Ingestion, pesticides

The general population will be exposed by ingesting pesticide residues on certain foods, so most of the tests will involve administration of the... 

Assume further that the only use of pesticide Q is to treat certain insect pests on apples that are to be consumed as fresh fruit (no juice). Our expert on human food consumption patterns and rates tells us that high-end consumers of apples, those consuming at the 95th percentile of the distribution of consumption rates, eat approximately 0.3 kilograms (300 grams) each day (about two-thirds of a pound). If these consumers are not to ingest pesticide Q intakes in excess of... 

The general population will be exposed by ingesting pesticide residues on certain foods, so most of the tests will involve administration of the chemical mixed into the diets of the test animals. Some studies in which the chemical is put into a vapor or aerosol form will be conducted because some pesticide workers may inhale the substance. Skin toxicity studies are also needed because of possible pesticide worker exposures by this route. The principle here is straightforward try to match the routes of exposure to be used in the tests to the likely routes of human exposure. 

Understanding the disposition of chemicals in organisms and how the body deals with a chemical once exposure has occurred should be described using the principles of toxicokinetics and toxicodynamics. The former includes the study of the time course of the disposition primarily of xenobiotics and examines the role of absorption, distribution, metabolism, and excretion (ADME) on toxicity. Each one of these components can be influenced through structural changes. Toxicodynamics includes the rate of absorption and excretion. This time-dependent phenomenon represents how fast certain chemicals can enter and leave the human system. Pesticides create problems to human and animals because they persist and remain in the body after ingestion. Pesticides are also time-dependent phenomena and represent how fast certain chemicals can enter and leave the human system. 

Encapsulated dia2innon sold as Knox-Out 2FM is a commercial encapsulated pesticide formulation said to have reduced dermal and oral toxicity as well as prolonged effectiveness. The capsules, prepared by interfacial polymeri2ation, are claimed to be highly effective against cockroaches with no objectionable odor and low insect repeUence. The capsules are beheved to function as a contact poison when insects walk on it and as a stomach poison when insects preen capsules stuck to their legs and ingest them (71). 

Figure 3-5 graphically depicts the information that currently exists on the health effects of methyl parathion in humans and animals by various routes of exposure. The available literature reviewed concerning the health effects of methyl parathion in humans described case reports of longer-term studies of pesticide workers and case reports of accidental or intentional ingestion of methyl parathion. The occupational exposure is believed to be via the dermal and inhalation routes. The information on human exposure is limited in that the possibility of concurrent exposure to other pesticides or other toxic substances cannot be quantified. 

Children can be exposed to endosulfan by eating food contaminated with the pesticide, by accidentally ingesting the pesticide if it is stored around the house, or by breathing air contaminated with the pesticide if it is sprayed on nearby fields. There are no known unique exposure pathways for children. We do not know if children s intake of endosulfan per kilogram of body weight is different than that of adults. 

The most important routes of exposure to endosulfan for the general population are ingestion of food and the use of tobacco products with endosulfan residues remaining after treatment. Farmers, pesticide applicators, and individuals living in the vicinity of hazardous waste disposal sites contaminated with endosulfan may receive additional exposure through dermal contact and inhalation. 

One major problem caused by Section 409 (c) (3) of the Federal Food, Drug and Cosmetic Act, commonly known as the Delaney Clause , which governed the registration of pesticides was the statement, No additive shall be deemed safe if it is found to induce cancer when ingested by man or animal,... . Dr Fred R. Shank, Director, Center for Food Safety and Applied Nutrition, US Food and Drug Administration, in... 

This approach requires frequent visits to the nest or filming the feeding behavior of smdy species to guide human collection of food items. Although the former process is a direct measure, both procedures allow reliable assessment of pesticide ingestion by indicator species. 

Studies may be designed for estimating exposures to a wide array of wildlife, including birds, mammals and amphibians. Many regulatory requirements involve birds, and less emphasis is currently placed on other species. As regulatory requirements evolve, ecological risk assessments will be required for more species. This may require alternative approaches for food item analysis to allow estimates of pesticide ingestion. 

A dietary supplement may be safe when taken in the recommended doses but may become dangerous in higher doses. However, patients may develop side effects even when ingesting recommended doses. Adverse reactions may be due to allergic reactions, dietary supplements containing toxic substances, mis-identification of plant, mislabeling of plant, natural toxic substances such as pyrrolizidine alkaloids in comfrey, unnatural toxic substances such as heavy metals, or pesticides. 

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