WATER SAFETY

Historically the focus of public health initiatives has been the provision of clean water. This has been addressed by such factors as wastewater treatment and chlorination of water supplies. The Public Health Service institutes water boiling advisories with flood conditions as a means to reduce risk of waterborne illness. Advice includes avoidance of drinking from streams to avoid parasitic infections such as with Giardia species. Contamination of water supplies with heavy metals is also of concern. This includes lead poisoning as previously discussed in Chapter 12. Lead may contaminate home drinking water from either lead pipes in older homes or lead solder in newer homes. It is recommended that tap water be run for 1 to 2 minutes each morning to lower risk of lead poisoning.

Water testing is used to help identify problems in a water supply and develop strategies to keep the public safe. An example of this occurred in 2004 when two groundwater wells in Virginia were found to have natural uranium levels either at or above the Environmental Protection Agency (EPA) recommended limit of 30 mcg/L. As a result, a stop-drinking water advisory was issued until a water treatment system could be installed to remove the uranium (Wyatt and colleagues, 2008).

Another heavy metal of concern in drinking water is arsenic, with high concentrations being greater than 10 mcg/L. The arsenic can be found in groundwater from natural geologic sources. Naturally occurring arsenic in the bedrock of the Northern Appalachian Mountains belt was first recognized in the late 1800s. Within this high-arsenic region, between 6% and 22% of households using private drinking-water wells contain high levels of arsenic (Peters, 2008). Other areas near the Appalachian Mountains known to have high arsenic content include portions of Maryland (Haque, Ji, and Johannesson, 2008) and the New England states.

There are contamination issues such as in mining or industrial areas. These include southeastern Michigan, where 8% of the population is estimated to be at risk from home drinking water. It was found that water used for cooking had an insignificant impact on arsenic ingestion (Meliker and colleagues, 2006). In western Nevada, arsenic concentrations in wells averaged greater than 70 mcg/L with a range of nondetectable levels to 3000 mcg/L (Thundiyil and colleagues, 2007). In northwestern New Jersey, increased arsenic levels in groundwater have been noted near the now-closed Franklin Mine. Seasonal variation was found as a result of dilution of arsenic concentrations in river water content. During high stream flow in fall, winter, and spring there was a lower concentration, whereas concentrated levels were found during low flow in summer (Barringer and colleagues, 2007). Due to seasonal variation, it is advised that multiple testing times of arsenic levels be undertaken to help ensure safe water supplies.

Areas of former apple orchards are at increased risk of arsenic contamination of water supplies. Lead arsenate pesticides were widely used in apple orchards from 1925 to 1955. Soils from historic orchards in Virginia and West Virginia contained elevated concentrations of both arsenic and lead, consistent with pesticide source. Fortunately, there is some evidence arsenic tends to remain in the soil with limited movement into groundwater from surface soils (Robinson and colleagues, 2007). A study in a western Massachusetts apple orchard found the arsenic is confined to the top 20 cm of the soil (Newton, Amarasiriwardena, and Xing, 2006).

Although arsenic is considered a neurotoxin, other adverse health implications have been suggested. These include bladder cancer, with mortality among white men and women being relatively high in the New England region, New York, and New Jersey, where well water and arsenic levels have been implicated (Ayotte and colleagues, 2003). The link between arsenic and cancer risk appears to be impaired DNA repair processes (Andrew and colleagues, 2006). In utero exposure to arsenic is associated with increased risk of allergic disease as well (Selgrade, 2007). Epidemiologic studies suggests a link with arsenic and cardiovascular disease risk factors The findings indicate an effect of chronic arsenic exposure from drinking water on vascular inflammation (Chen and colleagues, 2007).

Methods of arsenic removal from household drinking water have been developed. The method using ferric sulfate coagulation with sand filtration was found to be effective and affordable (Yuan and colleagues, 2003).

Another problem with water safety is residues from therapeutic drugs. This can occur from human waste into the sewage system. Both illicit drugs and pharmaceutical medications have been found in surface waters of rivers and lakes in Italy and Great Britain. These include cocaine, opioids, amphetamines, cannabis derivatives, codeine, and methadone. Because most of these residues still have potent pharmacologic activities, their presence may have potential implications for human health and wildlife (Zuccato and colleagues, 2008). Similar findings are likely in the United States. Increased levels of pharmaceuticals can come from hospitals and long-term care centers that routinely dispose of unused narcotics monthly by flushing them down the toilet. The Drug Enforcement Administration (DEA) is amending its regulations to allow, where state laws permit, retail pharmacy installation of automated dispensing systems at long-term care facilities. Automated dispensing systems would allow dispensing of single-dosage units and would reduce the problem of excess stocks and disposal (Drug Enforcement Administration, 2005).

In the southeastern United States over 40% of male largemouth bass were found to have intersex gonads, suggesting exposure to estrogen-based or other antiandrogenic chemicals (Hinck and colleagues, 2008). Estrogen content of water may be linked to current increased rates of infertility.

HEAVY METAL CONCERNS DURING PREGNANCY AND EARLY CHILDHOOD

Heavy metals such as lead, arsenic, and mercury are neurotoxins and can cause irreversible damage in the brain development of young children. Blood lead concentrations of an infant have been found to be largely affected by maternal blood lead levels. Women with higher blood lead levels have been noted to have lower hematocrit and serum levels of folate and ascorbic acid with low intake of thiamin (Lee, Chun, and Song, 2005). Thus diet counseling of pregnant women to ensure adequate intakes of iron, folic acid, and vitamins B₁ and C may help to lower lead levels in infants. Young children may be exposed to high levels of lead found in paint chips and dust containing lead. Because lead has a sweet taste, children have been known to chew on windowsills, on which old lead paint may be found. If inappropriate lead-paint removal from an older home is done, lead may be found in high concentrations in soil and house dust such that children may be exposed.

Arsenic exposure from treated wood as used in outdoor decks and playground equipment is another threat to children. Arsenic absorption can occur through skin contact. The sand surrounding the playground area may accumulate arsenic from decaying wood of the equipment. The most significant intake of arsenic and lead by children is orally through hand-to-mouth transfer (Hemond and Solo-Gabriele, 2004). For this reason, young children should be reminded over and over not to put their hands in their mouths unless their hands are first washed. See later section for more on international concerns of arsenic toxicity.

Excess mercury needs to be avoided. Mercury induces mitochondrial dysfunction with reduction in energy metabolism, oxidative stress, inflammation, dyslipidemia, hypertension, stroke, renal disease, and immune dysfunction. For this reason, some fish products need to be used sparingly because of their mercury content. Selenium reduces the effects of mercury toxicity (Houston, 2007).

Lead is a well-known neurotoxin, and young children are now routinely screened because of its adverse impact on brain function. Calcium supplements in the form of bone meal tend to be high in lead and should be avoided. Other potential lead-contaminant sources are wine decanters with lead crystal (storage of wine in decanters is discouraged); ceramic dishes with a lead glaze; food left in opened cans that have lead solder; household water pipes that are either made from lead (such as those found in older homes) or have lead in the solder (running the tap water for 1 to 2 minutes before use each morning is advised); lead paint (now illegal in the United States but still found in older homes); lead-based fuel, including its fumes; and dirt and dust contaminated with lead residue. Younger children are particularly susceptible to lead poisoning, in part because of an increased risk of exposure from playing in dirt contaminated with lead (one reason that washing hands before eating is so important) and from eating peeling lead paint, which has a sweet taste.

SAFE FOOD SUPPLIES

Various measures have been taken to help ensure a safe food supply. These include using individual servings of condiments at restaurants and plastic seals on jars with screw-on lids. Behind the scenes, food inspectors oversee food-processing methods and restaurant adherence to safety guidelines. Such guidelines include storing food at safe temperatures and using safe food-handling procedures (see section on food poisoning).

Environmental impacts on food supplies include heavy metal contamination in water irrigation. Rice, due to its high need for water, is a potentially important source of arsenic contamination. However, arsenic toxicity varies greatly with species. Rice from the United States may be safer than rice from Asia and Europe due, in part, to the variety of rice grown in the United States (Zavala and colleagues, 2008). A wide variability within U.S. rice grain appears to be influenced by region of growth related to environmental contamination. Rice grown in California showed lower amounts of arsenic than in other states (Zavala and Duxbury, 2008).

Although there are water safety guidelines for tolerable arsenic content, there are no criteria for arsenic content of food. One so-called food is rice milk, with samples in Great Britain found to have up to three times the amount allowed in water. Because rice milk is essentially the water that rice was cooked in, this issue may best be resolved by defining rice milk as a substitute for water because it does not contain milk or significant quantities of rice (Meharg and colleagues, 2008a). Various varieties and sources of salmon have been shown to have a low level of mercury (Kelly and colleagues, 2008). Carnivorous pike and long-lived fish contain the highest muscle mercury values (Jewett and Duffy, 2007). Research in Great Britain also found about one third of baby rice cereals contain arsenic. Again, as a food source it is not regulated for arsenic content, but it was found to have levels high enough to prevent its being sold in China, which has regulatory limit of 0.15 mg/kg inorganic arsenic. It was noted when baby inorganic arsenic intake from rice was considered, median intake based on body weight equates levels higher than water regulations permit (Meharg and colleagues, 2008b).

A new potential carcinogen was identified in 2002. Acrylamide is a substance formed from the amino acid, asparagine, and sugars or starches under high heat conditions. Grains and potato-based foods are the primary sources. The chemical reaction known as the Maillard reaction, which causes browning in foods, is part of the cause. Thus, although bread is low in acrylamide, the longer it is toasted, as noted with the darker color, the more acrylamide that is formed (Jackson and Al-Taher, 2005). In yeast breads there is a lower content of acrylamide formed than in nonyeast breads. This is due to the impact of yeast feeding on the asparagine, resulting in a lower content (Granby and colleagues, 2008). The most promising near-term technical solution is the use of the enzyme asparaginase to help reduce the content of this amino acid in starchy foods. This enzyme has the potential to achieve a 60% to 90% reduction for some products made from dough (Konings and colleagues, 2007).

Blanching potatoes in water, which removes some starch, combined with a shorter oven-roasting time was shown to be an efficient way of reducing the acrylamide content in potato wedges (Skog and colleagues, 2008). A higher level of sugar content of potatoes in 2006 was found, likely related to weather conditions during the growing season. This was reflected in a higher acrylamide content found in potato chips (crisps, as they are called in England), which was approximately twice as high as in preceding years (Viklund and colleagues, 2008). Children might be the most vulnerable group of the population, partly due to a high preference for French fries (Heudorf, Hartmann, and Angerer, 2008).

The new threat of bioterrorism has increased security around food supplies. For individual families the Centers for Disease Control and Prevention (CDC) recommends stocking private stores of food and water in case of emergencies such as radioactive fallout. With regard to nutritional needs, it is advised to have 1 gallon of water for each person for 3 days, along with nonperishable foods and infant formula as needed. Hand sanitizers should also be kept. Nonperishable foods include canned, dried, or packaged foods. Peanut butter and nuts do not require refrigeration. Milk could be made from the stored water and powdered milk. Stored water should be changed every 6 months, and food items should be replaced after expiration dates. Other emergency preparedness guidelines may be found at www.bt.cdc.gov.

Public health measures with food safety include warnings for persons with food allergies. Labels now routinely state if the food contains wheat or nuts. Fixed eruption is a characteristic condition with recurrent reddened skin area in the same location. Two cases of fixed eruption due to quinine contained in tonic water have been observed (Muso and colleagues, 2007). A 71-year-old woman was noted to have fixed eruption along with burning and itching of the area due to cashew nuts (Fukushima, Kidou, and Ihn, 2008).

Other behind-the-scenes actions to ensure safe food supplies, such as analyzing nutrient content of foods, occur at the federal level. The USDA nutrient content data between 1950 and 1999 for 43 garden crops showed significant declines in six nutrients (protein, calcium, phosphorus, iron, riboflavin, and ascorbic acid). Average declines ranged from 6% for protein to 38% for riboflavin. These declines are believed to be primarily a result of use of high-yield crop varieties in this time period, the tradeoff being yield versus nutrient content (Davis, Epp, and Riordan, 2004).

Further efforts at the federal level include research on safe use and regulations for food additives such as preservatives on the Generally Recognized as Safe (GRAS) list. The 1958 Food Additives Amendment was designed to protect the consumer. Because of this legislation, food additives (substances added to foods, generally to make them safer to eat) used in processed food must be proved safe by industry before they can be incorporated into any food product. Additives must meet strict guidelines for inclusion in the GRAS list. Examples of food additives include nitrites, used to prevent botulism in cured meat products. Ascorbates and other ingredients are added to maintain quality in meat products. Only minute quantities of these additives are used, usually in amounts lower than might exist naturally in many food products. The USDA requires that additives meet the following requirements:

Table 14-1 lists typical food additives. Table 14-2 lists food- and nutrition-related responsibilities of federal agencies.

Pasteurization of milk has long been used as a method of destroying harmful bacteria. Generally, adequate heat will kill harmful pathogens. Some individuals advocate the use of raw, unpasteurized milk for its nutrients that may be damaged with the heat of pasteurization. However, this is not without risk. In late 2005, health officials in Clark County, Washington, noted a higher-than-expected number of Escherichia coli (E. coli) cases among residents. It was found the consumption of raw milk was the common factor among these individuals, and further testing verified E. coli contamination. Because of this case, legislation was passed that clarified that state licensing requirements apply to all milk production facilities, including cow-share programs (Denny, Bhat, and Eckmann, 2008).

Food irradiation is being used in the processing of high-risk foods such as meats to eliminate infectious pathogens. Harmful bacteria can develop internally in leafy vegetables that cannot be effectively removed by surface treatments. Irradiation has been shown to inactivate leaf-internalized bacteria (Niemira, 2008).

However, there is still public concern about possible adverse effects of food irradiation that may be justified. Irradiation of frozen corn and peas was found to cause a reduction in vitamin C content of both corn and peas (Fan and Sokorai, 2007). Although neither of these vegetables has a high content of vitamin C, this effect should prompt further research into the nutritional implications of irradiation. In a study of mice, vitamin K deficiency developed as a consequence of being fed a ration that had been irradiated (Hirayama and colleagues, 2007). There is not adequate evidence currently to support the unconditional endorsement of irradiation of food for consumption (Ashley and colleagues, 2004).

The debate on the benefits of organic foods continues. Recent labeling regulations have gone into effect to ensure that consumers are actually purchasing organic foods, if they desire. Organic foods are foods that were grown without the use of commercial fertilizers and pesticides. Generally speaking, persons purchasing organic foods are concerned for the environment, and many feel that the nutritional value is greater. There is some evidence to support this belief. Blueberries, for example, grown from organic culture yielded significantly higher phytochemical and antioxidant activity (Wang and colleagues, 2008). Organic crops in general have been noted to have a significantly higher amount of vitamin C, phytochemicals, and minerals and have higher dry matter content than conventional ones (Györéné, Varga, and Lugasi, 2006).

There also is less pesticide residue on organic foods. The widespread use of organophosphorus pesticides prompted the Children’s Pesticide Exposure Study in the greater Seattle, Washington, area. It was found by substituting organic fresh fruits and vegetables for corresponding conventional food items there were reduced levels of pesticide residue in children (Lu and colleagues, 2008).

On the other hand, the use of animal manure as a fertilizer for organically grown produce can increase the risk of foodborne pathogens such as Salmonella and E. coli. Good food hygiene practices at home are essential to reduce the incidence of foodborne illnesses (Leifert and colleagues, 2008).

The manner in which cattle are raised for human consumption can have an impact on health. In cattle the polyunsaturated to saturated fatty acid ratio (P:S ratio) was found to increase with duration of grazing, mainly as a consequence of the increased concentration of omega-3 fat (Noci and colleagues, 2005). Organic milk was found to have a higher proportion of polyunsaturated fatty acids (PUFAs) to monounsaturated fatty acids and of omega-3 fatty acids than conventional milk and contained a consistently lower PUFA:omega-3 ratio (which is considered beneficial) compared with conventional milk (Ellis and colleagues, 2006). This is primarily due to the diet of grazing cattle.

As the organic food movement continues, we may learn more about the nutritional benefits of this approach. One lesson learned is that many consumers are willing to pay more for organic foods. Although this is positive in the sense that it encourages more farms to be less reliant on pesticides, the consumer can be paying excessively for the nutritional benefits provided.

Genetically modified foods include traditional hybrid versions of plants. Traditional hybridization, or cross-pollination, has been used for centuries. Cross-pollination of plants occurs when the pollen from one plant is transferred to another. It can be either encouraged or discouraged, resulting in different varieties of the same plant. The cruciferous vegetables (broccoli, cauliflower, cabbage, Brussels sprouts), for example, originated from one plant. Broccoli is biologically much like cauliflower except that it is green and consequently higher in beta-carotene and vitamin C. Cauliflower is high in vitamin K because it is related to leafy green cruciferous vegetables. A variety of fruits and vegetables has been developed with hybridization. Genetic manipulation of plants has become more sophisticated owing to advances in the sciences of molecular biology and genetics.

It is now possible to physically extract genes from or add them to plants to change the characteristics of new generations of plants. Such crops are being grown extensively in the United States, South America, Africa, and China. Europe, however, has voiced significant objections to such genetic alteration and has been avoiding the practice of these methods.

One concern is the development of altered proteins in genetically modified foods that humans have not previously been exposed to. This may result in increased frequency of food allergies. To date the methodology used to prevent this potentially adverse outcome has been effective (Goodman and colleagues, 2005). Bioactive compounds have been found to be altered in genetically modified grapefruit. It was found that alterations varied according to the type of postharvest preservation used (Vanamala and colleagues, 2005). Because of potential nutritional issues, it has been advised that more research is needed to ensure genetically modified foods are safe for human consumption (Bakshi, 2003).

Related posts:

The Nutrition Care Process in the Health Care Setting Cardiovascular Disease The Art of Nutrition in a Social Context Carbohydrates, Proteins, and Fats Obesity and Healthy Weight Management Growth and Development Issues in Promoting Good Health

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