How microplastics in drinking water impact human health, environment
Director, Department of Public Health, Environment and Social Determinants of Health, at WHO, Dr. Maria Neira, said: “We urgently need to know more about the health impact of microplastics because they are everywhere – including in our drinking water,” says “Based on the limited information we have, microplastics in drinking water don’t appear to pose a health risk at current levels. But we need to find out more. We also need to stop the rise in plastic pollution worldwide.”
According to the analysis, which summarizes the latest knowledge on microplastics in drinking water, microplastics larger than 150 micrometers are not likely to be absorbed in the human body and uptake of smaller particles is expected to be limited. Absorption and distribution of very small microplastic particles including in the nano-size range may, however, be higher, although the data is extremely limited.
Further research is needed to obtain a more accurate assessment of exposure to microplastics and their potential impacts on human health. These include developing standard methods for measuring microplastic particles in water; more studies on the sources and occurrence of microplastics in freshwater; and the efficacy of different treatment processes.
WHO recommends drinking-water suppliers and regulators prioritise removing microbial pathogens and chemicals that are known risks to human health, such as those causing deadly diarrhoeal diseases. This has a double advantage: wastewater and drinking water treatment systems that treat fecal content and chemicals are also effective in removing microplastics.
Wastewater treatment can remove more than 90 per cent of microplastics from wastewater, with the highest removal coming from tertiary treatment such as filtration. Conventional drinking-water treatment can remove particles smaller than a micrometre. A significant proportion of the global population currently does not benefit from adequate water and sewage treatment. By addressing the problem of human exposure to faecally contaminated water, communities can simultaneously address the concern related to microplastics.
Meanwhile, animal studies have linked obesity and other health problems with exposure to bisphenol A (BPA). That is a common ingredient of many clear, hard plastics and the resins that line food cans. Concerns over BPA health impacts led manufacturers to start phasing out the chemical in products that make contact with foods and drinks. Now a study in children and teens suggests that even some BPA substitutes may foster weight gain.
Those substitutes — BPS (bisphenol S) and BPF (bisphenol F) — are now used as a lining in some aluminum food cans. They are also found in the paper used to print cash-register receipts.
Melanie Jacobson works in New York City at the New York University School of Medicine. Her team’s new study finds that overweight kids tend to have higher levels of BPS and BPF in their bodies than do normal-weight kids. That would suggest that like BPA, these chemicals are obesogens (Oh-BE-Suh-genz).
The group described its findings on July 25 in the Journal of the Endocrine Society.
Hormones control many of the body’s activities. At least in animals, BPA can mimic estrogens, a type of hormone. In fact, animal studies had shown BPA could cause harm by interfering with the body’s natural hormones. The new data suggest some BPA substitutes also may be hormone mimics.
“It is not surprising,” Bruce Blumberg says of the new findings. Previous research had linked BPA to obesity in both kids and adults. A cell biologist, Blumberg studies obesogens at the University of California in Irvine. He notes that a chemical’s structure, or shape, determines how it acts. And the chemical structures of both BPS and BPF, he notes, closely resemble that of BPA.
Exposure to obesogens “makes us more likely to get fat than we otherwise would,” says Blumberg. Studies in rodents, he notes, show that BPA makes fat cells larger. That can encourage the body to store more food energy as fat.
BPS and BPF have been studied far less than BPA has, notes Jacobson. For its new study, her team tapped into data from a national survey. It’s part of ongoing research to track the health and nutrition of children and adults across the United States.
Jacobson’s team focused on data for 1,831 people. All were between the ages of six and 19. The measured data included each person’s weight, height, and distance around the waist. People who are considered overweight have a higher weight and waist circumference than will others of their height.
The researchers used these data to compare each person’s body size. A normal body size for a 19-year-old girl is very different from that of a typical 6-year-old boy. So the researchers used a special calculation to adjust for age and sex. It “puts everyone on the same playing field,” explains Jacobson.
Her team then compared each kid’s body size to the number of bisphenols in their urine. BPA turned up in the urine of nearly every kid and teen (97.5 percent). Roughly 88 percent of them also had BPS. About 55 percent had detectable BPF.
Young people with higher levels of BPS in their urine were 16 percent more likely to be obese than were kids with lower levels. And kids with higher levels of BPF were 29 percent more likely to have abdominal obesity than were those with lower levels. Abdominal obesity is a high ratio of waist circumference to height.
The researchers found no link between BPA and obesity in the new data.
“Our findings suggest that these newer chemicals also may be a factor in child obesity,” says Jacobson. What the findings don’t mean, however, is that these chemicals are making kids fat. The study shows a correlation — or link — between two things: chemicals and obesity. That’s different from saying one caused the other. Indeed, Jacobson says, “We don’t know whether the chemicals caused the obesity.”
The national survey data provided a snapshot of kids’ body sizes and chemical exposures from a single point in time. The researchers have no way of knowing what happened first — the chemical exposure or obesity. Future studies could look to see whether bisphenol exposures lead to weight changes over time.
Scientists know that “a good diet and getting lots of exercises still are the most important things kids can do to maintain a healthy weight,” Jacobson says. Owing to her study’s new findings, she says kids may want to cut their exposures to BPS and BPF.
How? Avoid touching store receipts and eat fewer foods that come in cans, suggests Blumberg.
“Don’t microwave plastic food containers or put them in the dishwasher,” adds Jacobson. “When heated, [any bisphenols in them] are more likely to leach out into food and drink.”
Meanwhile, the WHO has recently published a report that looks at the impact of microplastics in drinking water on human health. They conclude that currently, the effects are unknown.
Do microplastics in drinking water directly impact human health? In 2015, humans produced around 407 million tons of plastic.
However, plastic does not biodegrade; instead, it breaks down into progressively smaller pieces of plastic. This means that in our environment, there are pieces of plastic measurable in both meters and nanometers.
Tiny pieces of plastic, or “microplastics,” end up everywhere — including the water supply.
A recent review collated 50 studies wherein scientists found microplastics in freshwater, drinking water, or wastewater. Some of these studies counted thousands of microplastic particles in every liter of drinking water.
Theoretically, if a person consumes them, some microplastics are small enough to pass through the gut wall and enter the circulatory system. Whether or not this happens, and whether or not it impacts human health, remains unknown.
Because plastics are ubiquitous in the environment, and because they are not going away, it is vital that we understand the effects — if any. A recent WHO report set out to develop a clearer picture.
The WHO report outlines three possible routes by which microplastics could impact human health:
*Physical: Microplastics could enter the body and damage internal structures.
*Chemical: For instance, plastic additives such as plasticizers could enter drinking water.
*Biofilm: Microorganisms might attach to microplastics and form colonies, which could cause harm.
Although the report finds that evidence of all three routes is incredibly limited, it concludes that the latter two are of least concern.
According to the researchers’ analysis, microplastics larger than 150 micrometers probably do not enter the human body; smaller particles may get in, but they believe that uptake is limited.
Absorption of nanosized particles might be more common, but again, data are limited.
Animal studies have produced evidence to suggest that our bodies might absorb very small microplastics. However, the WHO report explains that these studies used “extremely high exposures that would not occur in drinking water.”
The lack of available information is not surprising; the public’s keen focus on plastic is a relatively recent phenomenon. In general, a lack of interest means a lack of funding and, therefore, a lack of research.
Two recent studies underline the ubiquity of microplastics; one finds them in table salt, the other in human feces.
When the researchers looked at toxicology studies, the evidence was equally sparse.
The authors write that the studies “are of questionable reliability and relevance, with some impacts observed only at very high concentrations” that “do not accurately reflect potential toxicities that could occur at lower levels of exposure.”
“We urgently need to know more about the health impact of microplastics because they are everywhere — including in our drinking water,” explained Dr. Maria Neira, director of the Department of Public Health, Environment, and Social Determinants of Health at the WHO. She added: “Based on the limited information we have, microplastics in drinking water don’t appear to pose a health risk at current levels. But we need to find out more. We also need to stop the rise in plastic pollution worldwide.”
The WHO end their report with a call to focus on treating water contaminated with feces.
They explain that treating drinking water properly also removes the majority of microplastics. They said, “According to available data, wastewater treatment can effectively remove more than 90 per cent of microplastics from wastewater.”
In many parts of the world, people do not have access to clean water. The impact of feces contaminated water on human health is well established.
“By addressing the bigger problem of exposure to untreated water, communities can simultaneously address the smaller concern related to microplastics in surface water and other drinking water supplies.”
The WHO also recommends continued efforts to minimize plastic usage. Even if microplastics do not make their way into the water supply, they will not disappear from the environment.
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