Lead toxicity – Dangerous to humans and vultures alike!

Vultures feeding - Vulture restaurant @ VulPro - Photo Mandy Schrode
Vultures feeding – Vulture restaurant @ VulPro – Photo Mandy Schroder

Understanding Lead Poisoning

All Birds of Prey, especially long lived, slow breeding species such as vultures, are at risk of lead poisoning.   Vultures and other animals are exposed to lead shards when feeding on animals that have been killed by lead bullets as well as from the entrails left behind by hunters.  It also highlights the responsibilities of places housing raptors such as vultures to ensure that their enclosures are lead free, this applies to lead free paint and a lead free water supply, a problem in many older facilities where water was routinely piped in lead pipes, soil needs to be lead free and vegetation supplied needs to be lead free too, another factor to consider here are the emissions from lead based petrol.

Interesting Fact

New world vultures such as the Californian Condor are far more susceptible to lead poisoning than our Old World Vultures

In large quantities lead is detrimental to the nervous and reproductive systems

Radiographs from a Cape Vulture chick showing severe osteodystrophy caused by lead toxicity
Radiographs from a Cape Vulture chick showing severe osteodystrophy caused by lead toxicity

of vultures.  A vulture with lead poisoning will show weakness and anorexia, the most dangerous symptoms are not easily detectable until serious damage has occurred.  The Cape Vulture experiences osteodystrophy  (softening and degeneration of the bones) and reduced reproductive success. For a slow breeding species like the Cape Vulture this has a huge impact on the species population numbers, as well as the number of vultures who experience poor bone development resulting in ongoing fractures and ultimately death.

We need to educate farmers, landowners and hunters regarding the effect and dangers of lead toxicity on our wildlife and endangered species such as vultures. If carcasses killed using lead bullets are to be left accessible to vultures, bullets and any shards of lead need be removed. Hunters also need to be educated about using environmentally safe, non-fragmenting copper bullets.

Why is Lead such an issue?

  • Lead bullets are designed to shatter or fragment on entry, this leaves small particles scattered throughout the carcass which scavengers ingest.
  • Lead toxicity in the Californian Condor has also proven to lead to lead accumulation in bone over time
  • Vultures are a long lived, slow breeding species. This means that their recovery from population drops is too slow.
  • Vultures scavenge communally, meaning that a single contaminated carcass can poison several vultures.

Understand the Role of Hunting

Every healthy ecosystem needs to be managed by checks and balances; hunting is a natural part of the environment that predators rely on for survival.  Man may no longer need to hunt to survive but he is necessary for keeping populations under control thanks to our impact on the environment.  The scraps that hunters leave behind help to feed many scavengers and hungry predators, because of this we need to encourage hunters to use non-lead bullets.  The effect of lead is not just seen on our vultures but affects our other wildlife as well.

Scary Fact

A terrifying fact is that more than 500 scientific studies published since 1898 have documented that worldwide, 134 species of wildlife are negatively affected by lead ammunition.

Human Health Concerns

South Africa is a country of meat lovers and game meat is a roaring trade whether it is biltong or a venison roast, studies worldwide are increasingly showing that lead fragments can also be found in wild game meat processed for human consumption.  Added to this we are exposed to lead fuel emissions, plants and vegetables that have absorbed lead and lead found in water carried in old lead pipes.

Lead toxicity in humans can have horrific consequences over time, developmental abnormalities in newborns and children, and may even result in death.  In adults the symptoms range from high blood pressure and joint pain to a host of other health issues in between.

The World Health Organisation lists the key facts about lead poisoning as:

  • Lead is a cumulative toxicant that affects multiple body systems and is particularly harmful to young children.
  • Childhood lead exposure is estimated to contribute to about 600 000 new cases of children developing intellectual disabilities every year.
  • Lead exposure is estimated to account for 143 000 deaths per year with the highest burden in developing regions.
  • Lead exposure is estimated to account for 4% of the global burden of ischaemic heart disease and 5% of the global burden of stroke.
  • About one half of the burden of disease from lead occurs in the WHO South-East Asia Region, with about one-fifth each in the WHO Western Pacific and Eastern Mediterranean Regions.
  • Lead in the body is distributed to the brain, liver, kidney and bones. It is stored in the teeth and bones, where it accumulates over time. Human exposure is usually assessed through the measurement of lead in blood.
  • There is no known level of lead exposure that is considered safe. Lead poisoning is entirely preventable.

Hunting using Non Lead Bullets

Lead bullets have been used because their design allows a for quick clean kill. The rapid expansion of the bullet provides the hydrostatic shock needed to give a quick kill but also results in lead fragmentation.

The modern lead free bullets still allow for the rapid expansion resulting in a clean kill, but don’t result in the fragmentation that is so dangerous for humans and wildlife alike.  For those who do love to hunt, there are a number of websites which offer advice and guidance on the use of non lead bullets.  They also host interesting and yet terrifying information showing just how far lead fragments travel in the body.

References:

http://www.atsdr.cdc.gov/csem/csem.asp?csem=7&po=10
http://www.mayoclinic.org/diseases-conditions/lead-poisoning/basics/symptoms/con-20035487
http://www.who.int/mediacentre/factsheets/fs379/en/
http://www.azgfd.gov/w_c/california_condor_lead.shtmlhttps://www.nps.gov/pinn/learn/nature/leadinfo.htmhttp://www.defenders.org/california-condor/preventing-lead-poisoninghttp://www.futurity.org/lead-californias-condors-831052/http://www.ncbi.nlm.nih.gov/pubmed/12685072http://projectvulture.org.za/threats/poisoning/lead-poisoning/

Link for hunting with non lead bullets:

http://www.huntingwithnonlead.org/videos.html

http://www.ventanaws.org/species_condors_lead/frequently-asked-questions-about-condors.htm

https://www.peregrinefund.org/subsites/conference-lead/PDF/0108%20Pain.pdf

http://www.sciencedirect.com/science/article/pii/S0269749108004478
Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s