Lead – Frequently Asked Questions
Lead is a naturally occurring heavy metal, often used in industry. It can be dispersed widely in the environment through contamination of water, dust, soil, and some paints.
Lead can affect everyone, but children under five years of age are at greater risk because they tend to put their hands or other objects into their mouths; they absorb more ingested lead than adults; and their brains are still developing so they are more sensitive to the effects of lead.
Lead gets into our bodies when we breathe in lead dust or fumes in the air or if we eat food or drink water that contains lead.
Why is there lead in soil?
Soils can contain lead in varying amounts, depending on their geological source. Factors which affect the amount of lead in soil include:
- Age and building materials used in houses. Most houses built before 1970 contain lead-based paint. After 1970 lead levels in paint dropped, but old paint may be unsafe if disturbed during renovations. Slag, containing lead, has also been used in parks and gardens and homes as fill and/or to provide drainage.
- Proximity to emissions. Homes near industries that produce or use lead may have lead dust fall into their homes or gardens.
- Homes near heavy traffic may have higher levels of lead in soil due to exhaust from lead petrol, although this has decreased with the use of unleaded petrol.
- People may bring lead into their homes and yards as a result of their work or hobbies (eg lead solder, furniture restoration and lead sinkers).
A level of 300 parts per million (ppm) of lead in soil has been set as a level for further investigation by the National Health and Medical Research Council (NHMRC).
What should I do if I have lead in soil?
Homeowners who think they may have lead in their soil should get advice from the NSW Office of Environment and Heritage or from their local council on reducing soil lead levels.
The NSW Lead Management Action Plan (NSW Interdepartmental Lead Taskforce, Environment Protection Authority, 1994) sets the following levels for remediation which could be used as guidelines for a site specific / child specific residential property:
- < 300 ppm - no action
- 300 - 1,500 ppm - grass cover or other appropriate barrier
- 1,500 - 5,000 ppm - top dress with 50 mm clean soil and grass cover
- 5,000 ppm - soil replacement (top 200mm)
Management strategies should recognise that there is a difference between contaminated land that is a direct and immediate health risk and that which does not pose a health risk (but should still be recognised as a potential hazard).
What can the homeowner do?
If your home or gardens are contaminated by lead, the following suggestions can minimise the risk of lead exposure:
- Wash hands thoroughly after playing outside and touching pets, paying particular attention to dirt from under the nails and ingrained dirt
- Wash hands before eating and preparing food
- Thoroughly rinse fruit and vegetables before eating
- Wash toys, dummies and bottles frequently
Children should have a healthy and varied diet. Children who have dietary deficiencies in iron, calcium, and vitamin C are more susceptible to harm from lead exposure. Diets with sufficient iron and calcium help reduce the absorption of lead into the blood and Vitamin C may help the kidneys to remove it.
Garden and outside play
Children need safe areas in which to play. Plans for your garden should include:
- Barriers over bare soil, such as grass, garden beds, mulch or bark chips
- Separate areas used by adults for hobbies or activities that may generate sources of lead exposure (eg stripping down old furniture or spray painting of cars)
- Keep painted surfaces that are accessible to children in good repair
- A cover over the sandpit to protect it from pets or other animals that may carry lead
After working in the garden, it is important that shoes be removed or cleaned prior to entering the home, as they can carry lead onto floors and carpets. Children who play in the garden should always take their shoes off prior to coming indoors for the same reason.
Research indicates that some leafy vegetables collect lead-bearing dusts more readily from the environment than other vegetables eg. lettuce and silverbeet. These plants are not recommended for consumption by young children or pregnant women when grown in lead contaminated gardens.
Always remember to thoroughly wash all fruit and vegetables prior to storage and eating. This removes any surface dirt which may contain lead.
Compost and mulch are excellent, natural ways of improving the nutrient content of your vegetable beds. Compost provides organic matter - which helps to reduce the amount of accessible lead in the soil of vegetable beds. Increased soil quality will also promote vegetable growth.
Keeping of chickens
Poultry foraging for food in lead contaminated soils may swallow enough lead to cause their eggs to become contaminated with lead and could be unsuitable for consumption. To protect poultry from lead contamination:
- Do not allow the poultry to range freely through the yard
- Keep poultry in a poultry house paved with a concrete or bitumen floor. A 100–150 mm layer of straw, wood shavings or rice hulls should be placed on the floor of the poultry house. The litter should be kept at a depth of 150 mm by adding more fresh material when necessary
- All poultry require access to a dust bath. Provide a large shallow pan (such as a kitty litter tray or children’s wading pool) filled with loose uncontaminated soil, sand, hardwood ashes or a combination of these within the poultry house
- Ensure the poultry house is constructed of materials free of lead
- Wash eggs prior to use
Where else can lead come from in the home?
Nearly all cases of acute lead poisoning in children admitted to children's hospitals in recent years have been attributed to home renovation activities.
Most houses built before 1970 contain lead paint. After 1970, lead levels in paint dropped but old paint and flaking paint may be unsafe if disturbed during renovations. Unsafe renovations where old lead paint is removed or prepared for over-painting are the most common causes of lead poisoning.
Open-flame torches create dangerous fumes. Dry sanding without water creates lead dust. Fumes and dust can be breathed in, eaten or can contaminate the house, its contents and surrounding areas. You can renovate safely if you take precautions and use the right equipment.
Lead contaminated dust
Many older Australian homes and buildings have lead dust in their ceiling cavities, wall cavities and under the floor. This may have come from industrial pollution, exhaust emission from use of leaded petrol, unsafe renovations or demolitions.
To reduce this hazard, it is recommended that cracks, ceiling roses and some vents be sealed to stop dust leaking into rooms. Also, wet wipe surfaces before preparing food or drinks, window sills, ledges and flat surfaces at least weekly and after vacuuming and wet mop rather than sweep floors.
What about lead in fish caught in the lake?
In 1997 studies conducted by a steering committee managed by the Hunter Public Health Unit found that lead levels in fish were an average of 0.22 mg/kg which is under the food standard level of 0.5 mg/kg. The Public Health Unit recommended that fish intake be limited to 1.35 kg of fish per week to prevent excess selenium intake which should also protect against excess lead accumulation, however, lead in fish should be taken into account in the management of children with already elevated lead levels.