Effects of lead on human health

Note: The GWCT, along with most other wildlife organisations, does not have human health experts on its staff. The following advice has been produced by human health experts at the Food Standards Agency (FSA), who are qualified to give advice on the consumption of game shot with lead ammunition.

Is lead toxic to humans?
Lead is toxic and has a threshold tolerance of zero which means it is not possible to set a level of intake below which no health impacts would be expected for either wildlife or humans^1,2.

How does the toxicity of lead compare to other metals?
Other metals we are exposed to such as cadmium, mercury, tin, aluminium, and copper are less toxic than lead; some of them require at least ten times the dose to reach the same level of toxicity. Unlike lead, they all have tolerance thresholds for either wildlife or humans, so exposure below that level would be considered safe^3-6.

Does the human body need some of these metals?
Yes. Copper is an essential element required at low levels for proper functioning of the body, but it is toxic in high doses. However, lead is not required by the human body and remains toxic in even the smallest quantity.

How does lead enter the human body?
By breathing particles suspended in the air, drinking water, eating food, and (particularly children) ingesting soil and dust. Water and food are the main sources of lead in adults, while lead in air is now at very low concentrations^1,2.

What happens to the lead that is ingested?
The amount of ingested lead that the body absorbs depends on age and various other dietary factors, for example calcium and protein intake. In a well-nourished adult, around 15-20% of dietary lead is absorbed and the rest excreted².

Where in the body is lead found?
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. Around 95% or more of lead in the body is in bones and teeth, and less than 5% is in blood and soft tissues^2,7.

How long does lead stay in the body?
Lead levels in the blood and soft tissues vary quite rapidly, rising and falling in line with exposure over the course of a month or so. Longer-term lead accumulation occurs in the bones and teeth, which can store lead for decades and can therefore be an indicator of lifetime exposure^2,7.

Does lead stored in the bones stay there for life?
Lead in the bones and teeth usually exchanges very slowly with the blood but can be released gradually over a long period of time. This exchange may happen more rapidly during certain illnesses such as kidney disease, or events such as pregnancy, breastfeeding, or broken bones^2,8.

How does lead affect human health?
Increased levels of lead in the blood are associated with effects such as reduced IQ and hearing, increased blood pressure, and reduced kidney function. Children are particularly vulnerable to IQ reductions even at very low levels of lead^2,7,8.

Was lead removed from pipes, paint and petrol on human health grounds?
Yes. Increased knowledge about lead toxicity and its impact on human health prompted the removal of lead from pipes, paint and petrol.

Has this reduced human lead exposure?
Yes. Human blood lead levels in the UK are ten times lower than they were 30 years ago⁸. The main source of lead exposure now is from food and drink¹. The food includes lead-shot game; the FSA advises people who eat such game regularly to reduce their consumption.

Which foods do humans get the most lead from?
Intake of lead from background sources is unavoidable. In the average diet, humans ingest lead through a variety of foodstuffs such as bread, tap water, beer, tea and potatoes, as well as those we are encouraged to eat more of for health reasons (fresh vegetables, cereal products)¹. Although these foods and drinks contain very low levels of lead from background sources, they are consumed in relatively large quantities and consequently make up a significant proportion of lead exposure in the average diet. Although the consumption of lead-shot game is avoidable, people consuming this meat, even at low to moderate levels, will substantially increase their exposure to lead⁹.

What is the FSA’s advice on eating lead-shot game?
“Consuming lead is harmful; health experts advise to minimise lead consumption as much as possible. Anyone who eats lead-shot game should be aware of the risks posed by consuming large amounts of lead, especially children and pregnant women”.

and

“To minimise your risk of lead intake, if you frequently eat lead-shot game meat, particularly small game, you should cut down your consumption. Exposure to lead can harm the developing brain and nervous system. So, cutting down the amount of lead-shot game eaten is especially important for toddlers, children, pregnant women and women trying for a baby”.

Has the FSA given advice on the number of portions of game that should be eaten?
No, but it does say: “There is no agreed safe level for lead intake. Independent scientific expert groups across the European Union advise that exposure to lead should be reduced as far as possible.”

So how do I know if I am a frequent consumer of lead-shot game?
We contacted the FSA to clarify this. It stated that:

“The levels of lead in game are very variable so that the people who consume the largest quantity of game shot with lead ammunition may not have the highest lead exposure. Because of this, the FSA has not given advice in terms of only consuming a certain number of game portions as it could be misleading. However, broadly, lead exposure and the risk of adverse effects associated with lead is likely to increase as game consumption increases. Therefore, individuals who consume a lot of game (more than a few times a month as a rough guide) should reduce consumption, particularly of small game or game birds killed with lead shot. This is particularly important for children and pregnant women because of the risk to the developing nervous system even at very low levels of lead exposure.”

The term “high consumer” of game meat and offal used by EFSA (2010) described adults with a mean frequency of consumption of game meat of one 200g game meat meal per week, averaged over a year.

Is the FSA advice the same for everyone?
No. Toddlers, children, pregnant women and women trying for a baby should avoid eating lead-shot game because exposure to lead can harm the developing brain and nervous system¹⁰.

How do levels of lead in game meat differ from those in non-game meat?
A report published by the EFSA in 2012 gives the average measured level of lead in non-game meat as 16 parts per billion (ppb), with 5% of samples having levels above 60 ppb¹. Putting these numbers in context, the EU maximum regulatory level of lead in non-game meat (excluding offal) is 100 ppb. The same report gives an average measured lead level of 48 ppb for venison, 155 ppb for hare and 344 ppb for pheasant meat, with 5% of samples having levels above 124, 475 and 982 ppb respectively.  The report states “Particularly high results were recorded for … pheasant meat, presumably associated with the use of lead ammunition.”

What contribution does lead-shot game make to overall dietary exposure?
Meat shot with lead ammunition forms a very small part of the average UK diet. However, there are people who consume shot game regularly, often throughout the year, and this is likely to increase exposure. FSA advice is that those who eat lead-shot game should minimise the amount they eat, especially if eating small game animals such as pheasant and partridge.

Can I reduce my exposure by removing lead from the meat?
Removing lead shot and some tissue from around the impact area and wound channel (see this video) can help reduce the total lead content of the meat. However, lead ammunition fragments on impact, particularly if it comes into contact with bone structures within the carcass, and these micro or nano-particles are impossible to detect during meat preparation^11,12.

If these particles are so small, surely they won’t contribute significantly to exposure?
Smaller particles have a relatively larger surface, which leads to proportionately greater exposure than may come from intact pellets. A single shot carcass has been shown to contain many of these undetectable fragments¹². Exposure can be increased if the meat is cooked in an acidic liquid such as wine or vinegar, because the acid aids the release of lead from the pellet or fragment into the meat, from where the body can absorb it^13,14.

Who advises the UK government on the safety aspects of lead in human food?
The UK’s Food Standards Agency (FSA) which works closely with the European Food Safety Authority (EFSA) and the UK Committee on Toxicity (COT). Current advice on lead-shot game is based on a study of consumers of wild game, conducted by the FSA in Scotland and published in 2012¹⁵.

Does the EFSA set a lead risk level?
There is no agreed safe level for lead intake. The European Food Safety Authority’s expert Panel on contaminants (CONTAM Panel) concluded in 2010, following a review of the available data, that the Provisional Tolerable Weekly Intake (PTWI) was no longer appropriate and that a new guidance level could not be established, as there was no clear threshold below which the Panel was confident that adverse effects would not occur. The opinion concludes that current levels of exposure to lead pose a low to negligible health risk for most adults but there is potential concern over possible neurodevelopmental effects in young children². This conclusion was confirmed by the Joint FAO/WHO Expert Committee on Food Additives in 2010.

How many people consume game in the UK?
It has been estimated that at least one million people in the UK consume wild game at least once per year⁹. Surveys indicate that at least tens of thousands of people from the shooting community are high-level consumers of game, much of which will have been shot with lead ammunition¹⁵.

References

1. European Food Safety Authority. (2012). Lead dietary exposure in the European population. EFSA Journal, 10:2831.
2. EFSA Panel on Contaminants in the Food Chain (CONTAM). (2010). Scientific Opinion on Lead in Food. The European Food Safety Authority Journal, 8:1570, 1–151.
3. European Food Safety Authority. (2012). Cadmium dietary exposure in the European population. EFSA Journal, 10:2551.
4. Gaetke, L.M., Chow-Johnson, H.S. & Chow, C.K. (2014). Copper: toxicological relevance and mechanisms. Archives of Toxicology, 88:1929–1938.
5. European Food Safety Authority. (2015). Scientific opinion on dietary reference values for copper. EFSA Journal, 13:4253.
6. European Food Safety Authority. (2004). Opinion of the Scientific Panel on Contaminants in the Food Chain on a request from the Commission related to mercury and methylmercury in food. EFSA Journal, 34:1–14.
7. Agency for Toxic Substances and Disease Registry. (2019). Toxicological Profile for Lead. Draft for public comment.
8. National Toxicology Programme. (2012). NTP Monograph on health effects of low level lead.
9. Green, R.E. & Pain, D.J. (2015). Risks of health effects to humans in the UK from ammunition-derived lead. In: Proceeding of the Oxford Lead Symposium: 27–42. (eds. Delahay, R.J. & Spray, C.J.) Edward Grey Institute, University of Oxford, Oxford. 
10. Food Standards Agency. (2017). Lead-shot game.
11. Kollander, B., Widemo, F., Ågren, E., Larsen, E.H. & Loeschner, K. (2017). Detection of lead nanoparticles in game meat by single particle ICP-MS following use of lead-containing bullets. Analytical and Bioanalytical Chemistry, 409:1877–1885.
12. Knott, J., Gilbert, J., Hoccom, D.G. & Green, R.E. (2010). Implications for wildlife and humans of dietary exposure to lead from fragments of lead rifle bullets in deer shot in the UK. Science of the Total Environment, 409:95–99.
13. Mateo, R., Rodríguez-de la Cruz, M., Vidal, D., Reglero, M. & Camarero, P.R. (2007). Transfer of lead from shot pellets to game meat during cooking. Science of the Total Environment, 372:480–485.
14. Mateo, R., Baos, A.R., Vidal, D., Camarero, P.R., Martinez-Haro, M. & Taggart, M.A. (2011). Bioaccessibility of Pb from ammunition in game meat is affected by cooking treatment. PLoS ONE, 6:e15892.
15. Food Standards Agency. (2012). Habits and behaviours of high-level consumers of lead-shot wild-game meat in Scotland. Ref: J10106.