In the U.S., mothers of low socio-economic status (SES) are far less likely to breastfeed than college graduates, by differences of nearly 2 to 1. (see CDC chart on left and (113) (114)) The same kind of difference applies in the U.K., as evidenced by data showing 60% vs. 28% difference in breastfeeding rates according to socio-economic status breakdown.(115). An Australian study found a 75% vs. 33% difference to be typical.(116). Therefore it is obvious that fewer infants of low-SES parents in the U.S., U.K. and Australia would receive the high concentrations of neuro-developmental toxins that are contained in breast milk. By contrast, in the Scandinavian countries (Norway, Sweden, Denmark and Finland), almost every mother breastfeeds, at least initially (see Section 1.2.p.1 of www.pollutionaction.org/breastfeeding-and-autism-and-cancer.htm); and their rates of breastfeeding are still very unusually high after three and more months. There seems to be no data indicating lower rates of breastfeeding among mothers of low SES than among high-SES mothers in the Nordic countries. It appears that, when (after the early period) breastfeeding becomes less universal, the decline may not be among the same groups as in the U.S. and U.K.; whereas in the U.S. and U.K. later children are likely to be breastfed for shorter periods (see below), the opposite was found to be the case in a Norwegian study (117). Apparently infants from all sectors of society in the Nordic countries receive about the same exposure to the toxins in breast milk at least at first, and probably later also.
Given the above, and knowing about the high concentrations of developmental toxins in typical breast milk in contemporary developed countries (see www.breastfeeding-and-autism.net), is it surprising that autism rates in the U.S. are far higher among children of college graduates than among children of high school graduates? (see www.pollutionaction.org/surprises.htm) And that, in what have apparently been the only studies in Nordic countries making such comparisons, such a difference has not been found?
Parental age and breastfeeding: In a U.K. study, finding the same relationship that had been found in previous surveys, it was found that an average of only 58% of mothers under age 20 breastfed, compared with 87% over age 30 (119). In an Australian study, it was found that breastfeeding at six months was positively associated with older maternal age, with “Adj OR per 5 year increase in age 1.58…,” which indicates a greatly increased breastfeeding percentage with each additional 5 years of age (120). It has also been found in several studies that older mothers continue breastfeeding for longer periods than younger mothers, including in the U.S. (121)
It is also well known that the body burden of persistent developmental toxins, which become concentrated in breast milk, increases with years of exposure to the environment, including years of ingesting foods that contain those toxins. "PBTs (persistent, bioaccumulative and toxic chemicals) accumulate in the lipids of humans, and neither urinary nor fecal excretion is a significant route of elimination." (121a)
Given the above, should it be surprising that autism rates are far higher among children of older mothers than among children of younger mothers? (see www.pollutionaction.org/surprises.htm)
Birth order and breastfeeding in the U.S.: Birth order associations point in the same direction as socio-economic status and parental age: In all cases, if a category normally includes less breastfeeding, there are fewer children in that category who turn out to have cancer.
Data from the U.K. Department of Health for 1995 shows a 17% decline in rate of breastfeeding rate between the first and later births (128). Apparently many women experience pain or other difficulties in breastfeeding, which results in not breastfeeding subsequent babies. In a Canadian study, it was found that “not having previous breastfeeding experience predicted its continuation,” which is to say that later babies, if breastfed at all, will normally be breastfed for a shorter period than a first baby (129).
First babies in countries with medium or lower rates of breastfeeding are not only (a) more likely to be breastfed, and (b) likely to be breastfed for longer periods, but they are also (c) fed much more potent doses of toxins. The mother’s accumulated body burden of persistent toxins is partially excreted in breast milk; with each succeeding baby, the mother’s lifetime accumulation of persistent toxins has been reduced by breastfeeding of the preceding baby. A study of breast cancer risk factors published in 2008 looked into concentrations of dioxins that were measured in various tissues of 27 infants that had died unexpectedly; information was provided by the parents about birth order and breastfeeding history of the infants. It was found that the closer the infant had been to first in birth order, the higher the dioxin concentrations in the deceased infants’ tissues, “thus showing” (according to the study’s authors) “that the mothers can decontaminate themselves by breast feeding” (130). Having observed that, the authors had no hesitation about encouraging breastfeeding as a means of “decontaminating” the mothers, even after seeing clear evidence that the excreted toxins were absorbed by the infants, in direct proportion to the excretion from the mothers.
Given the above, should it be surprising that autism rates are by far highest among first-born children, about half as high among children fourth in birth order, and that the rates progressively decline from first to fourth children? (see Section 1.2.s.1.c of www.pollutionaction.org/breastfeeding-and-autism-and-cancer.htm)
To sum up preceding paragraphs as they relate to childhood cancer: Babies later in birth order are less likely to be breastfed, they are likely to be breastfed for shorter periods, and the levels of persistent toxins in later breast milk will be lower as a result of the earlier breastfeedings. And those babies who are breastfed less (and babies fed breast milk with reduced toxicity) are less likely to later have cancer than other babies.
Remember from earlier that childhood cancer incidence has also followed these same patterns: higher incidences of both breastfeeding and cancer among firstborn babies, among babies of older mothers, and among babies of parents of higher socio-economic status. In addition, cancer incidences in the U.S. West (the region with relatively low levels of environmental carcinogens) correlate nearly perfectly with the variations in levels of breastfeeding among different states. (see Section 1 of http://www.breastfeeding-and-cancer.info/ ) near end of section)
The CDC shows rates of breastfeeding among blacks or African Americans at 6 and 12 months after birth as being about half as high as among whites (142). According to another source, breastfeeding among blacks after the first days is even lower than half of the rate among whites: “Not only have Black women initiated breastfeeding at roughly half the rate of White women, but the majority of Black women who do breastfeed introduce formula to their infants while still in the hospital” (143).
Hispanics: At least two studies have found breastfeeding rates among Hispanics to be consistently lower than among whites: (Colley and colleagues, 1999; Ryan and colleagues,1991) (144). Note in Figure 1.3 that ASD rates among U.S. Hispanics are also lower than those of whites. (Lower autism among Hispanics could also relate to a diet that is typically higher in grains and beans, with less dioxin-containing fats, dairy products and snack foods compared with the typical American diet.) Death rates from cancer are more than a third lower among Hispanics that among non-Hispanic whites.(89a)
One study found breastfeeding not to be lower among Hispanics, but that study was carried out by a land-line telephone survey, which probably missed many of the Hispanics who are of the lower economic strata in which breastfeeding is less prevalent.
Given the above, should it be surprising that autism rates are about half as high among blacks as among whites, and that Hispanics are in between?
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(113) http://www.cdc.gov/breastfeeding/data/NIS_data/2000/socio-demographic.htm Also The Surgeon General’s Call to Action to Support Breastfeeding 2011 U.S. Public Health Service at http://www.surgeongeneral.gov/topics/breastfeeding/calltoactiontosupportbreastfeeding.pdf, p. 8
(116) J. Paediiitr. Cliihl Health (2()00) 36,164-168 Rates of breastfeeding in Australia by State and socio-economic status: Evidence from the 1995 National Health Survey S Donath and LH Amir The Key Centre for Woirien's Heatth. University of Melbourne. Melbourne. Victoria. Australia
(117) Lande, B., et al. (2003), Infant feeding practices and associated factors in the first six months of life: The Norwegian Infant Nutrition Survey. Acta Paediatrica, 92: 152–161. doi: 10.1111/j.1651-2227.2003.tb00519.x
(118a) Black Breastfeeding Advocacy: It Takes All Styles By Kimberly Seals Allers WeNews commentator February 23, 2012 Womensnews.org at http://womensenews.org/story/sisterspace/120222/black-breastfeeding-advocacy-it-takes-all-styles
(119) Infant Feeding Survey 2010: Early Results A survey carried out on behalf of the NHS Information Centre by IFF Research, University of York, UK, Section 2.2.1
(120) Factors associated with breastfeeding at six months postpartum in a group of Australian women Della A Forster et al. International Breastfeeding Journal, 2006 1:18
(121) Research Handbook on the Economics of Family Law, Cohen and Wright, p. 176, citing Scott et al, 1999, and Ynge and Sjostrom, 2001; Maternal and Child Health Journal Volume 2, Number 3 (1998), 167-179, DOI: 10.1023/A:1021879227044 Factors Associated with Very Early Weaning Among Primiparas Intending to Breastfeed Melissa Avery et al; Clinician Support and Psychosocial Risk Factors Associated With Breastfeeding Discontinuation Elsie M. Taveras, et al., Pediatrics, 2003, Vol. 113
(121a) Environmental chemicals in human milk: a review of levels, infant exposures and health, and guidance for future research Judy S. LaKind, et al., Toxicology and Applied Pharmacology 198 (2004) 184– 208
(129) Factors Influencing Full Breastfeeding in a Southwestern Ontario Community: Assessments at 1 Week and at 6 Months Postpartum Tammy J. Clifford, PhD Human Lactation, 2012
(130) Dioxin emissions from a municipal solid waste incinerator and risk of invasive breast cancer: a population-based case-control study with GIS-derived exposure Jean-François Viel, et al. International Journal of Health Geographics, 2008, Volume 7, Number 1, 4
(143) Am J Public Health. 2003 December; 93(12): 2000–2010. Low Breastfeeding Rates and Public Health in the United States Jacqueline H. Wolf, PhD
(144) Breastfeeding Initiation and Duration: A 1990-2000 Literature Review Cindy-Lee Dennis, RN, PhD, in JOGNN in Review, Vol. 31. No. 1