PubMed Health⌕ Search

Biomedical subjects

I Caldwell

Publications and source records attributed to I Caldwell.

7 recordsLinked to original sources
PubMed2006

The costs and benefits of reforestation in Liping County, Guizhou Province, China.

Reducing greenhouse gases in the atmosphere is becoming a pressing issue for the global community. Afforestation and reforestation are promoted worldwide as an effective means of sequestering carbon. For its national interest and global concerns, China has made great efforts to protect its existing forests and develop programs of afforestation and reforestation. Based on two surveys recently conducted in Liping County, Guizhou province, this paper investigates the economic changes associated with the implementation of the "Grain For Green" policy. Based on the analytical framework of benefit cost analysis, this paper concludes that the implementation of the reforestation of sloping agricultural land policy would not be possible if there were no government subsidies for the peasants. The short term economic returns of land and labour from forestation are substantially lower than those generated from grain or cash crop production on the steep slope lands. The government subsidies provide great economic incentives for peasants to take part in the project. The subsidies in fact have elevated peasant income in rural Liping. The estimated potential economic returns of plantations over the long run indicate that the removal of the government financial subsidies would not create an economic crisis for the peasants if the current market conditions continue.

Agriculture↗
PubMed1993

Exposure to styrene in the general Canadian population.

As part of an environmental health assessment in Canada, estimates of the intake of styrene by the general population were derived. Concentrations of styrene reported in air, water, soil and foods in Canada were reviewed in detail. Data on ambient air, collected by Environment Canada, showed mean concentrations of 0.09-2.35 micrograms/m3 at 18 sites across the country. In a national pilot study of indoor air in 757 homes across Canada, the mean styrene concentration was found to be 0.28 microgram/m3. The range of mean concentrations of styrene in treated water from 80 supplies in Ontario's Drinking Water Surveillance Program was 0.050-0.250 microgram/L. In limited testing of uncontaminated urban soils in southern Ontario, the styrene levels were less than 10 micrograms/kg. In a small Canadian survey, the compound was not detected (limits of detection, 1.0 microgram/L for liquids and 0.005 microgram/g for solids) in composite samples of 34 groups of food purchased in Windsor, Ontario. On the basis of these monitoring data, daily intakes of styrene were estimated for the general population. Intakes from ambient air ranged from 0.004 to 0.17 microgram/kg body weight per day and those from indoor air from 0.07 to 0.10 microgram/kg body weight per day for various age groups: infants, toddlers, school-age children, teenagers and adults. Intake from food was calculated to range from < 0.11 to < 0.58 microgram/kg body weight per day. The estimated intakes from drinking-water and soil were negligible. Potential exposure from cigarette smoke, on the basis of the styrene reported in mainstream smoke (10 micrograms per cigarette) and a smoking rate of 20 cigarettes per day, was estimated to be 2.86 micrograms/kg body weight per day for adults.

Adolescent↗