Action News vol 10 no 3, June 2010, ISSN 1324-6011
Incorporating Lead Aware Times ( ISSN 1440-4966) and Lead Advisory Service News (ISSN 1440-0561)
The Journal of The LEAD (Lead Education and Abatement Design) Group Inc.
Editor-in-Chief: Anne Roberts
In China, where is the lead contamination coming from?
Food (via Soil contamination)
It is common to use effluent as a fertiliser in China. This results in accumulation over time, within fields, of heavy metals.- cadmium, chromium, copper, nickel, lead and zinc (Cd, Cr, Cu, Ni, Pb and Zn). The longer fields have been subject to effluent irrigation the higher the level of heavy metal accumulation (10/04/08) (Xiong). This could be a possible pathway for higher than average lead blood levels, for instance in agricultural workers. It may also be plausible, if lead works its way up the food chain, those eating greater quantities of meat would have a higher blood lead level - but this is speculation.
“Heavy metal accumulation in soils at three field sites subject to effluent irrigation.” ( Xiong, 2003).
RESULTS AND DISCUSSION: In soil, the average contents of Cd, Cu, Pb and Zn are 0.097, 22.6, 26.0 and 74.2 mg/kg, respectively. In the water of the Yangtze River Basin, the concentrations of Cd, Cu, Pb and Zn are 0.080, 7.91, 15.7 and 18.7 microg/L, respectively. In reference to human activities, the heavy metal pollution comes from three sources: industrial emission, wastewater and solid waste. The environment such as soil, water and air were polluted by heavy metals in some cases. The contents of Cd, Cu, Pb and Zn even reach 3.16, 99.3, 84.1 and 147 mg/kg, respectively, in the soils of a wastewater irrigation zone. These contaminants pollute drinking water and food, and threaten human health. Some diseases resulting from pollution of geological and environmental origin, were observed with long-term and non-reversible effects. CONCLUSIONS: In China, the geological background level of heavy metal is low, but with the activity of humans, soil, water, air, and plants are polluted by heavy metals in some cases and even affect human health through the food chain.
Eating lead-contaminated foods
Lead contamination of food is more common in third world countries that do not have strong food standards. It has recently become an issue in countries that have been importing food products from such countries. Food can become contaminated where it is grown, or by cooking vessels or the containers in which it is exported or stored.
There are a number of ways in which lead contamination of food occurs. The most common way has been during the growth and development of plants grown in soil containing an unusually high amount of lead. The plant surfaces become contaminated with dust or soil, or the plants may take up the lead from the soil as they mature. Lead contamination of food can and does occur even in commercial farming. The lead contamination of soil occurs when lead, lead dust, biosolids (sewage sludge), fertilisers made from waste acids from lead smelters or any liquid containing lead is introduced to the soil. [China is a very heavy user of biosolids in agriculture] see: Giblin, A., Lead in
Eating Rice as a source of lead poisoning:
Lead can be emitted during the mining and smelting of mercury ores, because most such ores also contain lead. Lead is also emitted during the burning of coal. Researchers in Guizhou province, where there are 12 large mercury mining and smelting operations and heavy coal-powered industry, found that rice accounted for 94-96% of the uptake of methyl mercury (Raloff, 2010). They were not testing for lead, but it is likely that the rice was also a source of lead in the diet.
Methyl mercury averaged 9.3 micrograms of this especially toxic mercury per kilogram of rice in an area where people down an average of more than a half-kilogram of the grain each day (Raloff 2010).
“Heavy metal pollution in China: origin, pattern and control.” (Cheng, 2003)
Evidence within the China Sea shows a huge increase in lead content of sea sediments. “…in the wake of China's rapid economic growth and the lack of management regulations, the Hangzhou Bay is being contaminated by lead, among other pollutants, at a rate three times faster than the worst case in the western seaboard of U.S. three to seven decades ago. To halt this alarming trend and avert the possibility of serious contamination to the coastal environment, regulatory measures such as sewage treatment and the phasing out of leaded gasoline should be mandated urgently.” (Huh and Chen 1999)
The lead contamination is believed to have come from rapid economic growth and a lack of waste control practices. The main source is the Yangtze river, indicating that this catchment is receiving high levels of Pb. It follows that anyone consuming water or food from this area is also receiving high levels of lead. (Huh and Chen, 1999)
Wastewater from rivers near industrial sites near the city of Guiyu have lead levels 400 to 600 times higher than wastewater from uncontaminated river would. Waste management rules are poor or non-existent (Brigden et al, 2005)
A study of a lake in eastern Qinghai province did not display excessive levels of lead content. However, the lake is in the less-industrialised west of China. (Virkutyte and Sillanp, 2006)
An additional study confirms that there are large amounts of lead particulates being deposited into the East China Sea, from where they are being transported (via a Biogeochemical cycle) throughout the world. (Lin et al, 1999).
Exposure to Lead from Leaded Gasoline (Petrol)
Leaded petrol was used in China up until 2000. (But see below: “doubt about the actual phase-out date”) Exposure to the lead from leaded petrol is usually through airborne particles, for adults, and via dust ingestion by children, in hand-to-mouth activity, particularly those living in houses and other buildings alongside heavily-trafficked roads.
An EVISA 2006 news article about a meta-analysis of childhood blood lead studies in China found:
Lead petrol phase-out:
While most industrial nations, including China, have abandoned or at least restricted the use of leaded gasoline, this is not the case for all parts of Asia and Africa.
What is happening?
Children living in urban or industrial regions (in particular in eastern China) had much higher levels of lead than those living in rural areas. The figures from meta-analysis of AAS and ICP-MS results contrast sharply with those of western counterparts, who have much lower lead levels on average.
Doubt about the actual phase-out date of leaded petrol for all road vehicles in China
In February 2003, the International Fuel Quality Center (IFQC) reported in Current Status of Leaded Gasoline Phase Out Worldwide that “even though leaded gasoline has been switched out in many Asian countries, it is most probably still available in small quantities in some “unleaded countries.” For example in China, some small refineries exist in rural areas that produce leaded gasoline. Also, smuggling of leaded gasoline is also present and cannot be completely dismissed. It can be assumed, however, that these quantities are very small. Most of the leaded gasoline is probably used in remote rural areas where it is out of reach of the government statistics.”
Other sources and pathways of lead poisoning in China
People in China, of course, are likely to be subject to the other sources and pathways of lead poisoning known to the rest of the world, namely: soil and dust containing lead (a legacy of industrial manufacturing, smelting and mining activities and leaded paint refurbishment), ceramics with a leaded glaze, leaded paint, recycling of lead acid batteries and electronic equipment with parts containing lead, water from tanks with lead solder, water from galvanised iron pipes or lead soldered plumbing, leaded PVC products, leaded jewellery, toys, ammunition, lead contaminated Chinese herbal medicine, cigarettes, etc.
What the evidence from water catchments in the more industrialised parts of the China shows is that there is a clear link between lead contamination of the environment and industrial activity. Coal use in China is rising steadily and it should be noted that coal naturally contains lead. Spectrographic analysis of particulates in Shanghai indicated that up to 45% of such lead may come from coal burning, and may well have exceeded petrol as a source if not for the phasing out of leaded petrol (Zhang et al 2009). In all probability the source of lead contamination is airborne particles, in which form lead is far better absorbed than when orally consumed, but that does not rule out food and drinking water as additional pathways, since, though leaded petrol for road vehicles was officially phased-out in China in 2000, there seems to be an upward trend in blood lead levels.
See also: “Biosolids used as fertilizer in China and other countries”, in LEAD Action News, volume 10, number 1.
Dangerous polluters are already moving their activities out to rural areas where rules and regulations are weaker. This will mean that while there will be an ongoing unusually high amount of blood lead in subjects in city areas and that rural areas where there are strong sources of lead contamination will also have abnormally high levels.
Information in Chinese about lead
The US Environmental Protection Agency’s Chinese website includes a factsheet on general information regarding lead paint in the United States at:www.epa.gov/lead/pubs/chance_chinese.pdf and www.environment.nsw.gov.au/resources/chinese.pdf
With encouragement from The LEAD Group, the New South Wales Health Department some years ago wrote an article about the dangers of lead in ceiling dust in ceiling voids (the space above the ceiling and below the roof). Are Chinese homes generally built with ceiling voids? If so, then the Chinese version of the article may be of interest: please see www.mhcs.health.nsw.gov.au/mhcs/publication_pdfs/5395/BHC-5395-CHI.pdf
The English version is at www.mhcs.health.nsw.gov.au/mhcs/publication_pdfs/5395/BHC-5395-ENG.pdf
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