Heated indoor swimming pools, infants, and the pathogenesis of adolescent idiopathic scoliosis: a neurogenic hypothesis

<p>Abstract</p> <p>Background</p> <p>In a case-control study a statistically significant association was recorded between the introduction of infants to heated indoor swimming pools and the development of adolescent idiopathic scoliosis (AIS). In this paper, a neurogenic hypothesis is formulated to explain how toxins produced by chlorine in such pools may act deleteriously on the infant's immature central nervous system, comprising brain and spinal cord, to produce the deformity of AIS.</p> <p>Presentation of the hypothesis</p> <p>Through vulnerability of the developing central nervous system to circulating toxins, and because of delayed epigenetic effects, the trunk deformity of AIS does not become evident until adolescence. In mature healthy swimmers using such pools, the circulating neurotoxins detected are chloroform, bromodichloromethane, dibromochloromethane, and bromoform. Cyanogen chloride and dichloroacetonitrile have also been detected.</p> <p>Testing the hypothesis</p> <p>In infants, the putative portals of entry to the blood could be dermal, oral, or respiratory; and entry of such circulating small molecules to the brain are via the blood-brain barrier, blood-cerebrospinal fluid barrier, and circumventricular organs. Barrier mechanisms of the developing brain differ from those of adult brain and have been linked to brain development. During the first 6 months of life cerebrospinal fluid contains higher concentrations of specific proteins relative to plasma, attributed to mechanisms continued from fetal brain development rather than immaturity.</p> <p>Implications of the hypothesis</p> <p>The hypothesis can be tested. If confirmed, there is potential to prevent some children from developing AIS.</p

Kinetic isotope effects in the gas phase reactions of OH and Cl with CH₃Cl, CD₃Cl, and ¹³CH₃Cl

The kinetic isotope effects in the reactions of CH₃Cl, ¹³CH₃Cl and CD₃Cl with OH radicals and Cl atoms were studied in relative rate experiments at 298&plusmn;2 K and 1013&plusmn;10 mbar. The reactions were carried out in a smog chamber using long path FTIR detection and the spectroscopic data analyzed employing a non-linear least squares spectral fitting method using measured high-resolution infrared spectra as well as absorption cross sections from the HITRAN database. The reaction rates of ¹³CH₃Cl and CD₃Cl with OH and Cl were determined relative to CH₃Cl as: <i>k</i>_OH+CH3Cl<i>k</i>_OH+CH3Cl/<i>k</i>_OH+13CH3Cl}<i>k</i>_OH+13CH3Cl=1.059&plusmn;0.008, <i>k</i>_OH+CH3Cl<i>k</i>_OH+CH3Cl/<i>k</i>_OH+CD3Cl<i>k</i>_OH+CD3Cl=3.9&plusmn;0.4, <i>k</i>_Cl+CH3Cl<i>k</i>_Cl+CH3Cl/<i>k</i>_Cl+13CH3Cl<i>k</i>_Cl+13CH3Cl =1.070&plusmn;0.010 and <i>k</i>_Cl+CH3Cl<i>k</i>_Cl+CH3Cl/<i>k</i>_Cl+CD3Cl<i>k</i>_Cl+CD3Cl=4.91&plusmn;0.07. The uncertainties given are 2&sigma; from the statistical analyses and do not include possible systematic errors. The unexpectedly large ¹³C kinetic isotope effect in the OH reaction of CH₃Cl has important implications for the global emission inventory of CH₃Cl