Michele Lucarelli, NBS Technical Author, following work done on sections C20 and M60 with respect to lead in paint, provides some background to the issue.
Exposure to lead, even at low levels, can cause a wide range of problems, including:
- permanently lowered IQ;
- learning and behavioural problems;
- delayed or reversed brain development;
- memory loss;
- stunted or slowed growth;
- hearing loss;
- neurological or kidney damage;
- spontaneous abortion; and
- erectile dysfunction and fertility problems in males.
In extreme cases it can cause encephalopathy, coma or death.
Children are particularly vulnerable as they are more likely to ingest paint chips, residual dust or contaminated soil, and their physiology takes up lead more readily than in adults; their central nervous systems are still developing and their bodies are unable to efficiently distinguish between calcium or iron, and lead. Lead is initially taken up by soft tissue but is also laid down in bone and, for females, can be released when pregnant. Lead in the skeleton may also be mobilised by vitamin D, usually through exposure to sun, and may produce irritability, loss of appetite, seizures or symptoms similar to 'flu. Owing to the body's difficulty in discharging lead, it is often seen as a cumulative poison.
One of the main culprits, lead in petrol, has been addressed in this country. Lead has also been removed from most new paints*, and although lead from old water supply pipework remains a concern, most of us have moved on, to worry about asbestos, or VOCs, or toxic off-gassing.
But current research suggests that blood lead toxicity levels are much lower than previously thought. Pre-1970, 'acceptable' blood lead levels were set in the UK at 60 μg/dL, reduced to 40 μg/dL in 1970, and reduced further to 25 μg/dL in 1985. Today blood lead levels as low as 10 μg/dL are now considered harmful, and increasingly there is talk of 'no safe level'. The current recommended international safety limit for lead in paints (including toys) is 0.06% (UK limit: 0.01%). The amount of lead in paint in older properties may be as high as 38%, with potentially 5-10 mg/cm². On average, children under six may absorb 50% of lead ingested.
The presence of lead-based paint must be highlighted in the pre-construction health and safety information. Portable isotopic X-ray fluorescent (XRF-i) testing is a cost effective method for determining the presence and concentration of lead. If found, or just suspected, there is a dilemma: to remove, or retain? Strategic risk appraisal is needed, involving the client, looking at current vs. future risk.
Risk assessments under CDM also require care. The designer's specification may infer a preparation technique which increases risk. When appraising the contractors' method statements, in-depth study is needed of testing, operations, containment, disposal, and clearance approvals.
Removal exposes people to the lead immediately, but eliminates long term and uncontrolled risk. If removal has been specified, infrared stripping is preferable to abrasive, blast or solvent techniques that produce hard-to-contain residues.
Disposal is normally the contractor's concern, but lead contaminated waste (including soil) needs special consideration. It might be incorporated in site waste and taken to landfill, but then classed on arrival as hazardous by the Environment Agency. To avoid time and cost implications, disposal should be discussed with all relevant parties at an early stage.
Over-painting, or 'abatement', aims to contain the hazard, but the risk of ingestion remains, whether from children eating paint chips or gnawing painted items, or ingestion of contaminated dust from future maintenance (preparation). If abatement is specified, containment, cleaning, and dust level monitoring pre- and post-construction are critical. Actual blood lead level screening may be needed, as in America. Lead-safe work practices and clean-up regimes can be time consuming, and require stringent attention to detail. Particular care should be given to methods of control in occupied premises, or where air circulation plant is in operation, and where operatives and site visitors could carry dust off site on clothing and shoes. Although workplace exposure is covered by UK law, reoccupancy levels are not, and this may be an area which sees future health and safety focus.
Reuse and recycling of elements which may have a lead-based coating also need careful risk and physical management. Upon completion, any retained hazardous or contaminated materials (including soil) should be highlighted in the health and safety file.
Further advice can be obtained from:
- British Coatings Federation [BCF - www.coatings.org.uk ], e.g. Old lead painted surfaces – a guide on repainting and removal for DIY and professional painters and decorators.
- Health and Safety Executive [HSE - www.hse.gov.uk ].e.g. Control of lead at work (third edition)
- Safety in Design [SiD - https://www.safetyindesign.org.uk/ e.g. Health Guidance Note H10.003 Lead paint.
* In the UK the use of lead-based paint was restricted in the 1960s, but some primers continued to be used for domestic timber window applications until the late 1980s. Lead-based paint can still be used for Grade I and Grade II* listed buildings, subject to approval. Anti-corrosive lead based paints may be used for metal surfaces, with sales restricted to trade and industry.