To explore the joint toxicity and bio-accumulation of multi-heavy metals and potential chemoprevention strategies, Male Sprague Dawley (SD) rats (n = 30) were treated orally once a week for six months with 500mg/kg•bw of eight heavy metals which were commonly identified in aquatic products in the Ningbo area including chromium, manganese, nickel, copper, zinc, cadmium, mercury, and lead. At the same time, 200mg/kg•bw of epigallocatechin-3-gallate (EGCG), trisodium citrate dihydrate (TCD) or glutathione (GSH) were administered to evaluate their antagonistic effects against adverse effects of multi-heavy metal mixture. The Morris water maze test was used to evaluate spatial learning and memory in the treated rats. Then the rats were anesthetized by pentobarbital sodium (40 mg/kg•bw) to obtain blood samples for biochemical analysis and organs (heart, liver, spleen, lungs, kidneys, brain, testis) to be conducted for biopsy and organ coefficients. Inductively coupled plasma mass spectrometer (ICP-MS) was used to analyze the concentrations of heavy metals. Results indicated that six months of exposure to a multi-heavy metal mixture under this experimental dosage resulted in accumulation in organs and adverse effects on the blood, reproductive system, and liver function. EGCG, TCD or GSH all showed certain chemoprevention effects against the joint toxicity induced by the multi-heavy metal mixture and indicated alleviation and the potential mechanism that also included the promotion of excretion of metals to which animals were exposed.

The systemic toxicity of different combinations of heavy metal mixtures (HMMs) was studied according to equivalent proportions of the eight most common detectable heavy metals found in fish consumption in the Ningbo area of China. The ion mass proportions of Zn, Cu, Mn, Cr, Ni, Cd, Pb, and Hg were 1070.0, 312.6, 173.1, 82.6, 30.0, 13.3, 6.6, and 1.0, respectively. In this study, 10 experimental groups were set as follows: M8 (Pb + Cd + Hg + Ni + Cu + Zn + Mn + Cr); M5 (Pb + Cd + Hg + Ni + Cr); M4A (Pb + Cd + Hg + Ni); M4B (Cu + Zn + Mn + Cr); M3 (Cu + Zn + Mn); Cr; Cu; Zn; Mn; and control. Sprague Dawley (SD) rats were orally treated with a single dose of each group every three days (10 times in total) for 34 days. After Morris water maze test, blood and tissue samples were collected to obtain biochemical, histopathological and western blot analysis. Results show abnormalities could be observed in different treatment groups, the M4B combination had the most significant change compared to all other groups. In conclusion, combination HMMs may have adverse effects on the hematologic, hepatic, renal and neurobehavioral function, and may also disturb electrolyte and lipid balance. Why M4B combination generated much higher toxic effects than any other combination mixtures or individual heavy metal needs to be further evaluated.

Background: Symptom severity in children with autism spectrum disorder (ASD) correlates with developmental level. Vitamin D is crucial to developmental level. Studies show inconsistent findings on serum 25(OH)D and ASD symptom severity. This study explores their association and the mediating role of developmental level. Methods: A total of 699 children aged 24–71 months were enrolled. Serum 25(OH)D levels were measured and children were categorized into normal vitamin D (NVD) and vitamin D insufficiency (VDI) groups. Symptom severity and developmental level were assessed using the Childhood Autism Rating Scale (CARS) and the Gesell Developmental Schedule (GDS). Structural equation modeling (SEM) was used to analyze mediating effects, and machine learning algorithms were employed to assess the predictive importance of developmental dimensions. Results: In the total sample, SEM revealed a masking effect: the indirect effect of serum 25(OH)D levels on CARS scores via developmental level was negative, whereas the direct effect was positive, offsetting each other and resulting in a non-significant total effect. The mediating effect was attenuated in the VDI group. Machine learning analysis further revealed that language dominates in the NVD group, whereas in the VDI group, the dominance of language is diminished, the predictive importance of personal-social also declines, and fine motor and gross motor show enhanced predictive importance. Conclusion: Vitamin D insufficiency may weaken the predictive importance of language and personal-social while enhancing motor domains. Sufficient vitamin D was associated with better developmental levels and lower symptom severity, highlighting the potential research relevance of nutritional considerations in studies of ASD symptom severity.