Question & Answer

The Evidence

• We were asked if water pipes that contain lead harm people’s health, but didn’t find any studies specifically about lead pipes. We mainly found studies on lead from various sources. This includes lead from traffic, paint, mining, battery manufacture and e-recycling plants as well as other sources.
• We found four systematic reviews about lead and health in general.
  • The first review looked at whether exposure to lead causes anaemia in children and did not find an association between lead and anaemia.
  • The second review was about lead and blood pressure. This review found that there might be a small association between lead exposure and blood pressure. However, this review is of low quality and dates from 1995.
  • The third review looked at a lot of studies on how lead affects babies and young children’s brain development. It found that children exposed to lead, either directly or through their mother before they were born, can have problems with brain development compared with children who were not exposed. However, we couldn’t be sure of how good these included studies were.
  • We found a fourth moderate-quality review about women of child-bearing age in Sub-Saharan Africa, including pregnant women and how different levels of lead affected them or their babies. Some studies followed these babies until they were older children or adults. There were mixed findings; some studies reported bad outcomes for mothers or babies when they were exposed to lead, and some did not find any bad outcomes.
  • Many of the studies in these reviews are what is called cross-sectional. That means that the scientists just looked at a group of people who are exposed to something (like lead), but there might have been other reasons for the bad outcomes they found (like smoking or age). Other studies in these reviews had few people in them so we can’t depend on their findings.
• A report from the World Health Organization (WHO) included studies on lead from lots of sources. They reported that exposure to lead was associated with neurological, physical and development problems in children, hearing loss, lower IQ (intelligence), mental health problem, reduction in being able to think and reason in old age and cardiovascular disease. It also reported that children who are exposed to lead are more likely to be aggressive or anti-social later in their teenage years. However, this report doesn’t tell us about how good these included studies are, and how much we can rely on them.

Guidelines and recommendations

• The WHO says that over a million people die from lead poisoning every year.
• The WHO fact sheet says that lead can affect many parts of the body and that can be stored in the bones. Lead that is stored in the bones of a pregnant women can cause her baby to be exposed, which can cause harm. They say that there is no safe level of lead for human health.
• The HSE also says that lead is harmful to health and notes that lead can get into drinking water from old lead pipes.
• Uisce Éireann, who are in charge of the majority of water supplies in Ireland, say that there are no lead water mains in Ireland. However, they say that there are still some old lead pipes connecting public water pipes to private supplies.