Toxicity biomarkers among US children compared to a similar cohort in France: a blinded study measuring urinary porphyrins

Figures & data

Table 1. Characteristics of children examined

Parameter	US neurotypical children^a (n = 28)	French neurotypical children^a (n = 28)
Male/female (ratio)	25/3 (8.3 : 1)	25/3 (8.3 : 1)
Mean age in years ± SD (range)	6.3 ± 2.8 (2–13)	6.2 ± 3.1 (2–13)
Mean fish consumption per week ± SD	0.6 (0.7)	1.4 (0.8)^b
Notes: SD, standard deviation; US children and French children were matched for age and gender. No study subjects had previously received chelation therapy. All children received childhood vaccines.
^aSubjects had CARS scores ≤18; ^bsignificant (p < 0.01) increase in mean fish consumption per week was observed among French neurotypical children in comparison to US neurotypical children.

Table 2. Comparison of the urinary porphyrin results reported for the groups of subjects tested

	Mean ± SD [range]
Metabolic parameter	US neurotypical children^a (n = 28)	French neurotypical children^a (n = 28)	P-value^b
nmol/gram creatinine
Uroporphyrins	22.3 ± 7.5	18.4 ± 8.5	ns
	[9–39]	[8–46]
Heptacarboxyporphyrins	4.2 ± 1.4	3.9 ± 1.6	ns
	[1.7–7.1]	[1.9–7.7]
Hexacarboxyporphyrins	0.90 ± 0.52	0.62 ± 0.29	<0.05
	[0.1–2.2]	[0.0–1.4]
Pentacarboxyporphyrins	4.8 ± 3.7	3.9 ± 1.5	ns
	[1.8–22.2]	[1.9–7]
Precoproporphyrins	18 ± 10.0	13.5 ± 7.9	<0.05
	[6–45]	[3–31]
Total coproporphyrins (I + III)	208 ± 114	151 ± 68	<0.005
	[74–544]	[70–340]
grams of creatinine/L	960 ± 453	953 ± 504	ns
	[308–2425]	[175–2760]
Notes: SD, standard deviation; ns, not significant.
^aSubjects that were neurotypical (CARS score ≤ 18). US and French children were matched for age and gender; ^bthe two-tailed non-parametric Wilcoxon matched-pairs signed-ranks test statistic was utilized.