Final answer:
Negative effects on a developing human may arise from pesticides, known as teratogens, which can lead to birth defects. Extreme temperatures can also impact fetal development.
Step-by-step explanation:
The factors that may have a negative effect on a developing human include pesticides, which are chemical agents. The presence of substances, such as certain pesticides like methyl iodide and environmental toxicants like bisphenol A, can act as teratogens. Teratogens can cause damage to a developing embryo or fetus, leading to birth defects. These agents can interfere with normal development by altering the environmental signals a fetus receives. Temperature can also be a factor if it's extreme enough to affect the mother's or the developing fetus's homeostasis, potentially leading to adverse outcomes.