Dear readers,

Here's another part of the comments we've prepared for ECHA's Call for Comments and Evidence records for the forthcoming ban on lead ammunition. This time the theme is lead-caught game and the impact on human health. We thank NAOOSP for cooperation.

This article is part of the comments we are on behalf of LEX z.s. filed with ECHA. In the previous article you could already read the results of our comparative test of lead and non-lead ammunition. LEX z.s. and our partners inquired into chosen areas (i.e. the influence of lead in environment, influence of lead on human health, and performance and safety of nonlead alternative ammunition). Other areas were addressed by our foreign partners.

This time we would like to thank Mr. Tomáš Vaněk - the chairman of the NAOOSP - who helped us very much to prepare relevant source studies related to the effects of lead and its alternatives on the environment and human health.

This article has its Czech version here: Vliv zvěřiny ulovené olověným střelivem na lidské zdraví

Effect on game meat harvested with lead ammunition on human health

authors: David KARÁSEK, Tomáš VANĚK

published: 16.12.2019

Abstract:

Lead is considered non-threshold substance and its content in the game meat is high. However, due to metallic nature of lead in game meat, normal computations methods shouldn't apply to estimating health risks related to this specific foodstuff, because its transfer to human organism may be much lower than expected. Before proposing any restrictions based on concerns about human health, it should be empirically ascertained how much lead from game meat is actually absorbed into human organism.

Lead as non-threshold substance

ECHA lead ammunition investigation report claims that lead is considered to be non-threshold substance, and that game meat may represent risk for human health, citing EFSA CONTAM panel scientific opinion on lead in food [EFSA 2013] as a source of both claims.

CONTAM panel notes and proves by results of scientific research that for three areas of human health – developmental neurotoxicity, cardiovascular diseases and nephrotoxicity – there is no “safe level” of blood lead level (BLL) under which no adverse health effect would be observed. CONTAM panel therefore recommended abandoning efforts to establish any safe level or allowed daily intake for lead, and using benchmark dose (BMD) concept instead.

BMD concept is based in idea of establishing benchmark response (BMR), defined as the smallest amount of adverse effect that should cause health concerns. From benchmark response, benchmark dose is computed as the dose which causes benchmark response and should cause health concerns.

As for lead, BMR was established as decreasing of child's IQ by 1 point for developmental neurotoxicity, increasing of blood pressure by 1 mm of Hg for cardiovascular diseases, and increasing risk of chronic kidney disease by 10 % for nephrotoxicity.

As these responses are causally linked to blood lead level (BLL), corresponding increase in BLL is + 12 µg/L for developmental neurotoxicity, + 36 µg/L for cardiovascular diseases and + 15 µg/L for nephrotoxicity. Using IEUBK model for children and Carlisle and Wade method for adults, daily BMD was set to 10 µg for 20kg child, or 90 µg (cardiovascular diseases) and 37 µg (nephrotoxicity) for 60 kg adult. Considering scientific evidence presented by CONTAM panel, we generally consider this approach to be right and proper.

Lead in game meat

CONTAM panel also claims that diet containing game meat and game offal are exposed to higher doses of lead, therefore health concerns cannot be excluded.

We object and question that conclusion due to following reason.

As BMR is measured by blood lead level, and BMD is derived from daily lead intake from food, actual BMD is dependent on uptake (rate of absorption of lead from food to blood through gastrointestinal system). Based on empirical observations, Carlisle and Wade equation translates

1 µg of daily lead intake into 0,4 µg/L of BLL. We believe that this absorption rate is roughly correct when considering general lead uptake from consumed food, as various actual absorption rates shall average in total.

However, these actual absorption rates vary with actual form of lead contained in the food. Rates of absorption are very different for metallic lead, anorganic compounds and organic compounds. In vivo tests [Baltrop & Meek, 1975] found following absorption rates:

In vitro tests simulating human digestive process [Quarfort & Holmgren 2012] also shown very low (< 2%) solubility of metallic lead.

Unlike most other foodstuffs, which contain lead compounds, lead in game meat is present in form of metallic fragments. As tiny as they may be, they are still large metallic object from biochemistry viewpoint, and according to mentioned studies, absorption rate of lead in metallic form is much lower than average. It is therefore erroneous to use Carlisle and Wade equation to deduce lead uptake for this specific foodstuff, because 0.4 converting factor is correct on average, but it should be much smaller for metallic lead. As for IEUBK model used for computation of children exposure, the program allows setting specific absorption rate for certain foodstuffs, including game meat. However, we don't know whether CONTAM panel used this option, or what absorption rate was used.

Studies of blood lead level in hunters and other persons consuming game meat seem to confirm that absorption of lead from game meat is very low. For example, Fustinoni et al. 2017 and  Haldimann et al 2002 found no correlation between consuming game meat and increased BLL. Iqbal et al. 2009 found increase of BLL by 3 µg/L, which is nowhere near 35.3 µg/L predicted by Carlisle and Wade equation (at the consuming rate presumed by CONTAM panel, i.e. 200 g of game meat / week).

Conclusion

From viewpoint of lead content and its influence on human health, game meat is very specific foodstuff. Metallic form of contained lead seems to have much lower absorption rate than other forms, which may cause significant difference between computed and actual benchmark dose of lead intake. More research is needed in this field, especially if any legal steps are considered due to perceived risk of consuming game meat.

Sources

EFSA Panel on Contaminants in the Food Chain (CONTAM): Scientific Opinion on Lead in Food, 2013

D. Baltrop & F. Meek: Absorption of different lead compounds. Postgraduate Medical Journal (November 1975) 51, 805-809.

Ulf Quarfort & Christer Holmgren, Lead in game meat - bioaccessibility of lead metal fragments, 2012

Silvia Fustinoni, Sabrina Sucato, Dario Consonni, Pier Mannuccio Mannucci, Angelo Moretto: Blood lead levels following consumption of game meat in Italy. 2017

Max Haldimann, Andreas Baumgartner, Bernhard Zimmerli: Intake of lead from game meat – a risk to consumers’ health? 2002

Shahed Iqbal, Wendy Blumenthal, Chinaro Kennedy, Fuyuen Y.Yip, Stephen Pickard, W. Dana Flanders, Kelly Loringer, Kirby Kruger, Kathleen L. Caldwell, Mary Jean Brown: Hunting with lead: Association between blood lead levels and wild game consumption. 2009

LEX z.s.

This article has its Czech version here: Vliv zvěřiny ulovené olověným střelivem na lidské zdraví