Dangers of Lawn Chemicals: Impacts and Alternatives

Every year, an astounding 80 million pounds of pesticides are sprinkled across the lawns and gardens of North America. These chemicals, which originated from attempts to repurpose gases used in warfare for domestic utility, are now designed to keep our lawns lush by any means necessary. They may fulfill their promise of aesthetic perfection—but at a considerable cost. Striving for the ideal green space, regrettably, often overlooks the quiet consequences that these substances introduce into our environments, and our lives.

In this final entry of our lawn series, we aim to uncover the hidden toxicity of these chemical applications, examining their impact on our health, our wildlife, and our planet.

Chemical Consequences for Wildlife Health

Impacts on Insect Pollinators

Pollinators are among the most intensively affected by lawn chemicals, with bees being particularly vulnerable. This is because most insecticides are broad-spectrum, meaning they don’t target a specific type of insect and instead effect any insect it comes in contact with. Chemicals such as neonicotinoids and pyrethroids can disrupt bee learning and navigation and weaken their immune systems, causing death and reducing populations. In addition, growth-regulating herbicides such as aryl triazinones and acetolactate synthase inhibitors can destroy the plants that pollinators—especially caterpillars of butterflies and moths— need to feed on. This greatly diminishes the availability of host plants where adults can lay eggs, severely disrupting their life cycles.

Consequences for Aquatic Wildlife

The impact of lawn care products extends beyond our gardens and into our waterways. Runoff from rainfall, which has been worsened by climate change in some areas, can carry herbicides and insecticides into streams, rivers, and lakes, contaminating them. Organophosphate insecticides, phenoxy and benzoic acid herbicides, and triazole fungicides are all highly toxic to fish and can degrade or even completely destroy aquatic ecosystem health. Similarly, pyrethroids, while less likely to leach into waterways, can still be found in significant quantities in many water bodies, where they are highly toxic to invertebrates.

Aerial view of a boat crossing a large body of water that appears unnaturally green and blue.
Runoff of organophosphates and other garden chemicals can lead to massive blooms of toxic algae. Lake Erie, 2018. Credit: NOAA

Effects on Birds

Birds have not been spared from the effects of these chemicals. Many birds are poisoned and killed by eating contaminated insects or plants treated with pesticides. Beyond acute poisoning, substances like historically used organochlorines (such as DDT) are known for causing long-term reproductive damage, including eggshell thinning, which can lead to population declines and possibly even extinction. Because 96% of terrestrial birds require insects to feel their young, both insecticides and herbicides can drastically reduce the amount of food available to birds in spring.

A bald eagle lays dead on the ground.
Even predatory birds can perish due to chemical poisoning, by consuming prey that has itself consumed exposed plants and insects. Credit: USFWS

Pets, Humans, and other Mammals

Mammals, including our beloved cats and dogs, encounter similar risks from lawn chemical exposure. Rodenticides and herbicides are toxic if ingested. For instance, pets and wildlife roaming free on treated lawns can absorb chemicals through their paws or ingest them while grooming. Pyrethroids in particular can cause infertility, damage to immune systems, and cardiac disease in humans. Even some ‘mammal-safe’ pesticides, such as triazoles, can ultimately break down into compounds that become toxic to mammals. Pesticide exposure is linked to severe health issues including cancer—for wild mammals, pets, and humans alike.

Long-term Ecological Impacts

On a larger scale, the widespread use of lawn chemicals significantly impacts local biodiversity. By eliminating crucial species within an ecosystem, these chemicals disrupt ecological balance and stability. The phenomenon of bioaccumulation and biomagnification—wherein chemicals are passed down from prey to predator and effects are worsened further along the food chain—means that these chemicals can remain active in the environment for decades. This has been the case for DDT, which was banned in the U.S. in 1972 and is still found in animal tissue over 50 years later.

A black and white photograph shows an aerial view of an airplane spraying a substance over a forested area.
Before it was banned, more than 1.3 billion pounds of DDT was sprayed over the U.S. to control insect pests. Oregon, 1955. Credit: USDA Forest Service

Toxicity of Common Lawn and Garden Chemicals

It’s vital to understand the environmental impacts of the myriad of synthetic lawn care products available on the market. Below is a table summarizing some of the most commonly used products, highlighting their active ingredients and the non-target wildlife/systems they are toxic to.

Look Beyond the Label

When selecting products, remember to approach marketing claims with caution. Labels often emphasize human safety and overall effectiveness, but often don’t fully disclose potential environmental impacts.

Take, for instance Roundup, a popular choice among gardeners. Roundup originally used glyphosate content until legal concerns about cancer in humans pushed the company to reformulate. The company advertised its new ‘glyphosate-free’ formulation as a healthier version of the product. However, even this new formulation kills 94% of exposed bumble bees.

BioAdvanced Fungus Control, on the other hand, is inherently highly toxic to fish, but not insects. However, when used alongside neonicotinoid insecticides (including the company’s own products), a synergistic effect occurs. When combined, these products dramatically increase overall toxicity to and declines of bees.

For an expanded list of the wildlife harmed by the 30 most common lawn pesticide chemicals, see here.

Safer Alternatives to Chemical Lawn and Garden Care

If you find yourself disturbed by the widespread environmental and health consequences of these chemicals, know that there are affective alternatives. The first step is to challenge your notion of what a ‘pest’ is. The idea that all insects are ‘bad’ fuels unnecessary use of pesticides, when the vast majority of insects are in fact beneficial.

Natural Pest Prevention

To reduce pesticide use, you can adjust garden and lawn are practices so that chemical control is not needed, or is needed less:

  • Replace non-native plants, including turf grass, with locally native species. These are far more resistant to native pests and generally need less care than non-native plants.
  • Choose a natural garden design with a diversity of native species. A mosaic of different plant species will both make it harder for pests to become established, and make any damage done less aesthetically obvious.

Natural Pest Removal

Two people standing beside a tree. A bat house is mounted on the tree trunk.
Providing habitat for pest predators, like bats, provides free, natural pest removal. Credit: The Co-op Group/Flickr

If you objectively do have a pest issue, you’ll be glad to hear that there are safe and sustainable ways to handle them. While there are instances where pesticides might be necessary, such as controlling disease-carrying mosquitoes or managing aggressive invasive species, everyday garden maintenance can often be achieved without pesticides—especially when tending to native plants rather than turf grass.

Integrative Pest Management (IPM) is an effective strategy that combines several natural approaches to controlling pests with minimal environmental impact:

  • Encourage natural pest predators to visit your garden by installing bird and bat houses.
  •  Consider hand-picking or using devices such as traps, insect vacuums, and exclusion barriers to directly remove or deter pests.
  • If pesticides are required, opting for a least-toxic alternative can help reduce risk to human and wildlife health. Many least-toxic pesticides are organic botanicals, essential oils or derived from other plant or natural mineral sources. Beyond Pesticides provides a list of least-toxic fertilizers, fungicides, herbicides, and insecticide products that are compatible with organic land management.

Read the previous blogs in this series: