop within 1-2 days followed by coma and then death on the fifth or sixth day. The organism is found in warm lake water, domestic water supplies, thermal water, and sewage. These sources are used for irrigation.

Tropical Flatworm (fluke)
Platyhelminthes; Bilharziais or Schistosomiasis
Infection of larvae from snails. Infects more than 200 million people and results in 200,000 deaths annually. Endemic (continuously present) in Africa, West Indies, South America, Near East & China. The larva burrows through skin to the liver and then to the whole abdominal area which becomes infected and leads to death. Symptoms are:
a) acute phase: 2-6 weeks abrupt abdominal pain, weight loss, headache, chills fever, muscle pain, diarrhea (sometimes bloody, dry cough, enlarged liver
b) chronic phase: diarrhea, abdominal pain, dry cough, enlarged liver. Prevention: don't swim wade shower unless you know the water is safe – it can be fatal. The larvae are in irrigation water.
Control is by 1 ppm CuS04, or antimony tartrate in water that eradicates the snails.

Fasciolopsis buski
; Fasciolopsiasis
A common parasite in humans and pigs in south China, Taiwan, Southeast Asia, Indonesia, eastern India, and Bangladesh. Humans are infected by eating cysts released by snails onto plants. Adult flukes mature in about 3 months and live in the small intestine. The number of parasites ranges from a few to several thousand. Symptoms: After an incubation period of 2-3 months, nausea, anorexia, upper abdominal pain, and diarrhea alternating with constipation. Irrigation water containing the cysts will spread the cysts on the crops.

Fasciola hepatica; Facioliasis; Sheep liver fluke;
Results from eating cysts on aquatic vegetables and contaminated salad produce. Herbivorous animals are the hosts. Disease in humans is worldwide by most prevalent in sheep raising countries. The leaf shape worm or fluke measures 3 cm x 1.5 cm. The infection has been reported - no doubt because of the size of the fluke - in Europe, mainland U.S.A., Hawaii, Canada, West Indies, Middle East, China, Siberia, and north, east, and South Africa.
In humans the cysts transform in the intestine and penetrate and migrate through the liver, and mature in the bile ducts where they cause necrosis and abscess formation. Although the infection is mild, three syndromes can develop: a) acute: enlarged and tender liver, high fever, pain, headache, anorexia, vomiting, and jaundice may appear. Early diagnosis is difficult because the eggs are not found in the feces for 3-4 months; b) chronic: blocked bile ducts.

Irrigation water containing the cysts will spread the cysts onto the crops. The cysts can also be introduced into the soil in manure fertilizers from sheep, or cattle.

Paragonimus westermani; Paragonimiasis; Lung Fluke
Infects humans through the Far East, West Africa,south and SE Asia, Pacific Islands, Indonesia, and New Guinea. Other Paragonimus species infect humans in China, Japan, and Central and South America.

Eggs reaching water in either sputum or feces hatch in 3-6 weeks. Larvae penetrate and develop in snails. Emergent cercariae encyst in tissues of crabs and crayfish. Human infection results when the cysts are eaten in raw, undercooked, or pickled crabs or crayfish. Or, they contaminate food vessels, drinking water, fingers, or food during preparation of the crayfish or crabs.

The cysts (metacarciae) change form and migrate to the lungs to form capsules of fibrous tissue reaching up to 2 cm in diameter. The lesion, which usually opens into a bronchiole, may subsequently rupture, resulting in the spitting of eggs, blood, and inflamed cells. The lungs may become infected resulting in a low fever, and dry cough initially. After, pain and a rusty blood flecked viscous sputum may occur.

Paragonimus is not transmitted by soil or water to humans but rather through crabs and crayfish which are often served in or with salads. Any kitchen or restaurant dealing with raw crayfish ('lobsters') or crabs imported from any of the above countries will have to deal with lung flukes or paragonimiasis.

Tapeworms (Cestodes)
Six tapeworms infect humans frequently. The tapeworms of concern are those capable being transmitted by eating plants.

Hymenolepis dimunta; Dwarf Tapeworm
Both larval and adult stages are found in the human intestine and there is no intermediate host. Eggs passed in the feces are immediately infective. Egg transmission in most cases is directly from person to person and can be transmitted in water and food. Therefore, farmers, and food handlers are distributors of the eggs onto the crops they handle. Irrigation water, whether sprayed or streamed is another method of distribution of eggs onto the crops.

Taenia solium; Pork tapeworm
Prevalent in Mexico, Latin America, Spain, Slavic countries, Africa, SE Asia, India and China. It is rare in Canada and the U.S. The pig is the intermediate host of the worm. The worm is found in its cyst form in the muscle. Humans become infected from larval stage of the worm when they eat undercooked pork. The tapeworm then develops in humans.
Humans can also be the intermediate host if they become infected with the larval stage by accidentally ingesting eggs in human feces. The eggs in human feces would be found in irrigation water containing sewage. This results in the formation of the cyst in humans and Cysticercosis follows (see below). The eggs are immediately infective. Large tapeworm infections are generally asymptomatic. Occasionally vague gastrointestinal symptoms (nausea, diarrhea, fatigue, hunger, dizziness) may attribute to infections.

Taenia solium; Cystercercosis
Caused by the larval stage of T. solium. Locations of cysts in order of frequency are: the central nervous system, skin, muscle, and eyeglobe. Symptoms: seizures, tense headache, vomiting, visual loss, altered mental status, nodules under the skin or in muscles (5-10 mm), calcified lesions on xrays of soft tissue.

Eichinococcus granulosus; Hyatid Disease
Caused by the larval form of the tapeworm E. granulosus. The tapeworm larvae may attack the liver, lungs,
muscles, bones, and other organs. Acquired from infected soil. The adult worm is found in dogs in South America, Africa, Australia, and New Zealand. Large cysts develop in the affected organs and may reach considerable size. Surgical removal of the cysts is the only treatment. If irrigation water containing this larvae is sprayed onto crops the infectious larvae will be transmitted to handlers of the produce.

Roundworms (Nematode)
Human infection results from the ingestion of infective larvae contained in uncooked food or raw produce or vegetables. The uncooked food can be either the intermediate mollusk host (snails, slugs, planarians) found in gardens and fields, or the transport hosts that have ingested the mollusks such as crabs, shrimp or fish. Leafy produce contaminated by mollusks or mollusk slime may also be the source of infection. Spray or stream irrigation water can also spread the larvae onto the crops. Incubation period is 1-3 weeks. Ingested larvae (.5x.025 mm) invade the central nervous system where during migration they may cause extensive tissue damage. Worms have also been seen in the eye. Symptoms: severe headache, fever, neck stiffness, nausea, vomiting, sensory abnormalities.

Ascaris lumbricoides; Ascariasis the Giant Intestinal Roundworm
Most common of all the intestinal worms. An estimated 1 billion people worldwide are infected. It is found in high prevalence wherever there are low standards of hygiene and sanitation or where human feces are used as fertilizer, either deliberately or in sewage irrigation water. Infection is specific for humans and occurs in all age groups although heavy infestations are found only in children.

Adult worms live in the upper small intestine. After fertilization the female produces enormous numbersof eggs that pass into the feces. Direct transmission between humans does not occur, as the eggs must remain in the soil for 2-3 week before they can become infective. Thereafter they can survive for years. If contained in the spray irrigation water the infective eggs will land on entire crops. Infection occurs through ingestion of mature eggs in fecal contaminated food, water, or infected crops.

When ingested the eggs hatch in the small intestine releasing motile larvae that penetrate the wall of the small intestine and reach the right heart via the heart veins and lymphatic network. From the heart they move to the lung, burrow up through the alveolar walls, and migrate up the bronchial tree into the pharynx, down the esophagus, and back into the small intestine where they grow to adulthood. The female worm, which reaches 14 inches in length, deposits her eggs in the intestine. Egg production begins 60-70 days after ingestion of infective eggs. Eggs pass out with feces.

Symptoms: a) Pulmonary phase: cough, wheezing b) Intestinal phase: vague upper abdominal discomfort; occasionally worms secrete poisons that can attack the nervous system and, in cases of severe infestation, nervousness, convulsions, delirium and coma may result; c) Egg passing; worms passed through rectum, nose, or mouth. Prevention: Can be cured with drugs

Dracunculus medinensis; Dracunculiasis
Occurs only in humans and is a major cause of disability. An estimated 3 million persons are infected on the Indian subcontinent, West and Central Africa north of the equator, Saudi Arabia, Iran, and Yemen. All ages are infected. Infection occurs by swallowing water containing the infected intermediate host Cyclops (copepods, water fleas) which can be found on produce and vegetables. In the stomach larvae escape from the crustacean and mature in subcutaneous connective tissue (just under the skin). The female worm which is 60 to 80 cm (24" to 32") long x 2 mm wide, moves to the body surface where its head reaches the dermis and starts a blister that ruptures on contact with water and discharges larvae which are ingested by copepods and fleas. Most adult worms gradually come out; some worms retract and reemerge; others die in the tissues, disintegrate and cause severe inflammation. Infection does not induce protective immunity.

Incubation period is 9-14 months. Most of the lesions appear on the foot and therefore people can't walk. Deep abscesses may form at the site of dying worms.

Traditional extraction of emerging worms is by gradually rolling them out a few centimeters per day on a small stick, especially if done along with drugs and sterile dressings. The process appears to be facilitated by placing the affected part in water several times a day. If the worm is broken during removal, secondary infection almost always results leading to abscess formation. Surgical removal of female worms can be done under anesthesia if they are not embedded deeply around tendons.

Creeping Larva Migrans (Creeping eruption)
CLM is prevalent throughout the tropics and subtropics, including southeastern USA, and is caused by larvae of dog and cat hookworms. The common site of infection is moist sandy soil contaminated by dog and cat feces.

At the site of larval entry, particularly on the hands and feet, up to several hundred tiny, intensely itchy red papules appear and wandering wormlike burrows appear under the skin. Two to 3 days later, eruptions appear as the larvae migrate at a rate of several millimeters per day. The parasite lies directly ahead of the advancing border. The process may continue for weeks. The lesions may become secondarily infected. With treatment the worms die.

If irrigation water containing this larvae is sprayed onto crops the infectious larvae will be transmitted to handlers of the produce.

Ascaris duodenale;Hookworm
One quarter of the world's population is infected. It is mainly in the tropics and subtropics. It causes over 50,000 deaths per year mainly in children. Humans are the only host to this 1 cm long worm. The worms suck blood at the attachment site in the upper bowel. One worm can produce 2000 to 8000 eggs per gram of feces. Eggs are found in the soil. They can be deposited onto crops with irrigation water whether sprayed or streamed, and spread during harvesting by workers or machines.

Enterobius vermicularis; Enterobiasis (Pinworm infection)
Pinworms are 8-13 mm long and common worldwide. Multiple infections occur in households with young children. Adult worms inhabit bowel areas. Female worms migrate through the anus to the perianal skin and deposit eggs in large numbers. The eggs become infective in a few hours and may then infect others if transferred by contaminated food or water, or hands. After being swallowed the eggs hatch in the duodenum and the larvae migrate down to the lower bowel to start the infection again. Contaminated irrigation water will distribute the eggs on the crop and or food handlers will spread the whipworm eggs during harvest.

Symptoms: insomnia, irritability, restlessness, itchy anal area, vague gastrointestinal symptoms. Worms are visible on perianal skin or stool.

Trichuris trichuria; Whipworm
Intestinal parasite common in people worldwide. Slender worms 30-50mm long attach by a whip like end to the large intestine. Eggs are passed to the soil where they become infective. Infections are acquired by eating an infective egg. Contaminated irrigation water will distribute the eggs on the crop and or food handlers will spread the whipworm eggs during harvest. Symptoms: Abdominal cramps, diarrhea, flatulence, nausea, vomiting.

Contaminant: Minerals

Toxic minerals in small doses over can cause disorders of bones, kidneys, nervous system, and blood Cadmium, lead, mercury = death in small doses and are the worst

Lead                Mental disability
Arsenic             Required by plants in trace quantities for photosynthesis
Asbestos          Asbestosis in lungs
Chromium         Required by humans in trace levels; toxic at high levels
Copper             Required by humans in trace levels; toxic at high levels
Mercury            Mental disability
Nitrates            Fertilizer and livestock sources
Nitrite              Poisonous in any amount in water: reject this water
Selenium          Required by humans in trace levels; toxic at high levels
Fluoride           Required by humans in trace levels; accumulation in food chain                              because its in everything, starting with water; hard to estimate end                        doseage; in large amounts considered a poison; linked to bone                              disease and cancer

Polyelectrolytes Also aluminum based flocculents in water purification; clumping makes easier filtration of particles; EPA classifies some of these as 'probable human carcinogens' & still permits use; banned by several countries.

Contaminant: Volatile Organic Chemicals

VOC's are absorbed through skin; 100,000 different chemicals

Gasoline & oils
Dioxins Pulp mills; Ontarians eat 80 times amount of dioxins liberal standards will allow
THM's Trihalomethanes; new dangerous chemicals created in water as a result of chlorine mixing with organic chemicals: these are known carcinogens; EPA says 100 ppm safe but European standards are 1 ppm.

Contaminant: Radioactive

Natural radon Radioactive pollution; cancers

Contaminant: Drugs and Food Chemicals

Antibiotics, estrogen analogues, antidepressants, birth control, aspartame soda pop sweeteners, amphetamines, hormones, sterilants, pain relievers, medical waste, etc.