Flower Blooming-Rose
Friday, March 27, 2009
Friday, March 20, 2009
Disturbed Lands
Much of the history of the park and the surrounding area is related in some way to mining and the westward expansion that it instigated. Although “Gold Fever” was the most common reason for staking a mine claim in this area, silver, copper, and other minerals were also prospected. The National Park Service has estimated that Joshua Tree contains about 300 abandoned mine sites, each typically including a shaft, an adit (or tunnel), a small waste-rock pile, a can dump, and perhaps the outline of rocks where a miner once pitched a tent.
Approximately 120 abandoned mine sites in Joshua Tree have a substantial opening and may represent a safety hazard. Twenty-one are old “mill sites” where gold was extracted from ore, leaving historic remains, but also potentially hazardous waste. Park visitors who come upon these sites, and certainly those who enter the shafts, tunnels, and structures, are at risk.
The park would like to reduce the hazards presented by abandoned mine sites as well as restore to a more natural condition the large areas of disturbance created by the 28 gravel pits documented in the park. However, there are a number of different values, not to mention pieces of legislation, that must be considered before action can be taken. Some mine sites are historic and protected under the National Historic Preservation Act. Mine sites sometimes provide habitat for bats, some protected under the Endangered Species Act. Many mine sites constitute “a permanent installation” within Congressionally Designated Wilderness in contradiction to the Wilderness Act.
The park has extensively evaluated 36 mine sites for treatment, calling on experts from each area of concern to help decide how each site should be treated. Of those, only two have been erased by cleaning up the area, plugging the shaft with polyurethane foam, covering the site with dirt and re-vegetating the area with native plants. Three others were left with the outward remains of the mining activity intact but made safer by the installation of a polyurethane foam plug deep enough to preserve the appearance of the shaft, but without the danger of a 100-foot hole. One mine was found to be habitat for an established bat colony, so a gate that allows bats entry, but poses a safety barrier to people, was installed.
Park staff will evaluate approximately 30 mine sites per year for the next four years, balancing safety, cultural, and natural values with applicable legislation.
Much of the history of the park and the surrounding area is related in some way to mining and the westward expansion that it instigated. Although “Gold Fever” was the most common reason for staking a mine claim in this area, silver, copper, and other minerals were also prospected. The National Park Service has estimated that Joshua Tree contains about 300 abandoned mine sites, each typically including a shaft, an adit (or tunnel), a small waste-rock pile, a can dump, and perhaps the outline of rocks where a miner once pitched a tent.
Approximately 120 abandoned mine sites in Joshua Tree have a substantial opening and may represent a safety hazard. Twenty-one are old “mill sites” where gold was extracted from ore, leaving historic remains, but also potentially hazardous waste. Park visitors who come upon these sites, and certainly those who enter the shafts, tunnels, and structures, are at risk.
The park would like to reduce the hazards presented by abandoned mine sites as well as restore to a more natural condition the large areas of disturbance created by the 28 gravel pits documented in the park. However, there are a number of different values, not to mention pieces of legislation, that must be considered before action can be taken. Some mine sites are historic and protected under the National Historic Preservation Act. Mine sites sometimes provide habitat for bats, some protected under the Endangered Species Act. Many mine sites constitute “a permanent installation” within Congressionally Designated Wilderness in contradiction to the Wilderness Act.
The park has extensively evaluated 36 mine sites for treatment, calling on experts from each area of concern to help decide how each site should be treated. Of those, only two have been erased by cleaning up the area, plugging the shaft with polyurethane foam, covering the site with dirt and re-vegetating the area with native plants. Three others were left with the outward remains of the mining activity intact but made safer by the installation of a polyurethane foam plug deep enough to preserve the appearance of the shaft, but without the danger of a 100-foot hole. One mine was found to be habitat for an established bat colony, so a gate that allows bats entry, but poses a safety barrier to people, was installed.
Park staff will evaluate approximately 30 mine sites per year for the next four years, balancing safety, cultural, and natural values with applicable legislation.
Tuesday, March 03, 2009
Plastics and the Microwave
Stories about the dangers of chemicals leaching from plastic into microwaved food have circulated on the Internet for years. As a result, the Food and Drug Administration continues to receive inquiries from concerned consumers.
Consumers can be confident as they heat holiday meals or leftovers in the microwave that the FDA carefully reviews the substances used to make plastics designed for food use. These include microwave-safe plastic coverings that keep food from splattering and microwave-safe containers that hold frozen dinners. Even microwavable popcorn bags, which look like paper, actually contain a metalized plastic film that allows them to reach high temperatures so the corn can fully pop.
Under the food additive provisions of the Federal Food, Drug, and Cosmetic Act, new substances used to make plastics for food use are classified as "food contact substances." They must be found safe for their intended use before they can be marketed.
"It's true that substances used to make plastics can leach into food," says Edward Machuga, Ph.D., a consumer safety officer in the FDA's Center for Food Safety and Applied Nutrition. "But as part of the approval process, the FDA considers the amount of a substance expected to migrate into food and the toxicological concerns about the particular chemical." The agency has assessed migration levels of substances added to regulated plastics and has found the levels to be well within the margin of safety based on information available to the agency. The FDA will revisit its safety evaluation if new scientific information raises concerns.
One chemical called diethylhexyl adipate (DEHA) has received a lot of media attention. DEHA is a plasticizer, a substance added to some plastics to make them flexible. DEHA exposure may occur when eating certain foods wrapped in plastics, especially fatty foods such as meat and cheese. But the levels are very low. The levels of the plasticizer that might be consumed as a result of plastic film use are well below the levels showing no toxic effect in animal studies.
Other claims have asserted that plastics contain dioxins, a group of contaminants labeled as a "likely human carcinogen" by the Environmental Protection Agency. "The FDA has seen no evidence that plastic containers or films contain dioxins and knows of no reason why they would," Machuga says.
Machuga says that consumers should be sure to use any plastics for their intended purpose and in accordance with directions. If you don't find instructions for microwave use, you should use a different plate or container that you know is microwave-safe. Such containers are made to withstand high temperatures.
For example, carryout containers from restaurants and margarine tubs should not be used in the microwave, according to the American Plastics Council. Inappropriate containers may melt or warp, which can increase the likelihood of spills and burns. Also, discard containers that hold prepared microwavable meals after you use them because they are meant for one-time use.
Microwave-safe plastic wrap should be placed loosely over food so that steam can escape, and should not directly touch your food. "Some plastic wraps have labels indicating that there should be a one-inch or greater space between the plastic and the food during microwave heating," Machuga says.
Always read directions, but generally, microwave-safe plastic wraps, wax paper, cooking bags, parchment paper, and white microwave-safe paper towels are safe to use. Covering food helps protect against contamination, keeps moisture in, and allows food to cook evenly. Never use plastic storage bags, grocery bags, newspapers, or aluminum foil in the microwave.
Stories about the dangers of chemicals leaching from plastic into microwaved food have circulated on the Internet for years. As a result, the Food and Drug Administration continues to receive inquiries from concerned consumers.
Consumers can be confident as they heat holiday meals or leftovers in the microwave that the FDA carefully reviews the substances used to make plastics designed for food use. These include microwave-safe plastic coverings that keep food from splattering and microwave-safe containers that hold frozen dinners. Even microwavable popcorn bags, which look like paper, actually contain a metalized plastic film that allows them to reach high temperatures so the corn can fully pop.
Under the food additive provisions of the Federal Food, Drug, and Cosmetic Act, new substances used to make plastics for food use are classified as "food contact substances." They must be found safe for their intended use before they can be marketed.
"It's true that substances used to make plastics can leach into food," says Edward Machuga, Ph.D., a consumer safety officer in the FDA's Center for Food Safety and Applied Nutrition. "But as part of the approval process, the FDA considers the amount of a substance expected to migrate into food and the toxicological concerns about the particular chemical." The agency has assessed migration levels of substances added to regulated plastics and has found the levels to be well within the margin of safety based on information available to the agency. The FDA will revisit its safety evaluation if new scientific information raises concerns.
One chemical called diethylhexyl adipate (DEHA) has received a lot of media attention. DEHA is a plasticizer, a substance added to some plastics to make them flexible. DEHA exposure may occur when eating certain foods wrapped in plastics, especially fatty foods such as meat and cheese. But the levels are very low. The levels of the plasticizer that might be consumed as a result of plastic film use are well below the levels showing no toxic effect in animal studies.
Other claims have asserted that plastics contain dioxins, a group of contaminants labeled as a "likely human carcinogen" by the Environmental Protection Agency. "The FDA has seen no evidence that plastic containers or films contain dioxins and knows of no reason why they would," Machuga says.
Machuga says that consumers should be sure to use any plastics for their intended purpose and in accordance with directions. If you don't find instructions for microwave use, you should use a different plate or container that you know is microwave-safe. Such containers are made to withstand high temperatures.
For example, carryout containers from restaurants and margarine tubs should not be used in the microwave, according to the American Plastics Council. Inappropriate containers may melt or warp, which can increase the likelihood of spills and burns. Also, discard containers that hold prepared microwavable meals after you use them because they are meant for one-time use.
Microwave-safe plastic wrap should be placed loosely over food so that steam can escape, and should not directly touch your food. "Some plastic wraps have labels indicating that there should be a one-inch or greater space between the plastic and the food during microwave heating," Machuga says.
Always read directions, but generally, microwave-safe plastic wraps, wax paper, cooking bags, parchment paper, and white microwave-safe paper towels are safe to use. Covering food helps protect against contamination, keeps moisture in, and allows food to cook evenly. Never use plastic storage bags, grocery bags, newspapers, or aluminum foil in the microwave.
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