The impact of atmospheric pollution on vitamin D status of infants and toddlers in Delhi, India

Abstract

Aims:To compare the vitamin D status of 34 children, 9-24 months old, living in an area of Delhi renowned for high levels of atmospheric pollution (Mori Gate), with a comparable age matched group of children from a less polluted (Gurgaon) area of the city. Methods: Serum concentrations of calcium, alkaline phosphatase (ALP), parathyroid hormone (PTH), 25-hydroxyvitamin D (25(OH)D), and 1,25-dihydroxyvitamin D (1,25(OH) 2 D) were measured. Haze scores, regarded as a surrogate marker of solar UVB radiation reaching ground level, were measured in both areas. Results: Mean 25(OH)D of children in the Mori Gate area was 12.4 (7) ng/ml, compared with 27.1 (7) ng/ml in children living in the Gurgaon area (p < 0.001). The median ALP (p < 0.05) and mean PTH (p < 0.001) concentrations were higher in children living in the Mori Gate area than in the Gurgaon area. The mean haze score in the Mori Gate area (2.1 (0.5)) was significantly lower (p < 0.05) than in the Gurgaon area (2.7 (0.4)), indicating less solar UVB reaching the ground in Mori Gate. Conclusion: We suggest that children living in areas of high atmospheric pollution are at risk of developing vitamin D deficiency rickets and should be offered vitamin D supplements.I n humans the main source of vitamin D is that formed in the skin by conversion of 7-dehydrocholesterol to cholecalciferol (vitamin D 3 ) on exposure to the sun's ultraviolet B (UVB) radiation. The importance of sunlight in the prevention and cure of rickets was observed over a century ago, by Palm, 1 who found rickets to be most prevalent in cities where people were exposed to low levels of sunlight. Vitamin D is essential for skeletal health and its deficiency results in development of rickets in growing children and osteomalacia in adults. There is concern that increasing atmospheric pollution related haze from industrial and vehicular sources might lead to absorption of UVB photons, thereby reducing the cutaneous vitamin D synthesis. 2-4Delhi (latitude 28.35°N) is one of the most polluted cities in the world; the vehicle population, a major contributor to the atmospheric pollution burden, has grown by over 12% annually for the past two decades. 5 In this cross sectional study we assessed the vitamin D status of infants and toddlers living in a downtown area of Delhi, renowned for high levels of atmospheric pollution, with a comparable group of children from a relatively less polluted area on the outskirts of the metropolitan boundary of the city. We hypothesised that serum total 25-hydroxycholecalciferol (25(OH)D), a reliable measure of an individual's vitamin D status, of children living in the area with high levels of atmospheric pollution would be lower than in those living in the less polluted area of the city.

Vitamin D status in a sunny country: Where has the sun gone?

“…We can also consider that during the winter people use more clothes and do not spend much time outdoors. Another potential factor that could relate to hypovitaminosis D is the air pollution, as previously shown by Agarwal et al 13 . Indeed, São Paulo still presents high concentrations of ozone and other air pollutants.…”

“…Indeed, São Paulo still presents high concentrations of ozone and other air pollutants. 13 Unfortunately, we could not evaluate the effects of air pollution in our sample because this would require a control group located in another city in similar latitude, but with a clean air. Other potential confounding factor would be the higher percentage of females in our sample.…”

Association of subclinical vitamin D deficiency with severe acute lower respiratory infection in Indian children under 5 y

“…Children may not be exposed to sunlight for lifestyle or cultural reasons. In addition, pollution may decrease the ultraviolet rays reaching the children (Agarwal et al, 2002).…”

Global vitamin D status and determinants of hypovitaminosis D

“…Seasonal variation in serum 25(OH)D levels, reflected as winter hypovitaminosis D, has been demonstrated in several studies [25,26]. Air pollution probably also plays a role in large cities [27]. Hypovitaminosis D is equally prevalent among rural and urban subjects, [23] but in some studies, urban subjects are found to be more deficient [24,28].…”