Approximately 20 to 25 of die population suffers from allergies, including hay fever and asthma. Pollen and spores arc important triggers of these conditions. The small lightweight pollen produced by many wind-polli-nated plants is the cause of suffering for millions of people. For many allergy sufferers, springtime and early fall arc when symptoms arc the worst. The pollination period for many trees is in the spring, while ragweed pollinates from mid-August through mid-October. Weather has significant effects on pollen release. Most pollen is released on warm, dry, sunny, and windy days. Cold temperature and high humidity delay pollen release, and rainfall washes the pollen out of die air. Thus, allergy symptoms may improve on cold or in this exercise, you will describe the relationships between daily ragweed pollen levels, weather, and your own (and your friends') allergy symptoms.
Insect and disease killers that come from plant extracts are called botanical pesticides or botanicals. Although derived from natural sources, botanicals are not necessarily safer or less toxic to nonpest insects, humans, and animals than synthetically derived pesticides. In fact, most botanicals are broad-spectrum insecticides, which kill both good and bad bugs indiscriminately. Some botanicals cause allergic reactions in people others are highly toxic to fish and animals and some may even cause cancer.
1 Only a limited number of pollen slides arc available commercially from biological supply houses. For the pollen in this exercise, you w ill need to make the slides yourself. The pollen can be collected from the field if you plan ahead, but it may be easier to order the pollen from a lab that prepares extracts for allergy injections. Four of til esc pollen types will also be needed to make slides for lixercisc C. Greer Laboratories. Inc. (P.O. Box 800, Lenoir, N( 28f 45 828-754-5327) stocks a wide variety of pollen types and charges about S3 to 58 per gram for common pollen types. Other labs around the country also have pollen available. One gram of each pollen type w ill be plcnry.
Acute toxicity is not the only property of a potential pesticide to be assessed. Its chronic (long lasting) aspect must also be tested. For example, its survival time on the surface of the leaf may influence its suitability, particularly on leaf crops, such as lettuce, which have a large surface area of pesticide deposit and which are eaten fresh. Pesticides must also be checked against their ability to cause irritation and allergies in humans and their ability to cause cancer. An active ingredient may be particularly toxic to other mammals, fish, earthworms, bees and predatory animals. When testing active ingredients, research workers remember very well the havoc that chemicals such as DDT caused in killing animals at the top of food chain (see also p52).
Buyers value light-brown seed above brown, and seed blackened by rain at harvest is of very low value in the market. Within Australia and in certain overseas markets seed must be tested free of salmonella, E.-coli, aflatoxin and coliform bacteria. Some in Australia want freedom from wheat or allergenic compounds. Seed sold for fresh leaf production must meet the purity and germination requirements of the buyer.
It has been suggested that a rise in the number of people susceptible to food allergies may be attributed to the introduction of new cultivars bred with methods that can trigger transposable elements. Peanuts, wheat, soy, and barley are examples of crops that may have acquired subtle mutations that trigger allergies. Extensive research would be required to confirm whether this is the case.
However, scientific groups in Italy and in the Switzerland are working on the development of cisgenic (see Chaps. 4, 6) apple plants with improved resistance to apple scab using the HcrVf2 resistance gene from the crab-apple Malus floribunda 821. A nearly identical project was started in the Netherlands. The Plant Research International (PRI), in cooperation with the private fruit breeding company Inova Fruit BV and two further partners, is also working on the development of HcrVf2 cisgenic apple varieties. Both projects are promising, but the commercialization of the first cisgenic apple cultivar in Europe is expected in 2013 at the earliest. Further objectives of ongoing projects are the development of low allergenic GM apple cultivars by silencing the major apple allergen Mal d1 and cisgenic apple cultivars with an increased amount of healthy compounds through up-regulation of the flavonoid biosynthesis using the recently identified MYB10 transcription factor of apple.
51 Ways to Reduce Allergies
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