Not only plastics ... chemicals too!

 Pesticides, phosphates, soap and shampoo, all have an impact on the natural world!  Dr Anjani Ganase looks at how everyday chemical use affects other species and the environment.

 

We impact our surrounding environment in more ways than we know. Humans alter the physical and biological landscapes and seascapes dramatically and silently. Less obvious are the chemical infiltrations that occur through some of our common activities. Our daily routines –  showering, cleaning the house, driving to work, all casual activities, even when we try to be mindful - all leave a footprint on the environment. Let’s look at a few chemicals that cause unintended collateral damage to wildlife.

 

The chemicals in our tyres

A recently published study finally cracked the mystery of dying salmon in the northwest USA. These deaths have occurred in creeks adjacent to urban centres. For years, scientists would observe salmon suffer behavioural changes including swimming in circles, and gasping, which eventually led to death. This became more prevalent where the streams that salmon would swim up during their spawning season were connected to storm water discharge points. The salmon would be diagnosed with “urban stream syndrome”. Years of research resulted in the breakthrough where scientists narrowed the chemical down to a common rubber preservative which would increase the life span of car tyres. Worn bits of the tyres on the road would wash into neighbouring rivers and streams and affect the salmon. While salmon is observed to be affected by this, it is unlikely that it would be the only species to be sensitive; and therefore action to remove the chemical during the manufacturing process needs to be considered. Think about the tyres that are dumped in the rivers and along the coasts of Trinidad and Tobago.

 

                                    From suburb to rainforest we are connected in our island ecosystem. Photo by Anjani Ganase

 

 

Pesticides

One common pesticide that is used globally to curb the presence of mosquitoes as vectors of major diseases such as malaria and Chikungunya, is the chemical called malathion. While the spraying of urban areas combats the spread of vector-borne disease, the wide use of the chemicals is also known to impact the many non-targeted insect species, including butterflies, spiders and even honeybees that are crucial pollinators. A review of malathion impacts to the environment in the USA has revealed that, while malathion readily breaks down in soils and water, it can still have significant impact on the small and more vulnerable organisms.

 

Organisms that are known to be impacted include amphibians, birds and even small mammals depending on the concentrations. When malathion leaches into lakes and streams, it is known to cause mortality in aquatic insects, especially during the early stages of development. Birds may experience short-term disorientation and changes in nesting behaviour; and in the days following spraying, birds often relocate to find healthy food because of the loss of food as a result of pesticide. Many wetland areas often get sprayed with malathion, and the chemical then gets flushed to the coastline and on to beaches. Think about the growing absence of insects – butterflies and bees. Surely there should be additional considerations when spraying in residential areas that are near to  aquatic life or natural spaces?

 

Furniture Stain Repellents

The chemicals used to protect carpets and food packages are known as perfluorinated compounds or PFCs for short. These chemicals have been found to leach and persist in the aquatic and marine environments. Scientists who monitored the impacts of pollution on marine turtles along the east coast of the USA found that juvenile loggerhead turtles were being physiologically affected by PFCs. The main diet of loggerheads are crustaceans that include mussels that filter feed the water column.  At sites close to urban centres, these mussels would have accumulated higher levels of PFCs in their bodies. The PFC contamination resulted in liver damage and juvenile loggerheads become immune-compromised. PFCs have also been found accumulating in larger marine mammals such as ringed seals in Canada and Bottlenose dolphins along the east coast.

 

Shampoos and Soaps

Many common household detergents, including most shampoos and soaps contain phosphates which work to soften hard water, and aid in the suspension of dirt particulates through the foaming process. The problem with phosphates is that they enter our waterways as wastewater via our drains; these are quickly absorbed by algae in rivers and lakes, and results in algal blooms or the eutrophication of our aquatic environments. Eutrophication reduces water clarity which impacts freshwater aquatic plants, and can lead to dead zones in areas of poor circulation as all the oxygen gets used up by the algae. This can result in fish kills or die off of aquatic organisms. Detergents also tend to sit on the surface of water as layers of foam, which reduces the exchange in gases across the surface of the water also adding to the production of dead zones. Detergents are also known to directly impact fish biology especially larval growth and survival, and also cause sublethal effects such as difficulty breathing and swimming. You may think that the individual household in Trinidad and Tobago may not significantly impact our rivers and waterways but think about the number of communities that line many of our major rivers. Most household wastewater ends up in our drains, rivers and then gets pushed out into the ocean around marine ecosystems.

 

We need to appreciate the full gamut of impacts to determine the true costs of using these chemicals.  Knowledge of it will give us the opportunity to be more mindful in our daily activities and to understand that in an island ecosystem, we are connected from ridge to reef. What we do upstream can change the life of the ecosystem downstream.

 

                                    The ocean receives whatever finds its way to the rivers. Photo by Anjani Ganase

 

 

 

 

References:

 

Mousavi, S. A., & Khodadoost, F. (2019). Effects of detergents on natural ecosystems and wastewater treatment processes: a review. Environmental Science and Pollution Research, 1-10

 

Newhart, K. (2006). Environmental fate of malathion. California Environmental Protection Agency, 1-20.

 

O’Connell, S. G., Arendt, M., Segars, A., Kimmel, T., Braun-McNeill, J., Avens, L., ... & Keller, J. M. (2010). Temporal and spatial trends of perfluorinated compounds in juvenile loggerhead sea turtles (Caretta caretta) along the east coast of the United States. Environmental science & technology, 44(13), 5202-5209.

 

SeaWeb. "Chemicals In Our Waters Are Affecting Humans And Aquatic Life In Unanticipated Ways." ScienceDaily. ScienceDaily, 21 February 2008. <www.sciencedaily.com/releases/2008/02/080216095740.htm>.

 

Tian, Z., Zhao, H., Peter, K. T., Gonzalez, M., Wetzel, J., Wu, C., ... & Cortina, A. E. (2020). A ubiquitous tire rubber–derived chemical induces acute mortality in coho salmon. Science.