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ABSTRACT
The distribution of physiological daily inhalation rates for pregnant and lactating females aged 11 to 55 years was determined according to total daily energy expenditures, energy costs for growth, pregnancy and lactation (maternal milk-energy synthesis and breast-energy output) in free-living females. Such published data were obtained using a methodology based on the disappearance rates of predetermined doses of doubly labeled water (2H2O and H2 18O) in urine from non-pregnant and non-lactating females (n = 357), as well as saliva from gravid and breastfeeding females (n = 91), monitored by gas-isotope-ratio mass spectrometry over an aggregate period of about 6,000 days. Monte Carlo simulations were necessary to integrate total daily energy requirements of non-pregnant and non-lactating females into energy costs and weight changes at the 9th, 22nd, and 36th week of pregnancy and at the 6th and 27th, postpartum week: 540,000 data were simulated. The present article confirms that physiological daily inhalation rates for under-, normal-, and overweight/obese pregnant and lactating females expressed in m3/day and m3/kg-day are higher than those for males. For instance, in normal-weight subjects, inhalation rates are higher by 18 to 41% throughout pregnancy and 23 to 39% during postpartum weeks: actual values were higher in females by 1.13 to 2.01 m3/day at the 9th week of pregnancy, 3.74 to 4.53 m3/day at the 22nd week and 4.41 to 5.20 m3/day at the 36th week, and by 4.43 to 5.30 m3/day at the 6th postpartum week and 4.22 to 5.11 m3/day at the 27th postpartum week. The highest 99th percentiles were found to be 0.622 m3/kg-day in pregnant females and 0.647 m3/kg-day in lactating females. By comparison, the highest 99th percentile value for individuals aged 2.6 months to 96 years was determined to be 0.725 m3/kg-day in CitationBrochu et al. (2006a). Air quality criteria and standard calculations based on the latter value for non-carcinogenic toxic compounds should therefore be protective for virtually all pregnant and lactating females. The present article highlights evidence that the current default assumption regarding the total daily air intake used by the Integrated Risk Information System (IRIS) to derive human equivalent concentrations in reference dose calculations is also underestimated compared to some higher 75th and 90th percentiles of physiological daily inhalation rates in pregnant and lactating females.
ACKNOWLEDGMENTS
The authors thank Dr. Kannan Krishnan for constructive comments in regards to the present article. Appreciation is also expressed to Mrs. Adèle Allen-Léonard for her collaboration in specific statistical calculations and to Mrs. Isabelle Brochu for the linguistic revision of this manuscript. The authors wish to point out that the views expressed in this article may not reflect the official policy of the Québec Ministry of Sustainable Development, Environment and Parks.
Web tables for this article can be viewed by accessing the publisher's website.
Notes
a Normal-weight males are defined in Table Web-1 according to body mass index cutoffs for females varying between 19.8 and 26 kg/m2 associated with the best outcome for both infants, in terms of birth weight, and mothers, in terms of delivery complications and postpartum weight retention (CitationIOM 1990).
b Observed p values based on Shapiro-Wilk normality tests.
c Calculated by converting TDERs reported in Table Web-4 into inhalation rates. Physiological daily inhalation rates = TDER*H*(VE/VO2)* 10− 3, where H = 0.21 L of O2/Kcal and VE/VO2 = 27. TDER = total energy requirement (ECG + TDEE). ECG = stored daily energy cost for growth; TDEE = total daily energy expenditure. The ECG and TDEE were based on doubly labeled water measurements: 2H2O and H2 18O disappearance rates from urine were monitored by gaz-isotope-ratio mass spectrometry during 7- to 21-day periods for 131 males aged 11 to 55 years (CitationBrochu et al. 2006; Butte 2000; Butte et al. 2000; CitationLayton 1993; Rogol et al. 2000; CitationIOM 2002).
d Percentiles based on a normal distribution assumption for all age groups. S.D. = standard deviation.
a Underweight, normal-weight, and overweight/obese female status as defined in Table Web-1 according to BMI cutoffs associated with the best outcome for both infants, in terms of birth weight, and mothers, in terms of delivery complications and postpartum weight retention.
b Observed p values based on Shapiro-Wilk normality tests.
c Calculated by converting TDERs reported in Table Web-1 into inhalation rates. Physiological daily inhalation rates = TDER*H*(V E /VO2)*10−3, where H = 0.21 L of O2/Kcal and VE/VO2 = 27. TDER = total energy requirement (ECG + TDEE). ECG = stored daily energy cost for growth; TDEE = total daily energy expenditure. The ECG and TDEE were based on doubly labeled water measurements: 2H2O and H2 18O disappearance rates from urine were monitored by gaz-isotope-ratio mass spectrometry during 7- to 21-day periods for 357 females aged 11 to 55 years (CitationBrochu et al. 2006; Butte 2000; Butte et al. 2000; CitationLayton 1993; Rogol et al. 2000; CitationIOM 2002).
d Percentiles based on a normal distribution assumption for all age groups.
a Underweight females are defined as those having a body mass index lower than 19.8 kg/m2 in prepregnancy (weight classification explained in Table Web-1).
b n Exp. = number of experimental non-pregnant and non-lactating females; n Sim. = number of simulated females. S.D. = standard deviation.
c Resulting TDERs from the integration of energetic measurements in underweight non-pregnant and non-lactating females (CitationIOM 2002; n = 81) with those during pregnancy (CitationButte et al. 2004; n = 17) and lactation (CitationGoldberg et al. 1991, n = 10; CitationIOM 2002, n = 28) by Monte Carlo simulations (Table Web-8) were converted into physiological daily inhalation rates by the following equation: TDER*H*(VE/VO2)*10− 3. TDER = total energy requirement (ECG + TDEE). ECG = stored daily energy cost for growth; TDEE = total daily energy expenditure. The ECG and TDEE were based on doubly labeled water measurements: 2H2O and H2 18O disappearance rates from urine or saliva samples were monitored by gaz-isotope-ratio mass spectrometry for a 7- to 21-day period per subject. H = 0.21 L of O2/Kcal and V E /VO2 = 27 for non-pregnant, non-lactating, and prepregnant females (CitationLayton 1993). During pregnancy VE/VO2 = 36.8 at the 9th and 22nd week and 36.2 at the 36th week. During postpartum, VE/VO2 = 34.5 and 34.2 for breastfeeding mothers at the 6th and 27th postpartum week respectively (CitationPernoll et al. 1975).
a Normal-weight females are defined as those having a body mass index varying between 19.8 and 26 kg/m2 in prepregnancy (weight classification explained in Table Web-1).
b n Exp. = number of experimental non-pregnant and non-lactating females; n Sim. = number of simulated females. S.D. = standard deviation.
c Resulting TDERs from the integration of energetic measurements in normal-weight non-pregnant and non-lactating females (CitationIOM, 2002; n = 172) with those during pregnancy (CitationButte et al. 2004; n = 34) and lactation (CitationGoldberg et al. 1991, n = 10; CitationIOM 2002, n = 28) by Monte Carlo simulations (Table Web-9) were converted into physiological daily inhalation rates by the following equation: TDER*H*(VE/VO2)*10− 3. TDER = total energy requirement (ECG + TDEE). ECG = stored daily energy cost for growth; TDEE = total daily energy expenditure. The ECG and TDEE were based on doubly labeled water measurements: 2H2O and H2 18O disappearance rates from urine or saliva samples were monitored by gaz-isotope-ratio mass spectrometry for a 7- to 21-day period per subject. H = 0.21 L of O2/Kcal and VE/VO2 = 27 for non-pregnant, non-lactating and prepregnant females (CitationLayton 1993). During pregnancy VE/VO2 = 36.8 at the 9th and 22nd week and 36.2 at the 36th week. During postpartum, VE/VO2 = 34.5 and 34.2 for breastfeeding mothers at the 6th and 27th postpartum week respectively (CitationPernoll et al. 1975).
a Overweight/obese females are defined as those having a body mass index higher than 26 kg/m2 in prepregnancy (weight classification explained in Table Web-1).
b n Exp. = number of experimental non-pregnant and non-lactating females; n Sim. = number of simulated females. S.D. = standard deviation.
c Resulting TDERs from the integration of energetic measurements in overweight/obese non-pregnant and non-lactating females (CitationIOM, 2002; n = 104) with those during pregnancy (CitationButte et al. 2004; n = 12) and lactation (CitationGoldberg et al. 1991, n = 10; CitationIOM 2002, n = 28) by Monte Carlo simulations (Table Web 10) were converted into physiological daily inhalation rates by the following equation: TDER*H*(VE/VO2)*10− 3. TDER = total energy requirement (ECG + TDEE). ECG = stored daily energy cost for growth; TDEE = total daily energy expenditure. The ECG and TDEE were based on doubly labeled water measurements: 2H2O and H2 18O disappearance rates from urine or saliva samples were monitored by gaz-isotope-ratio mass spectrometry for a 7- to 21-day period per subject. H = 0.21 L of O2/Kcal and VE/VO2 = 27 for non-pregnant, non-lactating, and prepregnant females (CitationLayton 1993). During pregnancy VE/VO2 = 36.8 at the 9th and 22nd week and 36.2 at the 36th week. During postpartum, VE/VO2 = 34.5 and 34.2 for breastfeeding mothers at the 6th and 27th postpartum week respectively (CitationPernoll et al. 1975).
a Underweight females are defined as those having a body mass index lower than 19.8 kg/m2 in prepregnancy (weight classification explained in Table Web-1).
b n Exp. = number of experimental non-pregnant and non-lactating females; n Sim. = number of simulated females. S.D. = standard deviation.
c Resulting TDERs from the integration of energetic and weight measurements in underweight non-pregnant and non-lactating females (CitationIOM 2002; n = 81) with those during pregnancy (CitationButte et al. 2004; n = 17) and lactation (CitationGoldberg et al. 1991, n = 10; CitationIOM 2002, n = 28) by Monte Carlo simulations (Table Web-11) were converted into physiological daily inhalation rates by the following equation: TDER*H*(VE/VO2)*10− 3. TDER = total energy requirement (ECG + TDEE). ECG = stored daily energy cost for growth; TDEE = total daily energy expenditure. The ECG and TDEE were based on doubly labeled water measurements: 2H2O and H2 18O disappearance rates from urine or saliva samples were monitored by gaz-isotope-ratio mass spectrometry for a 7- to 21-day period per subject. H = 0.21 L of O2/Kcal and VE/VO2 = 27 for non-pregnant, non-lactating, and prepregant females (CitationLayton 1993). During pregnancy VE/VO2 = 36.8 at the 9th and 22nd week and 36.2 at the 36th week. During postpartum, VE/VO2 = 34.5 and 34.2 for breastfeeding mothers at the 6th and 27th week postpartum postpartum, respectively (CitationPernoll et al. 1975).
a Normal-weight females are defined as those having a body mass index varying between 19.8 and 26 kg/m2 in prepregnancy (weight classification explained in Table Web-1).
b n Exp. = number of experimental non-pregnant and non-lactating females; n Sim. = number of simulated females. S.D. = standard deviation.
c Resulting TDERs from the integration of energetic and weight measurements in normal-weight non-pregnant and non-lactating females (CitationIOM 2002; n = 172) with those during pregnancy (CitationButte et al. 2004; n = 34) and lactation (CitationGoldberg et al. 1991, n = 10; CitationIOM 2002, n = 28) by Monte Carlo simulations (Table Web-12) were converted into physiological daily inhalation rates by the following equation: TDER*H*(VE/VO2)*10− 3. TDER = total energy requirement (ECG + TDEE). ECG = stored daily energy cost for growth; TDEE = total daily energy expenditure. The ECG and TDEE were based on doubly labeled water measurements: 2H2O and H2 18O disappearance rates from urine or saliva samples were monitored by gaz-isotope-ratio mass spectrometry for a 7- to 21-day period per subject. H = 0.21 L of O2/Kcal and VE/VO2 = 27 for non-pregnant, non-lactating and prepregant females (CitationLayton 1993). During pregnancy VE/VO2 = 36.8 at the 9th and 22nd week and 36.2 at the 36th week. During postpartum, VE/VO2 = 34.5 and 34.2 for breastfeeding mothers at the 6th and 27th week postpartum postpartum respectively (CitationPernoll et al. 1975).
a Overweight/obese females are defined as those having a body mass index higher than 26 kg/m2 in prepregnancy (weight classification explained in Table Web-1).
b n Exp. = number of experimental non-pregnant and non-lactating females; n Sim. = number of simulated females. S.D. = standard deviation.
c Resulting TDERs from the integration of energetic and weight measurements in overweight/obese non-pregnant and non-lactating females (CitationIOM 2002; n = 104) with those during pregnancy (CitationButte et al. 2004; n = 12) and lactation (CitationGoldberg et al. 1991, n = 10; CitationIOM 2002, n = 28) by Monte Carlo simulations (Table Web-13) were converted into physiological daily inhalation rates by the following equation: TDER*H*(VE/VO2)*10−3. TDER = total energy requirement (ECG + TDEE). ECG = stored daily energy cost for growth; TDEE = total daily energy expenditure The ECG and TDEE were based on doubly labeled water measurements: 2H2O and H2 18O disappearance rates from urine or saliva samples were monitored by gaz-isotope-ratio mass spectrometry for a 7- to 21-day period per subject. H = 0.21 L of O2/Kcal and VE/VO2 = 27 for non-pregnant, non-lactating, and prepregant females (CitationLayton 1993). During pregnancy VE/VO2 = 36.8 at the 9th and 22nd week and 36.2 at the 36th week. During postpartum, VE/VO2 = 34.5 and 34.2 for breastfeeding mothers at the 6th and 27th week postpartum postpartum, respectively (CitationPernoll et al. 1975).