Risk of dental aberrations in children in Beneris

Question

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.

Rationale

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.

List of parents:

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:
- Intake_PCDD/Fs(PCBs)_Fish is the average daily intake of PCDD/Fs (PCBs) from fish (all fish species),
- t(1/2) is the half-life (assumed to be 2737.5 days (7.5yr) for PCDD/Fs and 1460 days (4yr) for PCBs ),
- f is fraction absorbed from GI tract (assumed 0.95 for PCDD/Fs and 0.85 for PCBs ),
- BF% is the body fat percentage in children (see below),
- 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 ).

Body fat percentage (BF%) in 0-2yr and 2-18yr males and females was estimated using the Deurnenberg formulas . 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 ). 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 .

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)