View source for Risk of dental aberrations in children in Beneris

== Scope ==
'''Risk for dental aberrations in children''' describes the risk of developmental dental defects in children associated with exposure to PCBs and PCDD/Fs through fish ingestion. 

== Definition == 
Risk for dental aberrations in children is represented as a function of parent variables and is indexed by variable age and gender. It applies to age groups 0-2yr and 2-18yr.  

=== Causality === 
List of parents:
*[[Baseline risk of dental aberrations]]
*[[Intake of PCDD/F from fish in Beneris]]
*[[Intake of PCB from fish in Beneris]]
*[[ERF of dioxin on dental aberrations]]
*[[ERF of PCB on dental aberrations]]

=== Data === 

Exposure-response factors of PCDD/Fs and PCBs on developmental dental defects (enamel defects of all permanent teeth except wisdom) correspond to concentrations of PCDD/Fs and PCBs in serum lipid. In order to measure the impact of child's exposure to PCDD/Fs and PCBs from fish on the health endpoint of interest the conversion of the average daily intake of these contaminants into the serum lipid concentration was used. Assuming that the concnetration of PCDD/Fs and PCBs in body lipids is at a steady-state this conversion is:

Fat_concnetration_PCDD/Fs(PCBs)(ng/kg body fat) = (0.001*Intake_PCDD/Fs(PCBs)_Fish(pg/kg bw-day)*t(1/2)(days)*f)/(a*0.693*BF%(kg fat/kg bw))

where:<br>
- Intake_PCDD/Fs(PCBs)_Fish is the average daily intake of PCDD/Fs (PCBs) from fish (all fish species),<br>
- t(1/2) is the half-life (assumed to be 2737.5 days (7.5yr) for PCDD/Fs and 1460 days (4yr) for PCBs<ref>H.Park et al. Congener-specific approach to human PCB concentrations by serum analysis. Chemosphere, 2007.</ref> <ref>Doctoral thesis by H.Kiviranta. Exposure and human PCDD/F and PCB body burden in Finland. 2005. </ref>), <br>
- f is fraction absorbed from GI tract (assumed 0.95 for PCDD/Fs<ref>Dahl et al. Absorption of polychlorinated biphenyls dibenzo-p-dioxins and dibenzofurans by breast-fed infants. Chemosphere, 1995. </ref> and 0.85 for PCBs <ref>Juan et al. An input-output balance study for PCBs in humans. Environment International, 2002.</ref>), <br>
- BF% is the body fat percentage in children (see below),<br>
- a is the proportion of daily dietary intake of PCDD/Fs (PCBs) that comes from fish (0.82 for PCDD/Fs and 0.89 for PCBs <ref> M.L.Wiborg, H.K.Knutsen, O.Andersson, A.Buchert, T.Cederberg, P.O.Darnerud, A.Hallikainen, H.Kiviranta, K.Olafsdottir, K.Peters, EU maximum levels for dioxins and dioxin-like PCBs - impact exposure and food supply in the Nordic countries (table A4 in the Appendix)</ref>).


Body fat percentage (BF%) in 0-2yr and 2-18yr males and females was estimated using the Deurnenberg formulas <ref> http://www.halls.md/bmi/fat.htm </ref>. For children aged 15 years and younger the formula is 1.51*BMI(kg/m^2)-0.7*Age(yr)-3.6*Gender+1.4 and for individuals over 15 years the formula reads 1.2*BMI(kg/m^2)+0.23*Age(yr)-10.8*Gender-5.4, where Gender is 1 for males and 0 for females. For 2-18yr old children the combination of two Deurenberg formulas was used. In every age/sex group the BMI was estimated based on child's body weight and height as 1000*BW(kg)/(Height(cm)^2) and age was assumed to follow an uniform distribution (see population data <ref name="Population data"> Population of Finland years 1980 - 2007. http://en.opasnet.org/w/Image:Population_of_Finland_years_1980-2007.xls</ref>). Also the information about Spearmans's rank correlations between weight and age and between height and age in every age/sex group was used in the calculations. Moreover, for 2-18yr children, distributions of BF% were truncated with a miniumum BF% of 12% in females and with minimum of 3% in males.        

Since the exposure-response factors of PCDD/Fs and PCBs were derived for children in general the gender combined serum concentrations of PCDD/Fs and PCBs were estimated and used in the risk model. Proportions of males and females applied can be found here <ref name="Population data" />.

=== Formula === 

Risk = 1/(1+exp(-log(Baseline_risk_of_dental_aberrations/(1-Baseline_risk_of_dental_aberrations))-ERF_of_dioxin_on_dental_aberrations*(LOG_PCB_Fat_Concentration-Average_LOG_PCB_Fat_Concentration+LOG_Dioxin_Fat_Concentration-Average_LOG_Dioxin_Fat_Concentration)))


where LOG_PCB_Fat_Concentration = ln(PCB_Fat_Concentration+1) and LOG_Dioxin_Fat_Concentration = ln(Dioxin_Fat_Concentration+1)

=== Unit === 

== Result ==

=== References ===
<references />