Effects of Lead on the Environment
Text by Greene, Deni; Berry, Prof Mike; Garrard, Dr Jan. Funded by National Health and Medical Research Council (NHMRC), Commonwealth Environment Protection Agency (CEPA) and Dept of Health, Housing, Local Government, & Community Services (DHHLGCS). Published by Commonwealth Dept of Human Services and Health Published July 1993.
Graphics come from Volcano Art Prize (VAP) Website of The LEAD Group.
Other Recommendations - Recommendations for a National Strategy, from: Reducing Lead Exposure In Australia, Final Report Vol 1 - Pages ES 7 To ES 20
- Prohibit sale and use of lead shot, lead in children’s toys, paints and crayons, lead fishing weights, lead curtain weights and other products in which lead can be readily replaced.
VAP Entry 2013. Title: Lead Fishing Gear Creates Orphans, Lead-safety message: "Many species unwillingly ingest lead objects, which, if left untreated, will kill them. Respect them and reconsider your fishing gear choices." Photographer: Jennifer Lee Harackiewicz. http://volcanoartprize.com/portfolio-item/harackiewicz-jennifer-lead-fishing-gear-creates-orphans/
Effects of Lead on The Environment - From: Reducing lead exposure in Australians. Final Report Vol 1 - pp 21-23
Lead moves into and through ecosystems. Atmospheric lead is deposited on vegetation, ground and water surfaces. The chemical and physical properties of lead and the biogeochemical processes within ecosystems will influence the movement of lead through ecosystems. The metal can affect all components of the environment and can move through the ecosystem until it reaches an equilibrium. Lead accumulates in the environment, but in certain chemical environments it will be transformed in such a way as to increase its solubility (e.g., the formations of lead sulfate in soils), its bioavailability or its toxicity. The effects of lead at the ecosystem level are usually seen as a form of stress (US EPA 1986).
In general, there are three known ways in which lead can adversely affect ecosystems. Populations of micro-organisms may be wiped out at soil lead concentrations of 1,000 µg/g or more, slowing the rate of decomposition of matter.
Populations of plants, micro-organisms and invertebrates may be affected by lead concentrations of 500 to 1,000 µg/g, allowing more lead-tolerant populations of the same or different species to take their place. This will change the type of ecosystem present. At all ambient atmospheric concentrations of lead, the addition of lead to vegetation and animal surfaces can prevent the normal biochemical process that purifies and repurifies the calcium pool in grazing animals and decomposer organisms (IPCS 1992).
Exposure Routes for Lead to the Environment
The main sources of lead entering an ecosystem are atmospheric lead (primarily from automobile emissions), paint chips, used ammunition, fertilizers and pesticides and lead-acid batteries or other industrial products. The transport and distribution of lead from major emission sources, both fixed and mobile, are mainly through air (IPCS 1992). While most of the lead discharged into air falls out near the source, about 20 percent is widely dispersed. Studies have demonstrated that measurements of lead in Greenland rose and fell with the rise and decline of use of alkyl-leaded petrol in the United States, Eurasia and Canada over the past century (Rosman et al. 1993). The size of the lead particles will govern how far they move from the source.
Effects of Lead on Soils
It is known that lead accumulates in the soil, particularly soil with a high organic content (US EPA 1986). Lead deposited on the ground is transferred to the upper layers of the soil surface, where it may be retained for many years (up to 20,000 years). In undisturbed ecosystems, organic matter in the upper layer of soil surface retains atmospheric lead. In cultivated soils, this lead is mixed with soil to a depth of 25 cm (i.e. within the root zone). Atmospheric lead in the soil will continue to move into the microorganism and grazing food chains, until an equilibrium is reached.
Given the chemistry of lead in soil, the US EPA (1986) suggests that the uneven distribution of lead in ecosystems can displace other metals from the binding sites on the organic matter. It may hinder the chemical breakdown of inorganic soil fragments and lead in the soil may become more soluble, thus being more readily available to be taken up by plants.
Effects of Lead on Plants
Plants on land tend to absorb lead from the soil and retain most of this in their roots. There is some evidence that plant foliage may also take up lead (and it is possible that this lead is moved to other parts of the plant) (IPCS 1992). The uptake of lead by the roots of the plant may be reduced with the application of calcium and phosphorus to the soil. Some species of plant have a capacity to accumulate high concentrations of lead (IPCS 1992).
The pores in a plant’s leaves let in carbon dioxide needed for photosynthesis and emit oxygen. Lead pollution coats the surface of the leaf and clogs these pores, which hinders the movement of gases in and out of the leaf and reduces the amount of light reaching it. This results in stunting the growth or killing the plants, by reducing the rate of photosynthesis, inhibiting respiration, encouraging an elongation of plant cells, influencing root development or by causing premature aging. Some evidence suggests that lead can affect population genetics. All these effects have been observed in isolated cells or in hydroponically grown plants in solutions of around 1-2 µg/g of lead in soil moisture (e.g. the lead levels experienced by ecosystems near smelters or roadsides) (US EPA 1986).
Lead in air may be transferred to plants directly through fallout or indirectly through uptake from the soil. The pattern and degree of lead accumulation are largely influenced by the state of growth of vegetation; i.e. active growth periods in spring as compared to low growth periods through autumn and winter.
2015 VAP Entry. Title: Rainbow Bird. Lead-safety Message: Clean air for every person and every animal. Materials:Lead pencils and coloured pencils. Artist: Karina Wang. http://volcanoartprize.com/portfolio-item/rainbow-bird/
Effects of Lead on Microorganisms
Evidence exists to show that lead at the concentrations occasionally found near roadsides (i.e. 10,000 – 40,000 µg/g dry weight), can wipe out populations of bacteria and fungi on leaf surfaces and in soil. This can have a significant impact, given that many of these micro-organisms are an essential part of the decomposition food chain. The micro-organism populations affected are likely to be replaced by others of the same or different species, although these may be less efficient at decomposing organic matter. Evidence also suggests that micro-organisms can make lead more soluble and hence more easily absorbed by plants. That is, bacteria exude organic acids that lower the pH in the immediate vicinity of the plant root (US EPA 1986).
Effects of Lead on Animals
Lead affects the central nervous system of animals and inhibits their ability to synthesize red blood cells. Blood lead concentrations of above 40 µg/dL can product observable clinical symptoms in domestic animals. Calcium and phosphorus can reduce the intestinal absorption of lead (US EPA 1986). The US EPA report generalizes that a regular diet of 2-8 mg/lead per kilogram of body weight per day, over an extended period of time, will cause death in most animals. Grazing animals are directly affected by the consumption of forage and feed contaminated by airborne lead and somewhat indirectly by the uptake of lead through plant roots. Invertebrates may also accumulate lead at levels toxic to their predators.
2012 VAP Entry. Title: Still Life with Shot Gun Cartridge and Orchids. Lead-Safety Message: The use of lead shot ammunition by hunters is threatening the survival of our endangered raptors (vultures, hawks, falcons, eagles and owls), switch to non leaded shot now! Orchid Penjing Sculptor/Artist: Arthur Rouw. http://volcanoartprize.com/portfolio-item/still-life-with-shot-gun-cartridge-and-orchids/
Lead shot and lead weights can severely affect individual organisms and threaten ecosystems (IPCS 1992). After three to ten days of waterfowl ingesting lead shot, the poison will reach the bloodstream and be carried to major organs, like the heart, liver and kidneys. By the 17th to 21st day the bird falls into a coma and dies. Following the ingestion of lead shot, lead toxicoses has been observed in Magpie geese; Black swans, several species of duck (including Black duck and Musk duck) and Hardhead species (OECD 1993).
VAP Entry 2013. Title: Boat on pristine waterway, Lead-safety message: "Whether you’re painting watercolours or going fishing, buy lead free products." Description of Work/Material: Watercolour painting, non-toxic paint. Artist: Yvonne Preston. http://volcanoartprize.com/portfolio-item/boat-on-pristine-waterway/
Organic lead is much more readily taken up by birds and fish (IPCS 1992). Aquatic organisms take up inorganic lead through a transfer of lead from water and sediments; this is a relatively slow process. Organic lead is rapidly taken up by aquatic organisms from water and sediment. Aquatic animals are affected by lead at water concentrations lower than previously thought safe for wildlife. These concentrations occur often, but the impact of atmospheric lead on specific sites with high aquatic lead levels is not clear (US EPA 1986).
Title: Aboriginal tortoise. Lead safety message: Animals should not eat lead as they can be poisoned. Age 8. Materials: Dot Painting (Non Toxic Oil Pastels on Acid Free Paper). Artist: Leyanna Flaifel. http://volcanoartprize.com/portfolio-item/aboriginal-tortoise/.
IPCS (1992), International Programme on Chemical Safety, Environmental Health Criteria for Organic Lead , unedited draft, EHO, UNEP, ILO, Geneva.
OECD 1993, Draft OECD Chemicals Program. Risk Reduction Monograph No. 1 lead. Background and National Experience with Reducing Risk.
Rosman, K.J.R., Chisholm, W., Boutron, C.F., Candelone, J.P. & Goriach, U. (1993), Isotopic Evidence for the Source of Lead in Greenland Snows Since the Late 1960s’ Nature, vol. 362, 25 March, pp. 333-335.
US Environmental Protection Agency (1986), Air Quality Criteria for Lead, EPA Report No. EPA/600/8-83/028aF, Office of Health and Environmental Assessment, Research Triangular Park, North Carolina.