THE CHICKEN OR THE LEAD?
Just how healthy are the eggs from New Zealand’s backyard chickens? Kendall Hutt reports.
A study has found lead in the chickens and eggs of more than three-quarters of its sample size.
The study, published in the New Zealand Veterinary Journal, revealed there was mounting evidence the heavymetal was being transferred to eggs in concentrations high enough to cause a public health concern.
Experts are now encouraging backyard chicken owners to get their hens tested for lead.
‘‘If you live in a city and are looking at getting backyard hens because you perceive the eggs might be healthier, this may not be the case,’’ says one of the study’s authors, Liz Cowie.
‘‘Humans have left a legacy of lead in the paint on our buildings, from our leaded fuel, and other industrial and agricultural activities.’’
The SPCA science team said owners should contact their vet if they believed their chickens had been exposed to or ingested sources of lead. These could be soil contamination, batteries, golf balls, fishing sinkers, foil and some building materials, but lead-based paint was believed to be a primary source of lead toxicity in chickens – another of Cowie’s findings.
She found higher blood lead concentrations in hens from properties with pre-1940s homes and weatherboard cladding, so encouraged those with an older villa or bungalow to be extra vigilant. ‘‘I have also come across individual cases where the sources of lead ... have been the chook feed or older metal soldered water troughs, so it pays to have a critical look at the coop, feed and garden setup.’’ If ‘‘lead intoxication’’ was confirmed, the SPCA advised consumption of the exposed chickens’ eggs should stop
until it was determined they were safe to eat. ‘‘This includes not feeding eggs or eggshells back to your chickens or disposing of eggs shells in your compost,’’ the science team said.
Lead poisoning in adults could lead to mood changes, such as depression, memory loss, headaches, and numbness in fingers and hands.
Dr Adam Pomerleau, director of the National Poisons Centre, said while chronic lead exposure at low doses was ‘‘low-level stuff’’ for adults, there was the risk of ‘‘bad effects’’ on the development of the brain and central nervous system in children.
‘‘If there’s a house with leadbased paint, we recommend kids get tested.’’
Although 57 per cent of the study participants came from a postcode within an 8km radius of Auckland’s city centre, the director of Massey University’s Wildbase Research Centre said it was ‘‘common’’ and ‘‘not just an Auckland problem’’.
Professor Brett Gartrell, who supervised Cowie’s study, said he saw several chickens from the Manawatu¯-Whanganui region and a ‘‘sizeable amount’’ had lead exposure.
‘‘All over the country, it will be a problem and not just in New Zealand.’’
One of his vet technician’s own chickens was found to have lead poisoning this week and was being treated.
However, Cowie’s peerreviewed study was drawing mixed reactions from backyard chicken owners across Auckland.
Glendene resident Rinesh Solanki and his family kept two hens in their backyard and preferred them to commercial eggs because he knew what they were being fed.
‘‘My perception is the eggs are safe to eat.’’
But when told of the study, he said ‘‘Now you’ve scared me’’, and asked where he could get his hens tested.
‘‘If there are some issues there I want to knowmore about it and reconsider.’’