Pesticides food chain contaminate

Plant uptake is one of several routes by which an organic contaminant can enter man s food chain. The amount of uptake depends on plant species, concentration, depth of placement, soil type, temperature, moisture, and many other parameters. Translocation of the absorbed material into various plant parts will determine the degree of man s exposure—i.e., whether the material moves to an edible portion of the plant. Past experience with nonpolar chlorinated pesticides suggested optimal uptake conditions are achieved when the chemical is placed in a soil with low adsorptive capacity e.g., a sand), evenly distributed throughout the soil profile, and with oil producing plants. Plant experiments were conducted with one set of parameters that would be optimal for uptake and translocation. The uptake of two dioxins and one phenol (2,4-dichlorophenol (DCP)) from one soil was measured in soybean and oats (7). The application rates were DCP = 0.07 ppm, DCDD 0.10 ppm, and TCDD = 0.06 ppm. The specific activity of the com-... 

There is a vast range of aqueous organic pollutants with a wide toxicity profile. Some, e.g. polychlorinated biphenyls, certain herbicides, fungicides and pesticides, and organo-mercury compounds, are persistent and may bioaccumulate in the food chain. Trace contaminants such as sodium chloride, iron and phenols (especially if chlorinated) may also impart a taste to water. Typical consent levels for industrial discharges are provided in Table 13.10. 

Consequently, Europe has historically been a hotspot of environmental pressures because of the contamination caused by agricultural, municipal, and industrial activities and high population densities [5, 6], Such contamination has led to poor water quality in many European river basins [7-12], In addition, this pollution can cause the accumulation in river sediments of toxic compounds such as pesticides [13], surfactants [14], and alkyl polycyclic aromatic hydrocarbons (PAHs) [15], These can in turn act as a source to biota [16] and as a potential risk for entire ecosystems [17] if the compounds bioaccumulate, and thereby enter the food chain [18],... 

Biologically available organic contaminants may find their way into the food chain and be toxic, but they are also more easily decomposed and are thus removed from the environment. Slowly decomposed biologically available organic compounds, such as pesticides, may have long lifetimes in soil and thus pose a hazard to animals and humans. Biologically unavailable compounds, such as tars, produce undesirable characteristics in soil, such as water... 

The risk of groundwater contamination by pesticides stems mainly from the use made of aquifers for irrigation purposes, way by which pesticides can enter the food chain, and from its use also as resource for the production of drinking water. 

Contamination of soil and water also results from the use of pesticides and fertilizers. Persistent pesticides applied directly to the soil have the potential to move from the soil into the water and thus enter the food chain from both soil and water. In a similar way... 

Where analytical methods are available it is largely because of a crossfertilisation of effort from well-established areas of food contaminants work. For example, the steady development since the 1960s of methods of analysis for chlorinated pesticides led to the analysis of food for polychlorinated biphenyls (PCBs) since PCBs were readily detectable by general methods used to analyse food for organochlorine pesticides. The analysis of food for chlorinated dioxins and furans (PCDDs and PCDFs) at the very low levels at which they are found in food is a more recent development, and one that is an important precedent since it arose from interest in environmental contamination rather than because of cross-fertilisation of scientific methodology from an established area of food chemistry. Although dioxins were detectable some years ago at much less sensitivity in some pesticides, it was environmental interest that led to their study at very low levels in the food chain. 

The approved uses for chlorinated chemicals have now become so restricted that for some of them at least they are now more likely to contaminate food as a result of their persistence in the environment rather than from their direct use on the food chain. A former pesticide in this category is hexachlorobenzene. There... 

There are too many documented instances where food chain build-up of pesticides has occurred to list them all (29,30,35,47). The most minute amounts can be concentrated a thousandfold (30), and there is no predictable safe level for them in waters where food chain build-up can occur. The literature also reports pesticide contamination of waters and aquatic life over the surface of this country into the oceans and Antarctic, (2, 3, 19, 32, 39, 42, 48, 51, 52, 56). Blubber and oil from two whales washed up on the California coast contained DDE (1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene), DDD (l,l-dichloro-2,2-bis (p-chloro-phenyl) ethane) [TDE], and DDT. The highest value in the oil of one whale was 11 p.p.m. DDE, 6 p.p.m. DDT, and 8 p.p.m. DDD (38). 

Pesticide residues in humans, animals, and fish in areas remote from pesticide application can, in many cases, be attributed to an intermediate such as the food chain. Thus, migratory fish and birds can easily accumulate pesticide residues from foods directly contaminated by pesticide application. In those instances where the food chain cannot serve as a reasonable explanation, then, clearly, the atmosphere, including dust and rainfall, offers an alternative solution to pesticides translocation. 

Analysis of cows milk destined for consumption in Brazil, where endosulfan is used extensively in cotton production but on few other crops, foimd that 10% of samples contained traces of the pesticide. Earlier research conducted in Nicaragua imcovered traces of organochlorine residues in samples of cows milk from at least 38 different sites aroimd the country the most heavily contaminated milk came sites of intensive cotton production. Thus, globally, cottonseed used as animal feed represents a second significant pathway by which hazardous pesticides applied to cotton may enter the human food chain. 

Communities in India may also be exposed to hazardous cotton pesticides through the contamination of cottonseed and cottonseed derivatives - an important source of edible oil. Because of the intensive use of hazardous pesticides in cotton production much of the cottonseed oil entering the Indian food chain may be heavily contaminated . One analysis of cottonseeds collected from 5 locations in Punjab found detectable residues of the cotton pesticides ethion (WHO II), cypermethrin (WHO II), endosulfan (WHO II), chlorpyrifos (WHO II) the latter being 2 of the most common pesticides applied to cotton in India ... 

In addition to the food contaminants that have been discussed, there are also man-made chemicals that can inadvertently enter the food chain or water, for example pesticides, industrial chemicals, and substances fed to animals like antibiotics and anabolic steroids. Some of these have been discussed in Chapter 5. In addition, there are also contaminants that are derived from the packaging or processing of the food. An important example is the phthalates, chemicals that are added to plastics, some of which are used in packaging food or drink. These substances may leach out of the packaging and into the food. As they are beheved to have effects on the reproductive system (endocrime disruption) there is clearly concern about their potential appearance in food. This type of substance has also been discussed in Chapter 5. 

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