Biomarkers for tracking metabolic changes pre-post nutritional epigenetics diet/intervention to prevent autism and attention deficit/hyperactivity disorders in children

Table 2 Food ingredients with allowable or known heavy metal content

Potentially harmful dietary ingredients or chemicals	Allowable or known heavy metal content with reference	May contribute to autism and/or ADHD
Bleaching agent for flour (chlorine)	Hg[54]	Autism
HFCS	Hg[41]	Autism
Tartrazine (yellow 5, E-102)	As ≤ 3 ppm[55]	Autism; ADHD
	Pb ≤ 10 ppm[55]
	Hg ≤ 1 ppm[55]
Sunset yellow (yellow 6, E-110)	As ≤ 3 ppm[55]	Autism; ADHD
	Pb ≤ 10 ppm[55]
	Hg ≤ 1 ppm[55]
Sodium benzoate	Pb ≤ 2 ppm[56]	Autism; ADHD
Beta carotene, synthetic	Pb ≤ 10 ppm[57]	Autism; ADHD
	As ≤ 3 ppm[57]
Caramel	As ≤ 3 ppm[58]	Autism; ADHD
	Pb ≤ 10 ppm[58]
	Hg ≤ 0.1 ppm[58]
Sodium nitrite	Pb ≤ 2 ppm[59]	Autism; ADHD
Calcium chloride	Pb ≤ 2 ppm[60]	Autism; ADHD
Carrageenan	As ≤ 3 ppm [61]	Autism; ADHD
	Cd ≤ 2 ppm[61]
	Pb ≤ 5 ppm[61]
	Hg ≤ 1 ppm[61]

ADHD: Attention deficit/hyperactivity disorders; HFCS: High fructose corn syrup; Hg: Mercury; As: Arsenic; Pb: Lead; Cd: Cadmium; ppm: Parts per million.