ERF of methyl mercury on CVD risk in adults

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Scope

ERF of methyl mercury on CVD risk in adults describes quantitative relationship between methyl mercury (MeHg) exposure and risk of cardiovascular disease (CVD) in adults.

Definition

ERF of methyl mercury on CVD risk in adults is indexed by age variable. It applies to the last two age categories, i.e. adults aged 18-55yr and 55yr+ (both genders).

Causality

List of parent variables:

Data

Virtanen et al [1] found that every microgram/gram of mercury (Hg) in adult men hair increases (on average) the risk of CVD death by 10% (95% CI: 2% to 19%) and the risk of CHD death by 13% (95% CI: 3% to 23%). D↷
In Beneris the output of interest is the CHD mortality due to MeHg intake from fish. Thus, first based on [1] the central estimate and the 95% CI for the change (in this case increase) in natural logarithm of relative risk (RR) of CHD mortality per unit change in Hg hair concentration were derived. In general, the relationship between the percent change in RR (%RR) associated with c-unit increase in hair Hg concentration and incremental change in lnRR (beta) per unit change in hair Hg concentration is beta = (1/c)*ln((%RR/100)+1). Since Virtanen et al. obtained their result using Cox regression normal distribution was chosen to represent the uncertainty in the parameter of the log-linear model for RR. The mean and the standard deviation of this distribution are respectively 0.1222 and 0.0473. Then, in order to derive the probability distribution of ERF for MeHg intake from fish a one-compartment model as well as the information on the proportion of dietary intake of MeHg that corresponds to fish was used. Assuming that the concentration of MeHg in blood is at a steady-state the daily dietary intake of MeHg from fish corresponding to a given hair Hg concentration can be estimated as [2]

Intake_MeHg_Fish(ug/kg bw-day) = (a*1000*Concentration_Hg_Hair(ug/g hair)*b(1/day)*V(L blood))/(250(L blood/kg hair)*A*f*BW(kg bw))

where:

  • Concentration_Hg_Hair is the hair Hg conentration,
  • b is the elimination rate from blood (assumed 0.014,[3]),
  • V is the blood volume (assumed 5L[3]),
  • f is the fraction of absorbed MeHg that is distributed to the blood (assumed 0.059[3]),
  • A is the fraction of ingested MeHg that is absorbed from GI tract (asusmed 0.95[3]),
  • BW is the body weight of adult,
  • a is the proportion of daily dietary intake of MeHg that comes from fish (assumed 1, i.e.100%),
  • 250 is the hair-to-blood Hg concentration ratio[3].

The resulting ERF of MeHg exposure from fish for the lnRR of CHD mortality can be calculated as a product of ERF of Hg hair concnetration for lnRR of CHD mortality and (A*f*BW*250*0.001)/(a*b*V).

Unit

lnRR/ 1 (ug/kg bw-day) change in MeHg intake from fish

Formula

ERF_Hg_hair_lnRR*(1/a)*0.8007*BW*250*0.001

Result

References


  1. ↑ 1.0 1.1 Jyrki K. Virtanen, Sari Voutilainen, Tiina H. Rissanen, Jaakko Mursu, Tomi-Pekka Tuomainen, Maarit J. Korhonen, Veli-Pekka Valkonen, Kari Seppanen, Jari A. Laukkanen, Jukka T. Salonen. Mercury, fish oils, and risk of acute coronary events and cardiovascular disease, coronary heart disease, and all-cause mortality in men in Eastern Finland. Arterioscler. Thromb. Vasc. Biol. 25 (2005), p.228-233.
  2. ↑ Toxicological effects of methylmercury. National Research Council. National Academy Press, 2000.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 EPA (IRIS), 2001. http://www.epa.gov/iris/subst/0073.htm
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