Contamination, implications

Major chemical contaminants implicated in food safety include pesticides, herbicides, myeotoxins and antibiotics. These analytes have been targeted by numerous groups developing SPR biosensors. As these analytes are rather small (typical molecular weight < 1,000), inhibition assay has been a preferred detection format. Examples of chemical contaminants detected by SPR biosensors include pesticides atrazine and simazine (detection limits 0.05 ng/ml and 0.1 ng/ml respectively), mycotoxin Fumonisin B1 (detection limit 50 ng/ml ), and antibiotics Sulphamethazine, Sulphadiazine (detection limits 1 ng/ml and 20 ng/ml respectively). 

A comprehensive search (295) of the STORET water quaUty database, maintained by the U.S. EPA Office of Water, is used to evaluate the potential water quaUty implications of various herbicides. This database contains information on contamination of surface water (SW) and groundwater (GW) suppUes. The data are provided to give a general impression of the occurrence of a given herbicide in SW and GW (269). The U.S. EPA scheme for categorizing a chemical s carcinogenic potential is used for herbicides for which healthy advisory information (HA) is available. The U.S. EPA is continually issuing HAs for various environmental contaminants HAs available in Reference 269 were used in preparation of this article. 

The failure of plant by corrosion can be gradual or catastrophic. Gradual failure has few implications for safety providing it is monitored. Direct corrosion-monitoring techniques are described in Section 53.8. Indirectly, the correct interpretation of records relating to metal contamination of products or the loss of efficiency of heat exchangers, etc. can provide useful information. 

The metal lost from the inside of pumps, reaction vessels, pipework, etc. usually contaminates the product. The implications of this depend upon the product. Ppb levels of iron can discolor white plastics, though at this level the effect is purely cosmetic. Ppm levels of iron and other metals affect the taste of beer. Products sold to compositional requirements (such as reagent-grade acids) can be spoiled by metal pick-up. Pharmaceutical products for human use are often white tablets or powders and are easily discolored by slight contamination by corrosion products. 

Fish from Lake Erie are generally the least contaminated of all the Great Lakes IS), It has been speculated that contaminants in a more advanced eutrophic system become masked or removed by sedimentation within the food chain and have less opportunity to reach higher trophic levels 24), The management implications of this interaction between nutrient and contaminants needs to be further elucidated. 

Photocopies of journal articles relating to the Unipet process for the recycling of PETP developed by United Resource Recovery Corp. Details are given of the process which enables contaminated PETP to be recycled by the use of caustic soda which reacts with the PETP to yield ethylene glycol and terephthalic acid, followed by heating and evaporation of the EG which reduces organic impurities to carbon dioxide and water and leaves solid terephthalic salt. Its implications for the industry are also discussed. 

Lutter C, Iyengar V, Barnes R, et al. 1998. Breast milk contamination in Kazakhstan implications for infant feeding. Chemosphere 37(9-12) 1761-1772. 

PCBs have been implicated in the decline of certain populations of fish-eating birds, for example, in the Great Lakes of North America. Although their use is now banned in most countries and very little is released into the environment as a consequence of human activity, considerable quantities remain in sinks (e.g., contaminated sediments and landfill sites), from which they are slowly redistributed to other compartments of the environment. There continues to be evidence that PCB residues are still having environmental effects, for example, on birds and fish. 

There is an additional problem that has important implications for the bioremediation of contaminated sites when two substrates such as a chlorinated and an alkylated aromatic compound are present. The extradiol fission pathway is generally preferred for the degradation of alkylbenzenes (Figure 9.17), although this may be incompatible with the degradation of chlorinated aromatic compounds since the 3-chlorocatechol produced inhibits the activity of the catechol-2,3-oxygenase (Klecka and Gibson 1981 Bartels et al. 1984). 

Braddock JE, ML Ruth, PH Catterall, JL Walworth, KA McCarthy (1997) Enhancement and inhibition of microbial activity in hydrocarbon-contaminated arctic soils implications for nutrient-amended bioremediation. Environ Sci Technol 31 2078-2084. 

There are many peer-review publications reporting NoV outbreaks due to food and water. In spite of a recognized publication bias toward these outbreaks, there is a consensus that the scientific literature imder-estimates the contribution of NoV to food and waterborne disease (Efall et al., 2005 Hoffmann et al., 2007 O Brien et al., 2006). Source contamination of food and water is clearly implicated in NoV outbreaks around the world. 

Infectious complications of EN include aspiration pneumonia and infections related to delivery of contaminated EN formula. Aspiration is a complication with GI, mechanical, and infectious implications. Although GI infections owing to contamination of enteral formulas have been reported uncommonly, there is ample opportunity for these formulas to be seeded with organisms during the processes of transferring from the can to the delivery bag with ready-to-use formulas and during the process of reconstitution with powdered formulas. The so-called closed systems of delivery, wherein the formulas come from the manufacturer premixed in a delivery bag, should help to decrease the chance of formula contamination. 

Harrison JD, Hodgson A, Haines JW, et al. 1993. The biokinetics of plutonium-239 and americium-241 in the rat after subcutaneous deposition of contaminated particles from the former nuclear weapons site at Maralinga Implications for human exposure. Hum Exp Toxicol 12 313-321. 

Hutchins DA, Stupakoff I, Fisher NS. 1996a. Temperature effects on accumulation and retention of radionuclides in the sea star, Asterias forbesi Implications for contaminated northern waters. Mar Biol 125 701-706. 

Contamination is not restricted to natural products. Organic pigment powders are often precipitated from aqueous solutions and washed with water prior to drying. These have been found to contain high numbers of microbes and have been implicated in contamination instances. 

Benzyl alcohol contaminated with 1.4% of hydrogen bromide and 1.1% of dissolved iron(II) polymerises exothermally above 100°C. Bases inhibit the polymerisation reaction. In a laboratory test, alcohol containing 1% of HBr and 0.04% of Fe polymerised at about 150° with an exotherm to 240° C. Formation and iron-catalysed poly-condensation of benzyl bromide seems to have been implicated. See Benzyl bromide Molecular sieve, or Catalytic impurities See Other BENZYL COMPOUNDS, POLYCONDENSATION REACTION INCIDENTS... 

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