Water-Borne Lead

Surface waters may contain significant amounts of Pb when subjected to some special contamination. About 14% of representative drinking water supplies (i.e., piped drinking water) were found to contain more than 10 mg/1 in a 1963 to 1965 survey. Less than 1% was found to be in excess of 30 mg/1. On the other hand, rainwater collected near a busy highway may contain as much as 50 mg/1. 

Another serious problem related to water-borne Pb is lead shot left in the North America s lakes and ponds. A large number of waterfowls in the U.S. are poisoned or killed following ingestion of the shot. 

Food has long been a major source of Pb intake for animals and humans. Animals may ingest Pb-contaminated vegetation and become intoxicated. 

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Varanasi, U., P. A. Robisch, and D. C. Mauns Structural alternations in fish epidermal mucus produced by water borne lead and mercury. Nature 258, 31 (1975). 

Very little evidence associating water scarcity and an increase in outbreaks of faecal-oral water-borne infectious diseases exists in developed countries. A recent retrospective study performed in England provides some evidence that both low rainfall and heavy rain precede many drinking water outbreaks [3]. Yet, as stated earlier in this review, the situation is potentially different in developing countries [5-7, 9-12], where water scarcity, including droughts, leads to different circumstances that have a clear incidence in the occurrence of both water-borne and water-washed infectious diseases. 

Gill, T.S., H. Tewari, and J. Pande. 1991. Effects of water-borne copper and lead on the peripheral blood in the rosy barb, Barbus (Puntius) conchonius Hamilton. Bull. Environ. Contam. Toxicol. 46 606-612. 

Varanasi, U. and D.J. Gmur. 1978. Influence of water-borne and dietary calcium on uptake and retention of lead by coho salmon (Oncorhynchus kisutch). Toxicol. Appl. Pharmacol. 46 65-75. 

Polymerizing acrylic monomers in the presence of oil-modified polyurethane leads also to a grafting onto the polyacrylics, resulting in dispersions suitable for stable water-borne latexes with good adhesion properties and fair hardness properties [103]. 

Natural phosphorus compounds are not harmful to living organisms, and are even considered to be indicators of the quality of life. Their surplus may cause the eutrophication that enhances the production of biomass in ecosystems, that in surface waters can result in a limitation of oxygen availability that ultimately proves fatal to water-borne life systems. A slight surplus of phosphorus within terrestrial ecosystems may lead to limitations in biodiversity. 

Emulsion polymerization usually leads to high MM products and in many cases to MMDs somewhat narrower than found in polymers produced in homogoieous free-radical polymerizatioa The mechanisms of particle nucleation and radical aitry operative in emulsion polymerization, however, also lead to the formation of short water-borne oligomers (c. 2-20 monomo- units d Jending on the polarity of the monomer). The characterization of these tdigomeric species is of considerable importance from a mechanistic point of view [162-168]. 

Direct deposition, either by dry or wet pathways (Section 4.2) is only significant in the case of larger water bodies such as lakes or oceans. It has been estimated that more lead now enters the North Sea via atmospheric input, 15 000 tonne y" than is contained in the known water-borne inputs of 3600 tonne y" [1]. The estimated magnitude of different pathways of lead input to all the worlds oceans, including both industrial and natural sources is shown in Table 3.1. 

Polymers can also be used to prevent the adsorption of proteins to surfaces. For example, polyvinylpyrrolidone can prevent protein adsorbing onto a variety of surfaces and it can also displace adsorbed protein [ 18]. This has led, for example, to its application in the coating of filtration membranes in order to reduce biofouling. Polymers are also used to inhibit the adhesion of bacteria or water-borne micro-organisms onto siufaces [19,20]. Bacteria are usually surrounded by exoceUular polysaccharides that can aid adhesion to clean surfaces. Thus prosthetic devices and vascular implants carrying blood suffer from the build up of biofilms, leading to blockages and infection. This build up can be markedly reduced... 

Goetz, L. E., Springer, A., Transfer of Air-Borne Lead to Water, Chemistry Division, IRC, Ispra 1976. 

Within these general categories of pollutants are included most of the possible sources of recognized water-quality problems. Only bacterial and viral presences fall outside the group of pollutants to which industry contributes materially. (However, even they are not entirely outside the scope of the polluting activities of industry. For example, meat packing plants, and other food processors in lesser measure, contribute to the presence and viability of water-borne bacteria.) Manufacturing must stand near the top of, and very probably leads, any list of potential sources of water pollution. (See Table 3.3.)... 

The use of water borne coatings on steel can, in certain instances, lead to flash rusting, which is the rapid and irreversible formation of rust. This is especially true under conditions of high humidity, where the water component of the formulation remains in contact with the metal for extended periods of time, when the evaporation is slow. 

It is clear from the review of the data from the first 2 years of this study that the response variables are ideally described without recourse to information from the lead variables, since these were not selected from the eight possible explanatory variables for the best subset of regressors in either year 1 or year 2. The best regressors were as expected, selected from home environment, socioeconomic factors and birth weight. This may have been the result of the sharp fall in the water supply lead exposure, which took place shortly after these children were born. This would suggest that prenatal and early postnatal exposure to lead is less critical than continuing exposure over a period of years into early childhood. 

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