Restricted Use Pesticide Usage: South Central Oʻahu

Wahiawā-Ewa

Executive Summary (2020-2021)

This brief summarizes reported pesticide use in South Central Oʻahu during 2020 and 2021, focusing on chemicals applied near schools and residential areas. This includes analysis of RUP use in the communities south of Wahiawā, surrounding Mililani, Royal Kunia, Waipahu and south to Ewa Gentry.

2020 & 2021

The findings highlight ongoing public health and environmental concerns associated with the use of highly hazardous pesticides and pesticide mixtures.

Key Findings

Persistent use of highly hazardous pesticides

• Continued application of paraquat dichloride, increasing from approximately 531 lbs active ingredient in 2020 to approximately 953 lbs in 2021, despite its extreme acute toxicity and links to Parkinson’s disease.

• Substantial use of methomyl, oxamyl, diazinon, and naled, all acutely toxic insecticides that affect the nervous system and pose heightened risks to children.

Ongoing neurotoxic exposure risks

• Repeated use of carbamate and organophosphate insecticides, known cholinesterase inhibitors.

• These chemicals are associated with acute poisoning, respiratory distress, and long-term neurological impacts, particularly for developing brains.

Heavy reliance on synthetic pyrethroids

• Extensive use of bifenthrin, lambda-cyhalothrin, cyfluthrins, permethrin, esfenvalerate, and zeta-cypermethrin across both years.

• Synthetic pyrethroids are highly toxic to aquatic life and contribute to long-term contamination of waterways and sediments.

Chemical mixtures and cumulative exposure

• Communities are exposed to multiple pesticide classes simultaneously, including herbicides, insecticides, fungicides, and insect growth regulators.

• Regulatory systems evaluate pesticides largely one at a time, failing to address real-world cumulative and synergistic exposure.

Shift in risk, not reduction

• While soil fumigant use declined in 2021 compared to 2020, overall risk remained high due to increased reliance on other highly toxic chemicals, including paraquat and carbamates.

Schools at Risk

Pesticide residues travel miles from application sites into schoolyards, homes, water catchments, and air. Chronic exposure threatens children’s developing bodies, contributing to:

• Brain development impacts

• Respiratory harm and asthma risk

• Childhood cancer susceptibility

• Hormonal/endocrine interference

While some of the schools in Central Oʻahu that may be just over a mile away from usage, the multiple points of exposure along with the extremely high amounts of drift prone RUP’s applied nearby raises concerns about health risks. 

There are nine schools in this region located within one mile of RUP applications (2020-2021):

1. Ewa Elementary, Eva Villages  

2. Friendship Christian Schools, Ewa Villages  

3. Holomua Elementary, Ewa Gentry 

4. Honouliuli Middle, East Kapolei  

5. Honowai Elementary,Waipahu  

6. Kaleiopuu Elementary,Waipahu     

7. Mililani Uka Elementary, Mililani  

8. New Hope Christian School,Waipahu    

9. Solomon Elementary, Wahiawā

Why This Matters

South Central Oʻahu communities, including keiki and kūpuna, live and learn in close proximity to agricultural areas where these pesticides are applied. The data show that hazardous pesticide exposure is not declining, but rather shifting among chemical classes, leaving communities with ongoing health and environmental risks and limited regulatory protections.

The 2020–2021 pesticide use data for South Central Oʻahu demonstrate sustained exposure to highly hazardous pesticides near schools and communities. Without stronger safeguards that address cumulative exposure and real-world conditions, families will continue to bear unnecessary and preventable health risks.

If you want the full South Central Oʻahu Report, email safefarmssafefood@gmail.com