Exposures to environmental contaminants can pose risks to pregnant women's health, their developing fetuses, children, and adults later in their lives. Assessing risks to this potentially susceptible population requires a sound understanding of the physiological and behavioral changes that occur during pregnancy and lactation. Many physiological and anatomical changes occur in a woman's organ systems during the course of pregnancy and lactation. For example, blood volume and cardiac output increase during pregnancy, and other metabolic functions are altered to provide for the demands of the fetus. During lactation, nutritional demands are greater than during pregnancy. There are also changes in behavior during both pregnancy and lactation. For example, water consumption during pregnancy and lactation increases. These behavioral and physiological changes can lead to different environmental exposures than these women might otherwise experience in the absence of pregnancy or lactation. This paper provides a summary of information from the published literature related to behavioral and physiological changes in pregnant and lactating women that may affect their exposure or susceptibility to environmental contaminants, provides potentially useful exposure factor data for this population of women, and highlights data gaps.

This study measured 21 persistent, bioaccumulative, and toxic (PBT) pollutants in the US milk supply. Since milk fat is likely to be among the highest dietary sources of exposure to PBTs, it is important to understand their levels in this food. Nationwide samples were collected from 45 dairy plants in July of 2000 and again in January 2001. The levels of all chemicals in the chlorobenzene, pesticide and other halogenated organic groups were determined to be below their detection limits in all samples. National averages were computed for 11 chemicals or chemical groups found above the detection limits. The national average CDD/CDF and PCB TEQ concentrations were 14.30 and 8.64 pg/l, respectively, for a total of 22.94 pg/l. These levels are about half the values found in a similar study conducted in 1996. If this difference is in fact indicative of declining milk levels and assuming exposure levels from nondairy pathways have remained the same over this time period, this would result in an overall decrease in adult background dioxin exposure of 14%. Six PAHs were detected with national averages ranging from 40 to 777 ng/l. Cadmium concentrations ranged from 150 to 870 ng/l with a national average of 360 ng/l. Lead concentrations were consistently higher than those of cadmium, ranging from 630 to 1950 ng/l with a national average of 830 ng/l. PAHs showed the strongest seasonal/geographic differences, with higher levels in winter than summer, north than south and east than west. Average adult daily intakes from total milk fat ingestion were computed for all detected compounds and compared to total intakes from all pathways: CDD/CDF/PCB TEQs: 8 vs. 55 pg/day, PAHs: 0.6 vs. 3 mg/day, lead: 0.14 vs. 4-6 mg/day, and cadmium: 0.06 vs. 30 mg/day.

Usual intake estimates describe long-term average intake of food and nutrients and food contaminants. The frequencies of fish and shellfish intake over a 30-day period from National Health and Examination Survey (NHANES 1999-2006) were combined with 24-h dietary recall data from NHANES 2003-2004 using a Monte Carlo procedure to estimate the usual intake of fish and shellfish in this study. Usual intakes were estimated for the US population including children 1 to <11 years, males/females 11 to <16 years, 16 to <21 years, and adults 21+ years. Estimated mean fish intake (consumers only) was highest among children 1 to <2 years and 2 to <3 years, at 0.37 g/kg-day for both age groups, and lowest for females 11 to <16 years, at 0.13 g/kg-day. In all age groups, daily intake estimates were highest for breaded fish, salmon, and mackerel. Among children and teenage consumers, tuna, salmon, and breaded fish were the most frequently consumed fish; shrimp, scallops, and crabs were the most frequently consumed shellfish. The intake estimates from this study better reflect long-term average intake rates and are preferred to assess long-term intake of nutrients and possible exposure to environmental contaminants from fish and shellfish sources than 2-day average estimates.