Prevention of Iodine Deficiency Disorders (IDD) in Mexico: An overall successful story, but some lessons to be learned

Abstract

ObjectiveTo identify causes of persistence of endemic goiter in specific areas in Mexico, despite a mandatory salt iodination program established since the early 1960s.ResultsIn the mountainous state of Hidalgo school‐age children (SAC) had a prevalence of goitre between 6% (capital city) ‐ 21.2% (tropical low‐lands). Prevalence of low (<50 µg/L) urinary iodine excretion (UIE) ranged between 28% ‐ 52%. 97% of families consumed iodized table salt; only 50% of the samples were adequately iodized (>50 ppm). Goitrogens included consumption of yucca, sweet potato, broccoli and cauliflower; 24% of the population consumed water from wells contaminated with E. coli or heavy metals (arsenic and mercury). In the coastal state of Colima, goiter in SAC had a prevalence of 21 4%, with low UIE in 19.5% and high UIE in 32.0%. 92% of the population used coarse‐grain ocean salt, with 86.8% of locally‐iodized salt samples <50 ppm. Goitrogens included consumption of peanuts (31.5%), cabbage (30.1%), broccoli (27.7%) and cauliflower (25.7%). Median counts of colony‐forming units/100ml of drinking water were: 207.5 (well water), 151 (cisterns), 52 (private homes), 25 (elementary schools) and 12 (kindergartens). Percentile (P) IQ scores were: P5 (low): 48.5%; P5 to P25 (below average): 24 2%; P25 to P75 (average): 18.8%; P75 to P95 (above average): 3.6%; P95 (high): 4 9%. Moderate ID was associated with a 4.26 times higher risk of low IQ.