Environmental Factor, August 2011, National Institute of Environmental Health Sciences
Extramural papers of the month
- Some BPA-free bottles live up to their claim
- Genetic link determined for prostate cancer in African-American men
- Caffeine and UVB damage
- Prostate cancer risk increased with ambient exposure to pesticides
Some BPA-free bottles live up to their claim
University of Cincinnati researchers tested a variety of bottles claiming to be bisphenol A free and found some conflicting results, according to a new study. The NIEHS-funded study was prompted by consumer concerns and was conducted to see if bottles made of materials other than polycarbonate lived up to their claim or leached BPA into water stored in them for five days.
The bottles tested were obtained from retail sources and were made of polycarbonate, stainless steel, copolyester, aluminum with a copolyester lining, or aluminum with an epoxy resin lining.
As expected, the lab found that water stored in polycarbonate bottles contained BPA at the end of the five days. This confirmed previous results from the same lab. Aluminum bottles coated with an epoxy resin gave conflicting results depending on the manufacturer. Bottles obtained from discount stores released significantly more BPA.
The researchers conclude that just because a bottle is not made of polycarbonate, it is not necessarily free of BPA. Some alternative bottles were indeed BPA free but, based on these findings, consumers should be wary.
Citation: Cooper JE, Kendig EL, Belcher SM(https://www.ncbi.nlm.nih.gov/pubmed/21741673). 2011. Assessment of bisphenol A released from reusable plastic, aluminum and stainless steel water bottles. Chemosphere; doi:10.1016/j.chemosphere.2011.06.060(http://dx.doi.org/10.1016/j.chemosphere.2011.06.060) [Online 7 July 2011].
Genetic link determined for prostate cancer in African-American men
Scientists at the Keck School of Medicine of the University of Southern California have found a single-nucleotide polymorphism that occurs in about five per cent of African-American men, putting them at greater risk for developing prostate cancer. This research was supported by NIEHS and the National Cancer Institute.
The study examined about one million single-nucleotide polymorphisms across the genomes of 3,425 African-American men with prostate cancer and 3,290 African-American controls. The study is part of the Multiethnic Cohort study being conducted in a collaborative effort between the Keck School and the University of Hawaii.
In general, men of African descent are more susceptible to prostate cancer than others. The current study reports the discovery of a prostate cancer marker on chromosome 17 and builds on a previous finding by the same research team that elucidated a marker on chromosome 8. These studies support the need for additional genome-wide association studies to locate markers that may play a role in understanding racial and ethnic health disparities.
Citation: Haiman CA, Chen GK, Blot WJ, Strom SS, Berndt SI, Kittles RA, Rybicki BA,Isaacs WB, Ingles SA, Stanford JL, Diver WR, Witte JS, Hsing AW, Nemesure B,Rebbeck TR, Cooney KA, Xu J, Kibel AS, Hu JJ, John EM, Gueye SM, Watya S, Signorello LB, Hayes RB, Wang Z, Yeboah E, Tettey Y, Cai Q, Kolb S, Ostrander EA, Zeigler-Johnson C, Yamamura Y, Neslund-Dudas C, Haslag-Minoff J, Wu W, Thomas V, Allen GO, Murphy A, Chang BL, Zheng SL, Leske MC, Wu SY, Ray AM, Hennis AJ, Thun MJ, Carpten J, Casey G, Carter EN, Duarte ER, Xia LY, Sheng X, Wan P, Pooler LC, Cheng I, Monroe KR, Schumacher F, Le Marchand L, Kolonel LN, Chanock SJ, Berg DV, Stram DO, Henderson BE(https://www.ncbi.nlm.nih.gov/pubmed/21602798). 2011. Genome-wide association study of prostate cancer in men of African ancestry identifies a susceptibility locus at 17q21. Nat Genet 43(6):570-573.
Caffeine and UVB damage
According to recent findings from a team led by an NIEHS grantee at the University of Chicago, Outstanding New Environmental Scientist (ONES) awardee and former NIEHS fellow Yu-Ying He, Ph.D., caffeine promotes UVB-induced apoptosis, or programmed cell death, of unrepaired keratinocytes, thereby preventing carcinogenic transformation of the cells. Caffeine produces complex pharmacological actions and has been shown to be chemopreventive in non-melanoma skin cancer in humans and in mice.
These researchers investigated the molecular and cellular mechanisms involved in the pro-apoptotic effect of caffeine on UVB-irradiated HaCaT keratinocytes. Keratinocytes are the predominant cell type in the outermost layer of the skin. Pretreatment with caffeine increased UVB-induced apoptosis in the cultured keratinocytes. The experiments also showed that caffeine mediated to critical oncogenic pathways in skin tumorigenesis.
These findings build on previous work that demonstrated that coffee and regular exercise work together to kill off precancerous cells whose DNA has been damaged by UVB radiation.
Citation: Han W, Ming M, He YY(https://www.ncbi.nlm.nih.gov/pubmed/21561856). 2011. Caffeine Promotes Ultraviolet B-induced Apoptosis in Human Keratinocytes without Complete DNA Repair. J Biol Chem 286(26):22825-22832.
Prostate cancer risk increased with ambient exposure to pesticides
A new study from NIEHS-supported epidemiologists at the University of Southern California found that exposure to certain agricultural pesticides increases the risk of prostate cancer. This study adds to the mounting research that suggests insecticides, fungicides, and herbicides wreak havoc on the male endocrine system.
Exposure to methyl bromide and other organochlorine pesticides was associated with an up to two-fold increase in prostate cancer risk in the 173 men with prostate cancer in the study, when compared to controls. Captan, a fungicide used widely on apple orchards in the U.S., was associated with prostate cancer as well, but only at relatively high levels of exposure. The researchers conclude that efforts to limit the spread of pesticide residues into the environment are not as protective as they need to be to limit human exposure.
According the study, the most likely reason for the increased risk is a complex interplay of genetics and the environment. The researchers speculate that only those men with a certain genotype will develop prostate cancer if they are exposed to pesticides. Preventing exposure by reducing the use of pesticides, increasing organic growing practices, and other methods of limiting contact with pesticides would most likely prevent the disease from developing or progressing in these susceptible populations.
Citation: Cockburn M, Mills P, Zhang X, Zadnick J, Goldberg D, Ritz B(https://www.ncbi.nlm.nih.gov/pubmed/21447478). 2011. Prostate cancer and ambient pesticide exposure in agriculturally intensive areas in California. Am J Epidemiol 173(11):1280-1288.
(Jerry Phelps is a program analyst in the NIEHS Division of Extramural Research and Training.)