Most plastic products release estrogenic chemicals: a potential health problem that can be solved

Abstract

Background: Chemicals having estrogenic activity (EA) reportedly cause many adverse health effects, especially at low (picomolar to nanomolar) doses in fetal and juvenile mammals.

Objectives: We sought to determine whether commercially available plastic resins and products, including baby bottles and other products advertised as bisphenol A (BPA) free, release chemicals having EA.

Methods: We used a roboticized MCF-7 cell proliferation assay, which is very sensitive, accurate, and repeatable, to quantify the EA of chemicals leached into saline or ethanol extracts of many types of commercially available plastic materials, some exposed to common-use stresses (microwaving, ultraviolet radiation, and/or autoclaving).

Results: Almost all commercially available plastic products we sampled--independent of the type of resin, product, or retail source--leached chemicals having reliably detectable EA, including those advertised as BPA free. In some cases, BPA-free products released chemicals having more EA than did BPA-containing products.

Conclusions: Many plastic products are mischaracterized as being EA free if extracted with only one solvent and not exposed to common-use stresses. However, we can identify existing compounds, or have developed, monomers, additives, or processing agents that have no detectable EA and have similar costs. Hence, our data suggest that EA-free plastic products exposed to common-use stresses and extracted by saline and ethanol solvents could be cost-effectively made on a commercial scale and thereby eliminate a potential health risk posed by most currently available plastic products that leach chemicals having EA into food products.

Figure 1

Results of MCF‑7 assays shown as dilution response curves (%E2) for E2 (A), E2 and BPA (B), BHA (C), and %RME2 of extracts of plastic bags (D), a PC bottle (E), and a BPA-free bottle made from PETG (F). Abbreviations: PETG, PET glycol-modified polyethylene terephthalate; VC, vehicle control. Dotted lines represent 3 SD from the response. In B–F, the negative control (1% EtOH or saline) equals 0% E2. The E2 standard (10^–9 M) is the positive control diluted as indicated in C–F. Each point plotted is the average of three or four replicates for each concentration whose SD is very small and falls within the space taken up by each data point. In (A), E2 was dissolved in EtOH (standard extract) or concentrated 10× and rediluted to show that the EtOH concentration protocol has very little effect on the EC₅₀ of E2 (50% E2). The EC₅₀ of E2 is approximately 1.3 × 10^–13 M, and the threshold of detection (15% E2) is approximately 10^–15 M. The maximum E2 response was attained at 10^–11 M and remained constant at higher E2 concentrations. (B) The EC₅₀ of both E2 (as in A) and BPA is approximately 6.6 × 10^–8 M, and threshold detection is approximately 10^–9 M, all suppressed by 10^–8 M ICI. (C) BHA does not meet criteria needed for accurate calculation of EC₅₀ [see Supplemental Material, pp. 5–7 (doi:10.1289/ehp.1003220)]. EA is positive; its maximum response is about 50% E2 (i.e., 50% RME2) and is suppressed by 10^–8 M ICI. In D, commercially available plastic bags were extracted by 100% EtOH. Commercially available PC (E) and BPA-free (F) bottles were extracted with saline or EtOH as indicated.

Figure 2

Total EA released by some PC and BPA-free water bottles (W) and baby bottles (B). The leaching of chemicals having EA (measured as %RME2; excluding caps, nipples, and other components) were extracted using saline or EtOH as solvents and exposed to autoclaving, microwaving, and/or UV light (see “Materials and Methods” for details). BPA-free water bottles W₁, W₂, W₃, and W₄ are PETG, and W₅ is PET. BPA-free baby bottles B₁ and B₂ are polyethersulfone; B₃ is PETG; and B₄ and B₅ are PP. Orange bars indicate the data set for each individual product. The %RME2 for saline extracts is represented by solid black lines and for EtOH as solid red lines. Symbols represent the %RME2 of chemicals released by each assay of a product after an autoclaving stress, microwaving stress, and UV light stress (see figure key). The dotted horizontal line at 15% RME2 is the rather conservative value below which EA was considered nondetectable (ND) for any assay. For some products shown (e.g., PC B₁, BPA-free B₄), if one solvent and/or stress condition showed reliably detectable EA, other solvents and stress conditions were not subsequently tested. Some values plotted as 0% RME2 actually had slightly negative %RME2 values (–1% to –7% RME2) due to cellular toxicity.

Figure 3

Properties of monomers and polymers used to make common resins.