Like adults, children can be exposed to cyanide by breathing air, drinking water, touching soil or water, or eating foods that contain cyanide, but the amounts are usually low. Breathing second-hand tobacco smoke is a more important source of cyanide exposure for children. Serious exposures can occur when children accidentally eat certain fruit pits, such as apricot kernels, containing a cyanide-releasing substance. A high blood level of thiocyanate is a sign of cyanide exposure in children, as well as adults. If a pregnant mother is exposed to cyanide, for example, by exposure to tobacco smoke, the fetus will be exposed to both cyanide and thiocyanate crossing the placenta. Animal studies show that cyanide and thiocyanate can be transferred into milk and pass to nursing baby animals, and suggest that this may also occur in humans.
Effects reported in exposed children are like those seen in exposed adults. Children who ate large quantities of apricot pits, which naturally contain cyanide as part of complex sugars, had rapid breathing, low blood pressure, headaches, and coma, and some died. Cyanide has not been reported to directly cause birth defects in people. However, among people in the tropics who eat cassava root, children have been born with thyroid disease because of the mothers' exposure to cyanide and thiocyanate during pregnancy. Birth defects occurred in rats that ate cassava root diets, and harmful effects on the reproductive system occurred in rats and mice that drank water containing sodium cyanide.
Showing posts with label Take care. Show all posts
Showing posts with label Take care. Show all posts
21 February, 2009
17 February, 2009
Oxygen In Drinking Water Supply
As rainwater falls through the atomosphere, it collects oxygen gas. This dissolved oxygen is not the same as the oxygen in the water molecule. Dissolved oxygen is present in all rainwaters and surface supplies due to contact with the atmosphere. Just how much dissolved oxygen a water supply will contain depends on
Several factors:
1. Under high pressure relatively large quantities of oxygen dissolve in water. When the pressure is reduced, a proportionate weight of the gas escapes (Henry's Law).
Henry's Law. The English chemist, William Henry, formulated a law regarding the effect of pressure on a gas. The law states: The weight of a gas that dissolves in any given liquid is directly proportional to the pressure, providing the temperature remains constant. If one gram of oxygen, for example, dissolves in 100 cubic centimeters of water at atmospheric pressure, two grams of oxygen will dissolve under twice the normal atmospheric pressure, providing there has been no change in temperature.
2. The amount of minerals in a water affects its ability to dissolve oxygen. Distilled water can absorb more oxygen than well waters with higher mineral content. Obviously sea water, for this same reason, holds less dissolved oxygen than fresh water.
Well waters usually contain smaller amounts of dissolved oxygen than surface supplies. In deep wells there may be a total absence of the gas. However, an article in Science Magazine, June 11, 1982, pages 1227-30, states:
Contrary to the prevailing notion that oxygen-depleting reactions in the soil zone and in the aquifer rapidly reduce the dissolved oxygen content of recharge water to detection limits, 2 to 8 milligrams per liter of dissolved oxygen is present in water from a variety of deep (100 to 1000 meters) aquifers in Nevada, Arizona, and the hot springs of the folded Appalachians and Arkansas. Most of the waters sampled are several thousand to more than 10,000 years old, and some are 80 kilometers from their point of recharge.
Oxygen adds to the taste of water. For this reason a small amount of it is desirable in drinking water. We are all familiar with the "flat" taste which water often possesses after it has been standing in an open container for some time. The taste can be improved simply by shaking the water in a partially filled bottle. This reintroduced oxygen into the water will give it a more appealing taste. Despite this desirable feature, dissolved oxygen can be a source of serious trouble in a household water supply. The fact is that oxygen causes corrosion. In cold water, oxygen normally has little corrosive effect. In contrast, when the water is heated, the oxygen can cause serious corrosion problems.
A number of chemicals are used in industry to remove oxygen from a water supply. Sodium sulfite (Na2S03) is probably most widely used for this purpose. It reacts with oxygen at high temperatures to form sodium sulfate (Na2S04), in this way reducing the oxygen. There are a number of chemicals that react similarly with oxygen to effect its removal. The degree of success varies. For household purposes treatment is normally limited to the use of polyphosphates to coat the insides of water lines to protect the metal from contact with the oxygen.
Several factors:
1. Under high pressure relatively large quantities of oxygen dissolve in water. When the pressure is reduced, a proportionate weight of the gas escapes (Henry's Law).
Henry's Law. The English chemist, William Henry, formulated a law regarding the effect of pressure on a gas. The law states: The weight of a gas that dissolves in any given liquid is directly proportional to the pressure, providing the temperature remains constant. If one gram of oxygen, for example, dissolves in 100 cubic centimeters of water at atmospheric pressure, two grams of oxygen will dissolve under twice the normal atmospheric pressure, providing there has been no change in temperature.
2. The amount of minerals in a water affects its ability to dissolve oxygen. Distilled water can absorb more oxygen than well waters with higher mineral content. Obviously sea water, for this same reason, holds less dissolved oxygen than fresh water.
Well waters usually contain smaller amounts of dissolved oxygen than surface supplies. In deep wells there may be a total absence of the gas. However, an article in Science Magazine, June 11, 1982, pages 1227-30, states:
Contrary to the prevailing notion that oxygen-depleting reactions in the soil zone and in the aquifer rapidly reduce the dissolved oxygen content of recharge water to detection limits, 2 to 8 milligrams per liter of dissolved oxygen is present in water from a variety of deep (100 to 1000 meters) aquifers in Nevada, Arizona, and the hot springs of the folded Appalachians and Arkansas. Most of the waters sampled are several thousand to more than 10,000 years old, and some are 80 kilometers from their point of recharge.
Oxygen adds to the taste of water. For this reason a small amount of it is desirable in drinking water. We are all familiar with the "flat" taste which water often possesses after it has been standing in an open container for some time. The taste can be improved simply by shaking the water in a partially filled bottle. This reintroduced oxygen into the water will give it a more appealing taste. Despite this desirable feature, dissolved oxygen can be a source of serious trouble in a household water supply. The fact is that oxygen causes corrosion. In cold water, oxygen normally has little corrosive effect. In contrast, when the water is heated, the oxygen can cause serious corrosion problems.
A number of chemicals are used in industry to remove oxygen from a water supply. Sodium sulfite (Na2S03) is probably most widely used for this purpose. It reacts with oxygen at high temperatures to form sodium sulfate (Na2S04), in this way reducing the oxygen. There are a number of chemicals that react similarly with oxygen to effect its removal. The degree of success varies. For household purposes treatment is normally limited to the use of polyphosphates to coat the insides of water lines to protect the metal from contact with the oxygen.
Asthma could start in the womb- Latest Research
Children born in heavy traffic areas could be at greater risk of developing asthma due to genetic changes brought on by pollution and acquired in the womb, researchers said.
The new study conducted by researchers from the University of Cincinnati (UC) and Columbia University Mailman School of Public Health is published in the journal PLoS ONE.
The researchers studied umbilical cord blood from New York City children, and discovered evidence of a possible new biomarker — an epigenetic alteration in the gene ACSL3 — associated with prenatal exposure to polycyclic aromatic hydrocarbons (PAHs).
They pointed out that such chemical compounds are created as byproducts of incomplete combustion from carbon-containing fuels, resulting in high levels in heavy-traffic areas. Past studies have linked exposure to PAHs to diseases like cancer and childhood asthma.
The researchers said that their latest finding provides a potential clue for predicting environmentally related asthma in children, particularly those born to mothers who live in high-traffic areas while pregnant.
The team claim that theirs is the first study to examine the effects of prenatal ambient air pollutant exposure on epigenetic changes — which may disrupt the normal functioning of genes by affecting their expression but do not cause structural changes or mutations in the genes-linked to asthma.
Working in collaboration with researchers from Columbia’s Mailman School of Public Health, the team studied the relationship between prenatal PAH exposure and childhood asthma, hypothesizing that transplacental exposure to PAHs could “reprogram” foetal genes and lead to airway inflammation or asthma during childhood.
“Our data support the concept that environmental exposures can interact with genes during key developmental periods to trigger disease onset later in life, and that tissues are being reprogrammed to become abnormal later,” says Shuk-mei Ho, senior author of the paper, chair of UC’s Department of Environmental Health and the director of the Center for Environmental Genetics.
The researchers used biological specimens from the CCCEH birth cohort of mothers and children living in Northern Manhattan and the South Bronx, and analysed umbilical cord white blood cell samples from 56 children for epigenetic alterations related to prenatal PAH exposure.
The new study conducted by researchers from the University of Cincinnati (UC) and Columbia University Mailman School of Public Health is published in the journal PLoS ONE.
The researchers studied umbilical cord blood from New York City children, and discovered evidence of a possible new biomarker — an epigenetic alteration in the gene ACSL3 — associated with prenatal exposure to polycyclic aromatic hydrocarbons (PAHs).
They pointed out that such chemical compounds are created as byproducts of incomplete combustion from carbon-containing fuels, resulting in high levels in heavy-traffic areas. Past studies have linked exposure to PAHs to diseases like cancer and childhood asthma.
The researchers said that their latest finding provides a potential clue for predicting environmentally related asthma in children, particularly those born to mothers who live in high-traffic areas while pregnant.
The team claim that theirs is the first study to examine the effects of prenatal ambient air pollutant exposure on epigenetic changes — which may disrupt the normal functioning of genes by affecting their expression but do not cause structural changes or mutations in the genes-linked to asthma.
Working in collaboration with researchers from Columbia’s Mailman School of Public Health, the team studied the relationship between prenatal PAH exposure and childhood asthma, hypothesizing that transplacental exposure to PAHs could “reprogram” foetal genes and lead to airway inflammation or asthma during childhood.
“Our data support the concept that environmental exposures can interact with genes during key developmental periods to trigger disease onset later in life, and that tissues are being reprogrammed to become abnormal later,” says Shuk-mei Ho, senior author of the paper, chair of UC’s Department of Environmental Health and the director of the Center for Environmental Genetics.
The researchers used biological specimens from the CCCEH birth cohort of mothers and children living in Northern Manhattan and the South Bronx, and analysed umbilical cord white blood cell samples from 56 children for epigenetic alterations related to prenatal PAH exposure.
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