Here’s a nice write up describing a project that uses plants to clean up a polluted mine site, a process called phytoremediation. In this case, the possibility of harvesting plants that have accumulated metals and then recovering the metals for profit (“phytomining”) is being explored.
Bisphenol A (BPA), a chemical used in some types of plastics, has gotten a lot of public attention in recent years because of its estrogen mimicking effects and the public’s widespread exposure to it. Many manufacturers have removed BPA from products which come into contact with food, and in some jurisdictions there are now regulations limiting its use.
One of the chemicals that is used as a replacement for BPA is bisphenol S (BPS). BPS is chemically related to BPA and actually has the same inherent estrogenic activity which is problematic in BPA. However, BPS was thought to be a safer alternative because, it was claimed, it did not leach from plastics like BPA does.
That belief is now being questioned. An article at Scientific American details some of the research and concludes that the real issue behind the public safety problem is not so much that we can’t determine the health concerns associated with a particular chemical but that, “Currently, no federal agency tests the toxicity of new materials before they are allowed on the market.”
Bisphenol A (BPA) is an ingredient in some plastic products. It is useful in improving the properties of materials and products it is used in, but it has become a controversial subject. BPA is used in plastic water bottles, food containers, and other materials that come in contact with what we consume. BPA is used in small amounts and our exposure to it is probably very small. But BPA has known acute adverse health effects as an endocrine disruptor, and the human health risks associated with long term low exposure levels are difficult to assess. Figuring out how to balance the competing interests of a useful product versus the health concerns associated with its use is a messy regulatory situation.
As a precaution, BPA is has been phased out from some uses and has been banned in some jurisdictions and the search for suitable replacements is an area of active research. One potential replacement that has been reported recently is called bisguaiacol F (BGF). One notable aspect of BGF is that is can be produced from waste byproducts of the paper industry. Lignans are natural chemical compounds found in wood which are removed in the production of paper. This lignin waste is a disposal problem, so if it can be converted into a useful product (which is a replacement for a potentially harmful product) then two birds are killed with one stone.
So, is BGF a viable alternative to BPA? BGF is chemically related to BPA. Comparing the two chemical structures shown in the image, the two methyl groups (CH3) in the middle of BPA are removed and two methoxy groups (CH3O) are added on the ends. Looking at just the first modification, removal of the two methyl groups gives a compound called bisphenol F (BPF). BPF is a has the same endocrine disrupting concerns as BPA, so this modification alone is not sufficient to eliminate the potentially harmful effects. Looking at the second medication, the study’s authors claim that the introduction of the two methoxy groups will prevent BPF from binding to the estrogen receptor, which is the cause of BPA’s biological effects. As far as I can tell, the researchers have only used software models to predict the biological effects of BGF, so there is certainly quite a bit more work to be done to demonstrate its safety.
It is still too early to tell whether BGF will eventually be a viable replacement for BPA, but it is research like this that is the only real hope of bypassing the current messy regulatory situation.
Science writing in the news often irritates me, but I like this writeup about phthalates, “A Threat to Male Fertility” by Deborah Blum, in the New York Times’ Poison Pen blog.
This post on the Toxcentre blog is a nice review of the endocrine disrupting properties of cadmium.
The topic I have chosen to explore is how the metal cadmium (Cd) may potentially result in endocrine disruption. Endocrine disrupting compound (EDC) are those that have the potential to alter hormone pathways that regulate reproduction (Arcand-Hoy and Benson 1998). They have investigated widely in the literature as have the release of metals through anthropogenic activities. Cadmium is a naturally occurring metal but it is not essential in normal cellular processes so exposure and uptake of Cd can have adverse effects. Cadmium exposure can occur through ingestion of food or water containing Cd as well as inhalation. Inhalation exposure occurs most notably through cigarette smoke but also from coal burning. Cadmium can be food in food that is grown in soils containing either naturally higher Cd levels or in areas where the soil has been increased through anthropogenic uses (Silva et al. 2011).
Cadmium has been identified as…
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A recent spill in West Virginia of a chemical called 4-methylcyclohexanemethanol (MCHM) has been in the news for the last few days. It was being used to wash coal to remove dust from it before being transported. A storage tank leaked, allowing it to seep into a river where drinking water is obtained.
MCHM isn’t a commonly used industrial chemical and little is known about its toxicology or the health effects of exposure to it.
This brings up the interesting problem of how to handle this situation when so little is known about the chemical. The local authorities seem to be just telling the residents not to drink the water and waiting until it the problem resolves itself.
From looking at the chemical structure of MCHM, it doesn’t have any obvious warning signs. It is a low molecular weight alcohol, an isomer of octanol, which tend to be fairly benign. But sometimes chemicals can be harmful in surprising ways.